Dominos in HDPE

[4thisguy]

Hi all,
I'm interested in working with HDPE for some exterior projects and wondering if anyone has experience, specifically with using dominos.  First, I'm assuming the Domino will be successful in cutting HDPE as it's a pretty soft plastic, but any tips would be appreciated.  Secondly, I know there are a few glues/epoxies that are supposed to work with both wood and HDPE, but even if I can't use the dominos for full joining I could use them for alignment and then use another fastener.  Wondering how the Domino Connectors might hold in HDPE.  Alternatively, I think threaded inserts should be ok.  I believe welding is the "industrial standard" approach to joining HDPE, but that probably won't be a good solution for me as a home hobbiest.

Thanks,
Guy

 

[Birdhunter]

I’ve worked with both sizes of the Domino connectors and used hundreds of the standard Dominos in all sorts of wood. But, I’ve never touched HDPE. A quick Google search yielded a few glues that claim to bond to both wood and HDPE. I’d do some tests before entrusting the glue to a project.

The pull out strength of the Festool connectors lies in the expanding anchor. It’s teeth dig into the surrounding material when the anchor is expanded. My guess is the the connectors would work for normal stresses.

In some outdoor Ipe benches, I used a lot of large Dominos. I was unsure of their glue holding up over time. So, I “pinned” both ends using small screws after the tenons has been glued and clamped. The screws were under the benches so not seen.

 

[Bob D.]

Can you make dominos from HPDE scraps? Then you won't have differnet materials to join. This might allow for a wider selection of adhesives.

It's not too difficult to run off some long sticks of domino shaped material on the router table then cut to the required length. A little trial and error to get teh size right but shouldn't be that hard.

 

[MikeGE]

Polyethylene is a low surface energy material and is difficult to bond using adhesives.  I modified a large dog kennel for a friend so it would meet the Lufthansa maximum requirements as checked baggage instead of cargo. I tried at least a dozen different epoxies, glues, and tapes to bond the PE surfaces, and all have failed.

The only adhesive that worked is Permabond TA4610.  No surface preparation was needed, other than wiping down with acetone to clean the surfaces.  Assembly was easy, and for maximum strength, pull the pieces apart after joining them, and then put them together again with lots of clamps.  After 24 hours, the bond is strong, and I could not pull the pieces apart.

 

[Cheese]

I'd follow Bob's lead and fabricate Dominos from HDPE material. It takes a couple of rip cuts and then a roundover on the router.

I've worked a lot with the newer D 8/50 knockdown 8 mm Dominos. They should work fine in HDPE. They can expand by about .120". Here's an example.

[attachimg=1]

 

[Cheese]

The only adhesive that worked is Permabond TA4610.  No surface preparation was needed, other than wiping down with acetone to clean the surfaces.  Assembly was easy, and for maximum strength, pull the pieces apart after joining them, and then put them together again with lots of clamps. 

That's good information Mike... [big grin]...for adding adhesive or printing to HDPE sheets, we always had to first send them in for a corona discharge treatment.

 

[Bob Mircetic]

...First, I'm assuming the Domino will be successful in cutting HDPE...

My tablesaw has an HDPE type material on the fence faces.  One day I was using my fence as stop but I had my domino depth setting too deep for the material, and uhhhh.... I can confirm the domino will cut it no problem.  [embarassed]

[attachimg=1]

 

[rst]

I often use a 6" x 6" heavy aluminum angle fastened to my MFT to hold vertical pieces.  I plunged my domino 8mm thru and into the angle by a small amount...cutter still functions perfectly...really glad I plunge slow and controlled.