Router Shifts During Pocket Cut Out

Recently I have been encountering an error when running a file. I have made 50 - 60 of these previously with no issue. What I am encountering is my Pro XXL during a pocket hole cut in creating an oval cut, the router will stop just slightly on the x-axis; just a split second. This causes the subsequent cuts through the pocket to be off slightly leaving a lip and making the oval out of shape. In the photo I have labeled the sequence of cuts. This is not a complicated design; 5 pocket holes all using the same bit (#251).

To address this I have:

  1. Redone the file in Carbide Create by eliminating the original toolpath and recreating it.
  2. Inspected all my belts and replaced the x-axis belt just in case. I saw not issues with the previous belt.
  3. Lubricated the x-axis rails to ensure there were no hang ups or binding. I disconnected all electrical connections and removed the x-axis motor, since I was replacing the belt, and felt no resistance when moving the carriage left and right. But I still placed some small drops of oil from the kit ordered from Carbide 3D as a preventative measure.
  4. Tried a different bit. Changed from a #251 to a #201. No difference than the tear outs experienced since this is a laminated board; which I expected.

The results were are all the same with no change and the same issue same spot.

I am not familiar enough in reading the G-code and not sure if there something corrupting the file. It does not make sense since all the other pockets, layer by layer, the router movement is a continuous smooth movement. This one pocket hole is the only one which has a slight pause in the movement.

Thanks for your help and insights.


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This is either mechanical (check the machine mechanically, including lubrication), some sort of interference (a dust hose or cord or something else kept the machine from moving at some point and steps were lost), or electrical (a wiring fault kept a step from being made), or an issue with toolpath/tooling engagement (the tool was trying to remove more material than it was able to for a given move, or got pulled into the cut).

Check each aspect, and address as necessary.

Thank you for the response. I will look at all aspects referenced.

Regarding electrical, would there be a recommended method to test for this?



For the electrical, if you power up the machine and leave it for a bit, if there’s a poor connection you should be able to feel it by checking each connector — the high resistance of a poor connection should be hot.

Check your stepper motor pulley set screws. If you have loose set screws this can cause the problem you are having. There should be one set screw on the flat of the stepper motor.

Put a black mark across the end of the pulley and jog back and forth up and down and look at your black marks. If they are aligned good, if they are not aligned bad. If not aligned tighten up your set screws.

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Thank you for the suggestions. I have checked all the areas, stepper motor pulley set screws, warm electrical connections, and any potential hang up that would constrict the movement.

I have gone as far as to disassemble the carriage which holds the router. My purpose was to review all the wheels and apply some oil, from the kit ordered on Carbide 3d, to the rollers which move the router on the x-axis. Individually I applied oil to each of these small four rollers and ensuring they move smoothly along their tracks. This was completed one at a time to help keep it all aligned. However, I noticed after this when moving the carriage with the steel plate and four small rollers left and right by hand, there was small resistance at one point along the track. A resistance was not so great that it stopped movement, but required a little more pressure when moving it by hand. The reason this caught my attention, is when the small rollers were moved left to right individually they move very smooth. When they are collectively attached to the plate and moved left to right, they came across this point. Is it possible that the guides these rollers slide on move a little? Possibly bow a little due to climate change? I can see this area being a potential area impacting movement.


Post a photo of the part in question?

How much movement (or non-movement) is there?

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