Am I too careful?


After setting up another job today, I am starting to wonder if I am too conservative regarding my speeds.

For example, the current job i am running is taking about 8h from what my software estimates.

The roughing cycle is the longest part in it, at 7h. Maybe somebody can tell me looking at my parameters:

Stock: Mahogany, 150mmx58mmx25(z)
Endmill: #101 (0.125 diameter)
Passdepth: 0.014
Stepover: 0.03 (24%)
Spindle speed: 7500 rpm
Feedrate: 72 ipm
Plunge Rate: 18.75 ipm
Max Cut Depth for this roughing path is about 23mm. The path cuts away at least 50% of the wood, because my actual parts are only 12mm or so thick on z. I don’t have any other tools though to get the wood thinner, so I have to do it this way.

In general though, it seems fairly slow, since this is a tiny piece of wood.

I also attached a photo so you can see the setup.

I know that I can probably raise the stopover a little bit, but i want to make sure that the roughing doesnt leave any ridges where the smaller finish tool could get stuck at.

Oliver, you might try roughing with a .125" ball-end cutter. I typically rough with a ball-end with 50% stepover and stepdown and 3D roughing selected. The stairsteps are much smaller this way due to the round end of the cutter.

To remove the large stairsteps in the “old days” when I roughed with a flat endmill, I used to use a technique I called semi-finishing, which I described in several places at the MeshCAM forum:

But the stepover and stepdown will be very dependent on your material. I’m not a woodworker, but mahogany isn’t a really hard wood, is it? But even with a say, 25% stepdown and 50% stepover you’d be getting the advantage of the round-end cutter.

Hi Randy!

yeah i just use ball-ends usually, but i have not tried the 50% stepover and stepdown, maybe once this job (which is currently at 40% after 3h…) is done.

I am just wondering if this speed is something expected and normal, or if I am going to slow.

I also bought a .25 endmill from Carbide3d but I don’t know the speeds for it, because the ones i tried almost stalled the spindle. There is another thread where somebody tried the same and it sounded like the NOMAD might not be able to use the .25 without going really slow, which makes it take almost as long as a .125 bit at faster IPM.

Anyways, just trying to figure out whats ‘normal’ :smile:

Oh and Mahogany is fairly hard wood, its on the upper scale of hardness as far as i know.

I would find a way to rip your stock into 2 pieces.
An inexpensive band saw with a guide fence would be my suggestion
More tools are always good.

This has several benefits over using the mill to do it all.

  • You can get twice the parts out of your stock.
  • You wont add all that excessive wear on your end mills.
  • Cut times will be a lot faster.