More speeds and feeds

Hello all. I know this topic has been covered many, many times, but I’m looking for more real world experience.

Before I get into the details, I have a Shapeoko 2 with a couple upgrades - Acme z axis, NEMA 23 on Z, Makita router. I have not stiffened the X axis yet, but it’s on my TODO list. As soon as I get my X-Carve upgrade I will upgrade to NEMA 23 on X and Y as well. Not X-Carve per se, but close enough.

I have a project I’m working that I need to clear a lot of material - approximately a 7x9 pocket with a 3/4" depth. I ran the job using the stock dremel provided with SO2 using .05" DOC and 22ipm in Walnut. After ~3hours I got what I was looking for, but I have 5 more of these projects to make. The first job killed the Dremel and my shopvac wasn’t too happy either. So now I finally got the Makita upgrade I’ve been wanting for a long time.

Now that I have upgraded to the Makita, I’m interested in how to change the settings. I’ve seen DOC ranging from .11in to .25in for a .25" bit (as a general rule of thumb, I’ve never done more than 50% of the diameter of the bit for DOC) . I’ve also seen feed rates anywhere from 30ipm to 120ipm. That’s a huge swing.

So I’m really curious about balancing DOC and feed rate. I know it all depends on my specific machine, the material, and the bit, but what’s a good starting point? Again, Walnut and Maple with a 2 or 4 flute .25" bit. I’m thinking 50ipm at .125 DOC is “fairly” “conservative” - thoughts?

I’m also pondering 30ipm @ .25" DOC or 60ipm @ .11" DOC?

Any thoughts?

Looking forward to the discussion.


In hardwood with a ,25 bit, I usually cut at .125 DOC with a feedrate of about 60 ipm. I also keep the stepover at about 50%.

I have sucessfully cut oak at 90ipm at .125 DOC but even though it did a good job I felt I was putting a good bit of stress on the machine. I usually keep the speed setting of the Dewalt at about 2.

I have a 500x500 X-Carve with Dewalt 611 router and NEMA 23’s on the X and Z and NEMA 17’s on the Y

I have also learned that if your software allows ramp in cuts then you can increase the speed a bit (Vcarve allows this)
It is also best if you can tell the software to run conventional (versus climb) cutting if possible

I just did a test cut with Walnut at .125 DOC and 60ipm. All was well until near the end - things went bonkers and the machine with haywire. I’m not sure what went wrong, but I believe either I was skipping steps or some material got jammed up in the belts. Regardless, I had to abandon the job.

I will try again tomorrow with a slightly slower feed rate and DOC to see what happens.

Seems like the NEMA 23 upgrade might be an activity for tomorrow…or the X stiffening…

Thanks for the insight.


You may need to check the motor voyage pots on the Grbl shield.

I adjusted the pots prior to adding the makita. Will need to redo after upgrade to NEMA 23.

Which online calculators/formulas are good for speeds and feeds for hobby CNCs?

The calculator which is best suited for use w/ hobby-level machines is G-Wizard: Most (all?) others are intended for far more robust commercial machines.

It includes configurability to take into account machine rigidity (or lack thereof).

Nice licensing model — while it’s a subscription app, each year that one subscribes gets one 1HP in perpetuity for the G-Wizard Lite version:

I have so much to learn…what is the stepover?

The stepover determines how far the bit slides over on each pass when doing a pocket. A 100% stepover would move the bit a full bit diameter each pass. A 10% step over would move a .25 inch bit kisy .025 inches.

The larger the percentage the stepover the more tool marks and less smooth the bottom of the cut will be. A large cutover can also cause the bit to work much harder each pass, especially if the DOC is large.

The downside of a small stepover is that the pocket cuts will take longer.

In Easel the stepover value is set in the Advanced settings