Homing cf. Tool Length Setting

There are lots of posts and videos about home/limit switches for Shapeoko and X-Carve. However, there are fewer about tool length probing and what there are seem to treat this as a special case of limit switch functionality.

I have not got my X-Carve yet so don’t have any practical experience. However, I can imagine I will need to reset tool height after a tool change. This can be done by putting a metal plate on top of the work (as often described), but only if the first tool hasn’t milled away the whole of the top surface. What’s the best solution to this?

I see the Nomad 833 seems to have a metal pin in the base board and the description says it has a built in tool length probe. Has anyone done this with the X-Carve? It would surely make tool changes a lot quicker if the machine knew where to go (X, Y) to set its tool height and did it automatically on the press of a button.

Here is a sneak peek of a future accessory. This is a prototype we use in our shop. Grbl has the ability to drive the Z down until it sense the electrical connection between the bit and the metal puck. You use the thickness of the puck to determine the top of your material. The mass of the solid brass puck makes it quite stable.

We have a lot of accessories like this in the pipeline. We can’t commit to availability dates on any of them. We are focused on the basic product right now.

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Great stuff Paul, and if you can’t produce it right now maybe someone could just post a DIY feature on it. I am sure that would be well received. I would use this religiously.

Would this work if the top of the material had already been roughed into a non-flat shape prior to changing the tool for finishing? I guess the puck could be placed on the base board but the mill would need to be driven to the puck’s position before driving the Z down and getting the Z reference position.

How could this work to align the end of a new tool in the Z axis so that the cutting could continue?

It can also be used on the wasteboard if you want to reference off the bottom of the material. If you place the puck in a consistent spot you can use it for each tool in the project.

Routers such as the Shopbot use a plate. This is something that would be easy to duplicate.

I’ll try to get the process documented, so DIY’ers can try it.

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Thanks You Very Much!

Hi @DonDespain

Here is a video I found helpful on the subject of Z-probing… Since it is on the Shapeoko 2 it should apply pretty easily to the X-Carve:

http://youtu.be/f4ybGiXNN24

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Why not just use the stop probe from a Printrbot? I have an extra one that I may use to test this out with.

Nice…exactly!!! No that’s what I’m looking for. You guys are on the ball.

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That will be going on my wish list for sure

I just finished a DIY version of it:

You need to wire up the A5 analog pin [ed: fixed] of the Arduino to the touch plate, and then connect the bit to ground. I took a pair of audio jacks, wired up pin 5 and ground to one of them, and connected the other one to the touch plate and an alligator clip.

From there, you can use the “Touch Plate” feature in Chilipeppr, all you need to do is enter in your plate thickness, and hit “Run”. You can see in the video that after I zero it out, I remove the plate and tell it to go to zero on the Z axis, and it comes right down to the exact top of the work surface.

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@PeterJames,

What did you use as your touch plate?

It’s a copper surfaced prototyping board I had on hand:

But any flat conductive piece of material will work

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Hey, this sneak peak of future accessory, any closer to finally sale product? Any est date/price?

It’s A5, no? :wink:

Whoops, good call:

It’s the 6th pin, but I didn’t notice that they used a zero based naming convention. Looks like I’ve got some editing to do…

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Quick tip: You can use the ground wire on the Z-limit switch as a close connection point for the wire that clips on the bit (I connected my touch-plate to A5).

Has anybody tried “Depth Setting Rings” as descrbed here: http://precisebits.com/Reference/depth_setting_rings.htm

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ive been wanting to do this for days. thank you so much @PeterJames now i just have to convert to using chilipepper and make sure it will run on Ubuntu Linux which my cnc control PC runs.

i’m super excited… precision makes me happy.