Ridges at bottom of pocket

I am trying to make a circular pocket in wood, I can make the pocket but the bottom is not flat it leaves tiny ridges. also there is a tiny notch at the top, I will attach a pic to show, since i’m a newbie and don’t use all the right terminology :slight_smile: I am using a .250 flat endmill to make the pocket. Any help on whats going on and how to fix appreciated.


Please see http://www.shapeoko.com/wiki/index.php/Calibration_and_Squaring_the_Machine#Shapeoko_3 and the following sections, as well as http://www.shapeoko.com/wiki/index.php/Climb_vs._Conventional_Milling

thought I got it setup good, If you think thats what it is though, then your probably right, I will go over the machine and check it. thanks

Hey Brad-
I had the same issue (doing a square post). My ShapeOko was actually pretty square just on the initial setup, although I may have had the 1/4" end mill out too far (so that it had a tiny bit of deflection) or the DeWalt router sitting a bit high or low on the Z-plate, etc. When I installed the new smaller and stiffer Z plate, the ridges became much smaller and less noticeable (although still there, I can feel them rubbing my finger over them and see that at certain angles.)

Here’s the post I made about it a month ago including photos.

Hope this helps!

Thanks I am going to check the square of the machine soon, I feel that might be part of the problem. Should the pocket be completely flat or is it the nature of wood to still feel some small ridges? Do I need a newer z plate?(not sure what the newer ones even look like) my SO3 was bought last month.

Some ridging may be inevitable, depending on the nature of the wood when using a bit which will pull or push the wood fibers.

The new Z plate is nice, and a great upgrade, but it’s not necessary — if you’re concerned about it, my suggestion would be to just add some metal bars to the sides as a number of people have done: http://www.shapeoko.com/wiki/index.php/Shapeoko_3#Plate

In my case, the new Z plate made a noticeable difference, although in the course of installing it I may have just made my machine more true and that had more to do with it. But before I was able to flex the plate/router by a millimeter or more and now I can’t move it.

I also am holding the piece of maple that I made the pockets on. One side has the pocket from the old Z plate and the other from the new one, otherwise all settings and cutter were the same, etc. Its very noticeable which side is which because on the original side, there is a clear chevron pattern at either end of the rectangle tracing where the cutter turned and plunged lower each pass. On the other side, the ridges are much harder to see and they trace around the entire pocket, like the faintest foot print showing exactly where the router travelled as it spiraled it. I think that pattern would be present if I had routed the pocket by hand.

Good info, thanks. Curious you have a pic of the Z plate? I just took some time to check to make sure my rails were square and things were aligned. They were not perfect so I had to make adjustments and I feel everything is aligned.

One thing I did notice, is the Y Rails, one hits the ends before the other, I measured with my calipers and its about 1/16th gap. This was mentioned in the wiki link @WillAdams posted, I did not try the clamp fix in the Wiki to pull it inline. Should I try that or maybe its my base thats not square? It got late so I will have at it again this week and run some tests.

I did find a loose nut, and it wasn’t me :grin:

Ha. I forgot about loose nuts - in all seriousness, getting the eccentric nuts tightened all the way (180 degrees rotated) did more to improve the rigidity than anything.

The lovely Z-plate picture is from Edward Ford. Before there were any installation instructions, I wasn’t actually sure how the new Z plate gets mounted, especially since its a different shape than the original one. In fact, I first thought the idea was to bolt it onto the original plate in order to add rigidity. So the Carbide team, as always, was super helpful and I’ve been very happy with it ever since.

Ed sent me a new Z plate, he wasn’t sure it would help all the issues I had but he wanted to try, he overnighted it to me this week :slight_smile: Hell of a guy. Installed it last night and I am VERY pleased, that in combination with re-squaring the machine has virtually solved all my issues, As well as tweaking my tool paths and hold downs. I am happy now, but still learning :smiley:

I have had similar problems. Two things I have done to completely eliminate the ridges I was getting.

  1. Flatten the spoilboard - I put an additional 3/4 MDF spoilboard on top of the factory spoilboard and taped it tightly to the original. Then I flattened it with a 3/4 flat bottom router bit using a pocketing patch for the machine cutting area. I had horizontal lines across every run of the process indicating the router wasnt square. Sure enough, it wasnt.
  2. Squared up the router to the new flat spoilboard.
  3. Re-ran the spoilboard flattening gcode and now it is a smooth as a baby’s but.

Check your router squareness. We focus so much on the extrusion but often forget to check the router squareness.

Hope this helps. Made a huge difference for me.


Thanks for sharing your experience, do you have a link to that 3/4 bit you used to surface? I’m going to work on a new spoil board soon.


Thank you for you promptness :smiley:

When you surfaced the spoil board, how much did you take off with the pocket?

It really depends on how uneven you think it is. The first pass i took off .02 inches. Mark your board off with pen or pencil lines so you can see that they got removed. At this point I saw the uneven lines. So I squared my router and only took off .01 the second time. I could have actually taken off less that that but that is what I did.


What did you do to square the router? Adjust it within the aluminum holder? Or did you put paper or some other spacer in part of the holder to adjust how it sits? Thanks.

I ask partly because I’ve been frustrated with the MDF wasteboard not holding threaded inserts well, absorbing too much cutting oil, bowing, and all the general reasons that MDF is annoying. I’m considering getting the Carbide aluminum table (which I know is pricey), but naturally I wouldn’t want to then try to cut a pocket, so I’m hoping to get the router as perfectly square to that surface as I can.

Verified how it was out of square and by how much. Then I put in two brass washer shims between the router and mount to square it to the spoil board

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