Bit wanders at extreme edges

On y axis at left side bottom of 8 x 4 Sheet. Also wanders on the x axis when over on the right side (last 4~5 inches) on a 4 x 8 sheet. I can get it to cut straight if I press down on the router adding about 5lbs to the pressure.

Have extended chains on 12’ span.

wonder if it would be worth trying adding add’l bricks / weight . My sled isn’t really enough to hold the sheet flat if it has much curl to it

I added an additional brick to the existing 2. The sheets are very flat (3/4" cabinet grade ply" and I screw them to frame so they don’t move.

The bit seems to wander off the path and its off to the races with it biting into the direction of the chain with the longest and shallowest angle. Away from the chain with the steepest and closest angle.

I guess the $50 question is: is this a limitation of the machine even though its advertised as a 4x8 platform?

It has been shown to work, but could be considered a limitation of the system. Feeds and speeds, depth of cut, and sled friction may all have some influence here. Adding too much weight can ruin the motors over time. I typically push on cuts near the ends, in fact I cut an inch past the end and out of bounds on mine last week as part of the design… I have my latest frame set up as a 6’ wide system with an 8’ beam because of limited space (folding frame design up over my car). I had to “assist” the router on the very end where the work piece hung out far.

due to the angles, adding weight to the sled does very little to flatten the
workpiece. Instead you need to beef up the frame and screw the workpiece to the

the good news is that unless the piece is extremely warped, the fact that the
sled rides on the surface of the piece makes it ignore a lot of warping.

David Lang

What is the feedrate you are running at that location, and what is the tilt of your workpiece?

I’m running a 12’ beam with adjustable skirts and am cutting right at the edge pretty well after I slow down the feed rate to 25in per min. My tilt is around 15 degrees

I have the same set up. 12’ beam. I am running at 20in per minute using a 1/4" compression bit.
The material is flat, no warping. It is secured to the fully supported frame panel with screws at the edges of the material.

It’s not a jerky motion like something is hanging up, it just wanders off course like its got a mind of its own.

It’s driving me nuts as well as wasting material.

Any ideas?

my sled had issues at the bottom when it would hit the frame that stuck out past the plywood surface just a tiny bit and then it also had issues when the plywood I was cutting was super rough. I find that cutting down into a corner is much worse than cutting sideways or up from the corner since the chains cannot push the sled, just pull it. If the frame is steeper than 15 degrees, the issue is not enough down force on the cutting surface for plunging and if the frame angle is less than 15 degrees, then sled friction becomes more of an issue. Do you have a full skirt around your work piece? if not, is your sled tilting off the edge of the frame as it tries to cut near the lower corner or side edge?

The set up is exactly 15% per the digital gauge. Levels on X & Y axis confirm level and plumb. Full skirt shaved down to below work piece to preclude sled from catching as it slides to the edge of the workpiece. The material is prefinished one side birch plywood cabinet grade (very smooth).

Vertical cuts on both sides toward the edge it wanders to the center of the workpiece. On the right side the horizontal cuts wander up at about 8" from the side of the workpiece.

Slowed cut to 18" per minute. Router is at lowest setting with 1/4" compression bit. Chip size is good, not making powder and bit is not discolored from heat build up.

compression bits are a bad idea, they work on the idea that you have the center
of the bit at the center of the workpiece, which is not the case with the

can you post a video showing it misbehaving?

David Lang

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Well, I couldn’t get it to fail while filming. I put a fresh bit in it, and while it wandered a tiny bit at the end of the panel, I missed filming it.

But, can we pursue your statement that a compression bit doesn’t work well with the M2? I don’t understand your reference to the center of the work piece (meaning only 2’ either side of the center home location or cutting the centerline of the tool path versus the outside?)

Also what bits do work well with a full 4 x 8 sheet of 3/4" Plywood. This is the majority of the cutting I do, using the M2 as (hopefully) a very accurate panel saw.


I’ll see if I could add to this conversation about the bits and @dlang can correct me if I am out of place. A compression bit is essentially 2 bits in 1 (a down cut and an up cut). I think the up cut is at the bottom while the down cut is at the top. They are best used when you can do a full thickness depth of cut. This allows the up cut side to cut the bottom surface up towards the material, and the down cut side to cut the top surface towards the material. This is to help prevent tear out of the surface venires. The Maslow/M2, in my experience does not handle full depth cuts very well due to the feed rates being very slow. I’m not saying it can’t do it, but you are most likely going to have to slow the feed rate down even more to maintain the accuracy you would want in a panel saw-esque use.

I have found that single or “O” flute bits work. I have used both the 1/4in and the 1/8in bits from SPE tools and have had very good results. As they are both up cut bits, you may have tear out on the top surface, so that may need to be taken into account with which side of the material you have on top incase there is tear out. I have also seen people us a down cut bit for the first layer (maybe 1/8in deep), and then switch to an up cut bit to finish it out and prevent tear out on both sides. I have also used straight cut/mortising bits on ply with some varied success as well. the key with any CNC router/machine is to get the proper feeds and speeds for the material and bits you are using.

I hope this helps!

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Thank you for the input.
I am using a feed rate of 22" per minute, plunge rate 9in per minute, depth per pass at .11811 in per pass. I was using the 1/4" bit to get a deeper cut per pass as the M2 is not fast.