Sags, arcs, bows and such

Hi everyone,

I’m having trouble milling long, horizontal lines. It seems there’s a consistent upward arc as the mill travels across the right side of the machine. The machine also “slows” near the center of the cutting arear. There’s also slight bowing and arching when milling rectangle designs.

I’ve read about more powerful PSUs, adjusting chain sag, and feedrate. However, before I go down any of those paths, I’m curious if anyone can diagnose based on the photo below. The red area is the latest example.

was the top cut right to left? that looks like what is typical if the power
supply can’t keep up (or the sled is too heavy)

try cutting the other direction and see if the router follows the same path, or
if it sags more on the right side than on the left

this is based on it looking to me like the sag is not symmetrical around the
center, but instead sags more on the left side.

try slowing down your feed rate and see if the line across the top is straighter
that would also show that it doesn’t have the power too handle the higher speed.

David Lang

Hi David,

The cut was “left to right.” I’m going to try a new power supply (however, the current unit is the one that shipped standard with the Maslow kit so it should work, right?) Also, the weight of my sled is 24.6 Lbs.

I’ll try lowering the feed rate.




Did you have any luck after making adjustments? I’m curious as I have a design that would mostly be horizontal lines that I’m considering using the maslow for.

we had similar probs when started with Maslow, but after using a longer top bar the system worked proper!

Nice to hear. How long did you make the top bar for proper horizontal lines?

Our top bar is around 3600mm and distance of motors to working area 900mm

I haven’t had any luck…yet.

So far, I’ve bought a new PSU rated for 10 amps. It didn’t solve the problem. The theory was that maybe the stock PSU wasn’t powerful enough to accurately cut my design.

My next move is to replace my top beam with something longer per Buhlig’s recent suggestion. I plan to do that today. I’ll report back.


I replaced the top beam with one that’s 3600 mm and recalibrated the machine (note: the stock chains are not long enough so I had to freestyle some aspects of the calibration). However, the problem persists.

My next move is to order longer chains and begin experimenting with some of the Advanced configuration settings.