The Crispin Colloquy

G'day Jenny,
Replies take a while from me as I am only able to get on the internet Mondays and Tuesdays at the library. This is Monday as Australia is a day ahead of the U.S.
I'll see if I can get access to a scanner and work out how to post some pics.The knife works very well (it's a pusher).

DW, just reading about dropping the blade onto your thumbnail. If it's real sharp you shouldn't even have to drop it. Just place it on the angled nail under it's own weight and it shouldn't slip
Cheers
Duncan

Duncan,

True...but where's the fun in that?! There's no possiblity, no matter how sharp the knife, that you'll cut the end of your thumb off.

Actually now that I think about it I probably don't drop the blade more than an eighth of an inch but drop it I do...that's the way I was taught. I know that you're right about it, however. If the knife is sharp, it most certainly doesn't need to be dropped.

Too bad you can't get on more often. It reminds me of the supposed lag time for messages sent to astronauts on the moon. Send your message...20 minutes later they get the message. They respond and 20 minutes after that you get their message. Only the lagtime is a lot longer...are you sure you're not posting from Pluto?

Tight Stitches
DWFII--Member HCC

DW, I'd hate to see your fingernails!

re cheap grinders...They all seem to be 3450 RPMs. Isn't this too fast? Is it possible to use a lighting dimmer switch to slow the speed down, or is there some other kind of control that can be added to reduce the speed?

Jenny

Jenny,

What fingernails?

re grinders...not for the RazorSharp system or even a buffing wheel. Heck, I don't think slow speed grinders actually came on the market more than ten years ago.

But if you're looking for a slow speed grinder check out WoodCraft. I got mine for half the price of the Baldor. That said all I run on it are high grade white (ceramic?)grindestones. And all I use it for is rough shaping knives or sharpening M2 lathe chisels.

I might point out that if you are getting into shoemaking seriously....a finisher will do everything that a grindstone will and sometimes cooler.

Tight Stitches
DWFII--Member HCC

RPM advice needed, also grinder vs. buffer...I have found a couple bench grinders with variable speed of 2000-3450 RPM. Is 2000 slow enough? (The Koleff lastmaking book recomments a maximum of 1500 RPMs for a grinding/buffing.) If not, can the speed be slowed down with a dimmer type switch?

Here is a link to a buffer (3450 RPMs):
http://www.sears.com/sr/javasr/product.do?BV_UseBVCookie=Yes&vertical=TOOL&pid=0 0922625000

and to one of the grinders (2000 - 3450 RPMs) I'm looking at:
http://www.sears.com/sr/javasr/product.do?BV_UseBVCookie=Yes&vertical=TOOL&pid=0 0921154000&tab=des#tab

I'm not sure if either of these are 115 volt, or what size arbors they have.

Is there an inherent difference between a buffer and a grinder that would make one better than the other, other than grinders having guards and tool rests? Do the tool rests come in handy or just get in the way? I expect I'd have to take the guards off if I'm putting on wider wheels.

Jenny

DW, the Woodcraft low speed grinder is actually on sale. One problem for me, though. It weighs 40 lbs. (and I weigh about 115). I don't have a place to leave it set up, so every time I need to use it I'd have to lug it out of the closet!

Some of the grinders that are at Sears and Home Depot might weigh less. What I mainly expect to be using it for is sanding Cloud or Soleflex for making wedge shoe soles, and possibly for roughing up soling materials and veg tan midsole leather before cementing, using various sandpapers, including very coarse. Do you think I could get by with 2,000 RPM, or would I be likely to set something on fire?!

Jenny

Jenny,

You'd probably be alright with a 2,000 rpm grinder...get the eight incher. I'm not sure how you would mount sandpaper on it, though...I use a finisher so don't listen to me--there may be a way.

