Self-built handscrew - what am I doing wrong?

[Federico Mena Quintero]

Hi, everyone,

I found a friendly machine shop and asked them to make me a couple of threaded rods and nuts to make some handscrews. Here is my first build, but either I built it wrong, or I don't have the technique to actually use a handscrew...

http://farm5.static.flickr.com/4130/5011901818_d7a6867c3c_z.jpg

The two nuts on the left are threaded. The two on the right are not threaded. The center nuts are exactly in the middle of the jaws lengthwise. The edge nuts don't have any particular position, they are just "close to the edge" of the jaws.

My problem is as follows. When I clamp something, I tighten the middle screw. But then, the back of the jaws pulls together (as the jaws want to pivot on the center nuts, and the clamped piece spreads apart the front of the jaws). This either makes the jaws not parallel but tight enough, or definitely not tight if I want to make them parallel. Kind of what happens if you have a leg vise in your bench and forget to put the pin in the guide bar.

From the images I've seen of commercial handscrews, I noticed that the nuts are in a trapezoid, with the center nuts farther apart than the ones in the back of the jaws. Mine are all in the middle of the jaws' width - would this be a problem? (Or do the jaws really need to pivot for the clamp to work - I have not yet chiseled the little triangles that come out of the holes for the rods, so the rods are forced square into the jaws - they can't pivot right now except for a little play within their holes.)

Also, there is nothing to prevent the jaw with the unthreaded nuts from sliding up and down the rods - is that the way it is supposed to work, or do I need some sort of stop somewhere?

Finally, both rods are threaded in the same direction (righty-tighty). Do I need something crazy like rods with opposing threads?

(It is pretty much impossible to find handscrews here in Mexico; that's why I can't go look for a reference, and I wanted to make some myself.)

If all of this makes me look like a handscrew newbie, it's because I am one :)

Thanks for any advice!

[george wilson]

On commercial hand screws,the threaded rods are half right hand and half left hand. All 4 nuts are threaded,2 right hand,and 2 left hand. The jaws cannot slide freely up the shafts. You have made your clamps like machinist's clamps,or like old wooden screw clamps. The machinist's type are small clamps made of metal a few inches long,up to 4" long. They will not get much out of parallel since they do not have their screws cut both right and left handed.

They also have a little collar that goes into a ring cut into their "handles",which prevents them from sliding up and down the shafts. On both machinist's and old wooden screw clamps,2 handles are always up against the jaws.

Take a better look at a commercial hand screw.

[Bill Houghton]

George Wilson has explained how modern metal-screw handscrews work. The older, all-wood handscrews worked slightly differently, and I believe you were attempting to copy how they worked, although you may not have realized that's what you were doing.

Using your picture as an example:

1. The center screw - closer to the clamping tip of the handscrew - ran through the right jaw and threaded into the left jaw. This is how yours works right now.

2. The rear screw - farthest from the clamping tip - was threaded through the left jaw, as yours is. It then engaged a socket on the right jaw (generally, the end of the screw was turned down to the minor diameter of the threads, or thereabouts, and the socket sized for a very generous fit of that diameter).

You tightened up the center screw, leaving the rear screw "loose," until your handscrew was sized for the work being clamped. You created clamping pressure by advancing the rear screw so that it pressed against the socket on the right jaw, pushing the clamping end tighter.

All-wood handscrews have limited ability to clamp with the jaws out of parallel - if they get too far from parallel, they strain and can break the wood screws. The modern metal-screw handscrews permit the jaws to be quite a bit out of parallel, helpful for many clamping situations (like clamping something that's away from the edge of a board).

You might be able to salvage your project if you can get a new piece made for the bottom right nut that has a blind hole - not all the way through - the size of the threaded spindle. This will allow you to replicate the action of the all-wood handscrew, with the added advantage that you can clamp with the jaws out of parallel. Alternatively, although this will be messier, you could lock a nut on the rear spindle so that it presses against the unthreaded nut, enlarging the hole in your clamp jaw to provide room for it. The simplest way to do this is with two nuts, tightened against each other.

