Router bit marks on tab hold downs?

HI see attached pic. Not sure why I keep getting router bit marks where the hold

down tabs are at? idea?

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ok thanks. So would a tramming gauge be working my wild to buy?

I used a plastic carpenters rafter square from harbor freight to true up my x carriage when inbuilt my machine …

I can have similar markings on my setup (DIY CNC, not very stiff) when routing harder material such as hard wood/aluminium. In my case it is tool deflection and it gets more pronounced the harder I go. (For reference I do alu with 1/8" bit, 60ipm and 0.01" doc, 10k rpm.)

While moving on X/Y the spindle see a lot of sideway forces but X/Y is idle when Z move over the hold down tabs.
So when X/Y is idle and Z retract the bit disengage the material and spindle come into a relaxed state. This relieve the deflection causing the bit to engage slightly off of carve/track :slight_smile:

I agree, your head is not square.
get a dial indicator and tram in your head.
to get the best results, swing the largest circle that you can

Im going to have to agree with @RobertCanning on this one. Planing the surface of your spoil board will solve for many headaches, and likely this one as well. I added a secondary board so I didnt have to mess up my pretty inventables one, and it has helped tremendously.

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Hey Michaela could you give me a little info about your machine , design file and tools that you are using

I agree with everyone saying about not being in tram kinda

Your machine should always be in tram to your waste board

But to me that looks more like tool deflection or tool run out or flexing in your machine

HI its a xcarve 1000 using a 1/4 bit. seems to be more flexing if you ask me

Note it does it on all file tool paths. soft or hard wood


Yup looks like your machine is flexing

So would look at that

What is the height of your tabs?

I would cut continuously down to your tab height and then do the last pass all in one shot

Persionally I would bump your depth of cut up to .1" - .135"

What type of 1/4" bit are you using though?

I had this same problem. I fixed it by aligning the z-axis. Raising z to the top and inserting your longest bit or in my case, I used a 1/4" drill bit to better help visualize the alignment. It’s helpful if you can get a square small enough to fit under your router. It could be something cheap, but being able to place it directly next to the bit will be important.

Thanks for asking this question! I was getting the same marks on my tabs as well.

Hi aligned the z axis and it helped some.

ok thanks

I had similar issues and it ended up being the screws in the delrin nut on the Z axis were loose and the v wheels on the Z axis also needed to be tightened up. Just something else to check if you haven’t already besides what was stated above.

ok will check it out. thanks

I’ll respectfully disagree with the posters suggesting your z axis need to be squared (though certainly that would exacerbate the problem). These are dwell marks (google “cnc dwell marks”). The posters who have suggested deflection are correct. It’s caused by movement changes. Typically, the solution for dwell marks involves some combination of lead in/lead out and ramping. However, for your problem with tabs, the more common solution is 3D tabs (radial or triangular). With square tabs the bit dwells in one position while it plunges/retracts, allowing it to overcome the deflection and cutting more deeply into the wood, ultimately leaving a dwell mark. The solution involves either reducing deflection by (a) increasing rigidity (of the machine and/or by increasing the bit diameter), or (b) reducing feed (again, to reduce deflection); or - more realistically - avoiding any change in deflection by keeping the spindle in continuous motion though the use of 3D tabs.

Unfortunately, I don’t believe Easel has 3D tabs (don’t know, I don’t use it). I use Vectric software and for the most part completely eliminated my similar issues.


Hi I am using Vcarve desktop software

Hi yes I am using tabs and that is where I am getting the marks in the pic above