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Discussion Starter #1
I understand many of you on this forum are racers, machinists, ect.
I just bought a new tool for my shop :D and as soon as i learn how to use it i'm going to start building chassis parts for myself.
I was wondering if anyone on this forum had any experience in what's required to machine telfon or delrin, or whatever bushing material is common in machined type bushings.
Thanks!
 

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Well deepstaged could you be more specific as to what your wanting to machine. As for the type of product there are quite a few different products available. I have seen some people use UHMW which you can check out at;

http://www.plasticspecialties.com/index.html

I perfer Delrin overe UHMW for many reasons but it does cost a lot more. You should research and decide what meets your needs. Here is another link that talks about delrin for you;

http://www.interstateplastics.com/meta/fmdel.htm

Using a CNC lathe and milling machine to cut delrin is no different than Aluminum except you do not need your bit speed as high. The time it takes to machine the delrin for my parts is substantially quicker than machining aluminum.

Hope this helps you a bit.
 

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Ahhhhhh - that good ol' semi-solid uniaxially oriented fluoropolymer we all know and love -Tetrafluorethylene or PTFE or Teflon :D
That $hit is like machining a soft bar of Soap only much more abrasive!

I have to agree with the 'Mountie' there - depending on what you are trying to make, there are much better materials than pure Teflon usually available. Delrins or a filled Teflon like Vespel or the like would be much easier to machine.
Teflons have a low CF, but a very high Tg - which means they are as slippery as snot, but grow like crazy when heated! I use Teflons in my line of work because we need the absolute chemical resistance it offers, but it's a PITA at times.
Go get yourself a hunk and try to drill, tap and machine it. If the tolerances are off - just wait a couple hours, they'll change and you'll have to do everything over again.
The shops that work with this material alot usually 'anneal' it and then use tool wear compensating programs to machine it to hold tolerance. Of course Lazer Ablation is a promising looking option to get around the tool wear problems.

BTW - I'm not a machinist (but, I did stay at a Holiday Inn last month) just an old DuPont employee who got to meet Dr. Plunkett (Teflons Daddy) many years ago at a DuPont Function and has to deal with problems with the material daily.

Boy - now that was fun!
 

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I have heard it said that poly machines good by using high-speed grinding tooling on it but have no actual experience.. pdq67
 

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Discussion Starter #7
I like the looks of the delrin, and the cost is not bad @4.75 per ft.
Thanks guys.
If possible, i plan to make the bushings specific to my chassis, as well as for other projects.

Any tips on specific lathe cutters to use (carbide?) and feed/speed?
 

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For cutters I would recommend Carbide as a good start.
You can follow the feed/speed ratings for Stainless Steel as a start.
You will find the best settings on your equipment and temp.s from there.
Tool wear may become an issue if you try to remove to much material to achieve the finished dia, but you need to start with the largest Dia, near your finished max. dia. to assure that the piece stays stable during your machining operations.

The www.dupont.com site may contain more info on this stuff.

Now if someone would just ask a question about 'cross-linked photopolymers' my day would be complete...
 

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The delrin is more easily machined. Teflon is very abrasive as mentioned before, but would be ok for just making a few parts. It does move around dimensionally quite a bit though. The delrin can be machined with either HSS or carbide tooling. Use a very sharp nose radius with a highly positive tool geometry. A speed in the 1000 to 1500 surface feet/ minute range will work fine. In teflon I would recommend only carbide tooling with a sharp nose radius and positive geometry. I wouldn`t run more than 400- 500 sfm. or the tooling will wear rapidly. If you drill with a high speed steel drill, run it at approximately 50 sfm. Avoid letting the chips wrap on the workpiece or build between the tool and part or they will melt to the part. As far as feedrates and depth of cut you will have to play with them to provide good chip control in either material. Sometimes a deep depth of cut (.200- .300 per side) with a fairly low feedrate (around .003- .004 ipr. will work well if your setup is rigid. It will create a heavy chip that will fall to the bottom rather than wrapping on the part. Good luck, Brent
 
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