All,
This has been getting a little too long so I'm splitting it up in a couple of posts. To start an apology as I am probably going to cause more questions than I provide answers and this week doesn't look promising for having time to get into it deeper.
It is however too late to put the genie back in the bottle so here we go.
DW, I mostly agree with your post, minor points of contention are in the fact that the footprint is a definitive state of the foot.
It does reflect the structure of the foot in a given position and in a static position. This is not exactly the way the foot is going to be in the shoe. That even before structural corrections are applied if appropriate and/or necessary.
I believe the most important element that is often overlooked when building up the last medially is that you can not get away with only adding to the width in the forefoot and MPJ1 but also through the midfoot.
When you take a last and lay a ruler along the medial side from the heel to the ball you'll find that if you look at it from the top there is a fairly straight line. This straight line is not located on a single level when looking at the last from the side, in fact on the insole level the line pulls sharply to the mid-line.
When building up the forefoot and 1st metatarsal joint you have to maintain a similar straight line to the heel.
Don't get me wrong, I'm not suggesting to adjust the last as in image “B” in Rick's original question, moderate and keep the balance between medial and lateral.
Not doing so and only building up laterally will throw off the balance between the medial and lateral side.
At first glance the medial and lateral side are about as different as they can get. Once you start making last copies and patterns you will find the the surfaces have a lot in common. This is something that is extremely difficult to describe. Maybe a last pro like Bill can put it in words better than I can but having worked with many lasts and actually made lasts from scratch I know that the balance between the medial and lateral side needs to be honored.
I'm not exactly sure that I understand this correctly: So, in my minds eye, any build-up on the medial side to accommodate Rick's "B" schemata will only result in an insole overhang at the medial joint...at least until the shoe (and counter) has broken down sufficiently to allow the foot to shift medially.
I think I addressed that by indicating that you need to build up the last all the way back to the heel seat but let me know if I misunderstood this.
One "Last" Question
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relferink
Re: One "Last" Question
Suzanne, I agree with Brendan and think that proration plays an important role in the foot you describe. You bring up a great point the the boot will look goofy, it's going to be curved like a banana! The only way to offset this is by building up medially all the way to the heel seat.
Bill, Nice tool to have and be able to overlay the foot print to the last
Is there a way to add transparency to the foot and last? This to see by how much the top surface is removed from the underlaying surface?
I fully agree that a foot where the toes are placed more medial from the center line that is more inflared will do better in a last that has a more inflared front but that's mostly from the ball forward. By pivoting at the point you do I don't think your taper runs back far enough to the heel. Not that it won't work, just not as well as it could in my not so humble opinion.
Bill, Nice tool to have and be able to overlay the foot print to the last
Is there a way to add transparency to the foot and last? This to see by how much the top surface is removed from the underlaying surface?
I fully agree that a foot where the toes are placed more medial from the center line that is more inflared will do better in a last that has a more inflared front but that's mostly from the ball forward. By pivoting at the point you do I don't think your taper runs back far enough to the heel. Not that it won't work, just not as well as it could in my not so humble opinion.
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relferink
Re: One "Last" Question
Rick,
Last but not least. I have a little problem with the outline you use, the blue overlay in the original posting. Looking at the Harris mat, specifically the medial heel the blue outline is right up against the tracing, laterally it has a seemingly normal amount of space. It could be that the foot is like this but I see no evidence in any other part of the imprint that would suggest that this is accurate.
The placement of the ball line seems too far forward to me on the lateral side. The imprint below the line seems to be the 5th MPJ. The way the arch is not taken out is not such a big deal except when you get to the medial heel base, the direction into the last you use is important, with the line cut the way you did it does make it harder to see.
So here is what I came up with. It's a very rough draft as I enlarged and printed the image you posted on 8½ by 11 paper. Realizing that this was probably not the size the foot was I still applied all the usual elongation and such so they are out of proportion. Your last also seems to have extra elongation and is more square but since these are mostly cosmetic changes you can just imagine those or add them yourself. After I was done I re-scanned, re-sized smaller and posted. It's actually quite amazing it is still almost legible
Here is what I did. I set out a center line. This is not the LOMA!, it travels from the center of the heel through the center of the 2nd toe. The medial heel I corrected as I thought it would be. Could be that the outline was drawn under the foot, in that case move it out.
The ball line I moved to what I believe MTJ 5 is located, looking at it scanned back in it could probably have come down slightly more but you'll get the idea.
I centered the heel and drew a line from the centerline of the heel to a point at 60% of the length of the ball line. Next I connected the medial heel width point to the medial ball and the same lateral. This will set up my rearfoot.
For the forefoot you see two insoles lines, one black and one red. The black on is based on a straight forefoot, the red one a slightly flared. I think for this foot the red outline is the way to go. The normal setup for the forefoot is add your 15mm elongation and place a 90 degree line from the center line. The medial forefoot line is placed at 96 degrees from the ball line. The lateral forefoot line is placed at 71 degrees. These are help lines to draw in your toe model. As said before I choose a regular rounded model but make it longer and more square to get to your model.
