Router Runout - Router Cutting at an Angle

I tested the runout on my router and found it to be .011" out. I purchased some PreciseBits collets to see if that would remove it. It didnt. I spent most of this afternoon trying to shim the router to remove the runout. The best I could get is .005.

When cutting a 3X4 square the difference between the top and bottom of the cut is out about .008. I am at a loss as to what to do and am turning to you experts for help.

Any ideas?

I have trammed the wasteboard and best I can tell the router is square to the board. I cut some blocks on the table saw and installed the router back in to where it sat on the blocks. However I still cannot get the cut to be perpendicular to the table. I am not sure what is causing it. Maybe the bearings are out. I even bought a calibration rod for the collet to see if my bits might have been bent. It wasn’t that either. I am beginning to wonder if the bearings on the router are bad though it does not make any funny sounds. I have another DW611 router I use for shop routing. I may replace this one and see if that makes any difference. I guess I can check the runout on both while they are out of the CNC.

If you can change this at all by shimming the router your problem isn’t runout. You are probably looking at deflection due to cutting forces pulling the bit and / or machine into the cut. Easy way to test this is reverse your cutting direction. If the angle switches direction then you are dealing with deflection and need to change your feeds, speeds, cut depth, or tooling. Although, 0.005" is a pretty small number to be chasing.

Let me know if there is anything I can help with.

John Torrez
Think & Tinker / PreciseBits

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Not over 4". The measurements are from the top of the 4" side to the bottom of the 4" side. So .005 to .008 on .5 inch MDF

1/4 inch bit
50 inches / min
.125 inch DOC

Wasteboard leveled before trying to square. Working on some turkey calls. Need pretty close tolerances

No ridges but it was cut in one plane only. Maybe I need to change the plane 90 degrees and see if they show up. However, I am going to change up my wasteboard more like Phil’s instead of just a piece of MDF.

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