Slight drift during cutting

As shown in the photo, I’m getting x and y irregularities when cutting a v groove in a cribbage board. I’ve cut a cribbage board in oak and hard maple with exactly the same results in the same areas. The gcode from fusion makes these lines in a haphazard order… regardless, these lines should be straight like the code shows. I believe this is a mechanical issue with my 1000mm xcarve with the 661 router. Has anyone seen this and any ideas what I should try?

My belts are pretty tight and my vwheels are very tight… the machine holds home very well/doesn’t lose steps.

The vwheels being overly tight may be the cause your issue. Wheels should be tight enough to not turn (slip) with one finger, but turn with two.

I’ll try that first and report back, thanks for the tip.

  1. Is your Gantry squared up when you home the machine? I.e. is the right carriage same distance from from the front Y plate as the left where the limit switch is.

  2. Are your belts equal tension? 5-6lbs@1”?

2.1 Have you calibrated your steps on them machine?

  1. V-wheels might be too tight as noted above.

  2. Too aggressive of a cut and the spindle might be torquing radially.

  1. I square my gantry every time I start up off the back hard-stops. I can double check if my Y plate and X plate have similar distances to the gantry… Usually I just square my work piece off with the bit, moving up and down the Y to ensure I’m square with the machine.

  2. The belts have a similar tone when i pluck them, but I’m not sure how to measure belt tension. Is there a way I can test this without a gauge?

2.1 I have not calibrated the steps on the machine, but I’ve been happy with a 0.01" tolerance in XY.

  1. Checking the vwheel eccentric nut tension tonight for sure.

  2. 1000 mm/min with a 1/8" shank 60 deg bit (the one found here on inventables) on a thin line isn’t very aggressive in my experience, it may be slow even. Still an issue?

Had almost the same problem recently and it took some tuning to get it right.

Usual culprits stated above, idler wheels etc. I also found that my gantry was off on the X by 1 mm over its length (750mm m/c)

I tinkered and it got better. Then I was stumped so I asked my dad, machine tool maker for 50 year.

Simply put, there is a correlation betwen feed speed, depths of cut, plunge rate and most importantly spindle speed. i found this on the forum

Since then its like watching a Swan glide across a mill pond…I even get the magic chips we all long for…


I adjusted the vwheel/ eccentric nut tension to the recommendation from John above: “Wheels should be tight enough to not turn (slip) with one finger, but turn with two.” I also tightened the hardware that holds the vwheels on as I noticed they were a bit loose. Finally, I started using good feeds and speeds thanks to Adam’s spreadsheet and got “the magic chips” :grin:

See photo, looks like my issue is largely gone. Thanks everyone for the help!