pipemakersforum.com

Hello Friends,

I wanted to share some information with everyone and in particular those that are new to the craft. I have come across many pipes from new pipemakers in the past few years, and the connection sometimes will become loose. There are many reasons that may cause this to happen, but there are a few simple things that can be done to reduce the chance.

A few things that will cause the tenon to become loose:
1. Unstable material
2. Moisture or lack of
3. Wear from Friction

The number one cause is Unstable material, and this can be either the briar or other material that is the mortise, and the tenon if you are using vulcanite or plastics. If you use delrin/acetal rod, you will not have to worry about stabilizing the tenon.

Some really easy ways to stabilize the mortise or tenon can be done very quickly, and your customers will rarely have a pipe that develops a loose fit.

Stabilizing the mortise:
1. After you drill the mortise, use pin guages to stretch it out just a little. Do not put one in that is too tight.
2. Use a thin layer of either carnuba wax or shellac to line the interior of the mortise.

This will prevent the mortise from changing shape too much from moisture, and if you use a little wax on the inside it gives it some lubrication that will reduce friction.

Stabilizing the tenon:
1. before you make your final cut on the tenon, heat it up with either alcohol flame or heat gun and let it cool to room temperature.
2. Add some carnuba wax to the tenon after it is finished.

After the shaping cuts to the tenon, it will usually be larger from heat expansion. Heating and slow cooling, will return it back to its normal shape and relieve tension on the joint. The wax is for furthur lubrication to prevent excess friction.

Please discuss and comment. This is what I have learned from teachers, peers, and my own experience. I am sure there may be something better or alternative that can be done.

Best Regards,
Premal

Thank you for sharing that with us!

Cutting tenons I keep a little bottle of soapy water handy - a few drops keeps everything cool. As you say, Premal, if you heat it up, then a day later the thing doesn't fit right.


If I have briar that I think is maybe not quite as dry as I'd like, I'll drill the block and put it on a shelf for a week or two - let it dry out some more, change shape if it is going to. Then when I fit the stem, it is less likely to get too tight or two loose.


In some senses, there's only so much a guy can do - very extreme conditions will make it so that a tight fit from the factory gets loose, or worse, cracks on arrival/acclimatization at the destination. Delrin obviates some of this, but it's still possible that the briar moves more than the tenon material can accomodate, and then someone will have to add wax or do a little sanding....

I ran into a problem a couple days ago with delrin. My understanding is delrin does not expand like vulcanized rubber. I drilled a stummel as usual and made a tenon with 5/16" delrin rod. The past 3 or 4 times I did this I had an excellent fit but for what ever reason the tenon fit loose this time. I know you can replace the delrin but if the mortise is already drilled for a 5/16" tenon you wouldn't be able to use the same size. Could you go the next size up and sand it down? Or, would the shellac in the mortise help provide a tighter fit?

I have had acetal rods that were just a little undersized. Not sure why. It happens. Did you use a new drill bit to drill the mortise?

Everytime I order from a tool supplier, I always order a few delrin/acetal rods because of some inconsistancy. I throw away quite a bit. It is usually cause some will have machine marks in them, but I have noticed some have not been the correct size. I would suggest drilling at a little under 5/16 and then using a slightly undersized reamer. 5/16 = 0.3125 Drill at .3100 or smaller Ream at 0.3120 This will give you a perfect fit everytime. I would not suggest sanding delrin; it is some pretty nasty stuff when sanded. If you do not have a metal lathe to go up to the next size and cut it down, I would suggest to use a little shellac and wax in the mortise to tighten it up.

hawky454 wrote:I ran into a problem a couple days ago with delrin. My understanding is delrin does not expand like vulcanized rubber. I drilled a stummel as usual and made a tenon with 5/16" delrin rod. The past 3 or 4 times I did this I had an excellent fit but for what ever reason the tenon fit loose this time. I know you can replace the delrin but if the mortise is already drilled for a 5/16" tenon you wouldn't be able to use the same size. Could you go the next size up and sand it down? Or, would the shellac in the mortise help provide a tighter fit?

andrew wrote:I have had acetal rods that were just a little undersized. Not sure why. It happens. Did you use a new drill bit to drill the mortise?

