Re: [CAD_CAM_EDM_DRO] And UHMW is fine too! was Re: Using a porter cable router to cut aluminum

Ballendo,

I was not specific when I mentioned what types of machining he was attempting to do. This was UHMW about 3" thick and large width and length. He was drilling holes and counterboring deeply into it. Thats what was producing the heating problems. As I'm sure you know drilling into UHMW over an inch or so creates heating problems due to the material trying to close up on the bit. When I was there even the milling portion of it was not going well. I suggested that he relief grind the drills and counterbores (reduce the diameter just above the cutting face). I heard later that he completed the job so, he obvioulsy found solutions to his problems. One material that is a real pistol to keep from melting is ABS. Very frustrating. Delrin (acetal) is the machinists friend. That is the nicest material to machine. Precision UHMW? My experience with this material is everytime you clamp it down it distorts in every direction . Put a piece in a vise, like 1/2" and it will bow up in the
middle about 20 thou depending on its width. So, I'd have to try and find a happy medium between bowing and flying out of the vise. Of course a vaccuum fixture would allieviate alot of that for thin material. Carbide for plastics? Plastics like razor sharp cutters. (i'm talking about the mill here) Generally, carbide cutters for mills arent very sharp. They are meant for toolsteel where a keen edge is pointless. The material will wipe it away instantly. Carbide endmills are for machining very hard materials in the mill. Like D-2 , stainless and cutting through the case of thompson shafting. I know you guys use alot of Carbide in your routers. Carbide can take the heat alot better than high speed steel. Thats what destroys high speed steel, The cutting edge being thin heats quickly, weakens and goes bye bye.

Ron





ballendo <ballendo@...> wrote:
Hello,

UHMW was giving a router problems?!? This is another material that
routers cut day in, day out... (Okay, much of it is HDPE (Boating
accessories, cutting boards, wear strip; but the specs for HDPE and
UHMW overlap, and again my personal experience does not come near
matching this response.) I bet he was trying to take too big a cut.
UHMW is TOUGH, but not hard. Gummy. It "likes" to be cut in shallow
bites; trying to hog it out WILL lead to despair.

When I use my router to mill UHMW, I set the speed to 20K rpm
plus, and go like a bat outta **** feed-wise. Sometimes freezing the
UHMW first helps (in hot weather), but ya gotta watch the dims; if
it's a precision part. So you correct for it, just like any material
where heat changes the dimensions...

BTW, I don't use coolant per se, but do keep a stream of air aimed at
the cut point. I've always believed its real purpose was to clear the
chips, rather than cool (because I useta not use it and things worked
fine then too), but it does help. Carbide tooling for sure.

Hope this helps,

Ballendo

--- In CAD_CAM_EDM_DRO@yahoogroups.com, R Rogers
wrote:

> Of course the best way to prove anything is try it. But, I would

think that the router spindle speed would be way too fast, even with
a 1/4" cutter you'd need to be well under 2000 Rpm. A friend with a
cabinet shop called me one day for assistance and he was attempting
to machine UHMW (polyethylene) in a big gantry router and it was just
burning up the material. It didnt matter what speeds, feeds, coolant
methods or cutters we used. The spindle was just too fast. Thinking
back, I worked in a shop where they routered aluminum. They were
radiusing the edges of these large plates. It was just a table with a
router below. How well it worked I dont recall. I never used it
myself. I would be very careful with it. Press "cycle start" and run
like hell :-)

>
> Ron
>
>
> camfambmw540 wrote:
> Hi all, new to the group...seems like a very excellent group :-)
>
> My name is John; I live in the Chicago area. I have a nice compound
> milling table that I would like to use in a very simple cnc setup.
> My plan is to fabricate a very sturdy z axis for a porter cable
> router (1.75 hp), use the compound milling table as my x-y axis. I
> have 2 nema34 173 oz in stepper motors for the xy, still have yet

to

> get the z motors. I also have yet to get the controllers or power
> supply. I have a 1 GHz pc dedicated to my shop needs.
>
> I plan on cutting odd shaped holes (1.5"x2.5") into 1/4 and 1/2

inch

> 6061 aluminum. I also would like this setup to be able to assist me
> in making a much better cnc sysem (when wife approved funds become
> available).
>
> Question: Does anyone see flaws in my idea? Will I be able to cut
> holes of this size in aluminum (if I go slow and keep lubricant
> constantly sprayed on the metal)? Any suggestions on how to
> fabricate a z axis that will hold a porter cable router (simple
> plans??)
>
> Thanks all...sorry for such newbie questions
>
>
>
>
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