The model based on these proportions clips the big toe a little more than I like to see so I moved it over by about 7mm at the toe.
The red line is the bottom pattern I would take and apply to the last. I realize it's not to scale but apply this setup to your Harris mat and than lay the bottom paper to the last and you'll see where you want to end up. It's much more accurate than cutting out the an imprint and try to match that.
As said before, this week isn't going to give me much time to get into it deeper. I know this has probably raised more questions than it answered. Sorry for that .
One last thing; we must not forget that there is truthfully not enough information to draw conclusions on. Without seeing the foot, seeing how the Harris mat and tracings are made and learning about limitations in the foot and attached leg we are giving educated guesses. A slight difference in how to take the Harris mat imprint could cause major differences in interpretation. I interpret this as if I had made the print and I clearly didn't so take it as an educated guess. Take any recommendations as an area to focus on, not something to implement blindly.
Rob
Last but not least. I have a little problem with the outline you use, the blue overlay in the original posting. Looking at the Harris mat, specifically the medial heel the blue outline is right up against the tracing, laterally it has a seemingly normal amount of space. It could be that the foot is like this but I see no evidence in any other part of the imprint that would suggest that this is accurate.
The placement of the ball line seems too far forward to me on the lateral side. The imprint below the line seems to be the 5th MPJ. The way the arch is not taken out is not such a big deal except when you get to the medial heel base, the direction into the last you use is important, with the line cut the way you did it does make it harder to see.
So here is what I came up with. It's a very rough draft as I enlarged and printed the image you posted on 8½ by 11 paper. Realizing that this was probably not the size the foot was I still applied all the usual elongation and such so they are out of proportion. Your last also seems to have extra elongation and is more square but since these are mostly cosmetic changes you can just imagine those or add them yourself. After I was done I re-scanned, re-sized smaller and posted. It's actually quite amazing it is still almost legible
Here is what I did. I set out a center line. This is not the LOMA!, it travels from the center of the heel through the center of the 2nd toe. The medial heel I corrected as I thought it would be. Could be that the outline was drawn under the foot, in that case move it out.
The ball line I moved to what I believe MTJ 5 is located, looking at it scanned back in it could probably have come down slightly more but you'll get the idea.
I centered the heel and drew a line from the centerline of the heel to a point at 60% of the length of the ball line. Next I connected the medial heel width point to the medial ball and the same lateral. This will set up my rearfoot.
For the forefoot you see two insoles lines, one black and one red. The black on is based on a straight forefoot, the red one a slightly flared. I think for this foot the red outline is the way to go. The normal setup for the forefoot is add your 15mm elongation and place a 90 degree line from the center line. The medial forefoot line is placed at 96 degrees from the ball line. The lateral forefoot line is placed at 71 degrees. These are help lines to draw in your toe model. As said before I choose a regular rounded model but make it longer and more square to get to your model.
The model based on these proportions clips the big toe a little more than I like to see so I moved it over by about 7mm at the toe.
The red line is the bottom pattern I would take and apply to the last. I realize it's not to scale but apply this setup to your Harris mat and than lay the bottom paper to the last and you'll see where you want to end up. It's much more accurate than cutting out the an imprint and try to match that.
As said before, this week isn't going to give me much time to get into it deeper. I know this has probably raised more questions than it answered. Sorry for that .
One last thing; we must not forget that there is truthfully not enough information to draw conclusions on. Without seeing the foot, seeing how the Harris mat and tracings are made and learning about limitations in the foot and attached leg we are giving educated guesses. A slight difference in how to take the Harris mat imprint could cause major differences in interpretation. I interpret this as if I had made the print and I clearly didn't so take it as an educated guess. Take any recommendations as an area to focus on, not something to implement blindly.
Rob
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relferink
Re: One "Last" Question
Rick
One more thing I forgot to add as I was rushing with dinner on the table. The base of the 5th seems prominent. You may have to give it a little more room. This is however not at the feather line but a little above and possible a small depression on the insole. An adjustment at the feather line is only needed in extreme cases. So the line of the insole need to run slightly on the inside of the line that runs from the heel width point laterally to the lateral ball. (it's not all that clear from the image posted)
Rob
One more thing I forgot to add as I was rushing with dinner on the table. The base of the 5th seems prominent. You may have to give it a little more room. This is however not at the feather line but a little above and possible a small depression on the insole. An adjustment at the feather line is only needed in extreme cases. So the line of the insole need to run slightly on the inside of the line that runs from the heel width point laterally to the lateral ball. (it's not all that clear from the image posted)
Rob
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toeflower
Re: One "Last" Question
What do you use to trace around foot on Harris mat? When I try to do this the rubber to snags so easily.
