HDPE and perspex

Flippt · Post by **Flippt** » Wed Apr 01, 2009 11:54 pm

From what I understand, you can do the welding in several ways.

The one Leo and Mario are using is called Plastic rod welding, which is a special made tool for this job.

However, you can use 'Free hand', just heat up the plastic feed, and apply to the area you wish to reapir. Although it seems like a cheaper way, its more difficult to master and takes long time.

http://www.youtube.com/watch?v=MjSIkFvF ... re=related

http://en.wikipedia.org/wiki/Plastic_welding

Remote-Controlled Dave · Thu Apr 02, 2009 12:02 am

On a similar theme, but a slightly different topic, I remember a plastic robot called Agent Orange (robot wars seris 3). Those guys said they welded it together in the oven. Is this as daft an idea as it sounds? They probably ruined their oven...

muchalucha · Post by **muchalucha** » Thu Apr 02, 2009 11:17 am

ive welded plastic with a soldering iron before and , it just burns and the joint is very weak , i know there are some exceptions to this and i know ldpe is (becasue you can melt down ldpe plastic baggies to make various robot bits) , id have to buy a heat gun but they arent too expensive .

i thought acrylic and polcarbonate was the same , my step dad has acrylic that he casts and lathes and i didnt think it was the same stuff as i had been buying in sheets.

muchalucha · Post by **muchalucha** » Thu Apr 02, 2009 11:26 am

http://www.youtube.com/watch?v=FJ8dLq35 ... re=related

this looks interesting , they seem to be melting a metal mesh into the join and then covering it with plastic , looks like polyethyliene as well

muchalucha · Post by **muchalucha** » Thu Apr 02, 2009 5:02 pm

ive just bought ?11 of hdpe at direct plastics , i got it cheap in the clearance section , ive got a 10mm sheet and a 6 mm sheet. thanks for all the help

Im interested in welding it , but from what i can see , a paint gun gets too hot and a soldering gets hot enough , but is only good for thin plastic.

EDIT: would cynocrynolate be any good , its great on similar plastics

Post by **BeligerAnt** » Thu Apr 02, 2009 5:20 pm

AFAIK there are no glues or solvents that will join HDPE well, becuase the surface energy of HDPE is so low. PTFE is similar, as are most other "waxy" looking plastics. I have managed to glue foam tyres to HDPE (bottle top) wheels using Loctite Superglue, but it's hardly a high-stress situation.

For HDPE it's really nuts & bolts or welding. And you can't tap HDPE unless you use a rediculously coarse thread - it's too soft.

muchalucha · Post by **muchalucha** » Thu Apr 02, 2009 7:57 pm

can you screw into hdpe . will the thread just rip out if i screw i sheet of hdpe 90 degrees into another sheet.

razerdave · Post by **razerdave** » Thu Apr 02, 2009 9:01 pm

If you use a thick enough sheet and a very coarse thread it will, but using 10mm HDPE and bog standard self tappers doesn't work very well, hence I use brackets now (My HDPE won't weld because of what it was treated with when it was cut)

Simon Windisch · Post by **Simon Windisch** » Thu Apr 02, 2009 9:15 pm

I managed to tap a M6 threads into 12mm RG1000 (see my previous link) very successfully. However, in my next FW build I'm going to use inserts to bolt into.

Simon

muchalucha · Post by **muchalucha** » Thu Apr 02, 2009 9:44 pm

its just welding or bolts then

. ive already ordered it lol .

On a different not , i have tried using the motors offset so one is bout 2 inches further forwaerd than the other , it actully works very very well , and makes the whole thing a lot smaller just to bring that in

.