Router not cutting deep enough

I know that this seems trivial but I was having a hard time trying to determine whether or not the issue was either software, hardware or user error. Anyway, I used Makercam to load up the sled with tool paths file and exported the g-code and ran it on ground control. I then used Maslow to cut the sled but every time I cut the sled (around 5 already) on the plywood, the cutting depth was only about 0.5" instead of 0.8" which was what was the default.

I tried to systematically figure out what was wrong. Was it because the plywood was too thick (0.75")? Was it because the Z-axis wasn’t zeroed correctly (had to zero it every time)? Was it because Makercam wanted a value for the thickness of the plywood (default was 0)?

Anyway, to make a long story short, the problem lay with the fact that the bit was NOT installed correctly. Having said that, however, I backed out the bit from the collet so that the length of the bit was 1.5" and then set the cutting depth to 0.95" to ensure that it would cut all the way through the plywood and the into the spoilboard just to make sure.

However, when I did that and ran a file (circle, depth of cut 0.95") the bit just flew off the shaft at around 0.80" into the plywood. I inspected the bit and the router and didn’t find any damage so I reinstalled it only to bring down the bit about 0.25" down leaving about 1.25" out of the collet.

Typically, when I install a bit into a router, I bottom out the bit and then back it out about 0.125" to make sure that the bit doesn’t fly out. Having the bit stick out 1.25" seems risky and dangerous to me but I don’t see any other way to ensure that the bit will cut all the way through the plywood.

Please advise. Thank you.

I am not sure you are Zero-ing it correctly. So it doesn’t really matter how you install the bit in the router, but once you do you have to move it down to exactly where you think zero should be and then hit “Set Z zero” (Not exact term) in the Z axis page.

the most common cause of this problem is that the Z axis as a lot of play in it,
by putting a bungee cord over the top of the router to pull it down towards the
workpiece, it’s far more reliable.

you need the bit to stick out far enough to reach through the wood, that may
require using a longer bit, or a extending the bit a little. You need to zero
the Z axis (so the bit is just at the surface of the workpiece/sled) and then
see if you have enough travel left in the Z axis to make it through your

David Lang

I forgot to tell everyone that I did put a bungee cord on the top of the router to make sure that the bit is cutting at the right depth. The bit that I’m using is the standard 2" double flute up spiral bit that I purchased from Maslow.

Is it normal for the bit to be placed that far out of the collet (ie. 1.25")?

I zero the Z axis every time I either adjust the bit or start running the file just to make sure.

What doesn’t help is you loose length in your bit from the thickness of your sled. 2" bit minus .75" think sled minus .875" (.75 material being cut plus and extra .125 to be sure you cut through) only gives you .375 in the collect (not ideal).

It will depend on the router too, the rigid router can be lowered until the collet is about 1/8th inch above the surface of the wood. This lets you cut 3/4 plywood with a 2 inch bit and still have 1 inch in the collet

I think I’m good. Since there’s about 3/4" of the router bit in the collet, it shouldn’t be enough to have it come out abruptly like the last time when it had only 1/2" in the collet.

Hey Bar, have you considered that the forces at play regarding the router bit? I’m thinking that typically the router is vertical when being used. Since it is literally suspended by two chains their are more forces which would have an effect on the bit coming loose during an operation. Since it is spinning at a high velocity and there are higher lateral forces than there is relative to the downward force of the router and gravity, wouldn’t it come off more easily?

if the collet is properly tightened on a correctly sized bit, there should be very little danger of the bit coming loose. It sounds like you are well familiar with routers, so if you are experiencing your bit coming out, I would check the diameter of the bit to make sure it isn’t too small for the collet you are using. If that is fine, I’d then check to make sure there wasn’t a problem with the collet (such as debris in the flexing slots) preventing it from tightening on the bit.

If all that is good, and the bit seems to be securely mounted prior to your cut, but then comes loose, I’d probably look at the feed speed and depth of cut per pass as potential issues.

@Jayster also raises a good point regarding sled thickness. If you have a very thick sled, you may want to look into a longer bit.

Can you give us some more information about your setup? Which router you are using, the thickness of your sled, whether you are using the stock z-axis, etc.

Also, perhaps a walk through of how you are zeroing your bit?

This portion of your post is what concerns me most:

While only having a 1/2" in the collet is not especially safe, I wouldn’t expect the bit to fly off under normal, or better yet, conservative use.

Thanks Keith.
I made sure that there was no debris in the flexing slots by blowing compressed air on it. I then installed the bit making sure that the bit was secured in the collet leaving about 1.25" out of the collet. There is about 3/4" in the collet.
I set the feed rate at 0.10" and the speed was set to 13,000 RPM.

I’m using the Ridgid R22002 router with the Maslow Z-axis and ring kit. The thickness of the sled is 3/4".

When I go to Zero the bit, I lower the bit until it just touches the surface of the stock that I’m going to cut and then I choose the “define zero” in the z-axis settings.

I’ve made a test cut file (rectangle and triangle) and will run it today with the bit in about 3/4" in the collet and see what happens.

Thanks for all the help!

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I should make a macro for this. One thing to check is whether or not the head of the router is getting hung up on the z axis motor bracket. I had the same issue where it didn’t want to plunge deep enough and it turned out I had turned the z axis out of the way of the linkage kit and in doing so, I ever so slightly moved the motor bracket closer to the router. The head of the R22002 router is a little bigger than the body and when the router was lowered, the head would get hung up on the bracket and the router would pop out of the tab. When the zaxis would raise again, the router would snap back in to the tab… so it made it hard to figure out what was going on. So… Make sure the router head isn’t getting hung up on the bracket.

Edit: I added this to the troubleshooting section of the wiki.

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