You'd probably want to shorten the rear screw, so it's not hanging way out there.

This will have one big disadvantage over either the modern or the classic handscrews. If you let your rear screw fall out of the socket, the nut may fall out of the clamp and roll across the floor under a bench, probably just as you're in the middle of a delicate glue-up (I just have this vivid imagination, fostered by far too many bitter experiences during glue-ups). If you decide to try salvaging the project this way, you might consider a "plate" on each side of the clamp jaw for that nut, to keep it from trying to run away at the wrong time. The locked-nuts approach would be slightly better here, as you could leave a long "tail" on the rear screw to keep it in the nut longer.

If I listed the mistakes I made early in my shop "career" from not understanding the basic physics of things, you'd fall asleep before I finished. Good for you for trying something; an opportunity to learn something new.

[glenn bradley]

Do I need something crazy like rods with opposing threads?

Nothing crazy. That's how they are made. Nice looking clamp though. An impressive first effort.

[Bill Houghton]

I referred in my earlier post to the basic physics of things in the shop. This type of clamp is basically a lever - a fulcrum point and a force work together to apply pressure. If you tighten the clamp as I suggested in my earlier post - use the center screw to adjust clamp size and apply pressure with the rear screw - it's a first class or type one lever, as described in textbooks and any number of places on the Internet, including here: http://www.enchantedlearning.com/physics/machines/Levers.shtml

A leg vise, which generally uses the vise screw to apply the pressure against the adjustable pivot point at the bottom, is then a third class or type three lever.

Levers are used here and there in clamping. A clamping caul, for instance, may be curved so that, when the clamps are applied to each end, it applies clamping pressure first in the middle before distributing it to the ends. This is a second class/type two lever.

[Federico Mena Quintero]

On commercial hand screws,the threaded rods are half right hand and half left hand. All 4 nuts are threaded,2 right hand,and 2 left hand.

(Panic mode: on). I see! Man, I just looked in flickr for some more detailed pictures of handscrews, and you are absolutely correct. I have no idea if the machine shop can do left-hand threads... will have to ask them the next time I go by.


Take a better look at a commercial hand screw.

That's the thing - no one here has one (maybe some of the luthiers in a town close by), and you can't buy them anywhere.


George Wilson has explained how modern metal-screw handscrews work. The older, all-wood handscrews worked slightly differently, and I believe you were attempting to copy how they worked, although you may not have realized that's what you were doing.

Yes, pretty much. I thought, okay, all four nuts can't be threaded because then the jaws would always be at the same distance to each other. So one pair will have to be unthreaded. In my head, I didn't quite understand how the "bicycle pedals" motion would work; now I see that it doesn't work unless you have rods with half-left and half-right threads.


Alternatively, although this will be messier, you could lock a nut on the rear spindle so that it presses against the unthreaded nut, enlarging the hole in your clamp jaw to provide room for it. The simplest way to do this is with two nuts, tightened against each other.

You'd probably want to shorten the rear screw, so it's not hanging way out there.


Thanks, I think this is what I'll do. So with the same orientation as my photo, the rear spindle is made to push on the right jaw, which provides the leverage I was missing. I think I get it now.


Nothing crazy. That's how they are made. Nice looking clamp though. An impressive first effort.

Thanks :) I have another set of rods/nuts to make a second clamp, so salvaging this is definitely in order.

Thanks to all! I see that "real" wood-and-metal clamps need more exotic hardware than what I got made, but it's heartening to see that not all is lost.

[george wilson]

You can buy Chinese made handscrews so cheap now,it may not be worth the cost of making them. Harbor freight probably sells them. They aren't quite as nicely finished as Jorgenson's,but they work o.k..

You could just buy some for their metal parts,and make your own wooden jaws if you wanted to.