Thanks for the suggestions Brendan and Robert. Adding all along medial side is a consideration but Id have to grind somewhere to narrow things down again...except for in the forefoot. A while back I tried on a pair of JB Hill mules and as with most mules my heel overhung one side (cant remember which) hmmm. Adding onto the heel sounds logical but for now Im finally happy with my lasts. Tired of being the guinea pig, I just hope I never meet anyone with feet like mine.
sw
Thanks for the suggestions Brendan and Robert. Adding all along medial side is a consideration but Id have to grind somewhere to narrow things down again...except for in the forefoot. A while back I tried on a pair of JB Hill mules and as with most mules my heel overhung one side (cant remember which) hmmm. Adding onto the heel sounds logical but for now Im finally happy with my lasts. Tired of being the guinea pig, I just hope I never meet anyone with feet like mine.
sw
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btippit
Re: One "Last" Question
DW,
As I said in my original post, I realize this method is not one that, at face value, can be used by boot/shoe makers without destroying the last. I just tossed it out to see if anyone would be inspired to think of a way to accomplish the same thing or nearly the same thing with physical remodeling of an existing last or even if anyone thought it was a viable approach. As noted, it seems to have been useful to me (when done more properly and not for illustrating a point).
The original pedograph (there was only one) and original last bottom are in the first and third of the three pictures. The pedograph is black and the original last bottom is red. The reason I aligned them this way, and admittedly it was a quick alignment is that it more or less aligned the heel width and general forward direction of the backpart of the last and foot.
Rick - I added about 70% transparency to both the last and foot but maybe if I change the colors and the background it could be clearer. I worry about how well the pix will show up when posted though. Pictures in the forthcoming book will be much higher resolution and maybe someday I'll have time to host a webinar discussion on topics like this or do it at an HCC meeting or like gathering. Normally I pivot right on the ball width line but for this demo I went a little crazy to try to better illustrate the point.
Rob - Can't say that I can explain it any better than that. I think one of the problems is that this balance between medial and lateral sides on a last should be respected...IF the last was balanced correctly to begin with. I think a problem many people have is that some lasts that they purchase (even some of my styles in standard sizes) are not balanced that well to begin with so you end up having to start from scratch or less (if there is something less than "scratch"
.
Suzanne - First of all, welcome back. We've missed you! You bring up a good point that is one reason why I prefer "swinging" to just adding a medial buildup. If anyone else mentioned it during this discussion I apologize for missing it. You said that if you built up on the medial side you would have to grind off to maintain the width. Exactly. Assuming the last is relatively close to what you want in width, both in the heel and in the forefoot, any buildup to accommodate a radical example like I showed would make the forefoot of the last excessively wide.
I guess my "last maker's" mentality is that if the straight arrow below represents the last (and sadly, it does represent a LOT of lasts) and the broken arrow represents the foot, then it doesn't matter where you line them up...they will never line up properly. Widening the front of the straight arrow to make it meet the widest medial side of the broken arrow just seems to me to create extra volume for the foot to float around in unless that same amount is removed from the lateral side.
OK, that's a really crude illustration but I just realized what time it is. This, like most of our discussions has been very enlightening and again reinforces that what works for one might not work for another but if it works for you and your customer....that's all that matters. Goodnight everyone.
Bill “The Last Man Standing” Tippit
www.globalfootwearsolutions.com
As I said in my original post, I realize this method is not one that, at face value, can be used by boot/shoe makers without destroying the last. I just tossed it out to see if anyone would be inspired to think of a way to accomplish the same thing or nearly the same thing with physical remodeling of an existing last or even if anyone thought it was a viable approach. As noted, it seems to have been useful to me (when done more properly and not for illustrating a point).
The original pedograph (there was only one) and original last bottom are in the first and third of the three pictures. The pedograph is black and the original last bottom is red. The reason I aligned them this way, and admittedly it was a quick alignment is that it more or less aligned the heel width and general forward direction of the backpart of the last and foot.
Rick - I added about 70% transparency to both the last and foot but maybe if I change the colors and the background it could be clearer. I worry about how well the pix will show up when posted though. Pictures in the forthcoming book will be much higher resolution and maybe someday I'll have time to host a webinar discussion on topics like this or do it at an HCC meeting or like gathering. Normally I pivot right on the ball width line but for this demo I went a little crazy to try to better illustrate the point.
Rob - Can't say that I can explain it any better than that. I think one of the problems is that this balance between medial and lateral sides on a last should be respected...IF the last was balanced correctly to begin with. I think a problem many people have is that some lasts that they purchase (even some of my styles in standard sizes) are not balanced that well to begin with so you end up having to start from scratch or less (if there is something less than "scratch"
. Suzanne - First of all, welcome back. We've missed you! You bring up a good point that is one reason why I prefer "swinging" to just adding a medial buildup. If anyone else mentioned it during this discussion I apologize for missing it. You said that if you built up on the medial side you would have to grind off to maintain the width. Exactly. Assuming the last is relatively close to what you want in width, both in the heel and in the forefoot, any buildup to accommodate a radical example like I showed would make the forefoot of the last excessively wide.
