ABS plastic

[BenK]

I have a ABS plastic part that is .090 thick 16.00" long and 3.00" wide with a rib off center the long way down the part. I'm machining it out of a .375 thick block because of the rib. Any ideas on how I should cut this part?

[Mr. M]

Double sided tape to hold it down

[BenK]

We have 250 of them to do this order alone.

[Reko]

Mill the first side (ribbed side) in a vice, then, mill a fixture that accepts that shape. The second operation can be toe clamped into the fixture, and you might have to move clamps a few times, but this should produce good results.

[headhunter]

Sounds like a good application for a vacuum plate. Should be more than enough surface area to hold the part securely.

[Oscar R.]

Double sided tape or vacuum is what I would normaly use but removing that much stock from the part will more than likely warp it to the point that neither will hold it down properly. Much less hold tolorance. Especially if we're talking about an extruded piece of stock.

It might be best to rough and stress relieve with heat before finishing, if the specs allow it.

[headhunter]

With the right vacuum setup, I don't think the part will pull off. We routinely machine plastic as well as other materials using vacuum pressure to hold it with no problems. I have NOT machined a lot of ABS, so take it for what it's worth. But, a simple vacuum chuck makes for a short setup time, and easy change out if it will work for your application.

[Mr. M]

Yeah, for 250 I would try a vacuum plate if you can

[LancoUSA]

Can you use a blank vacuum table and take a bunch of material from one side and pre-stress your part?

[Teh Bear without Brains kinda idiot]

With the right vacuum setup, I don't think the part will pull off. We routinely machine plastic as well as other materials using vacuum pressure to hold it with no problems. I have NOT machined a lot of ABS, so take it for what it's worth. But, a simple vacuum chuck makes for a short setup time, and easy change out if it will work for your application.

~~~~~~~~~~~~~~~~~~~~~~~~~~

Yes It can !

It even can break itself from inner stresses if vacuum will hold it

I have seen it in the past

I would rough the part ,give it to rest for a day .finish the rear surface before other things

[Bruce Kanzelmeyer]

We often anneal parts that are thin that require heavy machining. Rough the part out leaving .01" or so to finish off. Bring the parts up to about 180 degrees F over about an hour time, hold at 180 for about 2 hrs. and cool back down to room temperature over a 2-3 hr period. Then run finish passes. Should end up straight as an arrow. Vacuum plate should work fine.

[Bruce Kanzelmeyer]

Sorry, its 200 degrees for ABS. 180 degrees is for Acrylic. Time period should be fine for 3/8" material. Make sure the parts are flat while annealing! They will stay in the shape you anneal them! check out this site for other plastic annealing information: Plastic Annealing