[CadRhino]

Is that acetal?
If so, do you use any special cutters toachone it or do you treat it like aluminum.
Thanks

There are other ways than relying on igs and STL. This shows 18 parts being made in one hit.
Attachment 275788
Several tool changes, but each tool change serves all 18 parts. Parametric programming is a major factor.

Cheers
Roger

[Steve Seebold]

Attachment 275668

This is one of my vise fixtures that machines 4 of these parts at once. The first side is done in the vise, then flipped and put on the fixture for the second side. The parts are small and a 6 inch vise will hold 4 pieces of these.

Nice job Mike. If you make a lot of those parts, you might consider setting an end stop on your vise and make a second fixture. Then you could have one fixture \ in the machine running and one on the bench loading.

It doesn't save a tremendous amount of time, but if you can save 3 or 4 minutes per load and you're making 100 pieces (25 loads), 3 minutes times 25 loads of parts, that's an hour and 15 minutes. Just thinking.

[Steve Seebold]

When I draw and program a job, I use GibbsCam. If I am running multiple parts in a set up, I will usually make 2 fixtures. That way, I will have one in the machine cutting and one on the bench being reloaded.

When I have a fixture like that, I can do the cutter path on the first part in the fixture, then when I post process it I will tell the post how many parts I want to make in this setup. The posted program will give me sub programs for each tool to run each part. I can tell the post to run either one tool all parts, or one part all tools. I will choose one tool all parts, then I will run tool 1 from the left side, tool 2 from the right side and so on. And like Mike at popspipes, I don't do big parts. Usually, a part that's 4 X 6 is a huge part for me.

[RCaffin]

Is that acetal?
If so, do you use any special cutters to machine it or do you treat it like aluminum.

Not sure what the material in the photo was. It could have been acetal, but for technical reasons it turned out that acetal (which is nice to machine) could not be used. So it is quite possible that the material was none other than cheap black (engineering) polyethylene.

Yeah, I know, a pain to machine because it feathers and flexes like mad. I found that a moderate spin, to keep the heat down, plus really sharp cutters, were the answer. Specialised aluminium cutters do help as they have the edges needed. Crude cheap carbide from China can machine plastics of course, but most of it does not have the nice sharp edges.

I had to do well over a hundred of these complex litle things. It became routine.

Cheers
Roger

[SCzEngrgGroup]

Not sure what the material in the photo was. It could have been acetal, but for technical reasons it turned out that acetal (which is nice to machine) could not be used. So it is quite possible that the material was none other than cheap black (engineering) polyethylene.

Yeah, I know, a pain to machine because it feathers and flexes like mad. I found that a moderate spin, to keep the heat down, plus really sharp cutters, were the answer. Specialised aluminium cutters do help as they have the edges needed. Crude cheap carbide from China can machine plastics of course, but most of it does not have the nice sharp edges.

I had to do well over a hundred of these complex litle things. It became routine.

Cheers
Roger

For plastics that tend to "feather", a straight-flute tool works wonders. I get excellent results on UHMW using carbide router bits.

Regards,
Ray L.

[popspipes]

Nice job Mike. If you make a lot of those parts, you might consider setting an end stop on your vise and make a second fixture. Then you could have one fixture \ in the machine running and one on the bench loading.

It doesn't save a tremendous amount of time, but if you can save 3 or 4 minutes per load and you're making 100 pieces (25 loads), 3 minutes times 25 loads of parts, that's an hour and 15 minutes. Just thinking.

Thanks Steve for the compliment!

I probably already have a lifetime supply of those and other parts I make for Junior, my parts mostly are small, I have one thats a bit over 16" long, I like the design and speeding up the machining process, then I tend to get a bit bored once the improvements are done.

From what I have seen of your parts they are first class! I am learning but am not there yet.

[CadRhino]

Thanks for everyone's feedback on acetal. I am going to be running a bunch of acetal parts and will be using my tormach as a vertical lathe with a slitting saw to cut the parts off of rod stick as they are finished.

Not sure what the material in the photo was. It could have been acetal, but for technical reasons it turned out that acetal (which is nice to machine) could not be used. So it is quite possible that the material was none other than cheap black (engineering) polyethylene.

Yeah, I know, a pain to machine because it feathers and flexes like mad. I found that a moderate spin, to keep the heat down, plus really sharp cutters, were the answer. Specialised aluminium cutters do help as they have the edges needed. Crude cheap carbide from China can machine plastics of course, but most of it does not have the nice sharp edges.

I had to do well over a hundred of these complex litle things. It became routine.

Cheers
Roger

[RCaffin]

Hi Ray

For plastics that tend to "feather", a straight-flute tool works wonders. I get excellent results on UHMW using carbide router bits.

I have plenty of carbide bits, but I have not tried a straight-flute one. OK, that goes on the list.

Cheers
Rogr

[Steve Seebold]

Quinco Tool makes an end mill that is a RIGHT HAND CUT LEFT HAND SPIRAL that works really good on plastics that have a feather edge after cutting.

The left hand cut doesn't lift the chip, it actually punches it down leaving a virtually burr free edge even on soft materials like HDPE.

They are on page 57 in their catalog and they only come in HSS, NO CARBIDE. They are available in sizes 1/4 thru 1 1/4, and trust me, I know they work, I have used them. A LOT.

TRUST ME!!! Sounds like a lawyer, doesn't it?

[MikeC8]

Onsrud makes carbide single flute cutters for plastics that work great, both in straight and spiral flutes. Its a standard upcut spiral, but works great on HDPE, as it keeps the cut path clear of chips, and doesn't melt the material. You can order them through mcmaster.