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I want to home X and Y only.

Posted: Sat Sep 10, 2022 10:48 am
by Sowest48
My build will result in a plasma unit and as such I'd like to home the X and Y only, not the Z.

I've read the documents on Acorn installation as well as the plasma documentation and the other document on axis squaring and pairing and I see no mention of this.

I will eventually use ohmic touch off so I see no need or process for Z homing. By process there is no Z limit switch.

Tim

Re: I want to home X and Y only.

Posted: Sat Sep 10, 2022 11:03 am
by tblough
You can home whatever axis you want in whatever order you want by creating a custom cncm.hom file.

Re: I want to home X and Y only.

Posted: Sat Sep 10, 2022 11:31 am
by ShawnM
Using the ohmic sensor plays no part in whether you have a home switch or not on the Z axis. And as posted by Tom, you can home any axis you want by editing the home file.

I would highly recommend installing a home switch for the Z axis if you are installing home switches on X and Y. Here's why, in plasma when you need to do a torch check or move the torch to WCS zero position or machine zero you'll want the Z axis to move to the home position or top of travel BFORE it rapids to another position on the table. If you have weights or clamps or anything on the material that is higher than your 1" safe height setting the torch is going to collide with those objects. It makes no sense to not add a home switch to the Z when you are adding them to the X and Y. If you were just going to do a "simple home" for all three axis that would be fine but adding two home switches on X and Y and not on on the Z is asking for trouble and more.

I have three home switches on my ShopSabre plasma table and wouldn't operate it any other way.

Cost of a new Duramax machine torch? $794.
Piece of mind knowing I protected it with a simple home switch? Priceless. :mrgreen:

Re: I want to home X and Y only.

Posted: Sat Sep 10, 2022 12:34 pm
by Gary Campbell
Cost of a new Duramax machine torch? $794.
Piece of mind knowing I protected it with a simple home switch? Priceless. :mrgreen:
+1 to that.

I have never figured out the DIY builders resistance to a Z homing switch. I would never operate without one. IMHO if forced to choose, I would take Z over XY

Re: I want to home X and Y only.

Posted: Sat Sep 10, 2022 2:28 pm
by tblough
Being old school here, I go for hardware limits on both ends of travel on all axis, especially on machines with the weight or speed to have serious inertia.

Re: I want to home X and Y only.

Posted: Sat Sep 10, 2022 2:42 pm
by cnckeith
i moved this post to the plasma forum

Re: I want to home X and Y only.

Posted: Sat Sep 10, 2022 4:26 pm
by Joey
The Safest and most reliable setup would be Shawn's setup so that the Z is always retracted as far away material as possible. The Safe height can be set to whatever height you would like and is not restricted to 1 inch. Limit Switches on the Z is always a good safe practice also. A Float switch for setting Z zero on touch off is also a good idea especially for production machines that do a lot of cutting and time is money. With Ohmic/Torch touch the material must be somewhat clean and you run the risk of a job interruption is the material is dirty or some debris gets stuck in the torch tip which happens on occasion. Shawns Machine runs a Ohmic/float switch combo which is the best of both worlds. This combo will initially use torchtouch/ohmic for the touch off but if this fails the float switch will automatically take over and complete the touch off cycle resulting is not interruptions. The Auto homing cycle changed to only home the X and Y axes if desired.