But one thing you should know...if you are storing stuff in a closet in your home--sanding leather, or god-forbid...cloud crepe, is almost as messy and dust creating as woodturning. You may not think it's so bad the first couple times but when you start finding this micro-film of grey dust in your kitchen and/or on your pillow you may think twice. I'll tell anyone...right up front...that this is as dirty a business and as detrimental to your health (if fumes and airbourne dust are not properly dealt with) as anything except coal mining and foundry work. Think twice before you try to do any of this in your den or sewing room.

Tight Stitches
DWFII--Member HCC

DW,
Nah, the problem is that I'm living in your tomorrow. The time lag is just the waiting for you guys to catch up
Do you remember the TV series "Max Headroom"?It was set in a Cyber Punk, high tech world, 20 minutes in the future. Just imagine the difference being a whole day ahead makes

That's why we were able to come up with the 'Black Box' flight recorder, the Australia II 'Winged Keel', the Victor rotary lawn mower, and well fitting, well shaped, 'Lastless' Shoemaking

Yours, in total modesty, humility, and with a big grin on my face.
See you next week,
Cheers
Duncan

P.S. the Plutonians say "Hi"

P.P.S. Thinking about your opening comment re. the edge and the thumbnail; don't take up skiving with a machetti


(Message edited by DMcharg on April 03, 2006)

Sharpening stones...does this look like a good deal?

http://www.knifeart.com/8inchtristone.html

The finest grit is 700, and Duncan posted above that he uses 2000 grit paper, so I'm wondering if 700 is fine enough?

The price is about half what Tandy charges for a similar product, although there are not enough details to completely compare the stones.

By the way, Tandy has a light box on sale for copying patterns this month:

http://www.tandyleather.com/prodinfo.asp?number=350100&variation=&aitem=1&mitem= 1

DW, I'm familiar with that fine layer of dust you speak of...after hand sanding several versions of my homemade lasts. Cloud dust is probably even nastier. Perhaps I can do machine grinding in the bathtub with the shower curtain closed!...I guess we pick our own poisons....

Jenny

Jenny,

I'd say that the surgical set was the better deal. You can find all kinds of carborundum or other coarse stones for rough shaping but once you get the initial shape and edge a good soft arkansas and a good black arkansas are probably all you need, especially if you intend to buff the edge with tripoli or jeweler's rouge. The tripoli/rouge is doing the same thing as the 2000 grit paper in Duncan's description--polishing and removing the "wire."

Tripoli...and rouge--red, green, brown...are abrasives. I don't know what they're equivalent to in sandpaper but it doesn't matter. Sandpaper designations are nearly meaningless without some reference to the matrix, the country it's being produced in, what its intended use is, and all sorts of other intangibles. But rouge on a leather belt is probably close to, if not even finer than, 2000. So, just stropping with tripoli is gonna produce that polished edge.

Tight Stitches
DWFII--Member HCC

DW, which is the surgical set? Also, for making a strop, is veg tan glued on a board grain side up the best way to do it?

Received my Dutch Tina knife yesterday. It's flat, and it needs sharpening!


Jenny

Here's the link to the surgical set:

http://tinyurl.com/lar8a

re: strop...that'll work. I've got both--leather glued to a piece of wood and a number of strops that are just leather belts anchored at one end to the bench.

Tight Stitches
DWFII--Member HCC

Thanks, DW...

Does anyone use the following tool types, and if so, what do you think of them?

Head knife for cutting and skiving:
https://www.siegelofca.com/itemdetail.asp?prodid=234

Skiving knives:
https://www.siegelofca.com/itemdetail.asp?prodid=256

Scroll down to the Osborne 469:
http://www.mainethread.com/cutting_tools.html

For cutting leather, I have been using shears. I'm reading the Al Stohlman book, Leatherworking Tools, and he seems really big on using a head knife for cutting, and also for skiving. Opinions?

Does using a knife give you a cleaner cut than shears? The edge of my fitter shoe insole is somewhat ragged and uneven. Or is it better to cut the insole slightly too big, and then trim it with a knife after it's tacked onto the bottom of the last?

