A different drawbore pin idea

[Jessica Pierce-LaRose]

I was looking at this leftover steel rod I have from making a pin for my leg vise, and wondering what to do with it, and thought of an idea for drawbore pins. Curious if this would make sense:

The "twist to apply pressure" idea of the "oblique cone" shaped pins from TFWW appeals to me, although the price (which I admit is fair for the item, just not my wallet right now, when I can make normal concentrically tapered pins work well enough) does not. Looking at a drift pin, and wondering if I could accurately file or sand something akin to that shape into it, I just wasn't quite sure, but I don't think so.

But I'm looking at this steel rod - it's the wrong size (I'm more apt to use 1/4" drawbore pegs than 3/8") but I began thinking - I tend to drill my drawbores with the same bit, and the offsets never vary that much. If I use the same size holes, I don't really need a tapering pin if I work that eccentricity into it, do I?

I'm thinking of taking some rod, chucking it in the drill and running it against a grinder or sander until it slides in and out what feels right. Then chuck it in a metal vise and filing a slight flat on opposite sides, and blend that in until the entire pin is a reasonably uniform oval/ellipse shape.

The idea is that the rod should slight right through the drilled hole. When the two parts are mated, the rod will slide through the hole one way (with the shorter diameter of the oval facing the tenon shoulder and the slightly protruding crescent that shows through the hole in the mortise ) if I've filed it enough. Twisting the rod will begin to show a wider diameter against that offset.

Granted, without the taper you'd have a hard time keeping the pin from sliding all the way up to the handle, and these pins would only be good for exactly one size hole, and probably only within a limited range of offsets; but I feel like it might work, and given how cheaply you can get a long length of steel rod, they probably even work out to be cheaper than drift pins - I'm not sure you really need hardened steel for this application.

The added benefit is that they could probably even work in drawbores where the hole doesn't go all the way through the frame.

Below is a cross section image of what I'm thinking - nothing exact. The dark brown color being the piece with the mortise and the hole through it. You can see the light brown of the slightly misaligned tenon and it's hole peeking through. The red is the cross section of the slightly ovalish proposed pin. As you see, it fits in one direction - the second picture, I've taken that same pin and in my graphics program, rotated it slightly, and you can see it begin to push against the walls.

pin1.jpg
pin2.jpg


So what do you think? Dumb idea? Is there another benefit of the tapered aspect of the pin that I'm missing, besides the ability to work with a bit of a range of hole sizes and offsets? I'm sure there is . . .

I guess at some point I'll just have to try it out.

[Jim Matthews]

It should work.

I don't think its' crazy, at all.
The taper makes it easier to insert, but unless it's deep that should not matter in practice.

[Jim Koepke]

My thoughts have been to do something like this. It isn't that difficult to also make a taper.

My main reason for not doing it as of yet is my lack of using draw bored joinery on any projects.

jtk

[Johnny Kleso]

Buy a Knife Honing Steel and sand off the file teeth on a belt sander
http://www.firstchoicefurnishings.co...rpening-steel/ $18 each or $24 at Amazon

[Jessica Pierce-LaRose]

That's a neat idea; but as long as I'm being cheap, I like the under 10 bucks for 6 or 7 feet of steel rod

[Derek Cohen]

Keep in mind that one does not need a drawbore pin(s) to drawbore joins.

As I use them (I have two Veritas pins), they are to clamp the joint together temporarily, or to test a joint's fit.

To facilitate the drawbored joint coming together I ensure that the wooden pins are tapered at the end. Recently i discovered that one could use an old fashioned pencil sharpener to .. well .. sharpen the ends to a taper. This then slides easily through the small space between the overlapping holes.





Regards from Perth

Derek

[Jessica Pierce-LaRose]

Oh yeah, I totally realize that - I've been drawboring without pins, as I don't actually have any. Always a good point to bring up, though.

Every now and then, I just find myself thinking in whatever particular instance, it would be handy to be able to have some to test for square, or see that the visible shoulders pull tight, or hold a frame together so I can figure out the panel size, without having to wrestle with clamps.

( Actually, I really just like making those octagonal handles and want an excuse to make more and use the last couple I made . . . Something about sitting there shaving a block of wood is just a nice way to wind down after work, and it's nice to get something done in the hour and a half or so after work and before bed. I think I need to take up whittling.)

I've been using the same pencil-sharpener thing, although in the larger pegs I used on my workbench, I still shaved 'em down by knife a bit afterwards to make the taper longer. I need to get an old crank pencil sharpener though, when you're doing a batch of pegs, the twist kind is a pain.


Darn, now I just realized I could have chucked the peg in a drill and the sharpener in a vise and done it that way. Oh well, too late now!

[Chris Friesen]

I thought of exactly this elliptical sort of shape when I first heard about TFWW's pins. I was actually quite disappointed when I found out they were just oblique cones. I think the ideal for 1/4" pins would be a long taper from 3/16 to 5/16 over maybe a foot or so, but profiled as you show in your pictures. Drop it into the hole and it should naturally align itself with the offset and wedge itself in the hole before bottoming out. Then twist it 90 degrees either way to tighten up the joint. I bet it would work brilliantly.