Is UHMW a good choice for this part?

[martin_05]

The headache saved by spending a little more to get delrin is well worth it.

As someone pointed out, I was looking at the wrong Delrin. $100 a sheet for the standard stuff is a lot more reasonable than the $600 teflon-impregnated flavor.

 

[MaxPrairie]

Whatever material you choose, you can get it blanked out by a plastics supplier to something that will work better for you and cheaper than mcmaster. Or just make the thing out of 6061 and black ano it.

 

[david n]

Acetal.................X100000

https://www.plasticsintl.com/

 

[MaxPrairie]

Acetal.................X100000

https://www.plasticsintl.com/

I would also recommend them, can't remember the last time I didn't get my material the next day.

 

[Booze Daily]

I machine a fair amount of UHWM. Mostly +/- .010 , so nothing critical. Worst part is deburring. You’re going to have to cut the burrs off with a razor knife.
It’s easy to make a nice looking part look like crap.

 

[MwTech Inc]

How many is a "bunch"??
If small quantity 3d print them

You say its only a spacer.........

 

[martin_05]

How many is a "bunch"??
If small quantity 3d print them

You say its only a spacer.........

All being considered based on testing. Thanks.

 

[Bigdawg]

We run a bunch of of plastics on our router, mainly acrylic and delrin. We use the single flute high helix polished carbide bits from Onsrud (65-000 series) or Amana tools, they call them spiral Q-Flute's, they are great for cutting plastics. They can go into regular collets and can be used on a mill, the issue you might have is do you have a fast enough spindle, especially on the smaller sizes, so that you don't have to go really slow on the feed.

 

[BoxcarPete]

This thread is a few months old but I would caution the OP to consider choosing something different than acetal for exposure to "household chemicals" because chlorine is like the boogeyman for acetal. It also happens to be the active ingredient of lots of "household chemicals" like bleach.

HDPE would probably be better if you haven't already committed to acetal.

 

[triumph406]

Get Acetal (copolymer) from a plastic supplier. Delrin (which is a homopolymer) from McMaster is expensive… but Acetal (similar but not the same) is less expensive. I would say they machine the same but a decent price difference. Please take note everyone, I am not mentioning anything about the differences is mechanical properties…

McM isn't always more expensive, there's been a few occasions recently where Acetal from McM has been very close in price to a local supplier.

I picked a piece of Acetal from a local supplier 1"x12"x36" it was $287

Acetal from McM 1"x12"x48" is $392.39. If you multiply $287 by 36/48 the equivalent price would be $294.29.

 

[latheman78]

The only reason to make anything out of UHMW is if you enjoy deburring.

 

[sterlingmnk4l2a3]

Made a mistake used UHMW for a multi part tripod head assembly. Slick and not quite suited for that. Took me a while to get speed feed and tool right to avoid the rose petalling on the lathe. Disconcerting to be turning what looks like a flower. Sharpest HSS is an absolute.

If working manually beware of ”grabbiness.” I wanted to open up the hole diameter and found if I used something too large upfront it would create melted thick blob “rope“ strings fused to itself and the stock. So after a series of increasing diameters used, I inadvertently didn’t have the tail stock locked down to the lathe when I got to the longish 1” drill in it. When I merely touched the drill to the UHMW block in my four jaw, the stock grabbed it, pulled it right through into the spindle and slapped the tail stock into the chuck, crash. I stood there thinking this is some alien stuff.

 

[SND]

I'd probably use HDPE. Cheaper than acetal and doesn't smell like fish when machining it...
But if it turns to high Qty, that thing looks like it should be injection molded.

 

[mhajicek]

I would also recommend them, can't remember the last time I didn't get my material the next day.

They're local to me; I can usually pick up my order same day. Place an order at 9am, pick it up at noon.

 

[50BMG DUDE]

That would require a right angle head, which I don't have. I've been looking for an excuse to buy one probably going back 15 years. I remember I had to machine lots of thin slots on a plate to make a large (12 x 24 in) heat sink with epoxy-bonded fins on 1000-series aluminum. I had a VF3-SS at the time. I was blown away by how fast and deep I was able to run a 0.047 end mill without breaking it. A right angle head would have made that job a LOT less painful.

Every time this happens I look at the cost of a right angle head and the job and say something like "How many times am I going to use this thing?".

Why would this part require a right angle head? Use a wider piece of material. Machine near complete, flip and finish...

 

[Wsurfer]

HDPE machines beautifully and easily. In that small of a part, warping shouldn't be too bad. That skinny flap on the part would concern me though. Cheap enough to try easily. UHMW sucks in every way . There are some wonderfully stable thermoset plastics, but $$$.