Problem with my Z

[meatbal80]

I have been having trouble with my z axis cutting to deep and digging into my spoilboard. I set my file to z at the table not the material. Then z-ed to the table. I have verified the z was correct by manually by plunging to z-0 with the router off and spinnging the bit to see if it cuts. In my file i have set the depth of cut to .74 inches to cut 3/4 MDF. I run the cut file and when it is done i have a nice grove cut into my spoilboard i havent measured it yet but it is at least .05. Any ideas what might be going on?

[Gary Campbell]

Joel..
What program are you using to toolpath?

Can you confirm in your material setup that zero to bed is selected? Most defaults are zero to top of material.

Here is an example from VCPro:

[meatbal80]

I am using v-carve pro the latest version, and yes i did confirm the z to table setting. I went out to look at everyting again and found that the cut gets progressivly deeper the more lineal feet i cut. I zerod to the table so that i would not have to worry about the exact thickness of the mdf since i know there are variations from each manufacturer.

[Gary Campbell]

Joel...
Can you confirm that the cutting file does not increase depth as it progresses?

IF not, I would check for loose bit. Upcut bits can pull themselves out. Downcut go the other way.

What is the Z move speed? Any chance you are loosing steps?

Have you checked the Z pinion Grub screws?

Do you have proper machine settings/unit values?

[meatbal80]

Gary,

The cutting file is not set to increase depth but it is running too deep to begin with.

I will check the bit but it is a strait bit.

The z move is 1 ips but on my last test run i dropped to .75 ips

The pinion grub screws? The set screw to hold the pinion firmly in place?

I believe the values are correct as i have measured many movements in the x and y. I set the values using the shop bot provided file which tech support directed me to based upon my specific model. If any changes were made it would have been by accident but i dont believe so. I also ran the z up and down (with no load) many many times to set the depth correctly for my z-zero (manually verified that the bit was not touching the material by spinning it to see if it cut then lowered .005 and repeated untill touched then backed off .005)before my last test run.

If i were loosing steps based upon to heavy a load or something being slightly loose wouldn't it make sense that the bit would get continuosly higher and not lower?

Just thought of: When i use the z-zero it seems to set the zero to low. I measured the zero plate multiple times all over and got the same reading every time +/- .005. I compensated by telling the SB controller program that the plate was thicker and still had the same issue. It seemed to set zero about .005 - .010 to deep everytime.

I will check:
That the stepper motor is seated well.
That the screw on the pinion is nice and tight and add some lock tight
That the router mount is firmly in place.
That the router it self is firmly in place.
That the berings on the xy car are nice and snug.
That all of the steel rails dont have any dings (used unit) or stuff built up on them.

Thanks Joel.

BTW - Gary were you a teacher at some point or did you grow up with teachers? You have alot of patience dealing with the "very grateful" new guy's problems.

[meatbal80]

Started checking items on the list first the pinions they look good and tight.
Before i removed the motors i checked for play, what is an acceptable amount?
I tryed to get one of the x axis motors to seat tight enough to where i could not shake the car at all when the motors are powered. The best i could do is get it to seat to where it barely moved but i could still see movement and hear a slight click. I didn't use any leverage to seat the motors, just held it up as i tightened the bolts. Double checked the manual and it doesn't give guidlines as to what is good.

[curtiss]

I might be missing something, but I would think one would always zero to the top of the material for nearly everything. In V Carve Pro a cut depth of .25 would mean .25 below the top of the surface. (the Bot would move to -.25 )

When you surface the table one would zero to the table of course.

Is it a long file, or does it get deeper after multiple runs of the same file ?

Does the bit return to the same height off the table (say 1 inch) after each run ?

[Gary Campbell]

Joel...
I will try to go in order.
By looking at the code in the file, did you verify that the cut depth is what you desired?

Put a mark on the bit where it enters the collet with a sharpie to see if it moves.

.75 or 1 ips should not fault the Z. Have you pulled the Z motor off and move by hand to see if there is a bind?

Yes... grub screws are the pinion set screws.

There have been instances where these settings have changed. Verify by following the steps that SB TS gave you.

You should not have that much variation in the Zero routine.

Higher... lower... depends on the action that caused the fault.

Your checklist is good.

No, never a teacher. Couldnt do it. No patience.