[Federico Mena Quintero]

A clamping caul, for instance, may be curved so that, when the clamps are applied to each end, it applies clamping pressure first in the middle before distributing it to the ends. This is a second class/type two lever.

This is a very nice idea. I use cauls often, but had not thought of curving the insides. Generally I just place something nice and heavy on top of the middle of the caul.

I guess someone already compiled a table of how much different types of wood can bend under different loads...

[Bill Houghton]

You can buy Chinese made handscrews so cheap now,it may not be worth the cost of making them. Harbor freight probably sells them. They aren't quite as nicely finished as Jorgenson's,but they work o.k..

Federico mentioned in his initial post that he's in Mexico. I don't know if Harbor Freight, also known in our family as Horrible Fright, has branches in Mexico.

I know a lot of folks (including us) aren't going to Mexico on vacation right now because of the drug cartel wars, but, if someone's driving down there, anywhere near Federico, this does seem like an errand of mercy - a corner of the trunk full of handscrews.

[Federico Mena Quintero]

I know a lot of folks (including us) aren't going to Mexico on vacation right now because of the drug cartel wars, but, if someone's driving down there, anywhere near Federico, this does seem like an errand of mercy - a corner of the trunk full of handscrews.

You'll mostly see violence in the northern states (although people there say that you *hear* about violence in the news, but don't actually see it in the streets). YMMV.

I'm pretty far from the border - think of Mexico City, then go straight East until you are about 100 Km from the coast of the Gulf. But if anyone wants to deliver schwag, I have my eyes on router planes and other plane-y tools :)

(Seriously, if anyone ever comes near Xalapa, Veracruz, I'd be more than happy to pay for a tool or two, and to treat you to excellent coffee/food. Nothing like a suitcase full of sharp metal to make you feel comfy in the airport.)

[Dave Beauchesne]

Federico:

Lee Valley sells the kits made by Jorgensen. The come with the hardware and handles - you make the jaws.

I made a set of three out of Yew wood and turned my own handles out of the same stock C/W copper ferrules.

Just a suggestion.

Dave Beauchesne

[Mike Siemsen]

Federico,
You asked, "From the images I've seen of commercial handscrews, I noticed that the nuts are in a trapezoid, with the center nuts farther apart than the ones in the back of the jaws. Mine are all in the middle of the jaws' width - would this be a problem?".
The reason for this is that the front jaws pull towards each other and the rear jaws push away from each other. Putting the front nuts on the outside leaves more wood to take the load and vise versa with the rear nuts.
You will get them to work.
Mike

[Federico Mena Quintero]

Lee Valley sells the kits made by Jorgensen. The come with the hardware and handles - you make the jaws.
I made a set of three out of Yew wood and turned my own handles out of the same stock C/W copper ferrules.


Oh, yeah, I saw those kits; they seem very nice indeed. This was more an experiment - "how hard can it be to make one?"...

How did you make the ferrules? I recently got Mike Burton's book on making tools for carving, and he suggests using caps for copper pipe as ferrules - maybe not the prettiest things in the world, but functional enough.

I'm running a little experiment to fabricate tools out of components made by locals (e.g. the metal hardware from the machine shop). Maybe some local woodworkers will be interested in the final tools. I know at least one cabinetmaker and a luthier who drool over the imported tools they could use, but those are too expensive for them. Kind of a "damnit, why is this not manufactured in my country" thing - Jane Jacobs' import-replacement and all that :)

(I'd *love* to get some nice LN planes and similar - but not everyone can afford them here. This is probably a good chance to give some work to the few remaining local blacksmiths. With everything imported from China these days, it seems that no one knows how to make anything anymore.)

[Federico Mena Quintero]

The reason for this is that the front jaws pull towards each other and the rear jaws push away from each other. Putting the front nuts on the outside leaves more wood to take the load and vise versa with the rear nuts.


