Bent/Curved-Shank Pipes: Drilling Draft/Smoke Holes, Etc.

[sumusfumus]

Being new to this forum, I have no idea if these questions were already addressed in the past. I tried to do a forum search, but came up with nothing, or at best, threads, with deleted photos, which makes these past threads IMO...totally useless. Aplogies for any redundancies.
So, I'll ask. Within the sketching process of drawing and designing a pipe profile, the designer needs to figure out how deep the tobacco chamber will need to be drilled and where, and also needs to predict and lay out smoke hole depth and locations in relation to the tenon/mortise joint within the shank. I get, and understand, I think, this step in the design process....but I am very confused when it comes to the actual drilling of draft/smoke holes in sharply bent pipes, or pipes having curved shanks like, for example a Danish-style free-hand. Accuracy when drilling is needed here, or, the pipe goes into the trash bin. Expensive mistakes and plenty of cuss words are the result.
It seems, (under ideal conditions), reasonable to assume that drills can cut only a straight hole, and to a predictable depth. Drills can't be made to generate a curved hole that can follow the center-line and match the curve of a pipe's shank. A steel drill isn't flexible. When making a pipe, the path of the drilled draft-hole will come dangerously close to a shank's top-walls when drilled to intersect with the bottom of a smoke-hole. Envision the tobacco/draft holes in a full-bent pipe.
I understand -from watching at all the badly made, You-tube videos- HOW smoke-holes are drilled but I cannot find one video that explains how to design, predict, and plot the path of the drilled holes that are needed to make a bent pipe having a correctly centered draft hole that intersects perfectly with the bottom of a tobacco chamber.
Does anyone even understand what I'm trying to ask? I'm so confused! I'm not even sure how to ask my questions, it's so complicated. Trust me....I know my way around a wood and metal shop. I've been drilling holes in wood/metal for over 55 years....and yet, I still cannot generate a drilled hole that will follow a curved path as it moves down the center-line of a curved section of wood or metal....like on the shank of a bent/curved pipe. Curved, one-piece shanks, especially, have to be a PITA to drill correctly.
Get my head straightened out, please. Are there methods for drilling curved holes? Flexible drills? Drilling techniques for generating curving holes? I need some schooling.
Frank

 

[georged]

Good questions, wrong forum.
Try this one:
http://www.pipemakersforum.com/forum/

 

[nevadablue]

I have seen youtube explanations on how to lay out the design. Once the design is laid out, and the stummel roughed out, one maker drills a slight hole on the far side of the bowl from the shank, in line with the draft hole. This shallow hole serves as a center point for a lathe center. He then puts a long draft hole bit in the lathe chuck, holds the stummel in his hand, with the lathe center in that alignment hole and pushes the stummel onto the drill bit with the tailstock. Seems to work fine. I will try to find that video for you.
Here it is, it is a long video, but IMO, a very good overall explanation.
https://m.youtube.com/watch?v=V49-YGYLzNg

 

[sasquatch]

There are methods for drilling curved holes, but only a very few pipes include them. One of the downsides is usually that the hole size is fairly large do to the apparatus involved - 3/16" is the smallest I've seen (Ser Jacopo uses this fairly frequently).
But most of the pipes you are looking at are drilled straight, with the carving of the shank being curved.
So here's a very bent pipe, lots of curvy, and a rough idea of how the drilling inside is done in straight lines all the same.

