Drilling Bent Pipes-Help!!!

[Progcat]

Hello Tyler and all,

I have a question about drilling half or three quarter bent pipes. I have folowed the steps outlined in this web site i.e. I use the 5/32 end mill to get a pilot hole, drill the airhole, position the mortise, square the shank, the then drill the mortise. I have tried this and I believe it to be the correct procedure. However, I believe I am making mistakes in the process because the air hole always seems to be high in the mortise and begins too close to the end of the mortise-like its on the roof of the mortise. The draw seems Ok if I use a burr to smear down the airhole. But, it just doesn't look right to me and especially not like some of my professionaly made bents. I do all my drilling on a metal working lathe and do not plan to return to a drill press. Any ideas as to what I may be doing wrong. Many thanks in advance


Progcat

Timothy Hynick

[Tyler]

There are a few things you can do to have the draught hole closer to the center of the bottom of the mortise.

1. Shorter mortise/tenon
2. Larger diameter mortise
3. False Mortise -- where you make a large mortise that is then lined with briar or another material to reduce the size of the mortise to a more normal diameter.

Of course, combinations of all of the above allow for even more wiggle room. If this isn't clear, feel free to ask clarifying questions.

Tyler

[JHowell]

I would just add to Tyler's suggestions that positioning the airhole high in the mortise and lowering it with wood removal to improve the draw/pipe cleaner passage is not at all unusual, even among high end makers. Almost all the bent pipes I've seen, even from the most illustrious makers, use this technique to some extent. It's possible to make it look bad, but cleanly done it seems to raise few objections.

[ToddJohnson]

If you're hand cutting stems, you can also put the draft hole through the stem off center in the tenon. Align a high draft hole in the mortise with a high draft hole in the tenon and you have a perfect connection without the need of ramping the draft hole to allow pipecleaner passage, etc.

Todd

[RadDavis]

Hi Todd,

Could you explain how to do that?

My mind is boggled.

Rad

[JHowell]

I don't know how Todd does it, but I'd shim the rod in the chuck so it's off-center to drill -- before turning the tenon if it's 1-piece, after gluing the tenon if it's Delrin. That would put the exit hole off-center too, so maybe that's not the way to do it. I don't know how many people are like me, but the way I clench a pipe it works best when the stem is rotated off-center about 5 degrees, so I try to make round-shanked pipes so that the stem can rotate without discontinuities. In that case, an off-center hole in the stem might not work, but if it's the kind of pipe where the stem can only go one place, it sounds like a neat trick. I've filed a relief in the top of the airhole in the tenon before so that the holes matched, FWIW, but I can't say that it made any difference. Maybe yes, maybe no -- too small a sample.

[KurtHuhn]

I face the shank first, then drill the mortis, then drill the airway. That way I can be dead sure the airway is in the center of the mortis. No guesswork.

[RadDavis]

Hi Kurt,

That works fine for fairly straight stummels, but when they are bents, you have to drill the airway at a shallower angle than the mortise in order to hit the bottom of the tobacco chamber.

The bigger the difference in the angles, the higher up from center on the mortise floor you have to begin the drilling for your airway. A larger and shorter mortise can alleviate this somewhat, but I've seen Oompauls that had the airway hole start in the upper mortise wall rather than its floor.

Without some removal of wood to bring the beginning of the hole down to the center (ramping), a pipe cleaner won't pass. If the tenon goes all the way to the mortise floor on this type of bent, sometimes air won't even pass, since the tenon covers the airway.

Rad

[ToddJohnson]

I don't know how many people are like me, but the way I clench a pipe it works best when the stem is rotated off-center about 5 degrees, so I try to make round-shanked pipes so that the stem can rotate without discontinuities. In that case, an off-center hole in the stem might not work, but if it's the kind of pipe where the stem can only go one place, it sounds like a neat trick.

Jack,

This is certainly not something I take into consideration. I assume that when someone is smoking a bent pipe they have the stem properly aligned. If the stem/shank are round then the stem can be rotated without any mis-alignment, but this is purely an aesthetic/tactile thing. I would imagine however that five degrees wouldn't make a difference in whether the holes were well aligned and the pipe took a pipecleaner.

One of the best ways to align the draft hole in the center of the mortise on a bent pipe is to cut a groove in the bottom of the mortise so that the draft hole can be drilled at the same angle but enter the mortise at its center. Once the draft hole has been drilled, then go back and square the shank removing most of the groove. Use a countersink around the mortise to remove the rest of the groove. I usually only have to resort to moving the hole in the tenon on pipes where the shank is very long and very bent.

Todd

[KurtHuhn]

Hi Kurt,

That works fine for fairly straight stummels, but when they are bents, you have to drill the airway at a shallower angle than the mortise in order to hit the bottom of the tobacco chamber.

The bigger the difference in the angles, the higher up from center on the mortise floor you have to begin the drilling for your airway. A larger and shorter mortise can alleviate this somewhat, but I've seen Oompauls that had the airway hole start in the upper mortise wall rather than its floor.

Yes, exactly. Which is why I drill the mortis first. I've not missed yet (since using this technique), and my pipes will pass a cleaner with no problem - even fairly deeply bent ones. When I've got the mortis drilled, I can align the airway bit to where the bottom of the tobacco chamber will be, and align the mortis floor to be intersected dead on at the same time. Easier to do on a lathe, but not impossible on a drill press. Yes, sometimes a larger mortis is necessary, but I usually figure that out while laying out the engineering on paper or the side of the block.

