How should I join Delrin to wood?

[Rick M]

I'm making a mallet with a wood face on one side, Delrin (a type of acetal plastic) on the other. Delrin is very slippery and doesn't glue well so I can't depend on adhesives. My plan is to join them with a round mortise and tenon. Pre-drill a hole through the Delrin, run a deck screw through it into the wood then plug the hole with another piece of Delrin; but Delrin can only be bonded to itself with special adhesives. Another option would be to pin them together but I would prefer not to have a pin visible. One last option I can think of would be to groove the mortise and tenons and rely on epoxy to form a mechanical bond but I'm afraid hammering will shear the epoxy. Thoughts or suggestions?

 

[Mike Davis]

Is this a round mallet or square?

If the face is round I would drill a hole in the mallet body, turn a tenon on the round face of delrin and press it into the mallet. You could also make/press a small pin through the side of the mallet to be sure it won't come out.

If it is square then about the only way is to recess holes to screw the sheet to the face of the mallet. you may be able to cut a recessed groove near the bottom of the hole and turn the plugs with a small lip to fit the recess.

 

[zapdafish]

I looked into this once before myself. Was planning to use it as feet for a coffee table so it could be pushed around easily

I ended up just using recessed screws.

http://www.doityourself.com/stry/how-to-glue-delrin#.U49s6Shc-pw

 

[Dave Richards]

How about using your mortise and tenon idea and a wooden dowel as the cross pin to keep the Delrin in place? It would be easily replaced if need be and you'd use no metal fasteners. I have an idea for a way to make the faces so they go in and lock in place with a quarter turn but that may be more trouble than you want to go to. I've got a couple of other ideas, too.

 

[CrealBilly]

Perhaps this may help you???

http://www.reltekllc.com/adhesives-for-delrin.htm

I use Delrin to make nuts for my bass guitars I build. Granted it's not a mallet and I'm not after a permanent bond but I found a thin coat of weldon #16 does a sufficient job holding the delrin nut in place in the wooden slot.

Thinking on this a little more... You may need to scuff the delrin glue surface with 40 grit or something like that in order to get it to hold. That is if you want to glue it to wood.

 

[Rick M]

Jeff, a (very) quick internet source turned up no online suppliers for Bondit and I suspect it is expensive, too much for a small project.
Mike, it's round.
Dave, the quarter turn thing sounds interesting but yeah, probably too much effort for a mallet.

Recessing a screw is the best option but I'll run the screw from the wood side into the Delrin to avoid a Delrin plug. The only reason I dismissed that idea originally is I'm afraid the Delrin may strip out but if I get it together tightly there shouldn't be enough movement for that to happen, I'll dab a little epoxy on the screw. It won't be a very big mallet anyway, no mortise chopping with this one.

If anyone comes up with more clever ideas let me know. I probably won't be joining them until tomorrow.

 

[Mike Davis]

I have a 2 inch diameter rod of Delrin about two feet long. I can turn a couple pieces if that is big enough.

 

[Mark Gottesman]

Maybe make the mallet by laminating it up. that way, you could do a tapered eye and maybe join the Delrin to the mallet with a Fox Wedged mortise and tenon. Or use some sort of keyed joint. Bed it with GOOP or Silicon Seal.

I am probably over complicating it.

 

[FredP]

sliding dovetail? cut a dovetail in each cut a double dovetailed key. do the same at 90*. cut the key into 4 pieces. slide the keys into place with glue on the wood side. turn to round. it would look kewl and should never come loose.

 

[nn4jw]

Since it's round I'd be tempted to turn a tenon the same size as one of my Forstner bits, drill and tap a 1/4-20 a hole in the tenon end (not the side of the tenon) of the delrin, use the Forstner to drill a hole on the wood face of the mallet, drill a centered hole on the recessed hole in the mallet face and then use a hanger bolt to mate the delrin face with the mallet body. Depending on the size of the mallet face you might want to use a larger than 1/4-20 hanger bolt.

 

[CrealBilly]

Rick are you making one of these? BTW Fred - Time to update your avatar, in-case you haven't noticed theirs a little more gray on top of your head now - Hey but at least you got something up there

 

[CarvedTones]

Another thought - if you go with the mortise and tenon idea, turn a small groove in the delrin tenon. Make an epoxy slurry with sawdust and fill the groove with it. Slide the tenon into the mortise and let it dry. The epoxy will stick to the wood and the slurry will dry rock hard.

 

[Hmerkle]

Rick,
This was my first thought...
I was thinking of the sheetmetal screw style one...
You may have to cut it to length after creating a thread in the plastic....

I don't think adhesive will work because of the "slipperyness" and the constant pounding it has to ta...

 

[zapdafish]

looks like delrin can be bonded to delrin so maybe screw one piece of delrin to the wood then glue the second piece of delrin to the first hiding the screw holes

 

[FredP]

Rick are you making one of these? BTW Fred - Time to update your avatar, in-case you haven't noticed theirs a little more gray on top of your head now - Hey but at least you got something up there

let's leave my hair outta dis discushun Jeff!:gar-La;

 

[CrealBilly]

let's leave my hair outta dis discushun Jeff!:gar-La;

:gar-La;

 

[Rick M]

Fred, the dovetail idea would be really cool but will have to wait for a different mallet. What I didn't mention is the joint will be buried inside a metal pipe.

The hanger bolt idea is solid, I like that idea a lot. Winner.

 

[Mark Gottesman]

For a couple of other ideas, check out "Lixie Hammers" and "Basa Hammers". Both are replaceable face hammers.

 

[ehpoole]

Hank,

I would expect the coarse threaded hanger bolt to work very well to serve as a threaded dowel to screw the Delrin head into -- in fact that was to be one of my two suggested alternatives. Simply drill an appropriately sized receiving hole into the Delrin face and screw it into place within the round hole that was also made to receive it.

My other suggestion was to be to simply pin it in place after insertion as others have already suggested. Even something as simple as driving an appropriately sized brad or finishing nail into the hammer head such that it pins the Delrin face into place will do the job very nicely.

It really all depends upon whether you want to be able to replace a worn Delrin face down the road. If so then the hanger bolt solution is likely best as it all just screws into place... And if not then pinning is a very effective solution.

Whatever you decide please report back to us. And, as always, best of luck!

Rick,
This was my first thought...
I was thinking of the sheetmetal screw style one...
You may have to cut it to length after creating a thread in the plastic....

I don't think adhesive will work because of the "slipperyness" and the constant pounding it has to ta...

 

[Rick M]

I originally considered a half lap scarf joint but figured the wood would break across the short grain since it wouldn't be glued. Then I considered a tabled lap joint using the handle as the wedge but that seemed too complicated for something that wouldn't be seen. Tomorrow I'll pick up a hanger bolt and go that direction. I'll take some pics and let you guys know how it turns out. The mallet will be given away but maybe the new owner will want to swap faces someday.