On Nov 14, 9:59*pm, "DoN. Nichols" wrote:
On 2011-11-14, Searcher7 wrote:
On Nov 14, 10:39*am, wrote:
On Sun, 13 Nov 2011 23:55:51 -0800 (PST), Searcher7
wrote:
I was wondering if it was common to use powered metalworking tools on
plastic.(Nylon, Delrin, ABS, UHMW, PVC, *etc.).
* * * * [ ... ]
I machine lots of plastics on machine tools made for metal. It's
important to keep the plastic cool. Acetal plastics (Delrin and
* * * * [ ... ]
I'm working on quite of few projects involving plastics and I guess my
biggest concern was gumming up my metal working tools.
* * * * Mostly not a problem. *On a lathe, you will get big balls of
strings from turning most plastics, but they can be pulled away by hand
once the lathe is stopped.
* * * * Push a drill or some other tools too hard into plastic, and you
will have the flutes fill with melted plastic, but once it cools, you
can usually chip it off with no harm to the tool bit itself.
My immediate concern is a project that involves creating a series of
3/16" wide and 1/16" deep grooves in Nylon at 1/8" intervals, and I'm
trying to figure out the best way to do this.
* * * * How precise do the grooves need to be. (Both the width and the
spacing of the grooves.) *That is the most hygroscopic of the materials
which you have mentioned, so it will change dimensions somewhat. *You
may need to machine under maximum humidity or machine the grooves
oversized to keep clearance.
* * * * I, personally, would use either a horizontal mill with a
conventional milling cutter (not an end mill), or a shaper with a tool
hand ground to the right width and to optimum sharpness.
* * * * You can use a two-flute end mill to do it -- but your speed will
be more of a problem (risk of melting the Nylon and spoiling the
workpiece). *The depth is shallow enough compared to the diameter of the
end mill so you should be able to do this in one pass. *I doubt that you
can set up with a liquid coolant (if you are still in your apartment),
but you might be able to use compressed air to both remove the chips and
to cool the end mill and the plastic. *(There are things available which
will turn compressed air into a flow of cold air out one end to cool the
workpiece, and dump hot air out the other end which you will have to
live with, because the hot air is produced by the process which also
produces the cold air. *But they take a *lot* of airflow, and you may
not be able to run a compressor that powerful in your apartment. *If
you've gotten a shop space somewhere, your options are increased. *Here
are some examples on eBay:
* * * * # 110772235707 (two of them for $150.00 starting bid for the two)
* * * * # 290376851464 (single one for $144.00)
* * * * Good Luck,
* * * * * * * * DoN.
--
* * * * * * * * * Remove oil spill source from e-mail
*Email: * | Voice (all times): (703) 938-4564
* * * * * (too) near Washington D.C. |http://www.d-and-d.com/dnichols/DoN.html
* * * * * *--- Black Holes are where God is dividing by zero ---
Thanks everyone.
To answer the questions, the grooves I have to make don't need to have
near perfect tolerances. I'm creating the grooves to place 3/16" wide
phosphor-Bronze strips in them for new contact blocks I'm making.
Making the grooves over-sized wouldn't be a problem because the 1/8"
distance between them is flexible. (In fact I may just go with 1/16"
between each groove).
The grooves, are just to make sure the strips don't shift. The
finished nylon pieces will be 4-1/2" long, 3/4" wide, and 1/4" thick,
and the grooves will be on the opposite 1/4" sides. Each strip will
wrap around into it's own groove.(Which will probably be the toughest
part of this project).
I was hoping that cooling would not be an issue because I'll basically
be making a 4-1/2" long grooves, moving over about 1/8", and then
repeating for a total of 16 of these grooves. I can then cut off 1/4"
thick slices with my band saw. (The other alternative is to cut off
the 1/4" thick slices first and make the grooves in each piece). :-)
I guess my mini mill(with sharp 3/16" end mills) is the best machine
for the grooving job, out of the what I have. (I just have to get it
fixed first).
I have a lot of Delrin, which is also my favorite, but I like to save
it for the critical stuff, since it is not cheap. :-)
BTW. I use this chart to get an idea of the properties of the plastics
I tend to have:
http://www.machinist-materials.com/c...r_plastics.htm
Thanks again.
(P.S.: Sorry if you received this twice. I had to make a correction in
the measurements, and I only post and view via Google Groups).
Darren Harris
Staten Island, New York.