Cutting deeper in areas???

[alboy]

Hi Jazz

How are you doing. I haven't tried to cut anything with such a fine text before although I have cut smallish text in a different font which seemed ok but can't say for certain if the problem had been there before, the signs etc I had been doing were fairly big, min 1" text. I had notice a couple of times when cutting templates out of 6mm ply that sometimes it wouldn't cut all the way through in parts but put that down to the material initially. I will check the Z axis coupling again. I reloaded the DSP software just in case but it didn't make any difference. Thought I had another problem as well but it just the tip broke off the V bit Doh. All axis return to home position at the end of a job. If I rerun the job on the same workpiece it does the same, so I suppose it's repeat accuracy is good lol.

Cheers

Alan

[JAZZCNC]

No you need to set a Zero work position and return to that not Home position. Reason being that home position is referencing a switch so it will and should always return to that position.
Returning to Zero work position will tell you if you have lost position thru missed steps or slipping couplings etc.

But before all this have you Surfaced the Bed.? . . . . With fine engraving you can't have any error in the bed.!

[alboy]

No you need to set a Zero work position and return to that not Home position. Reason being that home position is referencing a switch so it will and should always return to that position.
Returning to Zero work position will tell you if you have lost position thru missed steps or slipping couplings etc.

But before all this have you Surfaced the Bed.? . . . . With fine engraving you can't have any error in the bed.!

Sorry, was on another plane there. Confusing my MCS with WCS, don't know if that is a common phrasing but that is what DSP refers to as the machine home position and the Work home/zero position. Yes I have returned it to the zero work position after homing and then drilled down with a 2mm drill bit, did this 10 times and was spot on each time??

Al

[Clive S]

Sorry, was on another plane there. Confusing my MCS with WCS, don't know if that is a common phrasing but that is what DSP refers to as the machine home position and the Work home/zero position. Yes I have returned it to the zero work position after homing and then drilled down with a 2mm drill bit, did this 10 times and was spot on each time??

Al

So if I understand you, you are saying that it comes back to the zero work spot in X and Y as you are going down the same hole. But how are you testing the Z zero, is that coming back to the same spot. You could test this by setting work Z to say 10mm above the bed and checking it with a 10mm round rod or a spacer exact. Then run the machine and come back to work Z zero and see if the spacing is exactly the same. ..Clive

[alboy]

The machine is set to have a safe distance of 10mm above home position so when you home to the workspace the end of the bit will be 10mm from the workpiece surface. I set the machine to go from home position to work position and it seems to be accurate each time. I tested the gap with a piece of 10mm thick aly.
I set up a job to drill 10 6mm holes 0.2mm deep in a line across the x axis over a distance of 600mm. and as the holes are being drilled left to right, the far left hole seems correct but the holes get gradually shallower along the right of the axis. Machine bed spoil board seems nice and flat.

Al

[JAZZCNC]

Ok well if your sure it's returning to WC-Zero (forget MC-Z) after the job as finished and no steps are being lost then it must be the table or machine frame. (provided tool is secure in spindle)

The bed may look flat but if it's not exactly parallel to the cutter across the whole area then you'll get this issue. That's why you should surface the bed to be sure.
If you still have issues after surfacing then I'd be looking at the machine frame and if it's twisted etc.!

[Clive S]

The machine is set to have a safe distance of 10mm above home position so when you home to the workspace the end of the bit will be 10mm from the workpiece surface. I set the machine to go from home position to work position and it seems to be accurate each time. I tested the gap with a piece of 10mm thick aly.
I set up a job to drill 10 6mm holes 0.2mm deep in a line across the x axis over a distance of 600mm. and as the holes are being drilled left to right, the far left hole seems correct but the holes get gradually shallower along the right of the axis. Machine bed spoil board seems nice and flat.

Al

Ok first drill holes are not ideal as they will have a tapered bottom an end mill would be better as it will leave you with a flat bottom and you can could measure it better. Now you say the spoil board is flat, have you checked that with a 10mm spacer across the bed where the holes are drilled? If you have a DTI check to see if you have any end float in the Z axis. ..Clive

[alboy]

Cheers Guys

I will surface the spoil board again just to be sure but it does seem flat when i test the difference between the end of the bit and the surface using the 10mm block. I do not have a DTI but I have ordere one today so hopefully will be able to check things with better accuracy. Will let you know how it goes.

Al