Z axis flex issue w/ z axis eccentric nut mod & 30 min x axis mod

Hello folks, I’m seeing some notable flex on my z axis. I completed the 30 min x axis stiffening mod with bolts and large washers, and I did the z axis mod for the eccentric nuts (replaced spacers with nylock nuts, reg nuts and washers).

When I use the 1/4" 2 flute upspiral bit to cut, I see some notable flex. At least 1-2mm. Running 60 ipm / ~ <3 mm doc Dewalt 611 on 1. My v wheels are set just fine (have been adjusting them and frankly despise those little guys now).

When I switch to a 1/8" single flute upspiral bit @ 50 ipm / .08mm doc there’s very little flex at all. I want to be able to use the larger bit for long roughing passes to speed up production but cannot figure out how to deal with this flex issue.

Help? Please and thanks

I guess I just need to compensate for that when I carve? I’m not quite sure how to do that though… should I state in Easel or wherever that my bit is larger than it is? And then do a detail pass with a smaller properly sized bit?

(P.s. Thanks, Phil. You’re always a great help on the forums.)

I’m able to run 1000mm/min and 1mm DOC easily. Your speed works out at 1524mm/min. Are you saying you’re trying to do 3mm DOC ?. If so, I’d say back off either your DOC or speed until it’s workable. Either way, it’s still faster than your finish bit settings.

What is the material ? That in itself plays a large part in what you’re able to do with speed and DOC.

I can run that fast ~1500 mm/ min (DeWalt @ ~1) but with a bit that large and low DOC I’m finding the bit get too hot. To me, the purpose of using a bit that large is to clear as much waste material as quickly as possible. Even when I reduce the speed… there’s still some flex. If it’s going to flex no matter what, I want to know how to adjust my settings to compensate for that and still save time.

I believe 1 on the DeWalt is too slow. I use 3 and for a 1/4" bit I use 40 IPM and 0.1" DOC.

According to the calculations… if a 1/4" bit with 1 flute on MDF wants a chip load of .004-.007… I should be running the machine at 90ipm @ DeWalt 2 to get .005 CP. (Assuming DOC is a little less than half the bit size.)

Going high RPM and low IPM seems like it would just be continually dragging the toolbit against the wood, not getting big enough chips, and wearing down the bit. Am I reading this right?

Or am I missing something here? B/c my numbers seem high and I don’t want to break a bit.

Q2: When you say flat bit does that mean flat end mill? Are you using 1 or 2 flutes?

My 1/4" bits are the common 2 flute straight. The numbers I posted work for me. I will say the only time I have run my X-Carve over 80ipm is using my laser. Not that it can’t be done by my experience with machine seems like that is pretty fast. Fast ipm, low rpm and small DOC work well when cutting acrylic.

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where can I get more information on the linear rail Z axis.

Check the “It’s Alive” post, @ErikJenkins installed one on his XCarve. I think it’s somewhere around post 700… he provides an eBay link to the one he used.

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Here is the post where I mounted the new Z-Axis.

And the link to the one I bought:


Thank you, I take it you are very happy with the Z axis slide, could you please tell me what the overall height from the wasteboard to the top of the slide is, as I have my Xcarve bench folding up towards the wall, due to lack of space, so it can be pivoted out of the way when not in use, and it looks like it might be a problem, has anyone out there from the UK bought one of these, what is the total cost with postage VAT + duty + whatever else they add on

l[quote=“DarrylKegg, post:16, topic:24944”]
Check the “It’s Alive” post,

Thank’s Darryl

From the wasteboard to the top of the Z-Axis is just under 17 inches.

Thank’s Erik

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How is it your Z upgrade working out? @ErikJenkins

So far I have been pleased, the main reason for the upgrade was so I could add a rotary axis… I needed more z-axis movement. I wasn’t having any issues with the original axis at all when I did this… I just needed more clearance. The new axis is extremely smooth.


So effectively backwards? I’m thinking that would add more weight hanging off the X, but it’s an interesting concept…

How about 4 linear actuators that raise and lower the wasteboard? :smile:

Yeah, I just ordered my Z axis linear rail, I expect it to be here in a day or two and hoping to work the weekend on getting it attached. I have the 40x40 single box extrusion for OpenBuilds and I raised my X using extension plates on the X end plates, so I wasn’t overly concerned about the bottom of the Z beam causing issues, but I’m intrigued at the thought of reversing the mount.

I’m only wondering about the behavior of the rail in that orientation, esp when milling aluminum. The default orientation has the bulk of the rail attached to X, and only the small plate that carries the spindle moving up and down the rails. With it reversed, you’ve only got the small plate attached to the X, so I’m wondering if there’s ANY flex or torque on the rails or screw…

I’m going to play with it and see. A few extra holes in the back of the rail to test your theory can’t hurt anything. Worst case I put it back the other way around.

EDIT : I may just be over thinking it… :smile: back or front, there’s only the same number of mounting points to the X.

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Yeah, the more I think about the configuration the more I like it… I’ll definitely test it out ASAP and report back.

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