I guess my "last maker's" mentality is that if the straight arrow below represents the last (and sadly, it does represent a LOT of lasts) and the broken arrow represents the foot, then it doesn't matter where you line them up...they will never line up properly. Widening the front of the straight arrow to make it meet the widest medial side of the broken arrow just seems to me to create extra volume for the foot to float around in unless that same amount is removed from the lateral side.
OK, that's a really crude illustration but I just realized what time it is. This, like most of our discussions has been very enlightening and again reinforces that what works for one might not work for another but if it works for you and your customer....that's all that matters. Goodnight everyone.
Bill “The Last Man Standing” Tippit
www.globalfootwearsolutions.com
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romango
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Re: One "Last" Question
Robert,
Thanks for the analysis. In summary, you seem to advocate adjusting the last more at "b" in my original post. I understand this is based on some speculation as to some possible irregularities in the Harris print and some other intangibles. I worried about this too.
You have to watch that the customer doesn't roll their foot out while standing on the mat or you will get this lateral spread look. I did double check his feet to make sure this was not the case.
In any case, I've already made the last adjustment for the lateral spread. I'll make a fitter and see how to works out, keeping your comments in mind.
Thanks for the analysis. In summary, you seem to advocate adjusting the last more at "b" in my original post. I understand this is based on some speculation as to some possible irregularities in the Harris print and some other intangibles. I worried about this too.
You have to watch that the customer doesn't roll their foot out while standing on the mat or you will get this lateral spread look. I did double check his feet to make sure this was not the case.
In any case, I've already made the last adjustment for the lateral spread. I'll make a fitter and see how to works out, keeping your comments in mind.
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erickgeer
Re: One "Last" Question
Anyone, but mostly for Bill,
Does anyone know the appropriate type of tack for reinforcing the sharp corners of a turning model?
I guess they need to have a pretty strong cube shaped head for filing down.
Erick
Does anyone know the appropriate type of tack for reinforcing the sharp corners of a turning model?
I guess they need to have a pretty strong cube shaped head for filing down.
Erick
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jesselee
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- Location: Town of Niagara, NY, USA
Re: One "Last" Question
DA,
Try covering the last with Saran Wrap or other similar stretch plastic wrap. This is what I do and tape it with transparent Scotch tape. I then submerge the last in plaster, bottom up with a plastic covered piece of cardboard like Bristol board to effect the sole contour. Around the profile goes a piece of plastic wrapped Bristol board that basically separates the last in two parts. This makes a 3 part mold.When suitably dry the sole edge area can be trimmed, then apply Vaseline and pour the plaster over the sole area. When the last is removed you get a very accurate cavity to pour your compound in.
Hope this helps.
JesseLee
Try covering the last with Saran Wrap or other similar stretch plastic wrap. This is what I do and tape it with transparent Scotch tape. I then submerge the last in plaster, bottom up with a plastic covered piece of cardboard like Bristol board to effect the sole contour. Around the profile goes a piece of plastic wrapped Bristol board that basically separates the last in two parts. This makes a 3 part mold.When suitably dry the sole edge area can be trimmed, then apply Vaseline and pour the plaster over the sole area. When the last is removed you get a very accurate cavity to pour your compound in.
Hope this helps.
JesseLee
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btippit
Re: One "Last" Question
Erick,
There is actually a very special "last model tack" that is used. It has a rounded head with a strip down the middle of the head. The shaft is extremely narrow at the end, to the point of being like a needle, before it expands towards the head. As it's driven into the bevel you file on the featheredge, the tack actually rotates "supposedly" lining up those stripes after the tacks are all in. Easier said than done.
The only supplier I ever knew of for them was D. B Gurney in Whitman, MA. There number was 781-447-4411. I assume they're still in business but with the advent of hard plastic models and now digital last technology and with JV being the only last factory left in the USA, I'm not sure if they still carry model tacks but it wouldn't surprise me if they did. They've been a very loyal and thorough supplier to the industry for....about forever.
If they don't have them maybe Allen Smith at JV would spare you a few. They come in 5 pound boxes. No idea what the price is.
Bill “The Last Man Standing” Tippit
www.globalfootwearsolutions.com
There is actually a very special "last model tack" that is used. It has a rounded head with a strip down the middle of the head. The shaft is extremely narrow at the end, to the point of being like a needle, before it expands towards the head. As it's driven into the bevel you file on the featheredge, the tack actually rotates "supposedly" lining up those stripes after the tacks are all in. Easier said than done.
The only supplier I ever knew of for them was D. B Gurney in Whitman, MA. There number was 781-447-4411. I assume they're still in business but with the advent of hard plastic models and now digital last technology and with JV being the only last factory left in the USA, I'm not sure if they still carry model tacks but it wouldn't surprise me if they did. They've been a very loyal and thorough supplier to the industry for....about forever.
If they don't have them maybe Allen Smith at JV would spare you a few. They come in 5 pound boxes. No idea what the price is.
