Engraving small font - the bit digs deeper and deeper as the job goes on. 6040z

[xoneeleven]

We checked the nut at the bottom, and it was fine.

So, we took both the couplings off and examined them further.

The first thing we noticed was that the couplings appeared to be mounted slightly too low. So, when we put the motor housing back on, it may have been pushing the couplings down on the cylinder.

Here is what we did to patch/remedy the issue:

1: Used a dremel tool with a cutoff wheel to lightly score the cylinder (to create some friction for the couplings to adhere to)
2: Moved both coupling halves up slightly on the cylinder.
3: Reassembled and ran a job.

So far, the results are positive. There is no slippage of the couplings.

NOTE: We did originally try to wrap a tiny sheet of aluminum around the cylinder to use as friction, but the tolerances of the couplings to the cylinder was too tight. It would not fit. So, we came up with an alternative idea in scoring the cylinder to create friction.

Anyway... Thanks for the tips. The tip on the aluminum sheet is what mainly led us to success. (that idea eventually led us to consider creating friction using a different method)
Let's hope this stop-gap method works over time.

[Clive S]

Originally you said the cutter bit was being dragged down into the job I don't think fixing the coupling will have anything to do with the first fault as the two halves of the coupling are not fixed together. So either the bit was loose and came out of the collet or the fixed bearing is faulty. Only time will tell.

[magicniner]

If the bottom coupling was slipping on the shaft most slip would have been when working against the greater force required to lift the Z axis rather than when lowering, resulting in Z gradually slipping down,

- Nick

[cropwell]

I do not fully understand what this 'cylinder' is that you are refering to. I can only surmise that it is the Z axis end shaft.
If you get any slipping on this joint, you might try using loctite bearing cement.

[lucan07]

The coupling was loose and slipping rubbing against the screw it obviously caused the Z axis to lose steps and therefore its integrity.

[magicniner]

The coupling was loose and slipping rubbing against the screw it obviously caused the Z axis to lose steps and therefore its integrity.

When I pointed that out you said it was the cutter pulling into the work :D
;-)
- Nick

[lucan07]

My point was even with the 6040 I could not see the axis slipping down 3.75mm as the rubber is only friction fit, Fred came up with steps and it became obvious, as I said I am no machinist a Bricklayer for 20years and an analyst programmer for 20 years the conversation just didn't ring true until the missed steps was mentioned allowing something logical to being factored in as a cause.