Help with z axis

Help with z axis

Postby jdunnett26 » Sun May 01, 2016 12:06 am

Hi,

I have been having issues with the z axis not holding the programmed carving depth.

I had set the carving depth at 0.1 inch
I loaded the code into the shark control panel.
Jogged the machine to where I wanted it to start from.
I manually set the x,y,z axis's at 0.000
I then jogged the machine a bit and used the move to 0.000 button to see if I set the axis properly.
I then set up the touch plate, and used the shark control panel to detect the touch plate.
I then ran the code with out a bit to test it.
I then put the bit back in and dectected the touch plate again.

The code ran fine with out the bit, then on the second attempt with the bit, it worked fine until part way through. The bit went through the material, scratched my table, and the Bit broke.

I am not sure why the machine will not hold The depth that I programmed on the z axis for the entire tap file. It worked properly for the first time that I did a test run with no bit.

Does anyone have any ideas?

Thank you in advance for all your help.
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Re: Help with z axis

Postby FixitMike » Sun May 01, 2016 12:42 am

Did the Z axis attempt to move too high and get stopped by the end of the Z travel? That will make the controller think the router is higher than it actually is, resulting in the bit going lower after the stop occurs. There will be a stuttering sound when the carriage attempts to go beyond the solid stop.

Was the carriage Z0 higher with the bit in when the run failed? That could cause the problem I mentioned above.

Note to others: Shark CNCs do not have any program or limit switch limits. They just hit the frame if you attempt to move too far.
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Re: Help with z axis

Postby jdunnett26 » Sun May 01, 2016 3:24 am

Hi FixitMike

To answer your first question, no it did not. The machine had run through half of the tap file then started a plung downward. There was no stuttering sound, the bit just started dropping down. I had to hit the e-stop button to make the machine stop before it blew a fuse due to being embedded in the machine.

Can you explain what you mean in the second question?

Thank you,

Jeanette
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Re: Help with z axis

Postby FixitMike » Sun May 01, 2016 4:34 am

After you put the bit in, and reset the Z0, was the Z carriage higher than before when it was at Z0 without the bit? So it might have hit an the upper limit during the cut. However, from your description it doesn't sound like that was the problem.

If you repeat the cut does the problem repeat? If not, it is not a G-code problem. I would suggest you contact NWA to see if they have any suggestions. I've not had any problem like that with my Shark. The closest was when I failed to tighten my spiral upcut bit in the chuck adequately, and it pulled itself out far enough to hit the table.
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Re: Help with z axis

Postby martin54 » Sun May 01, 2016 12:39 pm

How thick a bit of material are you trying to cut, I can't help thinking you are trying to lift the z axis to high as Mike has already suggested.

When you ran the program without a bit in it & everything went fine did you start at the same z height as you did with the bit in or was your initial z height lower when you ran without the bit?

You might want to ask this question on the shark forum as well as there are more shark users on there than on this forum.
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Re: Help with z axis

Postby jdunnett26 » Mon May 02, 2016 3:19 pm

I ended up contacting the manufacturer. Below is what they said.

My two thoughts right off the bat are that the Z axis is slipping when the router is powered on, or that you are hitting the Z limit and losing your Z zero position. If it is slipping then you can test this by turning power onto the machine and trying to physically move the Z axis up or down. If you can then there is something loose that would need to be tightened down, if it doesn't then everything is secure and it likely isn't anything loose. You may also want to check the file to see how high up it moves for its safe Z height and it's rapid Z movement clearance. If it goes to high it will hit the upper limit and make a grinding sound and lose the zero position causing immediate problems.

FixitMike, they said a very similar thing to what you said. Thank you for all your help.

Jeanette
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Re: Help with z axis

Postby SteveMI » Tue May 03, 2016 4:11 pm

Another potential cause is that the collet let the bit come loose and the bit became a screw going into the work. If the bit is an upcut and you are not using climb cutting, that could be the issue. I have seen it several times on ER collets.
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Re: Help with z axis

Postby abh6 » Thu Nov 10, 2016 4:28 am

Hello, I am new to CNC, Vectric Desktop and the Shark Piranha. I have the same issue using thick material AND the zero touch. The carriage over runs the Z limit because it picks up so high when we press RUN. For example, everything cuts fine on a 1/2 thick piece of plywood, but cuts too deep on a 1.5" thick piece because it reaches Z limit. Everything zeroes fine, but the bit always raises to 1.2 inches above the work piece after it finds the 0 touch plate. Thanks for any help.
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