Bill “The Last Man Standing” Tippit
www.globalfootwearsolutions.com
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erickgeer
Re: One "Last" Question
Thanks Bill, I called up Gurney this morning- the person who answered the phone thought that they did have the last model tacks, but that I needed to speak to someone else next week to confirm it.
Erick
Erick
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romango
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Re: One "Last" Question
Nothing earth shattering here but I wanted to pass along my experience making a last copy. This is a straight forward 2 part plaster paris mold.
I then filled it with Smooth-On 300Q, 2 part liquid plastic. This sets up in 1 minute, which make you rush a little more than I'd like.
I then put in a screw hole from the top and sawed it in half with a bit of an offset at the center of the cut, added a bit of cardboard to take up the blade width, put in a screw and I'm done!
The 300Q is very bright white so it looks like plaster, but it is hard plastic. Not quite as nice as the original polyethylene (?) factory last because it's harder to nail (but still works fine).
The plastic costs ~$30 per pair. Plaster paris is very cheap. Making the plaster mold is messy but I can see that, once you get the proper buckets and tables and tarps set up, it may be done with not too much work and a lot of waiting (for plaster to dry fully).
I'm still looking for an expanding foaming plastic, I've seen used in Holland, that will be easier to nail and require less because it expands (making it cheaper). Smooth-on has several but none are dense enough as far as I can see.
There's a plastic supplier in Portland that I have a lead on. Hopefully they will have what I am looking for.
I then filled it with Smooth-On 300Q, 2 part liquid plastic. This sets up in 1 minute, which make you rush a little more than I'd like.
I then put in a screw hole from the top and sawed it in half with a bit of an offset at the center of the cut, added a bit of cardboard to take up the blade width, put in a screw and I'm done!
The 300Q is very bright white so it looks like plaster, but it is hard plastic. Not quite as nice as the original polyethylene (?) factory last because it's harder to nail (but still works fine).
The plastic costs ~$30 per pair. Plaster paris is very cheap. Making the plaster mold is messy but I can see that, once you get the proper buckets and tables and tarps set up, it may be done with not too much work and a lot of waiting (for plaster to dry fully).
I'm still looking for an expanding foaming plastic, I've seen used in Holland, that will be easier to nail and require less because it expands (making it cheaper). Smooth-on has several but none are dense enough as far as I can see.
There's a plastic supplier in Portland that I have a lead on. Hopefully they will have what I am looking for.
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Re: One "Last" Question
Rick,
In a previous life I cast some large architectural
three dimensional castings with 2 part polyurethane..
Getting the mold filled before the polyurethane started to cure was a problem. I had a few mishaps that looked like a solid waterfall of plastic from the bucket to the partially filled mold.
Solved the problem by putting the unmixed part A and B into the freezer to chill a bit before combining.
Since these plastics generate heat when they cure, it bought enough time to get the mold filled before the chemical reaction set off.
Don't know if it works with your plastic, but it sure helped me.
Just another 2 cents....
Georgene
In a previous life I cast some large architectural
three dimensional castings with 2 part polyurethane..
Getting the mold filled before the polyurethane started to cure was a problem. I had a few mishaps that looked like a solid waterfall of plastic from the bucket to the partially filled mold.
Solved the problem by putting the unmixed part A and B into the freezer to chill a bit before combining.
Since these plastics generate heat when they cure, it bought enough time to get the mold filled before the chemical reaction set off.
Don't know if it works with your plastic, but it sure helped me.
Just another 2 cents....
Georgene
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large_shoemaker_at_large
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Re: One "Last" Question
Hi Rick
I pass a couple ideas past you. I use plaster bandages to make the mold. I use Glad cling wrap (wonderfull stuff) over the last. Wrap with Plaster bandage so ther is about 3 layers all over and wait till it is just set up and cut the plaster down the midline of the last. Then let it set fully. depending on humidity and temp. 2-3 hours. take off the last and over nite it is dry enough to work with. I coat the inside with paste wax you would use for your car. Heat it with a heat gun to smooth the wax. Then reassemble with a plaster bandage. Then I pour in auto body filler or spoon it in. In about and hour depending on how much hardner you put in it is set. cut plaster off and wipe the last down and you almost done. I have used 2 part foam but getting it is a pain and costly. The Otto bock 400 is the densest I have seen I believe it is about 40 pound per cubic foot. Vs foam in a boat is about 2 pounds per cubic foot. You can hammer nail screw the 400 and it is like oak. If you use the 2 part the mold has to be strong enough to resist the expansion factor.
Georgene Good solution to a problem! I would like to talk more about the architectural molds a local mason wants some gargoyls made. I made some plaster Gopher heads for a special effects fellow to blow up for a commercial. To much fun!
A mention of safety here!! anything that internally makes heat is a potential fire hazard. From Tung oil to polyester resin and 2 part foam. any time I mix or use a cloth with tung oil or Boiled lineseed oil it goes outside to cool down. back in the old prosthetic days I saw cups go up in smoke as to much hardner was used or the person got distracted and didn't get it thinned out fast enough to dissipate the heat.
