saw making questions

Re: saw making questions

ThomD


>In the Japanese saw field there is a lot of hand tensioning being done. There was a good article in Woodwork Magazine a while back. The special tensioning hammers (presumably similar sheet metal versions in the US though not exactly) as still sold.

I find that hacksaws are hard to use on sheet what with vibration and teeth catching. I use a 4" wheel cut-off or shears. You may burn a little metal and you can simple grind that back.

I haven't made a panel saw, so i hope someone with specific answers chimes in.

Hon Metate

Jorge Castaneda ~ Downeast Maine


>I think that is the name of the japanese process to make saws true, google it.

Re: saw making questions

Adam Cherubini, NJ


>First, I think a lot of the old saw making literature is advertising hooey. "Tensioning" may well be one such subject. I have no idea what is happening when you strike a piece of sheet metal with a hammer and I'm the sort of person who should know such things.

I think folks tapped blades to straighten them period. Here's what I do:

1) I attempted to lap the table (?) of my anvil at least remove any little knicks that stick up

2) I put the saw down on the anvil hump side up, and tap very lightly with a smoothly polished planishing hammer. I just use the weight of the hammer head alone and tap away. Its amazing but even the lightest taps have some effect. I'm careful to move all around the plate - not just focusing on the toothed side. In fact, I stay away from the toothed edge because I'm afraid of relieving whatever "tension" I produce with the hammer by cutting the teeth.

3) I check often and bend it by hand and check again.

I got a neighborhood shear to cut up my saw plates. Not easy to cut by hand.

I drilled handle holes. I don't know how to match the handle holes to punched holes. So I drilled the steel with a low angle split point bit. I had to resharpen the drill bit after every 2 holes or so.

The 1095 sprind steel is tempered. If it wasn't it would crack when you bent it. But you could soften it further if you wanted to. I woudn't. Good luck with the saw. I've made 4 so far and have a few more in the works. If money were no object, I'd like to buy a sheet metal brake/break and a shear.

Adam

Re: saw making questions

ThomD


>Basically what happens is with the right gear you are locally stretching or shrinking, and you may be doing this directionally or all around. There are hammers for each of these functions. So obviously direction stretching will take the curl out. Other things may be required to deal with bubbles etc. There may be some work hardening that is being manipulated.

I never like the hokum explanation. Things may be hokum but it's an easy out in the first instance. Amd everything we do as woodworkers is pretty much subject to the same kind of dismissal. There are modern machines that do this to rolled steel saws in a single pass. You can see the little tick marks on the saw blade where they were stretched.

Re: saw making questions

Andrew Lunn


>Thom, thanks for the information about Woodwork Magazine. I'll see if I can find that article.

Yeah, it looks like sheers might be the way to go. When you say you use a 4" wheel cut off, are you talking about a wheel in an angle grinder? Thanks again.

Andrew

Re: Hon Metate

Andrew Lunn


>Jorge, I didn't have any luck trying to google Hon Metate. Have you had luck looking for it on the web? Any links you could pass along? Thanks a lot, Jorge.

Andrew

Re: saw making questions

Andrew Lunn


>Adam, thanks for the information.

I read something somewhere where Bob Smalser was saying that you can make blades thinner if they are tensioned, and that untensioned blades must be thicker in order to maintain enough stiffness. I guess it sort of made sense to me when I thought about it. I imagined that you're spreading the metal just a bit with each blow, and that a bunch of blows arranged in a particular way could very well create a stiffening effect. But then i don't know--I'm the one here asking all of the questions! I was wondering if there was some pattern of blows that was more advantageous than others in terms of creating a balanced tension in the saw--or if it is a process that is more approximate and subjective, where maybe you pepper it everywhere and then adjust it for straightness.

I thought you could probably punch your holes in the metal first, putting them where you want them, and then lay your blade over top of your handle blank and mark your holes on the blank where you want them. Pretty much the same deal as fitting a new handle to an old blade--which i actually saw somewhere online; Mike w. and a D-8.

Thanks again for the info.