Jenny

Hi Jenny,

Head and round knives are extremely versitile tools and can be used to do anything from skiving to pointing straps to cutting circles. There are only two prequisites, one is skill developed by the operator, and the other is the knife needs to be SHARP. Round/head knives are sharpened on both sides.

If you wanted to just skive, then the (Blanchard) straight knives are good. However, they need to be seriously sharp as well, normally you'd (assuming your right handed) push the blade from your right across to your left (with the longest side closest to you, this puts the bevel side up.) These knives are sharpened on one side only.

More power to y'awl.

T.

Jenny,

The knifes you buy are not really sharp and will not be till you have sharpened them a bunch of time. I use a couple of tools a little different form mentioned above, I use a Diamond wet stone, they come in different grades, I know mine is red and probably quite rough in comparison. [url=newurlhttp://www.amazon.com/o/redirect?tag=amd-google-20&path=search-handle-url/index=tools%26field-keywords=diamond%20sharpening%20stone%26results-process=default%26dispatch=search/ref=pd_sl_aw_tops-1_tools_7252103_2]example of diamond wet stones[/url]

Than I use an oil stone, not sure what it is but it works for me. I never use it with oil but use water or saliva, not even olive oil as I have seen used. Oil will stain leather so when you have just sharpened a tool on your bench and put a piece of leather down to cut it may end up with a bad stain.

My strop is a piece of hardwood on one side, leather pulled over the other side but not glued down. I did use chrome tanned leather, scraped off most of the grain and added a simple polishing compound I get a my local home center made by Dremel, item # 421, there may be others but this works for me. Looks like this, just not this big

PS I use the regular Tina knife, straight blade. Non of the rounded stuff. I have tried it but my regular all purpose Tina knife works best for skiving on a piece of glass.

Rob

Thanks, Rob. re your strop...how is the leather attached to the board?

I ordered the surgical sharpening stone set (three stones) that DW posted a link to, and a strop from the same place. Could have made one, I know, but have too many projects going at the moment! There seems to be a huge variety of tools and materials out there! Very interesting to hear about them all.

Jenny

Sharpening question...In Al Stohlman's Leathercraft Tools book, he does most of the sharpening with a circular motion. However, the instructions that came with my sharpening stone set says NOT to grind, but to make a smooth sweep with the blade. These instructions seem contradictory. What is the prefered method? Also, how wide a sharpening bevel should one make? Is 1/16" enough? Thanks.

Jenny

Jenny,

Almost any stone, being stone, will leave micro-grooves or striations in the steel. This is not too surprising considering that, under a microscope, the finest of stones still looks like the surface of an old lava flow. If you want to get down to the nitty-gritty when those striations in the metal run crosswise to the direction the knife is being pushed, they tend to create friction and to resist the easy movement of the knife through the leather. Think of the striations in a mill file.

Maybe this effect is so minimal that most people would not notice it. But it is there. If you sharpen with a circular motion the striations in the metal are all ever-whichaway. And there is no direction that you can slice in which the metal is not working against you to some extent.

When I sharpen, I move the blade across the stone with the exact same motion I intend to use when skiving or cutting or whatever. If I going to push the knife...as with a skiving knife...I push the blade across the stone. Then I turn it over (if I'm going to sharpen the other side) and push again. If I'm going to pull the blade...as with a clicker knife...I pull the blade across the stone as I sharpen.

I also try to visualize the edge of the blade slicing a very thin...a micro-thin...layer off the top of the stone.

As for bevels...remember this: the steeper the bevel--a sixteenth inch bevel, for instance--the longer whatever edge (or degree of sharpness) you can achieve, will last. But a shallow bevel...one that runs from the edge of the blade to the spine of the blade...will be sharper by an order of magnitude, even though it may not last as long. However! This means it must be a true, flat (or hollow ground) bevel and not a rounded approximation.

Tight Stitches
DWFII--Member HCC

DW, thanks. What does "hollow ground" mean?

