What epoxy?

BSTpipes

That'll do, Pig.
Sales
#2
Don't screw them in, would be my advice. The physical bond you want is more like a waffle pattern, some random criss-crossed thing on BOTH the tenon and the walls of the socket it's going into. I use a dental pick on the vulcanite and scrape out deep grooves, and I use a 1/8" carving gouge on the delrin, again cutting a half dozen or so deep grooves and pockets. Same can be done with a dremel tool. I have a picture on my other computer, I'll see if I can dig it up.

Better epoxy might help, but a really roughed up surface makes it a secondary consideration. I use the JB Weld plastic bonder now. But I've used 5 minute standard epoxy with success.
 

Notow1

Well-known member
Sales
#3
George Dibos has a good video of how to glue a delrin tenon on His youtube channel. I usually use the T-88 epoxy and it seems to work well. I think Chris Askwith threads His delrin tenons as well. I have only used delrin a couple of times and prefer cutting integral tenons.
Norm
 

Maddis

Well-known member
#4
Your probably do this, but it's important to have somewhere for the compressed air to escape when gluing the tenon in. I used to drill out the tenon before gluing to serve this purpose, then drill it again after the epoxy cured. There's also a difference between work time and curing. 5-minute epoxy, for example, gives you five minutes before it turns hard, but it takes much longer to cure. I always gave it 12 hours minimum before testing the strength of the bond.
 

Cramptholomew

It's, like, Phyllis Diller funny.
Sales
#5
I've used a bunch of brands. The ones that have worked well for me are G-Flex (24 hour cure, my favorite), the Gorilla 5 min and the 5 min Loctite. The 5 min JB Weld is garbage, however, I'm interested in @BSTpipes suggestion of their Plastic Bonder. It doesn't look like it comes in clear though. I suppose the black would fit this purpose fine, though.
 

Mrm1775

Well-known member
Sales
#6
I also cut several grooves with cross cuts in delrin and whatever it is bonding to.
I've been using Bob Smith industries 5 minute epoxy from VF and let it cure overnight.
Like @Maddis stated, I like to have a relief hole and I clean both pieces with DNA before glue up.
I have trouble with it if it doesn't cure overnight
 

N80

Well-known member
#7
Thanks guys. I've seen George Dibos video. I've tried it and still had failures. Same with waffle patterns etc. I've been using T-88.

I also drill the airway hole in the delrin tenon before gluing and polish it afterward too.

But, looking back, the failures have been random and I'll bet it is because I did not allow adequate curing time. Primarily just because of not paying attention. Now I just feel stupid.

Anyway, I'm going to get some G-Flex or maybe the Bob Smith referred to above and just be conscientious about cure times.

Thanks guys.
 

MichaelE

Well-known member
#9
Epoxy will not bond to Delrin. Hence all of the suggestions of grooving and roughing up the Delrin.

It actually just 'holds' the Delrin through those roughed up grooves and cross-hatching and will not bond to it as other materials would.

I don't have any pipe making experience, but I do have a lot of experience using a lot of different adhesives on a lot of different materials.
 

RDPipes

Mental Illness is a Terrible thing to Waste!
Sales
#12
I wait 24 hours for the epoxy to dry ((G-flex) before putting any stress on the stem, I've never had a failure.
You score your tenon properly and the fit is tight there should not be a problem.
There should be no rush to use it, patience is a major key to making pipes.
 

N80

Well-known member
#13
There should be no rush to use it, patience is a major key to making pipes.
Agreed. I seem to have to relearn this about every third pipe. At this point I'm pretty much certain that the cause of my issues has been working on the pipe (pulling stem in and out) before epoxy has fully cured. By the way, none of the failures has occurred after the pipe was finished.

However, according to George Dibos, he gets a fair number of high end pipes for repair due to tenon failures. Turned tenons and delrin.
 

RDPipes

Mental Illness is a Terrible thing to Waste!
Sales
#14
Agreed. I seem to have to relearn this about every third pipe. At this point I'm pretty much certain that the cause of my issues has been working on the pipe (pulling stem in and out) before epoxy has fully cured. By the way, none of the failures has occurred after the pipe was finished.

However, according to George Dibos, he gets a fair number of high end pipes for repair due to tenon failures. Turned tenons and delrin.
Well I reckon I'm pretty safe then, my pipes aren't High End. LOL!
 

DocAitch

Well-known member
#16
A couple of caveats.
1) Be very careful heating a stem to bend it with a Delrin tenon. The heat can cause failure of the bond- especially the short and thick ones like an Author. I wrap wet cloth or paper towel afound the stem at the shank face to help reduce the heat at the bond.
2) Drilling the tenon separately may introduce a slightly non concentric draft if there is any runout in your chuck. I drill my Delrin with an undersized vent hole just to prevent pressure build up when gluing, then after the epoxy sets, I drill the tenon and rod together. This procuces a concentric draft with no offset or step.
I use the G Flex 655 ( https://www.amazon.com/655-8-Pre-Th...611523185&sprefix=g+flex+epoxy,aps,170&sr=8-3 )which is the thicker variation.
I have also found that adding pigment to the mix is helpful especially when using translucent acrylic. I generally use black but have used beige with white Delrin tenons.
I also argue that using a rough ( 35-40 GRIT) sandpaper to score the tenon makes more sense than any of the other roughing methods
F1F06EB7-CC52-42FF-A34D-01DBDC2501EF.jpeg
My reasoning is that the resistance to shear forces is in the EDGE of the epoxy projection into the Delrin which faces the direction of force. Therefore, the more EDGES (and lengths of edge) that are present, the higher the resistance (and strength) of the bond.
Also, in regard to orientation, circular cuts (from a lathe) will resist tension and compression forces (push and pull), and parallel cuts will resist torque (twisting). Diagonal cuts have edges oriented to resist both tension/compression and torquing.
3DF6F2A6-A713-40F7-87B6-836B19943BFD.jpeg
DocAitch
 

DocAitch

Well-known member
#17
I also think that threading a tenon is a waste of time. The threads will provide good resistance to tension/compression , but almost no resistance to torque forces.
DocAitch