Andrew

Re: saw making questions *LINK*

mikew


>What's that burning feeling my ears are getting?

Take care, Mike


D-8 index...

Re: saw making questions

Andrew Lunn


>Yup. That looks familiar! Thanks for posting, Mike. Would you mind telling me what is the kerf on that ts blade you use there to cut the slot for the blade in the handle? Thanks, Mike.

Andrew

Re: Hon Metate

ThomD


>Here is the issue, I guess. Man, time flies, I thought it was a few years ago:

Issue 68 April �01

Mark Burhans�Profile

Turning Chessmen

Graceful Chest of Drawers

Balinese Mask Carving

Carving with Air Chisels

Metate�Japanese Saws

Women Woodworkers

Cross-Hatch Adhesion Test

Re: or CNC

ThomD


>That's what i use for a lot of this kind of work, if I can't saw it, or shear it with the sheet metal air shear I have, then it starts to get nasty. Wherever you bought it, don't they have a big shear? The type that drops down and would just separate this stuff along any lines you want.

Also, these days, it's amazing what you can get if you got to a waterjet place. Say you get ten people here interested in having a perfect version of Adam's saw done to my CAD (when I get back home if anyone is interested). Then get some anxious waterjet guy just to bang out the blank. That way the whole thing, all the little details and quirks can be lasered or watered, and no fooling around. That's what the metal guys do. I am following this series in Home shop machinist, and it starts out something like this: "While you are having the main frame parts to the machine laser cut..." So we all pay for our blanks and go off to our respective shops with files and handles in hand...

Re: saw making questions

ThomD


>About the same thickness as the stock you are using? in other words a finer saw, since the kerf of one has to suit the stock of the other. Or if you are making a rip saw, could you get away with a quick cut with the saw after sharpening before setting?

Re: saw making questions

mikew


>Hi Andrew,

About 42 thou/ Looks wider than it is as I muffed up right at the opening a littl. Rasping the handle eliminated the wonky cut as it wasn't very deep.

Before you ask, I hand made the blade I used. I wouldn't recommend it. The Disston closed-tops use a 7" diameter blade to cut the blind kerf. That's why more pictures are not on the website of me cutting it.

Make an open top. Or buy a vertical mill and have a 7" blade made. That's what I have and use now.

Take care, Mike

Re: saw making questions ****

mikew


>Expect to do a little filing no matter how the blanks are cut out...

Take care, Mike

Re: saw making questions

paul womack


>First, I think a lot of the old saw making literature is advertising hooey. "Tensioning" may well be one such subject.

For a myth, they went to a lot of effort, including making special hammers and anvils for the task.

BugBear

Re: Hon Metate

Andrew Lunn


>Awesome, Thom. Thank you very much.

Andrew

Re: or CNC

Andrew Lunn


>Thom, I bought the metal online from McMaster-Carr. I don't know if they cut stuff before shipping or not. But to tell the truth, I would really prefer a way to do it myself.

It would be fun, though, to make saws with people here, if others were interested. And sure, i'd be interested to see your CAD drawings of Adam's saw. Thanks for the offer.

Andrew

Re: saw making questions ****

Andrew Lunn


>Wow, Mike. You should warn people before you go flashing stuff like that. I think I burned a retina. Really terrific work. Looks like a Seaton Saw. Absolutely beautiful.

Andrew

Re: saw making questions

Andrew Lunn


>Yeah, looks like an open top is in order for now. I figured that saw blade you used would have to be awfully thin; my thinnest one is still wayyyy too thick. Thanks for the information, Mike.

Andrew

Re: saw making questions

Andrew Lunn


>Bugbear, do you know what their anvils and hammers looked like? Or have a link? I've seen a little about tensioning on the Disston Institute website, in an older document about a tour of the their factory. Thanks for chiming in.

Andrew

Re: saw making questions

Todd Hughes


>I have a couple saw makers anvils and they are basicaly large square bocks of steel with a loop handle out the side. Base is slightly larger then the top....The hammers traditionly looked like what is called dog head hammers where the front part of the hammer in front of the eye is much longer then the part behind the eye.Believe the Japanease smiths used a very simular looking hammer.