Our local museum was using 2 part foam and polyester resin to make a prehistoric scene and the whole thing burnt in a terrible fire. As i watched the pics on the local news I saw immediatly the cause of the fire. All the waste and scraps were put in a 45 gallon drum, were they finished curing and ignited. If they would have taken the drum outside they would have prevented the fire.
Last word if you have a fire with anything plastic don't be a hero Get the hell out and call 911. I caught a lung full of smoke from a smoking piece of acrylic and It damn near killed me!!
Work smart, read the MSDS sheet and believe it.
Regards
Brendan
I pass a couple ideas past you. I use plaster bandages to make the mold. I use Glad cling wrap (wonderfull stuff) over the last. Wrap with Plaster bandage so ther is about 3 layers all over and wait till it is just set up and cut the plaster down the midline of the last. Then let it set fully. depending on humidity and temp. 2-3 hours. take off the last and over nite it is dry enough to work with. I coat the inside with paste wax you would use for your car. Heat it with a heat gun to smooth the wax. Then reassemble with a plaster bandage. Then I pour in auto body filler or spoon it in. In about and hour depending on how much hardner you put in it is set. cut plaster off and wipe the last down and you almost done. I have used 2 part foam but getting it is a pain and costly. The Otto bock 400 is the densest I have seen I believe it is about 40 pound per cubic foot. Vs foam in a boat is about 2 pounds per cubic foot. You can hammer nail screw the 400 and it is like oak. If you use the 2 part the mold has to be strong enough to resist the expansion factor.
Georgene Good solution to a problem! I would like to talk more about the architectural molds a local mason wants some gargoyls made. I made some plaster Gopher heads for a special effects fellow to blow up for a commercial. To much fun!
A mention of safety here!! anything that internally makes heat is a potential fire hazard. From Tung oil to polyester resin and 2 part foam. any time I mix or use a cloth with tung oil or Boiled lineseed oil it goes outside to cool down. back in the old prosthetic days I saw cups go up in smoke as to much hardner was used or the person got distracted and didn't get it thinned out fast enough to dissipate the heat.
Our local museum was using 2 part foam and polyester resin to make a prehistoric scene and the whole thing burnt in a terrible fire. As i watched the pics on the local news I saw immediatly the cause of the fire. All the waste and scraps were put in a 45 gallon drum, were they finished curing and ignited. If they would have taken the drum outside they would have prevented the fire.
Last word if you have a fire with anything plastic don't be a hero Get the hell out and call 911. I caught a lung full of smoke from a smoking piece of acrylic and It damn near killed me!!
Work smart, read the MSDS sheet and believe it.
Regards
Brendan
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jenny_fleishman
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- Full Name: Jenny Fleishman
- Location: Chicago, IL, USA
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Re: One "Last" Question
Rick,
I am using Smooth-On products for my lasts and may have a solution for you with the "tack-a-bility" issue. I had the luxury of going to a Smooth-On distributor, and they kindly allowed me to try pounding some tacks into various samples of their products. I found the 300 much too hard to tack into. So I tried some of their "semi-rigid" products, figuring they'd have a little more give.
What I decided on was Smooth Cast 45D. I'm lasting a pair of shoes now on lasts I made with it, and I'm very happy with it. I added some Urefil 7 to the mixture. It's a powdered filler that is supposed to reduce shrinkage, but can also make the material more brittle, so I used a conservative amount--one part 45D A, one part 45D B, and one part Urefil 7. It is plenty rigid, but takes tacks well. I would say there might be, at most, one percent shrinkage. Working time is also reasonable.
I'm using Vytaflex 40 for my molds, which is much more expensive than using plaster, but has advantages. I'm still tweeking my moldmaking method, and I'm sure it's more laborius thay your 2-part plaster cast. That was the very first method I used, and because of the angle of the tread area, I found it impossible to find a midline for the mold that would avoid locking the last into the mold. I'm amazed you're able to do it! That was why I went to a three part mold, but that's all history, and obsolete now that I've discovered Smooth On products!
I will bring one of my 45D lasts to the HCC meeting.
Jenny
I am using Smooth-On products for my lasts and may have a solution for you with the "tack-a-bility" issue. I had the luxury of going to a Smooth-On distributor, and they kindly allowed me to try pounding some tacks into various samples of their products. I found the 300 much too hard to tack into. So I tried some of their "semi-rigid" products, figuring they'd have a little more give.
What I decided on was Smooth Cast 45D. I'm lasting a pair of shoes now on lasts I made with it, and I'm very happy with it. I added some Urefil 7 to the mixture. It's a powdered filler that is supposed to reduce shrinkage, but can also make the material more brittle, so I used a conservative amount--one part 45D A, one part 45D B, and one part Urefil 7. It is plenty rigid, but takes tacks well. I would say there might be, at most, one percent shrinkage. Working time is also reasonable.
