Thread: Machining HDPE considerations

Could be an indication of cutting in the wrong direction. Plastics and metals like to be climb cut.

and use a very sharp cutter

Well, I'm designing in Aspire. The 3D Roughing toolpath is a Z-Level raster along Y. The only other option is a 3D raster. I'm not sure what this does though. The finishing toolpath is a climb cut, but the noise is during the roughing. As for the cutter, it's a brand new 4mm, 2-flute carbide ballnose, only used on one other small cut in a pine stud.

It probably didn't help that the clamp wasn't holding properly and the job moved some, and I ended up holding it in place with a pushstick while it was cutting, so I'm not sure if it might have been vibration from looseness?

Russell.

Yes, vibration can make add a lot of noise. I don't think you can avoid conventional cutting when using a roughing path in Aspire, so the best you can do is make sure the workpiece is held securely.

You might want to pick up a single flute "O" flute bit for plastics, though, it'll cut much better.

Originally Posted by Ger21

You might want to pick up a single flute "O" flute bit for plastics, though, it'll cut much better.

+1

And don't be afraid to run a fast feed speed

Rain's been keeping me out of the shed, so I'm behind schedule, but the weather seems to be clearing a little, so I'll have to start shopping for those single 'O' flutes.

As for the speed, I think I'm running as fast as the couplers are rated, but I'm still trying to figure out whether 1500mm/m is truly the max they can operate at. I'm not going to tempt that fate till I have some more experience though.

Russell.

i was running 3d cut , 8mm carbide bullnose 2 flute spiral at 40mm/s or 2400mm/m ( flat out for HDPE) , with a real shallow 2mm cut
12,000 rpm

rough cut with a 2mm pass
finished with 0.4mm pass

each mould was 5 hours ( 3 of them in HDPE )

>??? dont know if im doing it right , but it works , ???

the 45deg finish cut , left hairs on 2 sides ( not climb cut ) but they rub off with your thumbnail

i think the max speed for your couplers is more for out of balanced product , but then again i wouldnt like to see it hit a stop at full speed
ive backed my acceleration right off for a "smooth change of direction "

as for the rain , a 200mm heavy dew over night is normal here , i think QLD needs to build better drains , there deadly 8 foot deep ones on the sides of the roads in darwin , the drains arnt deadly , it when someone hits a drive way they die

LOL on the "dew".

How did you fit an 8mm bit? I thought 7mm was the max these could take?

Russell.

saw some E11 collets on ebay at 8mm and also bought a 1.5mm and 1mm , to complete the cheep set 2-7.5mm , think they were out of germany

cheers ken