Thumbnail dies

[jhnarial]

I am thinking about making a set.I don't have a lathe or a mill.I do have a drill press and a 4'' grinder and a die grinder.

Poor people have poor ways

I spent last night studying about them.I like Richards (The Rod Doc) design but most of the pictures have been taking down.

I would take any advice I can get.Whats the angle of the pin,what type of jig is needed to weld the square stock to the die.For a perfect line up.

Can I use mild steel?

Whats the best way to drill for the pin and do you just run a allen to hold the pin in.

I need to know more about the sweet spot (smile).

Also how much to radius on both upper and lower die.

Like I said I don't have very many tools but usually can make them work.I have a lot of practice making dew with what I have.

[Bob]

Originally Posted by jhnarial

I am thinking about making a set.I don't have a lathe or a mill.I do have a drill press and a 4'' grinder and a die grinder.

Poor people have poor ways

I spent last night studying about them.I like Richards (The Rod Doc) design but most of the pictures have been taking down.

I would take any advice I can get.Whats the angle of the pin,what type of jig is needed to weld the square stock to the die.For a perfect line up.

Johnny, I made mine at 17 degrees which seemed to be the consenus angle at the time. For alignment, make a fixture that holds both shanks parallel with a gap for the dies, tack the dies halves together and hold them in place and weld to the shanks. Don't bother with holes in the dies.

Originally Posted by jhnarial

Can I use mild steel?

Sure

Originally Posted by jhnarial

Whats the best way to drill for the pin and do you just run a allen to hold the pin in.

With the die halves tacked together, set them in your drill press at the angle you need and drill about half way into them right at the parting line. till your pin will fit. I fully welded the pin in and dressed it to a small radius, then polished them.

Originally Posted by jhnarial

I need to know more about the sweet spot (smile).

Also how much to radius on both upper and lower die.

I just free lanced these two things, started testing them once I got them blended but before polishing. You need to drop off the operator side of the lower as much as you can as well as the sides. The upper has to be close enough to the pin to smash the metal, but open enough above to let the metal gather. The upper side clearance can be kind of a loose fit to the pin. I made on on the mill and lathe, but you can adapt to fit you tools. Here's some pics of the build.

Bob

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[Bob]

Tried to add more, but came up with a blank screen. Center the pin on the parting lind at the corners of the smile. Here's the rest of the pics. You can see in the 2nd pic the upper is a little too close to the pin, at least I thought so. I reworked it to move it back a little. No pics of that.

Bob

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[Kerry Pinkerton]

Nice documentation Bob. Thanks.

Johnny, if you don't think you can do these on your drill press, I'll do the top and bottom, set the angle and drill/mill the hole.

You can weld the pin, stems, and finess the surface.

Won't be able to get to it for a couple, three weeks though. It usually takes me a week after I get back from Oblong to pay off the honeydo debt.

[jhnarial]

Thank you Bob.You have really helped me a lot.If you ever need anything please let me know.Bob those dies are some of the nicest I have seen.


Kerry I think I will take you up on that offer.Thank you.If you tell me what materials I need I will buy them and send them to you.

I think it will be hard radius the edges even with a grinder.

[Kerry Pinkerton]

I've got some stock. You'll need some stem stock and figure out a way to weld it and keep the dies square and perpendicular to the stems. I might have some round stock for the thumb.

Tim Doty has made a few of these also.

Originally Posted by jhnarial

...I think it will be hard radius the edges even with a grinder.

Doing the edge reliefs with a side grinder and flap disk should be easy. The area around the thumb you can do with a rattail file. You'll be amazed what you can do with a file.

[Barry]

Wow Bob - those dies look GREAT!!
Dies in the chuck? - is that how you polished them? Please would you be so kind as to give a little more detail on how you did it?

Originally Posted by Kerry Pinkerton

Doing the edge reliefs with a side grinder and flap disk should be easy. The area around the thumb you can do with a rattail file. You'll be amazed what you can do with a file.

A file is probably a much better bet to get a consistent and nicely blended radius. Check out bherman's '37 chassis build on MM for what can be done with a file
http://www.metalmeet.com/photopost/s...y.php?cat=3435

Thanks
Barry

[Sean]

That is great, I think I might have to build a set. What material did you make them out of Bob?

Next I'll just have to build something to put them in.

[Bob]

Thanks guys,

Barry, what I used the lathe for mostly was to radius the outside of the dies. I offset them in the 4 jaw till my hand drawn circle turning pretty true and kind of hokied in the radius. I don't have any setup to do a real radius. I then blended it with my flap sander to the top of the dies. Took them out and hand worked the female to make the blend radii to the relief. DA sanded both dies to 320 grit. At that point, I took the finish of the lower up through various grits to 2000 grit wet and polished it using the buff held in the lathe, holding the dies by hand.

After tigging the pin, I blended it with small cone shaped stones with my dremel tool. My dremel died in the process...they aren't very industrial. Again, I sanded the grinded areas up to 2000 grit wet and buffed. Though the mill and lathe were used, there was a lot of hand work done on them. I figured that at $750.00 to buy a set, I could spend some time making them nice.

By the way, I think I made these from 4130 that I got some small hunks of. I never heat treated them though.

If I was to do another set, I think I would use those little sanding cones that attach to a mandrel and are run with a 90 degree air motor for the small blend radii. The kind of things you would port and polish a set of heads or intake manifold with.

Bob

[tdoty]

Don't think TOO much about the radii. The only thing that really touches the metal is the base of the opening on the top die (as the metal is bent up), the top of the pin and the smile area.

Get the smile flat and parallel - possibly the hardest part. Everything else is either support or clearance.

I've made dies with nothing more than a die grinder, a drill press, a chop saw and a welder. Drill for the pin and then use the die grinder to open up the slot for the pin in the upper die. Drill the hole for the pin plenty deep, drive the pin in (press it a bit if you can) and then weld under the pin at the edge of the die. No need to weld all the way along the pin, except maybe the fact that it looks nicer. It takes a lot more work to clean up the welds around the pin and the potential for disaster is pretty high.

Mild steel works fine. I've used a fair amount of mystery metal making metalshaping tools. The edges can tear up lesser grades of steel, especially if the edges of the sheet aren't cleaned up properly. I've used 4140 too; pre-hard and annealed. It all works. The life of the tool depends on the care taken in its use. I usually just use a bolt shank for the pin.

Bob's dies are sweet! I, however, am generally in too much of a hurry to use the tools to spend that kind of time on surface finish. Might explain why my stuff is so ugly. Hit the sheetmetal with 80grit after the part is finished and no one will ever know. The bright, polished finish, however, plays a big part in keeping the dies from rusting. I buff mine up with a ScotchBrite pad from time to time (or a Norton BearTex).

Biggest thing is to dive in and not overthink it.

Tim D.