Perfect, this makes a lot of sense. I thought the trapezoid would help when making the jaws non-parallel; I guess strength of the wood is just as important a consideration.

I'll go buy some nuts to lock the right-rear spindle, as Bill suggested - I'll post the finished pictures soon :)

[Pam Niedermayer]

Federico mentioned in his initial post that he's in Mexico. I don't know if Harbor Freight, also known in our family as Horrible Fright, has branches in Mexico.

I know a lot of folks (including us) aren't going to Mexico on vacation right now because of the drug cartel wars, but, if someone's driving down there, anywhere near Federico, this does seem like an errand of mercy - a corner of the trunk full of handscrews.

Just the job for the Post Office.

Pam

[Steve Branam]

You might try making some wooden planes. They work quite well, and the only real cost is the iron (single or double) if you have some decent hardwood. They just take a little practice to get used to because they handle a little differently from metal planes, but functionally they're the same. Can your blacksmiths make old-fashioned laminated blades (laid irons)?

I have an antique wooden screw that I was going to post a picture of, but I haven't been able to find it. I bought it last year with the plan of copying it. I'll post a machinist's screw, same design, just made of metal.

Making wooden handscrews seems like a fairly simple task once you have a good way to do the threading. Given an initial investment in a tap and thread box and a source of decent wood, you can make dozens of clamps. Even if the threads get chewed up, they can still work, and then they're easy to replace.

Making tap and thread box ought to be within reach of those blacksmiths. Roy Underhill reproduced Roubo's plans for them in "The Woodwright's Guide: Working Wood with Wedge and Edge".

When your resources are limited, you can fall back on the technologies and techniques of the 18th century. They work just fine, and the tool making is achievable with basic blacksmithing and woodworking facilities. Make some simple, crude ones first, then use those to make better ones. It's like rebooting your manufacturing capability on a small scale.

[Kevin Lucas]

I know you can buy brass ferules. I sort of cheated and got copper pipe fittings at the hardware store. I figure I can tap the edges over the top pretty easy. Future handle project experiment...

[Federico Mena Quintero]

You might try making some wooden planes. They work quite well, and the only real cost is the iron (single or double) if you have some decent hardwood. They just take a little practice to get used to because they handle a little differently from metal planes, but functionally they're the same. Can your blacksmiths make old-fashioned laminated blades (laid irons)?

Yeah, I've been meaning to build some planes! A friend has a beech tree that needs some branches pruned, so I'll see what I can get. (And there's a local park with gorgeous beeches that often get pruned - I'll see if the workmen are friendly; normally they are totally obnoxious when it comes to people asking for wood.)

I haven't talked to that one blacksmith yet, so I don't know if he can make laminated blades. In the worst case I can ask him to temper the non-laminated blade well, I suppose.

Are softwood planes just a no-no? If it sounds like I don't know what I'm talking about, you are 100% right :)

I have a spare, new blade for a Stanley-clone #5, the usual rather thin kind. I guess it can't hurt to try making a wooden plane with that one.



Making tap and thread box ought to be within reach of those blacksmiths. Roy Underhill reproduced Roubo's plans for them in "The Woodwright's Guide: Working Wood with Wedge and Edge".

Yeah, I got that wonderful book recently. I do want to experiment with making my own threading equipment. The machine shop said "but we'd need a CNC router to make custom taps/dies", which didn't sound right - certainly people built those before CNC routers, didn't they.

This is certainly encouraging - http://www.youtube.com/watch?v=CdWPOx_UpzE (that guy's channel on youtube has some very cute tricks for various things).


Make some simple, crude ones first, then use those to make better ones. It's like rebooting your manufacturing capability on a small scale.

Exactly. I'm all for bootstrapping technologies.

Thanks for all the encouraging words; this makes me feel that I'm not that crazy.

