Which type of delrin is best used for links and why?

[Ripperfi]

You mean acetal acetron right? Both delrin and acetron are acetal's.

[downtown]

Delrin purchased in downtown San Diego is the best...
In My opinion only of course ..

The different colors seem to have different densities when machining them.
Black being a bit harder more rigid and at times more brittle than the lighter colors

[xirtic]

I buy A LOT of Delrin in both WHITE and BLACK from McMaster Carr. Never have had any issues.....but I do prefer the white. It machines a little better IMO.

[binaryterror]

As I posted in RC4WD's Yellow X-Lox regarding colorants.

Anytime a material be it a form of rubber, plastic, gel is colored it will effects its properties in some way. To make a material colored some sort of colorant (which is not the material) is added, sometime mixes of colorants are added.

To make colors they use non-natural (at least to the base material) substances to get those colors. Those substances can wreck havok on properties all for the sake of looks. Other times the substance might help one property and hurt another. It's always a trade off.

Most commonly odd is industry standard blacks. They are often over colored to get them out faster. They do test for the opacity of blacks and over coloring guarantees a good run color wise. It can though effect the material. I too find black delrin to always be the "harder" version when compared to white.

One thing many might not know about Acetal and Nylons is their problems with poor cast/molds creating pockets or problems. These can be minimized by boiling the parts and then cooling. This will heat the parts at the molecular level and allow them to re-seat themselves in a better manner thus gaining you the most optimum properties. As we've become a nation of "faster, I want it now and cheap" many companies are running molds, extrusions, casts even faster and cooling the parts faster causing this molecular structure to become even more jeopardized.

[theslowguy]

Amazing write ups! I Recently discovered PTFE Delrin and made a custon skid for my truck. All I have to say is WOW. It slides almost too good. If Im not careful the truck will slide sideways off rocks, like there is butter on the bottom of the truck.

[53 willys]

is this the right stuff for a chassis then?
I'm gonna order some to have around..might try my own chassis..but I wanna get the right stuff..from what I read this is it..but I wanna make sure
thanks
http://www.mcmaster.com/#8575k113/=42lroo

[Ripperfi]

Originally Posted by 53 willys

is this the right stuff for a chassis then?

Yep you got it.

[DeweyCJ5]

so i got this from McMaster-Carr

1830T11Black Delrin Tube 1/4" OD, 1/8" ID, 5' LengthIn stock at $3.97 Eachordered 2 sticks got them the next day, $6.00 shipping and it took all of a half hour to cut and tap all of the links for my swx including the steering one

[Ripperfi]

Not too shabby for 14 bucks

[timeout]

Is there any way to make bent links from this stuff?


jimmy.p.

[Ripperfi]

Why yes there are multiple ways to accomplish bent links with this stuff. You could use mechanical pressure to force a bend or apply heat and then bend. The thicker the material the more pressure/heat will be needed. I just found out something new on this stuff. After making a bend, place the piece in boiling water for 5 to 15 minutes depending on thickness of material. The heat from the water helps the molecules tighten up and strengthens the entire piece. Same principle as stainless steel. Great stuff.

[DeweyCJ5]

i was wondering if you could boil it... then put it in a jig while still hot for bent links ?

[big_boss]

This is a very helpfull thread, thanks guys.

[Ripperfi]

Boiling water is not hot enough to make bends. It will cure the plastic and make it harder to bend. A cheap disposable toaster oven set to 350-375 degrees would work. Plastic releases toxic and noxious gasses when heated up and might be absorbed in the oven then transfered into food. It would be trial and error for the first few pieces until you got the times and process down. For smaller diameter rod, try using a vice and mechanically bending it.

[xirtic]

I use a $10 heat gun from Harbor Freight for +/- 10 seconds on the bend point while the delrin is in the jig. Then just bend it. (All work is done in a well ventilated garage.)

[flake99please]

For the record, there are at least 64 different variants of Delrin, each with unique properties. Stick with a Acetal Homoploymer (POM) and you should be fine. If a glass filled variant is required for a little extra torsional strength go no higher than 5% by volume.

If you want to form a tube then I suggest you make a jig from steel that you slide the rod into. Heat this in milk as this boils at a higher temp than water for about 15-20 minutes, then plunge the parts in iced water to cool. Pushing the rods out is a bit tricky, but they will come out formed to the shape you want.

Using the oven as suggested above should only be done outside as there is a significant risk of producing formaldehyde gas if the Acetal is heated too high!