Z-axis steps/tool mark issues

[timspec]

Got my Mega V set up, but I've been battling with an issue where I'm getting noticeable steps on the bottom of my pockets (some cuts are cutting slightly deeper than others, leaving steps and tool marks on the bottom surface). This seems to mostly be where I'm doing full-tool-width slot cuts (somewhat inevitable due to my geometry - letters and numbers in a pocket with spacing just over the tool diameter), but even with very low feeds and cut depths, I'm still having the issue (see pic attached). 

I've already done the following (FYI I'm using a 1/8" square carbide end mill @27k RPM, work piece is walnut):

-reinforced workbench top (2 layers of 3/4" MDF glued and screwed together) - this helped a lot but didn't solve it
 
-secured middle spoilerboard support to workbench top
to prevent it from lifting
-trammed router

-swapped out router (noticed some play in spindle so wanted to rule that out)

-reduced feed to as low as 15 IPM and depth of cut to as low as 0.001-0.005", with no significant improvement

-reduced tool stepover to 20% (though it still has to do full width slots)

-tightened anti-backlash adjustment

-re-adjusted Mega V wheels



I can't seem to figure it out...any help is appreciated!

 

[garymkrieg]

I didn't see that you surfaced your spoil board. Before you do that try and tilt you Z axis up and down, ie pull up on the router and push down on the router, and be sure that there is no play. If there is tighten your V wheels on you X axis.

[timspec]

Jul 3, 2020 15:51:43 GMT garymkrieg said:

I didn't see that you surfaced your spoil board. Before you do that try and tilt you Z axis up and down, ie pull up on the router and push down on the router, and be sure that there is no play. If there is tighten your V wheels on you X axis.

Thanks, garymkrieg. Yes I was waiting to surface the spoilboard until I got this resolved and finished this one project where the workpiece is larger than the working area of the table.

I already tightend up all the V wheels but that didn't fix it...


There is some axial play in the router spindle (0.005" measured with dial indicator), so perhaps that is the issue? I had tried swapping the router out with another brand new one to see if that was the culprit, they both had a similar amount of axial play and it didn't fix it, so I assumed that amount of play was "normal" (it's hard to notice any play until it's mounted to the machine). Is it normal to see that amount of axial play in a Dewalt router spindle?

[Bruce]

Are you using an 1/4" to 1/8" adaptor with a 1/8" endmill in the router? I have to really crank down on the adaptor to make sure it is secure.

[timspec]

Jul 5, 2020 2:25:56 GMT Bruce said:

Are you using an 1/4" to 1/8" adaptor with a 1/8" endmill in the router? I have to really crank down on the adaptor to make sure it is secure.

Thanks Bruce, no I'm using a 1/8" Elaire collet.
FYI the axial play exists in both the 1/4" Dewalt and 1/8" Elaire collets

[Bruce]

Any resolution to your issue?

[timspec]

Jul 11, 2020 16:47:23 GMT Bruce said:

Any resolution to your issue?

No not yet...will probably post a separate post about the router spindle play and see if that's a common thing and if anyone else has seen this result from it