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try acetal i find its better to work with
Hi Guys,
I've been a longtime lurker and have posted a few times (even though count says 1) and would like to introduce myself and ask a question.
I'm a hobby machinist/woodworker and bought my 1100 about a year ago, it was a school mill that was never powered up. I made my own stand from Tormach's plans. It was pretty straight forward and I would recommend the project to anyone with even basic woodworking skills. I will try to do a write up on the stand later and show what I changed and what I would do different next time. Anyway I am slowly making progress into the CNC world and appreciate all of the knowledge available on this board.
To my problem, I having a little trouble with delrin. I'm trying to use a slitting saw to cut strips out of .5" x 9" delrin block mounted vertically in my vise. I was using a 2.75" x .036" saw with 56 teeth, 800 rpm and 35ipm, conventional cut. (gwizard was showing 60ipm but I started slower) The cuts start out fine but the blade wanted to climb up and eventually snapped.(x2) It was machined dry but I was using an air hose to clear chips.
I'm thinking about trying a 3" x .050" saw with 30 teeth and maybe 2 passes.
Anybody have any recommendations?
Thanks,
John
Last edited by john2532; 04-15-2011 at 05:57 PM. Reason: intro
try acetal i find its better to work with
I always thought Delrin was acetal.
I think you are going way too fast. Delrin is a thermoplastic and it melts quite readily. You probaly had chips jammed between the teeth melting and gumming everything together.
What you need is as few teeth as possible and run no faster than about 200 rpm while slathering on soapy water to cool and lubricate.
An open mind is a virtue...so long as all the common sense has not leaked out.
Geof,
That makes sense regarding the speed. I'll slow it way down and try the soapy water. Thanks for the tip.
John
For me Delrin and Turcite machine well. I use a two flute high helix HSS endmill to machine Delrin and Turcite on the Tormach at very high speed with excellent results, no cooling. Also machine Delrin and Turcite on my lathe at high speed. Chips are a contiguous long string. If cooling is used, it is cold air stream from a Vortec cold air gun. I haven’t used a slitting saw on Delrin or Turcite but part-off on my lathe using an Iscar Do-Grip carbide insert blade at high speed with excellent results. http://i72.photobucket.com/albums/i1...KDK1010Bar.jpg http://i72.photobucket.com/albums/i1...DoGripChip.jpg
Perhaps your slitting saw is too fine a pitch and the long stringy chips can’t clear the fine pitch blade.
Don
I think that mackie67 was referring to the difference between Delrin, a homopolymer acetal, vs. copolymer acetal like Celcon.Originally Posted by Geof
I always thought Delrin was acetal.
Randy
I would also try some coolant or some light oil to keep the material from melting, always use a very sharp cutter with delrin,
Delrin cuts great, if you can keep cool,
Delrin is acetal. Delrin is the brand name while acetal is the generic name. Acetal is the best machinable plastic. I buy it from High-Tech Plastics Works great, lasts long.
Delrin and similar acetal plastics machine extremely well. Here are a couple of parts I machined from 5/8” Turcite X rod,( Boedeker Plastics : Turcite A, Turcite X Datasheet ) an acetal plastic similar to Delrin AF: http://i72.photobucket.com/albums/i1...f/TurciteX.jpg
Machining of the Turcite X was done dry, no cooling on my lathe and Tormach mill at very high speed. I probably could have used the Speeder when using 1/16” endmill for milling the keyway slot as the maximum speed on my Tormach is 5.1K rpm.
Don
PS Randy: You think that acrylic chips are bright, Turcite X florescent orange chips covering the mill and lathe are quite a sight.
I bet they are, Don. I've never machined Turcite X, but AF chips look like shaved chocolate to me...
Randy
Randy,
I agree AF chips do look like shaved chocolate. I used Delrin AF rod before finding Turcite A & X which I found were better materials than AF. Still have some chocolate AF stock next to the blue Turcite A and florescent orange Turcite X .The AF material seems to be like a fiber composite with fibers of PTFE woven throughout somewhat like fiberglass where the fiber structure is clearly visible, whereas Turcite is homogeneous.
Don
Last edited by Don Clement; 04-20-2011 at 12:07 PM.
Hi - Is your slitting saw razor sharp? If it was previously used on steel and has one edge more dull than the other, it will progressively wander off and snap.
Acetal/Delrin are both free machining but slippery and resist the cut if a cutter is flexible and even slightly dull. You need good sharp side rake/clearance on a side/face slitting saw
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