Jenny

see if this helps...increasing sharpness, decreasing longevity


Tight Stitches
DWFII--Member HCC

sorry, I forgot to mention...the bottom one is "hollow ground"

Tight Stitches
DWFII--Member HCC

DW,
I was trying to think of an easy way to explain that.
Adding my , the top profile makes for a stronger edge. The boners (butchers) here in the freezing works - do you call them meat processors(?) ie the guys that remove the bone from the carcus use the top profile because the knife stands up better if they hit the bone or their chain mail gloves.

You'd sharpen a hacking knife the same way so that it would handle hitting tacks or old shanks better when removing old soles or heels.

If a knife has to be seriously sharp then you'd use the bottom profile.
While were talking about sharpening, I use Ferrious oxide in a bar (sort looks like a very fine version of sand soap) and rub that onto a leather strop periodically. Lasts a long time, I've had this bar about 25 years now.

I liked the way you discribed the direction of travel when sharpening a blade, it does make a difference, and it's quite apparent if you use course paper to sharpen a knife then try using it without stropping it first.

More power to y'awl.

T.

The other thing is, if a blade has a lot of shoulder on it (as the top drawing shows) you can't lower your hand enough to perform a great skive.

More power to y'awl.
T.

Dw,T., Robert, and all,

Just a word of appreciation for all these responses to Jenny's inquiries about knife sharpening, and skiving. These posts have helped me alot.

My father (long gone now) put an unforgettable edge on knives. Though I watched him many times, I never completly understood what he was doing. Being in shoe related trades for over 3 decades, I thought I knew how to sharpen a knife. However, after reading these postings on sharpening, I took my old, under-utilized head knife to the sharpening stone. It's now sharper than ever! This knife has always impressed me how it can thin (a piece of leather) in the middle as well as skive, but I rarely used it - for lack of ability to sharpen it.

Not to be too wordy, I sharpened it sequentally on various grades from course (150 grit paper) to fine in 4 steps ( finally stropped on a oak tanned split leather, coated with the powdered grit fallen from various stones set on this leather for sharpening). Carefully I held a low angle (maybe about 15 degrees) on the blade. It took about an hour and a half to get it where I can skive without stressing my forearms. But now it "cuts like butter". I skive on a slightly arked backing surface. I use a marble backing surface that I sanded to shape. Marble seems to be soft enough that it does not blunt a good steel knife, yet marble can be shaped on our finishing machines. But the steel does groove the marble so that is another problem.

So my 2cents, too. And thanks for saving me from buying the mechanized bell knife skiver a little longer.

respectfully,

David Ulan

David,

Hey! That's what this forum is all about. I'm sure I speak for everyone on the Crispin Colloquy when I say if it helps, you're more than welcome to it.

With regard to the marble...if it's getting grooved you're setting yourself up for a train wreck somewhere down the line, in my opinion. The last thing you want is any unevenness under the leather you're trying to skive.

Get yourself an old cider jug...just a one gallon glass jug or jar. Either cut a rectangular hole in your bench so that the jug will be cradled (on its side) or make yourself a wooden cradle and mount the jug in it. If you can spare the room in a corner of the bench, cutting the hole is the best solution because it leaves the jug at the proper height to skive on. The size of the rectangle will determine how far the jug seats itself in the bench...naturally, you don't want the hole too big or the jug will fall through. So start small...you can always enlarge the hole--sooner...or later.

On the other hand, the cradle is movable and a little silicone glue will firmly seat the jug and prevent it from moving around on you. And the whole shebang can be stored under the bench or on a shelf.

Skiving on glass...the glass won't damage the knife and the knife won't damage the glass. And the glass is slipperier than the marble and scraps and skiving crumbs will slide off much more readily.

And don't give up on the idea of a bell skiver. Especially if you have a lot of skiving to do. I can sharpen a knife and I can skive by hand but, dern it, a bell skiver is one of those miracle machines that I wouldn't want to be without. I've got two and I've never regretted the money invested.

Tight Stitches
DWFII--Member HCC