Changing z

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creativescrollworks
Posts: 45
Joined: Thu Apr 12, 2018 4:40 am
Model of CNC Machine: Piranha LX

Changing z

Post by creativescrollworks »

I am setting the z point before cutting. However during the cutting it is going further than my set cutting depth. When I have it return to the home position, the bit goes into the wood.

Help????

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FixitMike
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Re: Changing z

Post by FixitMike »

If the chuck is not adequately tightened, an upcut spiral bit will pull itself out as you cut. Also, be sure the Z drive coupler screw is tight.
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mtylerfl
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Re: Changing z

Post by mtylerfl »

creativescrollworks wrote:I am setting the z point before cutting. However during the cutting it is going further than my set cutting depth. When I have it return to the home position, the bit goes into the wood.

Help????
Where are you specifying the Z-zero in your project? TOP or BOTTOM of the material?

Then, are you setting your Z-Zero to match your project when at the machine?

It sounds like you may be setting zero at the Top of your material in your project, but at the machine you're setting the zero to the machine bed (aka Bottom of material).

Do think that might be possible, or is it a gradual downward "bit slip" as mentioned before by Mike?
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martin54
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Re: Changing z

Post by martin54 »

Could be a number of things as Mike has already said either the bit slipping or a loose coupling are quite common.

Have you altered any of the settings for your control software? Setting the acceleration & deceleration to steeply can also cause lost steps as well :lol:

creativescrollworks
Posts: 45
Joined: Thu Apr 12, 2018 4:40 am
Model of CNC Machine: Piranha LX

Re: Changing z

Post by creativescrollworks »

Thanks.

Will check and try again tomorrow. Will ensure that chuck is adquately tighten (could be I'm being overly cautious tightening so as not to cause damage.)

It's a gradual downward "bit slip."

Z-zero is set for top of material in the project and for the machine.

Setting small pass depth.

M Queen
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Re: Changing z

Post by M Queen »

I agree with Martin. Sounds like you're losing steps.

A servo machine tracks movement and will generally fault if it loses position because of loss of steps, but most stepper machines have no feedback so they don't know if they've lost.

Z (your vertical axis) is usually pretty heavy and if the screw needs a little grease or a bearing is tightening up or if the user is over accelerating or even setting the speed too high on that axis, it can lose position.

I recommend cutting the speed on the Z axis to half what it is doing now and try it again. If you can reduce acceleration, I'd also lower that some, but do these steps one at a time. You'll want to know exactly what fixed it in the end and changing a bunch of things before testing is a good way to mess things up worse than they already are.

Machine position issues are tricky. I know, I do this for a living.

If you can't figure it out, contact your service technician.
Mike Queen
Microsystems World CNC (WinCNC)
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