[Andrae Covington]

I'm running a little experiment to fabricate tools out of components made by locals (e.g. the metal hardware from the machine shop). Maybe some local woodworkers will be interested in the final tools. I know at least one cabinetmaker and a luthier who drool over the imported tools they could use, but those are too expensive for them. Kind of a "damnit, why is this not manufactured in my country" thing - Jane Jacobs' import-replacement and all that :)

I am glad to see this, and I hope you are successful. There will come a time even here in the US when we will increasingly have to rely on locally crafted tools. Hopefully there will still be local blacksmiths and other craftsmen with the skills to make it happen.


Yeah, I've been meaning to build some planes! A friend has a beech tree that needs some branches pruned, so I'll see what I can get. (And there's a local park with gorgeous beeches that often get pruned - I'll see if the workmen are friendly; normally they are totally obnoxious when it comes to people asking for wood.)

Branch wood is probably going to be too unstable for handplanes. See reaction wood (http://en.wikipedia.org/wiki/Reaction_wood) for a brief explanation. You would saw / plane a rectangular piece and then watch it do a pretzel impression.:eek:


Are softwood planes just a no-no? If it sounds like I don't know what I'm talking about, you are 100% right :)It wouldn't hurt to experiment with. Better than branches at any rate.:p

[Pedro Reyes]

Federico, I sent you a PM.

regards

/p

[george wilson]

For short planes like coffin smoothers I expect reaction would be o.k.. You might have to cut it to shape,leave some oversize,then give it time to twist,or whatever.

[Federico Mena Quintero]

I am glad to see this, and I hope you are successful. There will come a time even here in the US when we will increasingly have to rely on locally crafted tools. Hopefully there will still be local blacksmiths and other craftsmen with the skills to make it happen.

One nice thing about this Internet age is that people are naturally inclined to sharing knowledge. Basically all that I've learned so far about woodworking has been from the net. People who share their knowledge deserve huge heaps of thanks.

Some friends and I are just starting a project to create "free workshops" of various crafts, and to release all the documentation/plans/etc. as Creative Commons-licensed material. Hopefully it will come out okay. I'm in the woodworking front; some others are in pottery, soapmaking, house construction, pedal-powered machines, and so. Tools are of course a big problem, but hopefully something that we can solve ourselves. There is a short description of the project here - http://people.gnome.org/~federico/news-2010-07.html#26 (http://people.gnome.org/%7Efederico/news-2010-07.html#26)


Branch wood is probably going to be too unstable for handplanes. See reaction wood (http://en.wikipedia.org/wiki/Reaction_wood) for a brief explanation. You would saw / plane a rectangular piece and then watch it do a pretzel impression.:eek:


Interesting! But who knows? If you make the cutters after the plane goes all pretzely, you may end up with some wicked moldings...

A few weeks ago while vacationing in another town, my wife and I walked through a square where city employees were pruning some big ficus trees. The workers were *totally* opposed to anyone taking a few branches home. They refused money; said that they could get fired if they got caught. I thought, yeah, right, like anyone is actually looking.

Anyway - when their truck left with the thickest and prettiest branches, I managed to pick up a smaller length of a straight branch. I brought it home with the intention of learning to use my froe. Now *that* was fun and tiring :)

Maybe the branch was too thin, about 12 cm in the thickest parts, and a bit knotty. I didn't manage to produce any useful wood except for some cute, straight strips after planing/squaring. (This is the first time I mill wood completely from scratch, so despite the useless size of the results, it made me learn a lot!)

Where was I. Oh, yeah, splitting branches rather than sawing them - I do want to experiment with that. Maybe the wood won't move as much, I don't know. Those big beeches aren't coming down anytime soon, fortunately; they are the reason for that park being lovely.

