Exotic Wood Extension Question

staffwalker · Post by **staffwalker** » Mon Apr 23, 2007 11:28 pm

Folks, I need to ask a very basic question.

Like several of you here, I don't own a lathe, so everything is done on a drill press. I have had rather good success with adding briar extensions without the benefit of a lathe and without having to "file"

) tenons.

The basic method I have used is to face the stummel with a 1 inch forster bit, drill the mortice, and the draft hole, while the block is still clamped. To add an extension I face both sides of a piece of scrap briar, drill through it with the same bit I used to drill the mortice, cut and prepare for glueing a piece of delrin (thanks to Kurt and his delrin instructions) which is long enough to bottom out in the stummel mortice and extend upward into the extension. I leave space above the delrin in the extension thus forming a new mortice in the extension. In this manner I don't have to cut a tenon on the piece I use for the extension while still giving me a very strong bond where the extension glues onto the stummel. I have completed several in this manner using briar and never has the extension cracked or split when inserting the delrin.

I throught I could do the same with exotic woods but such has not been the case. I have tried two times with mahogany and two times with yellow wood. Each time the wood split when I attempted to press the stem delrin tenon into the wood. The first time with each of the woods, I drilled the extension piece parallel with the grain, inserted the delrin, glued it and after the drying period attempted to insert the stem into the new mortice. The wood split with the grain. After each split (with both types of wood), I cut another piece, repeated the process but this time drilling my mortice size hole across the grain. In each case, with the grain and across the grain, the wood split. At this point, prior to sanding, the extension block measured approx. 3/4 x 3/4, so it wasn't a case of it splitting because I had sanded it too thin.

Is it not possible to use exotic woods to accept the stem tenon? The bit I am now using gives me a tight/snug delrin tenon to mortice fit. To shop for another bit slightly larger than the one I use now for the delrin would make a slightly larger mortice hole and prevent the wood splitting but I would no longer have a tight fitting mortice/tenon.

Any help or thoughts would be appreciated.

bob gilbert

Tano · Post by **Tano** » Tue Apr 24, 2007 12:59 am

Bob,

I'm assuming that the mortise you are creating is lined with delrin, including the extention especially if the wood you are using is not very hard.
Also I always end up sanding the tenon so that I don't have to force it too much.
I've also found that delrin and drill bits aren't always the same diameter, even if they were you would have to apply some force to join them together and guess which wall is going to give out first?
Maybe some of the more experienced makers could add their comments.

Frank · Post by **Frank** » Tue Apr 24, 2007 3:47 am

@Bob
I have used hardwood to extend shanks on a couple of basket pipes that had split shanks.
This is an example of one I did with a laminated extension. I'm not sure what the light coloured wood is, but the dark wood looks to be Padauk:

The stem/tenon are vulcanite.

I suspect that the briar wood has a stronger grain fibre bond than the harwoods you are using, thus the briar is less likely to split, especially if the shank is non straight grain.

If the wood is splitting, the problem is an oversized tenon. The solution might be to sand the delrin tenon down just a tad so you get a snug but not tight fit. Mind you, nylon is a crappy material to sand.

An alternative is to use a stabilized wood. I have some stabilized spalted maple I intend to try next, just as soon as I can get time away from my knives.

kbadkar · Post by **kbadkar** » Tue Apr 24, 2007 11:54 am

Rather than sanding down your delrin inserts, you can also lightly sand the ID of the drilled through extension... that would certainly be best for the removeable stem end, since the delrin stem insert will be seen. You can sand the drilled through extension with a smaller drill bit with sandpaper wrapped around.

Post by **KurtHuhn** » Tue Apr 24, 2007 2:36 pm

Bob, do you have a picture of your atempts and the results? To date I haven't had a problem with extensions - except that one that I tried to use with a military-type stem. It sounds like your fit may be too tight.

In order to keep the shank extension or stem ring from splitting, I always drill it with a bit that has a slightly larger nominal diameter than the one I use to drill the mortis on the briar. Also, I have moved away from using shank extensions as an integral part of the mortis (with the exceptions of the bamboo). I leave a short tenon of briar outside the mortis that the shank extenstion slips onto. When it gets epoxied, the epoxy will also help strengthen the assembly.

staffwalker · Post by **staffwalker** » Fri Apr 27, 2007 9:04 pm

Sorry to take so long to get back here but I have been away from the computer for a week. To answer your question, Kurt, no I don't have any pics. I threw the failed attempts away.

After futher consideration I have decided to forego exotic wood extensions until I have a lathe. The time required to do it with only sandpaper and a drill press just isn't worth it. Thanks to all who tried to assist me with my question.

bob gilbert