[RadDavis]

I drill my mortise first also, and I've tried drilling from the center on a full bent, but the bottom mortise wall kept getting in the way.

Todd, your method of cutting a groove to allow the angle and then going back and getting rid of the groove sounds like it's worth a try.

Would you end up with a pretty short mortise and tenon?

Rad

[ToddJohnson]

Todd, your method of cutting a groove to allow the angle and then going back and getting rid of the groove sounds like it's worth a try.

Would you end up with a pretty short mortise and tenon?

Rad

No, not really. I tend to use a slightly larger and shorter tenon than you would find on most European pipes, but nothing really out of the ordinary. I start out by drilling it a little bit deep and then cutting the groove. That way once you've removed it you end up with a mortise of more or less standard depth.

Todd

[RadDavis]

Thanks, Todd.

I'll give it a shot on my next full bent!

Rad

[Progcat]

Hi Everyone,

Thank you so much for your replies. You guys have great ideas and I have already tried the larger diameter mortise with good results so far on a half bent pipe. I would like to try drilling the mortise first and then the airhole. But I worry that if the mortise is at a steep angle the drill bit will wander if it doesn't hit the edge of the mortise right on. I though about using Tyler's suggestion of the 5/32 end mill on the inside of the mortise first to drill a pilot hole first. Of course, this would require a larger mortise to alow the end mill in. I was thinking of giving it as try. But as I said, your suggestions have already proved helpful

Tim (Progcat)

[JHowell]

Jack,

This is certainly not something I take into consideration. (snip)

One of the best ways to align the draft hole in the center of the mortise on a bent pipe is to cut a groove in the bottom of the mortise so that the draft hole can be drilled at the same angle but enter the mortise at its center. Once the draft hole has been drilled, then go back and square the shank removing most of the groove. Use a countersink around the mortise to remove the rest of the groove. I usually only have to resort to moving the hole in the tenon on pipes where the shank is very long and very bent.

Todd

Heh, heh, everyone has a different hangup. So, when you go back to shorten the shank to remove the groove, do you use an aircraft counterbore? I have to remember that you're handholding the stummel for all of this, but you'd still need a pretty good pilot to avoid misalignment between the mortise bore and face.

[ToddJohnson]

Jack,

This is certainly not something I take into consideration. (snip)

One of the best ways to align the draft hole in the center of the mortise on a bent pipe is to cut a groove in the bottom of the mortise so that the draft hole can be drilled at the same angle but enter the mortise at its center. Once the draft hole has been drilled, then go back and square the shank removing most of the groove. Use a countersink around the mortise to remove the rest of the groove. I usually only have to resort to moving the hole in the tenon on pipes where the shank is very long and very bent.

Todd

Heh, heh, everyone has a different hangup. So, when you go back to shorten the shank to remove the groove, do you use an aircraft counterbore? I have to remember that you're handholding the stummel for all of this, but you'd still need a pretty good pilot to avoid misalignment between the mortise bore and face.

Nope, I have various diameter steel tenons that are inserted into the mortise. The tenons, which are stair-stepped (think rod stock with a tenon cut on it) are inserted into the headstock of the lathe. Then the face of the shank is squared with a cut-off tool. This is the way I square every shank on pipes I drill by hand.

Todd

[JHowell]

Nope, I have various diameter steel tenons that are inserted into the mortise. The tenons, which are stair-stepped (think rod stock with a tenon cut on it) are inserted into the headstock of the lathe. Then the face of the shank is squared with a cut-off tool. This is the way I square every shank on pipes I drill by hand.

Todd

Well, I'll be dipped. Speed? I'm just imagining some of your shapes flying around, attached to the lathe only by a friction-fit tenon. Never a dull moment in the Johnson shop.

[KurtHuhn]

That was my thought too - glad I wasn't the only one that immediately was horrified at the potential destruction of briar....

Other than that, it sounds like great way to make the shank face square on pipes that are shaped before drilling. Thats a great tip! Until now I've been carefully sanding the face square - but that takes forever.

[jeff]

I'll chime in on this. Todd taught me this method this summer and after having learned and tried several other methods prior to and since learning his I can honestly say that the method described above is in fact the fastest and most accurate way that I've tried to this point. It takes only a minute or so and is very accurate. I've never had to take sandpaper to the shank face with this method, so it's a big timesaver for me. But, I'm sure there are plenty of others out there who have other tried-and-true methods that work just fine for them.

Jeff

[ToddJohnson]

Nope, I have various diameter steel tenons that are inserted into the mortise. The tenons, which are stair-stepped (think rod stock with a tenon cut on it) are inserted into the headstock of the lathe. Then the face of the shank is squared with a cut-off tool. This is the way I square every shank on pipes I drill by hand.

Todd

Well, I'll be dipped. Speed? I'm just imagining some of your shapes flying around, attached to the lathe only by a friction-fit tenon. Never a dull moment in the Johnson shop.

Yeah, I don't reccomend it unless you've seen it done and your tooling is set up for it. I've never had anything fly across the room, but I have run into a snag twice. There are a couple of shapes that I've actually had to take to a friend's shop to square because I don't have enough clearance over the sledge. Fortunately my friend runs facility services at Yale, so I have access to multiple tool-room lathes and other equipment. Anyway, it's a great method provided your tools are sharp.

Todd