PremalChheda wrote: I would suggest drilling at a little under 5/16 and then using a slightly undersized reamer. 5/16 = 0.3125 Drill at .3100 or smaller Ream at 0.3120 This will give you a perfect fit everytime.

This is great advice; straight fluted reamers in half thousandths up to .3125" are very useful. I have them from .310" on up. I also use a 5/16" drill bit that I've sanded down to about .308" to drill my mortise. Then I just take the diameter of the delrin I'm using and grab a reamer that's about .001" smaller, and I get a snug fit every time.

Thanks fellas, great info.

Andrew: I used the same drill bit I used for the other 3 that fit just fine. I think it may be that the delrin is not consistent as stated above. I have some experimenting to do now.

What I do to get a nice tenon fit is the following.
I have found a drill bit which is just undersized for good sized delrin. After drilling the mortise, it's next to impossible to get the delrin in.

I then take a slightly overlength piece of delrin, chuck it into my drill press and have it spinning on it's lowest speed.
I then slowly slide my pipe over and back out.

This causes 2 things:
- the delrin gets turned down to perfect size (it will still be a bit too wide and have scratchmarks, but after a quick polish the fit is perfect)
- the inside of the mortise gets polished by the delrin making it nice and smooth.

Afterwards I use this overlength piece of delrin and insert it into my acrylic rod to use it as a tenon.

I've only done it a handfull of times (haven't made more pipes), but it seems to work beautifully...

Great tips. It would take me years to figure all that out.

hawky454 wrote:I ran into a problem a couple days ago with delrin. My understanding is delrin does not expand like vulcanized rubber. I drilled a stummel as usual and made a tenon with 5/16" delrin rod. The past 3 or 4 times I did this I had an excellent fit but for what ever reason the tenon fit loose this time. I know you can replace the delrin but if the mortise is already drilled for a 5/16" tenon you wouldn't be able to use the same size. Could you go the next size up and sand it down? Or, would the shellac in the mortise help provide a tighter fit?

I have had the same problem, especially when I get in a hurry and drill the mortise hole too quickly.

I have found that if I drill at lower speeds and advance the drill bit slowly, backing out frequently to clear chips, that I get a good solid (even tight) fit. But, if I hog the drill bit into the wood I get a hole that is slightly too big.

I am drilling on a wood lathe.

Todd

Where do you guys get drill bits and reamers like those referenced below? I've looked around with no success.

e Markle wrote:

PremalChheda wrote: I would suggest drilling at a little under 5/16 and then using a slightly undersized reamer. 5/16 = 0.3125 Drill at .3100 or smaller Ream at 0.3120 This will give you a perfect fit everytime.

This is great advice; straight fluted reamers in half thousandths up to .3125" are very useful. I have them from .310" on up. I also use a 5/16" drill bit that I've sanded down to about .308" to drill my mortise. Then I just take the diameter of the delrin I'm using and grab a reamer that's about .001" smaller, and I get a snug fit every time.

BobR wrote:Where do you guys get drill bits and reamers like those referenced below? I've looked around with no success.

http://www.mcmaster.com/

BobR wrote:Where do you guys get drill bits and reamers like those referenced below? I've looked around with no success.

http://www.ebay.com

I looked at McMaster Carr and a few other places but couldn't find drills or reamers anywhere near those diameters (.3100 drill bit / .3120 reamer, reamers in 0.0005 increments?) I'm sure I missed them. Thanks.

Chucking reamer .3115

http://www.ebay.com/sch/i.html?_trksid= ... &_from=R40

Thanks.

BobR wrote:Thanks.

Welcome. My point is, it's easy to find this stuff. Do a search for "Chucking reamer" followed by any dimension available and you'll probably find one or two.

McMaster Carr also carries a huge number of chucking reamers if you look for them. If you weren't looking for "chucking reamer"s but only "reamer"s to begin with, that's likely why you ran into an issue.

And the OP is awesome advice.

No matter what size tenon I am working with I always drill undersize and ream. I use an accurate micrometer to measure the Delrin, be it rod stock or a molded/threaded tenon. Based on the measurement I'll select a reamer that .001 to .0015 smaller.
I get my screw machine length bits and reamers from MSC.
Chas.