pipemakersforum.com

Howdy folks,
So, I'm armpit deep in PITH practice.
Just about have my first attempt at a bamboo shank wrapped up
and it's gone well. I used a straight piece of bamboo, and was able to drill all the way through
so both ends were on the same axis. I'm using a wood lathe, and facing with a forstner bit.
Having both ends on same axis allowed me to use the drill bit as a mandrel in the tailstock
and face the opposite end with the forstner in the head stock.

Now, I'm trying to wrap my head around drilling and facing a piece of bent bamboo using the same
set up. Drilling I can do, it's the facing I can't quite figure out.

One thought I had was using something like this:

http://www.woodturnerscatalog.com/p/16/ ... -Piece-Set

used for facing pen blanks. I'm using 1/4" OD ss tubing, so if I drilled at 9/32,
that will accomodate for the 7mm mandrel in the barrel trimmer. That's a little bigger than
the 1/4 drill, but only 1/64" all around. I figure I could take up that slack with eboxy, if the ss tube was
too loose....

Am I way off here? Anyone have any other suggestions for facing bent bamboo on a wood lathe?
(ps. I don't have pin guages, which MIGHT help?)

Thanks in advance,
Jeremy.

I've used a piece of delrin successfully the same way as a pin gage is used. Results may vary.

I use pin gages. They are well worth it. You can indeed turn delrin down and use that, but I don't think you'll get as precise of a result. Delrin isn't as rigid as steel and is more likely to flex.

I agree with Jeremiah, actual pin gages are superior. I plan on getting a set as soon as I can afford it. For now though, I'm stuck improvising.

Okay, so let's say I have a pin guage, or a delrin rod turned to size.... help me with the next step. pin guage in the head stock, chuck up the bamboo, and use a turning tool to approximate a 90 degree face?

You're going to want to face the bamboo on the pin gage side, not the opposite end. You definitely want a 90° angle from the mortise.

If you're working on a wood lathe, a parting tool would be my choice for this step. I'm new at bamboo as well though, so someone chime in if I'm totally off base here.

sandahlpipe wrote:You're going to want to face the bamboo on the pin gage side, not the opposite end. You definitely want a 90° angle from the mortise.

yes, yes, I get this... but how do you insure 90 degrees? I understand the value of a metal lathe here, but it will be a while before I can afford one....

mightysmurf8201 wrote:If you're working on a wood lathe, a parting tool would be my choice for this step. I'm new at bamboo as well though, so someone chime in if I'm totally off base here.

ah! okay this seems good. is it possible to square my tool rest parallel with my headstock then hold a square to the tool rest, and test my parting tool against the square? this way I can get at least close to 90?

You'll be better off eyeballing it at first then checking with a straight edge after the cut. You'll be able to judge if it's high on the edges or in the middle and make a very small adjustment cut accordingly. If you can't get 90 exactly, a VERY slight undercut is better.

Jthompson1995 wrote:You'll be better off eyeballing it at first then checking with a straight edge after the cut. You'll be able to judge if it's high on the edges or in the middle and make a very small adjustment cut accordingly. If you can't get 90 exactly, a VERY slight undercut is better.

now we're talking! thanks, this is very helpful!
Jeremy.

Yes. If you're using a wood lathe, a parting tool is your friend. Face it then test the fit.

I think you've figured it out but to summarize, you're putting the bamboo on the mandrel what ever it may be. Get as tight a fit as you can without splitting it (duh). Move your tool rest to the left of the end you are going to trim. You've obviously got to get everything out of the way of the spinning bamboo. Turn by hand before hitting the power to make sure all is clear. Watch your rpm so you don't cause vibration or throw something. Yes, a very sharp parting tool is the weapon of choice here with very light cuts. Like the man said, square or slightly concave.

oklahoma red wrote:I think you've figured it out but to summarize, you're putting the bamboo on the mandrel what ever it may be. Get as tight a fit as you can without splitting it (duh). Move your tool rest to the left of the end you are going to trim. You've obviously got to get everything out of the way of the spinning bamboo. Turn by hand before hitting the power to make sure all is clear. Watch your rpm so you don't cause vibration or throw something. Yes, a very sharp parting tool is the weapon of choice here with very light cuts. Like the man said, square or slightly concave.

Excellent! Very very helpful, thank you gentlemen!
I'll give it a spin (har har) in the morning, and report back.

cheers,
Jeremy.

Concave on bamboo isn't recommended. Since bamboo isn't completely round, you run the risk of a slight gap where the radius to the center of the mortise is shortest. Sure, that's a really picky detail, but in my opinion, it's the details that make or break a bamboo shank.

sandahlpipe wrote:Concave on bamboo isn't recommended. Since bamboo isn't completely round, you run the risk of a slight gap where the radius to the center of the mortise is shortest. Sure, that's a really picky detail, but in my opinion, it's the details that make or break a bamboo shank.

Jeremiah is correct. If the two mating pieces are not both truly round there will be a gap, tho ever so slight depending on the degree of "concaveness"?? (degree of being concave?? Hell, I don't know). The epoxy should fill any such gap.

I face all my shanks on a pin gage with the Easy Wood Tools square cutter. Super easy to get a straight cut the first time. They make a small EWT you can pick up for $60 at Woodcraft (you can find it cheaper other places...). It is all I use to face shanks and cut tenons.

I have yet to try a bamboo shank, but as for the turning part, I would use a skew. But that's just me. I have some bamboo, so maybe I need to give it a try. In any case, good luck with it.

Also, don't spin the bamboo too fast. Bent pieces can flex (center of mass isn't spinning on the spindle axis) and cause a gap on the mating faces. Just make sure you knock off the shoulder on the bamboo mortise. That will help with gap issues without providing you with the little gap Jeremiah is talking about.

Make sure your tools are razor sharp too. Otherwise the bamboo will tear off instead of shave off.