[Steve Branam]

Some friends and I are just starting a project to create "free workshops" of various crafts, and to release all the documentation/plans/etc. as Creative Commons-licensed material. Hopefully it will come out okay. I'm in the woodworking front; some others are in pottery, soapmaking, house construction, pedal-powered machines, and so. Tools are of course a big problem, but hopefully something that we can solve ourselves. There is a short description of the project here - http://people.gnome.org/~federico/news-2010-07.html#26 (http://people.gnome.org/%7Efederico/news-2010-07.html#26)


Nice! I like the concept of recovering lost skills. I'm doing a basic intro to hand tools course on my blog, as well as teaching it through a local adult continuing education program.

Regarding wood for planes, if you get fresh-cut beech, you'll need to wait at least 1 year per inch of thickness for it to season (once you've prepared it for drying).

I'll offer a little heresy here and say you can probably make some kind of serviceable plane from softwoods, depending on just how soft. The sole will wear and need frequent flattening, which will soon open up the mouth too much, although that can be repaired. The body may also warp more easily. You might be able to stabilize it and give it wear resistance by gluing on a thin sole layer of hardwood (there are procedures on this forum for doing just that for wooden sole repairs). That allows you to stretch a precious supply of hardwood, or retrofit a plane after you get some.

But as with making multiple wooden handscrews, make a bunch, and when they wear out beyond usability, make replacements. If you can get a year or two of good use out of a softwood plane, wouldn't that still be worth the effort? Then you develop the skill to make them, so if you do get some better wood, you know how to put it to use.

Again, when your resources are limited, you have to get creative. You may have to sacrifice some characteristics of the tool, but you still end up with something usable. It just may take more effort to use.

[David Woodruff]

Federico, ditto George Wilson. The left hand - right hand thing is a natural mistake. The imports are OK for the wooden jaws, but the screws are horrible. Clunky is the word. Depending on how many of these you need, one can still buy the old ones with wooden screws for less than $50.00. I would rather have only one of these compared to half dozen harbor Freights'. Of course that is just me. My dad in the interest of reproducing the old skills made several wooden screws in both Acme and V threads.

[george wilson]

The Asian screws aren't acmes like the Jorgensons,true. For home shop use,they probably would do.

I got lucky back years ago. We have this huge outlet called the Williamsburg pottery factory. It has gotten ever larger over the years,and sells all kinds of things. I went there on one of my rare visits to it. They had a bunch of Jorgenson hand screws priced real cheap. I bought most of them on the spot. Years later,I'm still wondering if they might have put the price THEY paid on the tags???? Some months later,I went back,and there were SHARP price increases!!!:) I still wish they would stop putting non drying oil all over the wood.

[Federico Mena Quintero]

Nice! I like the concept of recovering lost skills. I'm doing a basic intro to hand tools course on my blog, as well as teaching it through a local adult continuing education program.

Oh my god, you are Close Grain! In fact I did bookmark your intro course a couple of weeks ago, when I got the link from another blog. I guess I'm just starting to put names to, uh, blogs or something :)

(Similarly, I just realized that George Wilson is *the* George Wilson. It's fantastic to be in such fine company.)


You might be able to stabilize it and give it wear resistance by gluing on a thin sole layer of hardwood

Great idea.

I'm still trying to find who in my town sells hardwoods. Every lumber shop has pine and some have cedar.

Around my town there are many coffee plantations, and people (especially builders) often use coffee wood to make handles for hammers or axes. It's pretty tough stuff. Maybe some creative laminations could make a good sole for a plane; no idea.

[Steve Branam]

Oh my god, you are Close Grain! In fact I did bookmark your intro course a couple of weeks ago, when I got the link from another blog. I guess I'm just starting to put names to, uh, blogs or something :)

(Similarly, I just realized that George Wilson is *the* George Wilson. It's fantastic to be in such fine company.)

Yeah, it's fun to connect people up! Conversely, my Google Analytics stats show that some mysterious person from Xalapa has visited my blog 14 times since March. Even more fun, I can now identify visits from Providencia, Chile, and near Harrisburg, PA as probably being specific people on this forum (you know who you are, and so does Google ;))! It helps to be visiting from a unique place name.

