making a military style bit

pennsyscot · Post by **pennsyscot** » Tue Jun 23, 2009 1:44 pm

I can't find any information on how to make a military style bit. I assume that there is an interfernce angle between the stem and mortise, does this angle need to be accuratley cut? How do you cut the taper in the mortise? Should I use the compound on my metal lathe to turn the taper on the stem? I was thinking about tapering a drill bit with a sanding disc and using that to drill the mortise, but how can I grind an accurate angle on the drill? How about making a cap for the shank, has anyone tried turning one from metal? Any advice or suggestions will be appreciated. thanks, Scot

Olivier · Post by **Olivier** » Tue Jun 23, 2009 2:39 pm

Never made a stem like this but I turn my own caps. Basically it's made from solid roundbar. I first drill a hole of the same diameter as the tenon right through and then open it up with a boring bar to the diameter of the shank. It is wise to chamfer the outer edges of the shank slightly to ensure a nice fit. If you are careful enough you should be able to get the walls down to less than 1mm thick. I have used brass, aluminium and stainless steel without any trouble. Titanium should also work well. Brass is a bit heavy and tarnish easily. Stainless is also heavy but alluminium weighs almost nothing.

Sasquatch · Post by **Sasquatch** » Tue Jun 23, 2009 7:49 pm

The mortise and tenon have to be cut very accurately, but really, the tenon can be a bit convex and still work - you need the thing to hook up at the bottom of the socket and somewhere higher up. I have a Peterson that wiggles because the top does not flare out enough, so the thing just kind of jams in in one spot.

I have been curious about using a tapered plug-cutter for this kind of tenon, but as you notice, finding a matching mortise cutter is not too easy.

Frank · Post by **Frank** » Wed Jun 24, 2009 2:23 am

Disclaimer: I have no idea if this is feasible, just a procedure that occurred to me.

If you have a metal lathe that can hold the stummel, and is equipped with a compound angle turret, drill your mortise hole to the smaller diameter, then, using a very small cutter, feed it into the mortise at a small angle to get the taper. You can use that same angle to cut the tenon on the stem.

Post by **KurtHuhn** » Wed Jun 24, 2009 8:10 am

Jack and I discussed this once, though I can't recall if it was on this forum. He suggested a tapered reamer with the right angle would probably work great. Incidentally, Morse Taper 0 is about the right size and angle - though you may have to cut off a bit of the tip to keep the mortis within reasonable length.

Essentially you drill the mortis using a regular drill bit, then you ream the mortis to a taper. When making the tenon, set your lathe's compound slide for a corresponding angle, and cut it to the right diameter. A MT0 is about 1°29' (or a smidgen under 1.5 degrees).

Note, I have not ever tried this. If you do, please report back.

kbadkar · Post by **kbadkar** » Wed Jun 24, 2009 1:07 pm

I remember a pipe tooling/supply website that was selling a military stem set-up - both a mortise and stem cutter, but I can't find it now. I spent a good hour yesterday poking through all my favorite links, but I might not have saved it. I'll post the link if I find it.

FredS · Post by **FredS** » Wed Jun 24, 2009 6:06 pm

Back in my toolmaker days, we considered anything less than 3° to be a "locking taper". So, if you try this, don't go more (or less depending how you look at it) than 3°, or else you won't be able to get the stem to "lock" in place. Also, I would suppose that if you go less than 1°, you may have a hard time getting it "unlocked".

kbadkar · Post by **kbadkar** » Wed Jun 24, 2009 6:28 pm

Ah, ha! It was Ken Lamb's website.

http://www.lambpipes.com/pipemakingtools.htm

Scroll down about 2/3rds and he's selling the 1-1/2 deg. tapered mortise cutting bit for $100 and a matching tenon cutting bit for $125, or the set for $200.

Looking at the picture, I'm not sure how the tenon cutter works?

pennsyscot · Post by **pennsyscot** » Wed Jun 24, 2009 7:14 pm

Thanks for the great suggestions. If I can find a cheap chinese MT reamer I think I'll try that first. No sense grinding up an expensive tool. If that dosen't work I'll try chuckin the stummel and using the compound. I appreciate the Ken Lamb link but 200 is a little pricey for me. Should I cut the mortise and tenon at exactly the same angle, or should the stem have a slightly larger angle? I think the difference in angle may be needed so that the stem jambs up tight. My peterson leaves a narrow ring on the stem. thanks, Scot

ToddJohnson · Post by **ToddJohnson** » Wed Jun 24, 2009 10:09 pm

Three degrees is standard, and yes, the compound slide is the way to go. You can also cut the taper in the mortise from your tool post using a boring bar or similar such setup. For the silver cap, you'll need a mandrel, some heat and a hammer. The mandrel and the briar shank will need to be a near identical match. The way this is typically done is that the mandrel is made, and a cutting tool for the lathe is created with an identical profile. Then the tool is used to shape the end of the shank with a shoulder of nearly identical depth to the thickness of the silver stock. 1 mm is fairly standard amongst the Danes. I don't ever do any silver work on my pipes anymore because it's just one of those things that doesn't really fit my style. I've done it in the past, but it was a stage I sort of moved through. When done well, it can create a truly lovely effect. Best of luck.

TJ

pennsyscot · Post by **pennsyscot** » Thu Jun 25, 2009 9:09 pm

Todd, thanks for the great info. If I understand correctly, I should turn the mandrel to the same shape as the shank will be, then form the metal to the mandrel by applying pressure while spinning on the lathe, similar to the way a silversmith would spin a cup. I assume that the mandrel will need to be turned from steel. Am I on the right track?

Post by **KurtHuhn** » Thu Jun 25, 2009 9:15 pm

Check out metal spinning. The procedure can be very similar. I've only done this a couple times, and it was hairy all the way, and never with silver (only copper and brass). It is fun, but the skills are entirely different from actually turning wood on a lathe.

For the mandrel/form, I used some rock maple that I picked up on ebay, though you can use steel or any sufficiently hard metal. You can even use aluminum,which you can also shape on a wood late with sharp tools.

All normal disclaimers apply - in short, don't do this unless you expect (and would like) to die.