Ive straightened many dozens of saws using just a small hammer and laying the blade on a regular anvil's table.Probably any hard flat suface would work.

Even though I once made a backsaw out of a shovel I have to confess to not understanding why if you want to make a saw you wouldn't just want to use an old saw blade for your source of material....Todd

Grimshaw On Saws

Patrick Gibbons, Houston, TX


>Grimshaw On Saws, published in 1880, has a section on the making of saws as it was done in American factories of the time. There are illustrations of the doghead hammer and the blocking hammer and their respective anvils. Grimshaw remarks that this is a skill of an experienced worker and not to be left to novices. The hammering was done after the taper grinding with the object of relieving thick or thin spots, curls, twists and other imperfections in the steel. He speaks of tensioning more in the context of circular saws which could pose a real hazzard because of the high rpms but discusses tensioning hand saws to even out stiff and loose sections. The need for hammering was determined by sighting and use of a straight edge made specifically for the purpose as well as bending the blank for seeing and feeling areas in need of adjustment.

Re: and while you're there...

William Duffield, on the Cohansey


>...don't forget to ask him if he has any old worn out carbide orifices from the water jet. They make fantastic burnishers for the card scrapers you'll want to make out of the cutoff scraps of saw steel. If he's cutting with an abrasive, you'll need to polish them before you use thme as a burnisher, but if he's just using water, they're probably fine as is.

Re: saw making questions

Adam Cherubini


>Its is a myth because, for starters, there's no tension involved- at least not on the side you work. Its "compressioning", if anything. The effect as I understand it is similar to shot peening- In fact, shot peening would probably do the exact same thing only better.

In addition to the compressive stresses caused by tiny amounts of plastic deformation, (which isn't necessarily good, btw) there's probably some amount of work hardening taking place which may have been the "hard and soft spots" mentioned in days of yore. But all this is happening on the molecular level.

But in true Disston fashion, he probably:

a) had no clue what he was doing since so much of this effect wasn't understood in his time. He just did what worked/what he had to do to make a straight blade (and sell saws)

b) used the correction of defects as a selling point. A better saw would be one with no "tension" in it. I have long suspected that the famous #12 is only different because its thinner than the similarly shaped #7. I think the blades that got over worked at the taper grinder became "special" saws- and got a higher polish and a fancy handle and the claim of being "extra refined London spring" as if it was a different material. We should all be so shrewd.

=================================================

The spring steel we buy today is really quite beautiful. My recommendation is to do as little as possible to it and avoid attempting to "tension" saw blades because Disston said it was an important step or an aspect of a high quality saw. Hogwash.

Further, I recommend to any would-be saw maker to immediately forget the notion that you can can use a shaped hammer to spread the steel in the direction you want. A round faced hammer (heck a ball peen would probably work) and tiny tiny hits arranged to produce what you want is the key. I would (and have) spread them over a wide area to avoid making a hard spot. Thus far I've not detected any hard spots on my new saws.

The planishing hammer - available at most auto body stores, works nicely because its head is shallow and leaves very little mark. Just keep it smooth and shiny and don't use it to drive nails.

I have tapped out many blades - maybe a dozen or more, tho all but 4 are as yet unfinished. I've tapped out the thinnest of my backsaws (.015) to make them straight before putting on their spines. After the spine is on, I hand tweak the spine, sighting down the blade all the while. Its not brain surgery. Before I hand file the teeth, I check it again. If its not true, I tap it with the planishing hammer.

That said, not all my saws are straight. It'd probably be better to say none of my saws new or old are perfectly straight. I have no idea what effect a slight curve has on actual use. I sorta don't want to know, so I'm happy to do what I can to avoid the situation.

That's all I know about saw straightening. Good luck you sawmakers. OH!...And don't listen to Todd. Make whatever tool you want. The fact that you can buy a better tool cheaper has never stopped us before!

Adam