gcode resetting my surface zero to Z-0.200"

[ger21]

No, do this:

Zero the Z axis on a block or spacer.

Rapid up 0.5", then rapid down 0.5" Repeat 50 times. (Up-Down-Up-Down-Up-Down.......)

Go to Z zero, and see if it's at the block or spacer.

[Mr.Chips]

When I had the Z acme shaft out and router out, I could slide the Z assembly very easily without and hint of dragging or binding.
I removed the acme shaft to mill flats on it so that the two flange bearing set screws completely engaged a flat spot rather than just tightened down on the acme thread. I also shortened the vertical uprights (1/2” 6061 alum) so that the spring coupling engaged the stepper and top of acme shaft more. I also swapped the X stepper for the Z stepper to see if that was effecting the operation, per Gary’s suggestion.

Thanks
HH

Her.
How fast rapids?
Why not set the bottom with an indicator rather than a 123 block?

[Wayne Locke]

it seems that you are revealing your problem piecemeal a little at a time which makes it hard. It seems that your issue is a mechanical one with the z axis. Knowing that you recently modified this axis definitely caught my attention and is the first place I would look. If it worked before the mods and not after that is a likely suspect.

Have you made any other mods prior to your problem.

You need to focus on one small thing at a time and try to troubleshoot with a laser and not a shotgun.

[GME]

The mods were made in response to the problem, not before it arose.

[Mr.Chips]

The problem came first what I did was to hopefully minimize the problem. And the problem persisted after the inspection preventive action.
I just posted a couple of hundred words detailing the before during and after. Please see i it should answer many questions

[GME]

The problem came first what I did was to hopefully minimize the problem. And the problem persisted after the inspection preventive action.
I just posted a couple of hundred words detailing the before during and after. Please see i it should answer many questions

Hager,

Just a suggestion, but you might want to post pics on this forum of your machine and how the the flange bearing fits into your machine design. I'd add a short explanation, as well. It may help folks understand your setup and aid in diagnostics.

FWIW, I suspect the flange bearing as possible culprit. With Z taken apart, it could turn smoothly and seem just fine. However, under a load, it could be binding and causing your stepper to lose steps. Unless it was making noise, how would you know? Also, it's end loaded, which, predictably, would cause it to fail sooner than when used "as designed."

Also, FWIW, CNC Router Parts posts Mach3 XML files for it's plug and play systems. The XML that uses an acme screw has a Z axis velocity of 200 ipm, which would be its top end for rapids. If you don't hear to the contrary from ger21, that's what I would use for the test he suggested.

I don't see a problem with using a dial indicator instead of a block, but an option would be to run the test twice. Once with zero to a block and once with the indicator.

ger21 didn't suggest using a 1 2 3 block, although it would work. He just generically referred to a block. It really doesn't matter, since you are going to get the block out of the way after zeroing anyway. You wouldn't want to crash into it.

Gary

[ger21]

Rapid means G0 moves, which are at the maximum speed of the axis.

Just use code like this:

G0 Z1
G0 Z0.5
G0 Z1
G0 Z0.5
G0 Z1
G0 Z0.5
G0 Z1
G0 Z0.5
G0 Z1
G0 Z0.5
....
....
....

I was just saying set your zero above the table so you don't crash into it when you go to zero after the test. You just want to see if it returns to the same zero position. A dial indicator is fine.

[wmgeorge]

But does he not have to put the Z under some kind of load?

Yes we are seeing bits and pieces of the problem emerge, some after the fact. What we are doing it troubleshooting and lots of things have been now been ruled out.

A far out one... I know stepper motors and drivers can never fail, right. Or connections never go bad, right? Is this a parallel port or ESS ethernet or USB? Interference from EMI or RFI?

Do Gerrys testing.

[Leo]

Second post on this one --- perhaps the BOB is faulty.

[Mr.Chips]

Thanks I didn’t know what rapids were.
I’ll try that.

[Mr.Chips]

Here is the code I ran for theee tests of 50 cycles each of rapids.
I used a digital indicator with a resolution of 0.0005”
I zeroed the indicator at the start of the three cycle test, and did not zero it again through the 150 cycle test.

After end of the 150 cycle run the indicator showed +0.0005”
Comments?????????
Suggestions....

Z0
G0 Z1
G0 Z0.5
...........repeated the G0 Z0.5 fifty times
Z0
M30
%

[Mr.Chips]

WMG
I’m using a desktop PC running XP it is never on line. Dedicated to CNC
Using parallel port.
Candcnc Control boards
Gecko 251X drivers

Mach3V2
VcarvePro 8.5

[wmgeorge]

Did you do the testing with the spindle or router you normally use powered on?

Has something else been added to your machine or computer? Changes? We seem to find something new in every post.

[Mr.Chips]

WMG

No I didn’t run the test with the router on, G didn’t mention this. I will run it again with the router on.

Yesterday I posted a full explanation and history of the CNC and what I saw and what I did, now I don’t see it???
Was it removed? It didn’t contain any attachments only text, and I didn’t see any comment on size when I submitted it.

Can it be retrieved?

I have posted several photos on the CNCZONE however I don’t have a way of sizing photos that meet this forums photo size limit I’m still looking though.

[wmgeorge]

Someone posted a few posts back about how to use a program to simply resize pictures.

Here it is, https://resizeimage.net

I can see your uploads just fine.