3D work - roughing passes

[matt_r]

Greetings,
I'm about to attempt a job where I have to do some 3D cutting in MDF. I'm working in Meshcam, so I can control my depth of cut per pass. My question is, for a 1" dia round nose cutter (2 flute), how deep can I go per pass, and at what speed. Again, this is a roughing program. I am running PRT96, with a PC router. Also, any tips on stepover would be appreciated.

thanks,

-matt

[paco]

For roughing, I usually set some thing in between 50-75% for the stepover. I would rotate the tool bit at about 15000-16000 RPM, I wouldn't plunge too fast 1-1.5"/sec. and would start my feed at 1"/sec. then speed it up until something start to go wrong. I'd say that with those setting, in MDF, you could have a stepdown of 0.5-0.75".

You might be wondering if you shouldn't set the PC to a slower RPM (with a 1" tool bit) but I wouldn't recommend since this router (PC 7518) doesn't keep a steady speed, mostly at 16000 and bellow, when working hard.

As wrote, I would be carefull with the plunge speed. It may sound wrong at it's first way but that's because it'll be machining a FULL kerf firts then your set stepover. That's a reason to start the feed (X & Y) slower than guessed...

[matt_r]

Exactly the kind of info I was looking for - thanks Paco.
Addtionally, in a previous post, you were discussing the merits of meshcam. I am using the 60 day evaluation copy right now, and I think I may buy it. So, thanks for the contributions to the board.

-matt

[paco]

Have you jump right at V2 Build 2226?

Something new should be release soon...

You may find the user group interesting to join in (get it through your e-mail).

[hespj]

"It may sound wrong at it's first way but that's because it'll be machining a FULL kerf firts then your set stepover. That's a reason to start the feed (X & Y) slower than guessed..".......Paco

For this reason I've tended to go with small stepdown and much higher feed speed. That first cut at a new level can be removing several times as much material as subsequent cuts - that doesn't seem right. The higher feed speed makes up for the smaller step down.

John

[paco]

Yes, that would work too... it's just that I like to challenge my dust collector!