Strange Z-axis problem: bit moves z- or z+

(crew) #1

So I am still trying to get my first correct cut from my Shapeoko.

the x, and y are doing great but I can’t seem to fix the z (using a Dewalt DWP11)

My first problem was that I don’t get enough depth. It was supposed to cut through the material 9.3mm, but instead but would cut about half that. I did some tinkering and stuff, and after a few unsuccesful tries here and there, I noticed that the bit would be deeper into the Dewalt after the job. I guess that the bit was not locked in tight enoough, so that it recesses deeper inside the dewalt, when it should instead be digging deeper down into the material, or that my feed rate was too slow and it was not spinning fast enough to withstand the forces from the wood when it is cutting.

So I tighten the router as hard as I could, and slowed down the depth per pass, and increased the RPM to make sure that the bit breaks down the wood faster when it plunges. Now it cuts all the way through. The problem however is that it cuts through my wasteboard!

And when I look at the router, the bit not extends farther down than before! I understand if the wood pushes the bit up the router, but I am not quite sure why it can also pull it out?

Any advice on what just happened?

Here are some details if it helps:

Original attempt (not enough depth):
Material: Soft Wood
Flat end, Single flute, 3mm diameter, 8mm flute length.
Depth per pass: 0.927
Stepover; 1.1350
Plungerate: 551.180
RPM: 15000

last attempt: (too much depth)
made following changes
Depth per pass: 0.300
Feedrate 480.060
Plunge rate; 240.030

(William Adams) #2

The machine has to be assembled mechanically so that it will resist the cutting forces and not deflect.

Use an endmill of a size which matches your collet and install per the instructions in the trim router manual. Suggest starting w/ a #201

Assemble the machine per the instructions (contact us at if you need help with anything.

Verify the machine per before each use. In particular, be sure to push/pull on the shaft of the installed endmill (not touching the cutting flutes)

Use the feeds and speeds from: — once the machine is operating reliably, calibrate per:

(crew) #3

Did all these already prior. As for endmill size, its a 3mm endmill which I believe fits the Dewalt DWP11. Re: RPM, I put it on dial 3, but in Carbide Create, it was placed at around 11,000RPM, would that have affected it?

Is the endmill moving out of the router (away from it) even possible with the wrong settings?

(ray) #4

the dewalt will not hold a 3mm bit without buying a new small 1/8 collet.
You need a 6mm bit for the collet you have.

(Dan Nelson) #5

I would stick with 1/4" (6.35mm) or 1/8" (3.175mm) bits if using 1/8" or 1/4" collets (1/4" standard Dewalt collet, and C3D sells a 1/8") you’re using unless you specifically have a 6mm or 3mm collet (there’s probably an aftermarket set like this). 0.35m or 0.175mm doesn’t seem like a lot, but it could be what’s causing what you’re seeing. Just my $0.02


(ray) #6

You can use a 6mm bit in a 1/4 collet and a 3mm bit in a 1/8" collet but you can’t use a 3mm bit in a 1/4" collet which is standard in the Dewalt dw611.

(Dan Nelson) #7

Can and should are a little different, this is why they make 3mm collets:,2 . Will an 1/8" collet “work” with a 3mm bit, probably so, but the OP is having issues with possible bit slippage which is why I suggested using a bit that is made for the collet being used. I’m sure many folks have tried this successfully, but if you reduce the number of variables the solution becomes clearer.


(crew) #8

Sorry about the confuson guys. I checked again and it was a 6mm bit (with 3mm cutting diameter), so it should fit well with the Dewalt DWP11. Given this, what could be the issue ?

(William Adams) #9

(EDIT: In most locales) It’s a 1/4" collet — 6.35mm, not 6mm. While ER (and ER-style) collets have a wider clamping range than ordinary collets, the corollary is a 6mm endmill won’t work in a 6.35mm collet (see the manual for your trim router).

See: for one option and for the other options.

(crew) #10

edit: I just checked the manual and it said it can accept 6mm to 8mm shanks. My endmill was 6mm. So it might not be a problem of tightness?
uh oh, did I potentially just damage my DWP11 by tightening a 6.35 collet over a 6mm shank? :sleepy:

(William Adams) #11

The manual should be correct, and in some locales, the collets are 6mm rather than 6.35 — the after-market collets are an upgrade over the stock in most cases, and usually have lower runout, so not a bad idea anyway — the Precise Bits ones are especially nice.

(Pete) #12

for what its worth, I bought a 6mm vbit and it would not clamp tight in my dwp611.

(Dan Nelson) #13

From the Dewalt DWP611 manual:

It’s says 6.4mm, but they probably rounded up from 6.35mm. Maybe a different model depending on what part of the World you live in. FWIW I can’t see there being any way of getting an 8mm shanked bit into this router, unless I used a really big hammer. Are you for sure using a Dewalt DWP611 router? I see in your posts you mention DWP11, which I assumed was a typo, but I don’t see a DWP11 router anywhere on the web. Maybe a different model?



(crew) #14

The Dewalt DWP11 is one of the standard router that they send out with the Shapeoko. Having said that, my basis for the 6-8mm was a DWP11 manual I found online ( which says that 6mm-8mm is ok. Interestingly enough though, as I got home, the hard copy manual I have omits the part about the size of bits that fit.

I think the issue is the 6mm shank on a 1/4" collet. I have since ordered a 6mm one from Elaire.