 

[sumusfumus]

Thanks for some answers. Actually, I am not yet a member of the Pipe Makers' Forum. Maybe I should just join, and go directly to a source for some detailed answers, although, I'm not even sure that I'll make more than 5-6 pipes....unless I really love the crafting process.
@ sasquatch:

A perfect representation of what I need. A picture IS worth a thousand words. On graph paper, I have drawn out a pipe design much like the pipe in the above photo. My main areas of confusion have been somewhat cleared up. The invisible stem hole (at the tenon-junction in shank, where it enters pipe mortise) is straight at this point, and it must meet the angle-drilled draft hole perfectly, or a pipe cleaner will not be able to be inserted into the bottom of the bowl for cleaning. This alignment can be problematic. The smoke hole, as drawn, is slightly less than 90 degrees to an imaginary center-line running from top to bottom of tobacco chamber, and when this smoke-hole line is extended towards the stem-end of the shank, it would exit the shank at or near the mortise wall. When you factor in the length of the tenon, these two holes need to at intersect exactly, or problems with inserting the pipe cleaner will arise. If the tobacco chamber was drilled less deep inside the bowl, let's say by 1/4"...the draft hole (red line) will pass dangerously close to the top wall of the shank where bowl and shank meet. Also note that the tobacco-chamber wall (on the nose-side of the bowl) is also thinner than the wall on chamber-wall on the far side of the bowl which is thicker....again, the problem area is where the bowl/shank blend into one another.
Without the possibility of easily of drilling a "curved" hole, certain designs of bent pipes can only be made if these necessary holes run close(r) to the top of the shank. Any miscalculations, misalignments, or the wandering of a drill bit off center, will result in a scrapped pipe.
But with your above photo-diagram being marked with chamber and draft hole placements, and by watching the video(s), my concerns have been verified.
My thoughts about these problems.....When trying to make a bent pipe, first, I will make a rough model of the pipe, and drill all the necessary holes, working out all the set-ups, and tooling before any machining of a good block of briar starts. Better to scrap a piece of cheap pine that to throw an expensive hunk of briar against the shop wall. I'm thinking that a good bench-top milling machine would have far more use when cutting these precisely located holes than a sloppy, less rigid, inaccurate, drill press. You can do almost every operation needed to make a pipe in a milling machine, especially precision location of critical holes. But then again, I watch videos of guys making pipes, by hand, drilling holes exactly where they need to be, without any special tooling. Go figure. I don't think I could do it.
Thanks for the video link, and the diagram of the bent pipe. Both helped.
Frank
Happy Labor Day! Enjoy what's left of the holiday.

 

[sasquatch]

Yeah, so the short answer is, design and build your pipe very carefully.
Helpful huh?
(I should get paid more for this)

 

[georged]

(I should get paid more for this)

Hey man, I tried. :lol:

 

[pitchfork]

http://www.pipemakersforum.com/forum/viewtopic.php?f=18&t=6720&sid=e9fbcef7bd32c3dd67030092dc308d77
http://pipesmagazine.com/forums/topic/defective-dunhil

 

[sasquatch]

Ahhhahaha I forgot about that contest thread. Too bad photobucket has mangled the pic links. It was really, really fun.

 

[jpmcwjr]

"....plus ça change, plus c'est la même chose." From that thread, applies to much today.
I'd still love to see a small drill that can do custom curves.

 

[sasquatch]

Yes, if I could add one unicorn tool to my shop, that would be it.

 

[sumusfumus]

So studying the interesting posted photos of bent pipes tells me that there really is no way to avoid having a draft hole coming close to the top wall of the shank when connecting the tobacco hole to the draft hole. In addition, there looks to be an optimum length of the tenon if stem hole and draft hole are to intersect at that "sweet spot" for pipe cleaner insertion without binding. All the holes are interrelated, and changing one hole leads to changing the position of the others.
Thanks for all the help, diagrams, links, suggestions, etc.
Frank

 

[sasquatch]

Yes, all inter-related, and some of us spend quite a bit of time finding a set of geometry and we do it again and again. I have one "standard" Hungarian/Oom Paul template that I use 90% of the time for those pipes, cuz it's just right.

 

[wayneteipen]

Designing bent pipes is all about compromises.

 

[newbroom]

I seem to recall reading about and watching a video of a Japanese Pipe maker who had figured out a method of drilling curved airways without 'steps'. I'm not sure what his name was.

At the time, I was just beginning to 'pipe up' but I recognized this as quite an achievement.