hdpe - joining

[billy breach]

What is the best screws for screwing HDPE sheets together? I used standard wood screws but they didn't seem to get that good a grip. is there any particular type of screw I should be using or thread type? I plan on screwing 12mm hdpe together.

Ta
Billy

[maddox10]

Re: hdpe - joining

As thick and coarse as possible.

Particle board screws I guess



The thinner piece is drilled trough with the same size as the outer diameter of the tread. The thick piece is predrilled with the inner diameter. And don't overtorque.

[psycho_fling]

Re: hdpe - joining

i found large wood screws work fine

[billy breach]

Re: hdpe - joining

something like these?

http://www.screwfix.com/p/timco-velocit ... -200/95274

[jonny]

Re: hdpe - joining

I just use chipboard screws, seem to work fine.

[Ellis]

Re: hdpe - joining

I used wood screws of some sort (I think they were standard) and when put together well they make for one heck of a connection, to the point where on several occasions our cordless drill/screwdriver (one of the lucky ones that still serves as a drill!) couldn't undo them.

[Eventorizon]

Re: hdpe - joining

In my materials lectures we have been researching processes like laser and sonic welding as well as extrusion welding for HDPE. I was hoping that I could hire an extrusion welder and build the armour for my robot with that but I cant find any companies that hire them out. Any ideas or is it overkill?

[billy breach]

Re: hdpe - joining

i would say yes overkill, use some screws

[maddox10]

Re: hdpe - joining

In my materials lectures we have been researching processes like laser and sonic welding as well as extrusion welding for HDPE. I was hoping that I could hire an extrusion welder and build the armour for my robot with that but I cant find any companies that hire them out. Any ideas or is it overkill?

I own a handwelder for HDPE, but it seems the welds are more brittle than the mother material.
I learned to back the welds uo with some bolted in/on supports.

[psycho_fling]

Re: hdpe - joining

There are a few robots about that have 'welded' hdpe shells , you can use a really powerful hot air gun and hdpe welding rods

[pressure]

Re: hdpe - joining

Skink is entirely made of such plastic.
The joins are tongue and grooved, then tapped m5 and scewed together with countersunk allen screws.
A bit over the top perhaps but it has lasted five years!
Problem with wood type screws is they don't always find the same thread when you take them out and put them back, so you end up with little or no grip and your bot coming to pieces in the arena!
Mike.

[billy breach]

Re: hdpe - joining

has anyone ever pressed a brass insert into the hdpe which is threaded and allows an m5 etc bolt to be screwed in? rather than taping the hdpe itself

[plargen]

Re: hdpe - joining

i used these on my bot

www.ebay.co.uk/itm/M4-X-10mm-Hex-Drive- ... 500wt_1054

[jonny]

Re: hdpe - joining

I believe there's a topic about this in the fw section a while back.

[billy breach]

Re: hdpe - joining

how did they work out?