Meanwhile I'll just bask for a moment in the glow of someone mentioning me and George in the same post. Ok, moment over, reality is I hope that in the rest of my woodworking career I'll be able to accumulate the knowledge and skill George probably had by the time he turned 21. :D


Around my town there are many coffee plantations, and people (especially builders) often use coffee wood to make handles for hammers or axes. It's pretty tough stuff. Maybe some creative laminations could make a good sole for a plane; no idea.

That could be pretty interesting. Does coffee fall into the same category as tropical hardwoods like rosewood, etc.? Those woods make good planes, Derek Cohen has a bunch on his website. If it's tough enough for hammer and axe handles, it's probably tough enough for planes, although it's possible it could have some other characteristics that aren't so good. For instance, though hickory is a top handle wood, you don't see any hickory-bodied planes. On other hand, apple is a good handle wood, and you do see apple-bodied planes.

[Don Orr]

Federico,

My simple observation would be to switch the 2 nuts on the back of your clamp. The right side of the picture should have a threaded nut in front and unthreaded nut in back. On the left it would be the opposite. This way it would work more like the old all-wood clamps. Draw with the front screw and push with the back screw. Try it and see if it works.

And good luck with your craft project.

[Federico Mena Quintero]

That could be pretty interesting. Does coffee fall into the same category as tropical hardwoods like rosewood, etc.? Those woods make good planes, Derek Cohen has a bunch on his website. If it's tough enough for hammer and axe handles, it's probably tough enough for planes, although it's possible it could have some other characteristics that aren't so good. For instance, though hickory is a top handle wood, you don't see any hickory-bodied planes. On other hand, apple is a good handle wood, and you do see apple-bodied planes.

It will take some experimentation. Coffee is a bush, not really a tree, and I don't know how thick or straight the branches can get. (I haven't really paid attention to the wood itself; it's easier to drool over the ripe red cherries than it is to peek inside the foliage to look at the branches). Apparently people are taking notice - http://knowledge.cta.int/en/Dossiers/Demanding-Innovation/Commodities/Documents-KIT-Library/Coffee2/Africa-Coffee-wood-suitable-for-high-value-end-uses

[Federico Mena Quintero]

My simple observation would be to switch the 2 nuts on the back of your clamp.

Unfortunately that doesn't work. You can push the clamp with the threaded nut in the rear, but then the unthreaded one wants to creep in.

I just finished putting the locked nuts, however, and a nice coat of BLO is drying on the clamp and just-smoothed handles. I'll post pictures when it is done :)

[bridger berdel]

This is a very nice idea. I use cauls often, but had not thought of curving the insides. Generally I just place something nice and heavy on top of the middle of the caul.

I guess someone already compiled a table of how much different types of wood can bend under different loads...


nah, just set the piece you want to use as a caul up on blocks and clamp it in the middle to the pressure you want, then strike a straight line along it. unclamp and plane to the line...

or if it's a caul for use with a clamp at each end, set it up that way and strike your line and plane.

[Federico Mena Quintero]

Sorry that I didn't post a picture of the finished version - it looks pretty much the same as the original, just with BLO applied and smoothed handles.

With the two locked nuts, it works perfectly!

[george wilson]

There is no reason why your clamps with 2 right hand screws will not work. Little steel machinist's clamps are made exactly the same way. You must keep the jaws pretty parallel as they will not take much angle.

Will your local machine shop let you look at a machinist's clamp? I mean the kind with 2 parallel jaws,just like the larger wooden ones,but made of steel.

The old time wooden handscrews were made with 2 right hand threads also. They do not clamp angled wood well either.

[Federico Mena Quintero]

Will your local machine shop let you look at a machinist's clamp? I mean the kind with 2 parallel jaws,just like the larger wooden ones,but made of steel.

Good idea. I'll ask them the next time I'm around - I promised to show them the finished clamp in any case.

[Bill Houghton]

I'm glad this worked out for you.