I'm using Vytaflex 40 for my molds, which is much more expensive than using plaster, but has advantages. I'm still tweeking my moldmaking method, and I'm sure it's more laborius thay your 2-part plaster cast. That was the very first method I used, and because of the angle of the tread area, I found it impossible to find a midline for the mold that would avoid locking the last into the mold. I'm amazed you're able to do it! That was why I went to a three part mold, but that's all history, and obsolete now that I've discovered Smooth On products!
I will bring one of my 45D lasts to the HCC meeting.
Jenny
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large_shoemaker_at_large
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- Full Name: Brendan Balon
- Location: Fort Qu'Appelle, SK, Canada
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Re: One "Last" Question
Jenny
Un familar to me do you have a link to the distributor?
Sounds interesting
Regards
Brendan
Un familar to me do you have a link to the distributor?
Sounds interesting
Regards
Brendan
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fred_coencped
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- Full Name: Fred Coen;Foot Comfort Center
- Location: Santa Fe, New Mexico, USA
- Contact:
Re: One "Last" Question
Rick,BJB Enterprises in Tustin,Ca. tel#714/734-8450carries rigid expandable Urethane product #TC-A&B.The best resist I have found is Beeswax sloshed around in the mold,then excess wax is pored out.The urethane expands about 3 times with a high psi force and creates heat .The results are a light weight and very hard easily nailable long lasting last.
They are less costly then others for rigid poly urethane.I have made many,leaving the last in one piece and removing the last from the shoe with a last hook,standing on one end and pulling up on the heel of the shoe.Sometimes it is more difficult,but even with bunions and forefoot dorsal bumps and accomodations for hammertoes I have always been sucessful in withdrawl of the last.Of course the last needs to be very smooth and the press glue on the surface makes it easier.
Johnsons paste wax works pretty good and silcone gell is pretty good too for the resist inside the mold.
Brendans way of holding the 2 part mold together with layers of plaster splints is also sucessful for me and fabricating the negative molds in 2 parts with plaster splints is how I prepare the 2 piece negatives,destroying the negative molds in the removal process.I like the molds you made and it sure looks doable to make multiple pairs.
OK,Bravo and good luck,your work is really just getting better and better,Fred
They are less costly then others for rigid poly urethane.I have made many,leaving the last in one piece and removing the last from the shoe with a last hook,standing on one end and pulling up on the heel of the shoe.Sometimes it is more difficult,but even with bunions and forefoot dorsal bumps and accomodations for hammertoes I have always been sucessful in withdrawl of the last.Of course the last needs to be very smooth and the press glue on the surface makes it easier.
Johnsons paste wax works pretty good and silcone gell is pretty good too for the resist inside the mold.
Brendans way of holding the 2 part mold together with layers of plaster splints is also sucessful for me and fabricating the negative molds in 2 parts with plaster splints is how I prepare the 2 piece negatives,destroying the negative molds in the removal process.I like the molds you made and it sure looks doable to make multiple pairs.
OK,Bravo and good luck,your work is really just getting better and better,Fred
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jenny_fleishman
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- Full Name: Jenny Fleishman
- Location: Chicago, IL, USA
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Re: One "Last" Question
Brendan,
Here is a link to the manufacturer:
http://www.smooth-on.com/
They have a link to "Find a distributor."
This is the link to the distributor I use:
http://www.reynoldsam.com/
Smooth-On offers a 2-day seminar for $450, which I did not take.
Reynolds Advanced Materials offers a 1-day workshop in various locations for about $60. I took this when they had one near Chicago, and it was well worth it. But now that I've determined which of their products seems to work the best, you probably can get by fine without it if you read the technical bulletin and/or talk to the help line.
Couple of tips: To get the lids of the gallon tubs, you need to take a box cutter (or other kind of knife) and cut the little tabs that are spaced along the bottom of the lid. Also, you have to REALLY scrape the bottom of the Part B tub hard to get all the stuff settled on the bottom mixed in.
The materials are not cheap. For most products they have a trial size available, though. The "gallon" size is really about two gallons--a gallon each of Part A and Part B.
Jenny
Here is a link to the manufacturer:
http://www.smooth-on.com/
They have a link to "Find a distributor."
This is the link to the distributor I use:
http://www.reynoldsam.com/
Smooth-On offers a 2-day seminar for $450, which I did not take.
Reynolds Advanced Materials offers a 1-day workshop in various locations for about $60. I took this when they had one near Chicago, and it was well worth it. But now that I've determined which of their products seems to work the best, you probably can get by fine without it if you read the technical bulletin and/or talk to the help line.
Couple of tips: To get the lids of the gallon tubs, you need to take a box cutter (or other kind of knife) and cut the little tabs that are spaced along the bottom of the lid. Also, you have to REALLY scrape the bottom of the Part B tub hard to get all the stuff settled on the bottom mixed in.
The materials are not cheap. For most products they have a trial size available, though. The "gallon" size is really about two gallons--a gallon each of Part A and Part B.
