Thread: Chris's Extruded Router.

Hi Rod
Just call it spelling laterally.


Good example of a Brain Study: If you can read this you have a strong mind:

7H15 M3554G3 53RV35 7O PR0V3 H0W 0UR M1ND5 C4N D0 4M4Z1NG 7H1NG5! 1MPR3551V3 7H1NG5! 1N 7H3 B3G1NN1NG 17 WA5 H4RD BU7 N0W, 0N 7H15 LIN3 Y0UR M1ND 1S R34D1NG 17 4U70M471C4LLY W17H 0U7 3V3N 7H1NK1NG 4B0U7 17, B3 PROUD! 0NLY C3R741N P30PL3 C4N R3AD 7H15.

PL3453 F0RW4RD 1F U C4N R34D 7H15

I (apparently) have a "strong" mind.

So heres my first cut.

Made a ton of errors when making the G-code but the first one turned out alright, the 2nd one I did right after it (half speed, WD40) it was able to move around too much and produced some funny circles. I have a feeling the straight double flute bits would produce a much better finish, I was using what I had which is a sharp HSS 6mm 2-flute spiral.

Tried removing the furr with a razor so ended up digging in a few places as you can see.


Anyone have any experience with this material? if so what was the best bit to use?

Maybe yes, maybe no. Depends on what the material is.

Bob Willson

Hi Chris,

Material looks soft - Delrin, Nylon or maybe HDPE?

In any case be aggresive with your cuts. Best lubricant is water and soap solution but I cut it dry. Keep increasing feed rate to get chips and your cuts will be cleaner. That means around 2.5 to 3m/min with a two flute cutter. If your machine is struggling to get the feed speed reduce your spindle speed. If it is your new machine then I reckon it might just go fast enough.

Two flute HSS cutters should be OK but if you have a four flute try that. You really have to experiement a bit and I know fellows that freeze soft plastics to get a good finish. Another thought is to offset your cut half a mm and do a final pass full depth to clean up the edges.

Couple of ideas to try anyway.

I have found 150 grit sandpaper the best for deburring the edges on the soft stuff. Blades tent to dig in too easy althought you could try a beburring tool.

HDPE maybe, I'm told it has excellent machining properties but I dont think he ever mentioned what type of plastic it is.

Was running at 5mm passes @ 3m/min 24k/rpm and 12K/rpm, I'll have a play with the settings again tomorrow and see what I can come up with, thanks rod.

If it is HDPE then go like buggery. A high helix angle mill bit is required to clear the swarf quickly so maybe reduce your depth of cut to half that to allow clearing the swarf before it re-melts. Offseting your cuts will help a lot as it give the swarf somewhere to fall on that final pass.

If you have a compressor then keep it blowing on the cutter to help clear swarf and cool the cutter down. Use your compressor regualtor to reduce air flow to about 30 PSI so you don't end up with stuff hanging from the rafters.

HDPE does give a good finish when you get it right.

Great looking!!! So are the timing belts as accurate as ball screws how well is the belts working.

Looks the goods. I like the look of the belt drive. I've seen one of Peter Homann's belt drive machines move so fast it shook the table it was resting on and visually it was hard to keep track off the head. Belt drives can do crazy speeds.

Brad.

Originally Posted by Bupton

Great looking!!! So are the timing belts as accurate as ball screws how well is the belts working.

Na, I dont think they are as good as ballscrews but so far they are doing good, tensioned correctly there is no visible play.

I'll see about getting a video up on the next piece I cut so you can see how it handles.

Timing Belts cannot be too bad, after all theyre used on most CO2 lasers these days and with such fine accuracy needed they seem to get very little stretch and wear.

Daniel

Originally Posted by twistedfuse

Timing Belts cannot be too bad, after all theyre used on most CO2 lasers these days and with such fine accuracy needed they seem to get very little stretch and wear.

Daniel

Yes, but i expect you don't get the lateral forces you get with a router on a heavy gantry.

I could be wrong but aren't lateral forces designed to be taken in by correctly locating/spacing your linear guideways and thus should not act on a ballscrew or timing belt.

Originally Posted by twistedfuse

I could be wrong but aren't lateral forces designed to be taken in by correctly locating/spacing your linear guideways and thus should not act on a ballscrew or timing belt.

Forces in the same axis as low friction slides or guideways will be resisted better by a ballscrew than by a belt is what I meant. The direction of the lateral forces from a router plowing through wood or aluminium can be all over the place. If those forces are in the same direction as your guides it is just the ballscrew or belt which is resisting the small movements which affect accuracy/repeatability. Sorry if my expression was unclear.

Fair Call. Can see where your coming from. Well noted.