Jenny
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thomd
Re: One "Last" Question
I have a last question:
There is one type of shoe that does not use a traditional last length: Rock climbing shoes. They are fitted to the dead end of the toes, and sometimes climbers do experience problems; loosing toenails etc... walking down from long routes. Some climbers will carry shoes on the climb for the decents, if their weight budget allows. Possibly point shoes are another example of shoes without extra last allowance at the toe.
I have climbing shoes left over from earlier years, but my current foot won't fit in them, so I can't really estimate the length they were, and often climbing shoes don't fit properly anyway since they are almost always too narrow - therefore they probably do have a little extra toe length whether they should for climbing purposes or not.
Climbers can get away with short toe allowance, because they are disposed to ignore minor pain; walk on the edges of their feet with legs bowed a little if they don't have a good fit; when climbing the toe does not generally creep forward.
So the question is, what amount of toe allowance is the bare minimum for a custom fitted shoe, that will only be stood in, but not walked in without some discomfort or crunching of the toes? The shoe will probably not be particularly comfortable even for standing, very snug.
There is one type of shoe that does not use a traditional last length: Rock climbing shoes. They are fitted to the dead end of the toes, and sometimes climbers do experience problems; loosing toenails etc... walking down from long routes. Some climbers will carry shoes on the climb for the decents, if their weight budget allows. Possibly point shoes are another example of shoes without extra last allowance at the toe.
I have climbing shoes left over from earlier years, but my current foot won't fit in them, so I can't really estimate the length they were, and often climbing shoes don't fit properly anyway since they are almost always too narrow - therefore they probably do have a little extra toe length whether they should for climbing purposes or not.
Climbers can get away with short toe allowance, because they are disposed to ignore minor pain; walk on the edges of their feet with legs bowed a little if they don't have a good fit; when climbing the toe does not generally creep forward.
So the question is, what amount of toe allowance is the bare minimum for a custom fitted shoe, that will only be stood in, but not walked in without some discomfort or crunching of the toes? The shoe will probably not be particularly comfortable even for standing, very snug.
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large_shoemaker_at_large
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- Full Name: Brendan Balon
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Re: One "Last" Question
ThomD
I made some "Tabis" shoe/slippers fro a dance troop here last spring. 0 toe allowance. The material was soft and made a little snug so they would stretch to fit.
These were unlasted shoes.
To get a pattern I wrapped packing tape around the foot. Drew the top centre line and sole line, then carefully cut the tape off at the line. Add a bit of seam allowance and sew away.
I can expand if you would like
I made some "Tabis" shoe/slippers fro a dance troop here last spring. 0 toe allowance. The material was soft and made a little snug so they would stretch to fit.
These were unlasted shoes.
To get a pattern I wrapped packing tape around the foot. Drew the top centre line and sole line, then carefully cut the tape off at the line. Add a bit of seam allowance and sew away.
I can expand if you would like
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thomd
Re: One "Last" Question
Thanks Brendan, these shoes will be pretty sturdy, and built on a last that will need to be modified from normal specs. To some extent I can probably wing it, because I have reached the stage where these shoes will be used by me only lightly even full toe allowance would not hamper the level of rock climbing I can still contemplate.
I just wondered how close one could get before agony sets in. It seems as though a zero clearance shoe might be a problem, and full toe allowance might be excessive. I thought I might ask because some folks do make custom rock shoes, and there might be other similar really tight fitting shoes, maybe figure skates, that would allow one to trim the toe allowance a bit.
I just wondered how close one could get before agony sets in. It seems as though a zero clearance shoe might be a problem, and full toe allowance might be excessive. I thought I might ask because some folks do make custom rock shoes, and there might be other similar really tight fitting shoes, maybe figure skates, that would allow one to trim the toe allowance a bit.
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rbs
Re: One "Last" Question
looking for some used cowboy lasts in northwest also half inch heel hieght lasts for work style
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thomd
Re: One "Last" Question
As the small guy who only wants a few lasts, I took advice and tried to buy them. Seems like this is fraught with problems from weather, postage, getting people to respond, breaking up sets. Frankly it all sounds pretty reasonable to me. Sending wooden blocks hither and yon across international borders is not the kind of thing the new economy excells at. So I think it may be back to the drawing board, literally, and then to the bandsaw.
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large_shoemaker_at_large
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- Full Name: Brendan Balon
- Location: Fort Qu'Appelle, SK, Canada
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Re: One "Last" Question
ThomD
What size lasts are you looking for? and style? Got lots and as soon as I get to Saskatoon will have more.
I can send you a plaster cast of anything I have and you can fill it with Bondo works just fine or High density PU foam is also great.
I have some odds and sods I may part with for some metal work??!!
Did you get a chance to look at those hook knives I Emailed you about?
Regards
Brendan
What size lasts are you looking for? and style? Got lots and as soon as I get to Saskatoon will have more.
I can send you a plaster cast of anything I have and you can fill it with Bondo works just fine or High density PU foam is also great.
I have some odds and sods I may part with for some metal work??!!
Did you get a chance to look at those hook knives I Emailed you about?
Regards
Brendan