Zeroing Bits

[kubotaman]

I have a Shopbot ATC and am getting quite tired of putting the ground on the bits and then applying the zero plate to tell the program where the surface is prior to cutting. Most all the newer CNC's have an automatic way of zeroing the bits prior to cutting. Is there a way that ShopBot has eliminated this procedure and made it less cumbersome. The bit is not grounded on my HSD spindle which makes it harder to do automatically. Any help is appreciated.

[jerry_stanek]

Shopbot sells a pressure touch plate that you could mount and not have to attach the ground to your bit

[kubotaman]

Jerry Ill call them and see what they have. Thanks!

[dlcw]

I messaged them yesterday asking for a quote on the Z-zero pad. Hopefully I'll hear from them today.

[jerry_stanek]

Here is a link to it

https://store.shopbottools.com/products/pressure-sensitive-z-zero-plate

[dlcw]

Ordered a fixed plate for my ATC and a non fixed one to replace my aluminum zero plate. The big spindle with the ATC uses ceramic bearings so the bit is isolated from ground. Thus the need for the alligator clip on the bit to z-zero. Hopefully i can get rid of the ground clip with the pressure plate.

[matt_raymond60]

Can this be used on all models or just ones with the ATC?

[scottp55]

Matt...doesn't need to be ATC.
I seem to remember seeing someone with a Desktop sticking it in an area not used, and they even modified their Z-Zero routine with that location.
scott

[EricSchimel]

Wait... On an an SB ATC don't you zero each bit in the holder once to the fixed plate on the rack so all of the tool heights are stored in the SB software. Then when you start a job you either zero with any tool to the top of the material, or the table and the zero height is added (or subtracted) from each tool as it's called in a job?

As far as I know you shouldn't have to zero each tool as it's picked... Then again I'm only reading the docs, I've never owned an SB ATC, but I have used a few...

[dlcw]

Eric, you need to zero all the bits to the plate, then anytime you change a bit, you need to zero that new bit to the fixed plate. I have a 10 tool ATC and I change bits regularly depending on the type of job I'm doing. I have extra bit holders to facilitate this bit changing. When I do change, I have to rezero all the bits to the fixed plate. Each bit requires attaching the ground clip to the bit. With the pressure switch, this step is eliminated. This should make zeroing all the bits much faster.

[Ryan Patterson]

Looks like you already found the solution. The pressure plate is a nice add on to avoid using the clip.

Just a little information explaining the ATC. There are a couple things you have to do differently with an ATC than with a manual change.
The first is to get the length of each bit in the tool holders this is done with CN,72 "Zero Tools in Rack". This routine only needs to be run on the bit that has changed. If you are first setting up then CN,72 would have to run through all the bits. Then if you replace a bit in a tool holder only that tool number would have to touch off the fixed plate with a CN,72. This routine is used to record the length of bit in the tool holder for when you make an automatic tool change the Z zero is updated for the new length.
The C3 is different with an ATC as it will home/zero all 3 axis, ZY and Z. The Z zero will have the Zero location set to the location from running CN,73 "Get Plate Offset". Typically this would be the top of your spoil board. Then everytime your run C3 the Z zero will be to the top of the spoil board. With the CN,72 and CN,73 set you really should never need to use the standard touch off plate C2.

[EricSchimel]

Ahh I gotchya... It's surprising that you can't get a ground signal through the spindle like you can on the HSD ShopBots... Does the ATC spindle have ceramic bearings or something?

[dlcw]

Ahh I gotchya... It's surprising that you can't get a ground signal through the spindle like you can on the HSD ShopBots... Does the ATC spindle have ceramic bearings or something?

Yes, it does.

[Robert_Purvis]

Looks like you already found the solution. The pressure plate is a nice add on to avoid using the clip.

Just a little information explaining the ATC. There are a couple things you have to do differently with an ATC than with a manual change.
The first is to get the length of each bit in the tool holders this is done with CN,72 "Zero Tools in Rack". This routine only needs to be run on the bit that has changed. If you are first setting up then CN,72 would have to run through all the bits. Then if you replace a bit in a tool holder only that tool number would have to touch off the fixed plate with a CN,72. This routine is used to record the length of bit in the tool holder for when you make an automatic tool change the Z zero is updated for the new length.
The C3 is different with an ATC as it will home/zero all 3 axis, ZY and Z. The Z zero will have the Zero location set to the location from running CN,73 "Get Plate Offset". Typically this would be the top of your spoil board. Then everytime your run C3 the Z zero will be to the top of the spoil board. With the CN,72 and CN,73 set you really should never need to use the standard touch off plate C2.

The pressure plate is a game changer but I wish they would have an option to change the routine so you don't have to hit enter that you attached the clip and I could say hey.. touch off tools 1,3,4,6 and it will just do them all automatically. You however, just changed my life with the cn73. Never realized that was what that was for so I did a c2 every time even if not changing tools since a c3 set zero at the limit swich.

[EricSchimel]

I'm sure you could edit the script to remove that part... Just look at the code as it goes by in SB3 and see if you can spot the line where it asks you to hit enter. Find it, then go into the code and comment it out.

[dlcw]

Another issue I've found, that I can't compensate for, is when using boring bits. Because the bit has a brad point, that is where the zeroing takes place, not the cutting flutes. On larger diameter boring bits, this can be as much as 2.5mm difference. Makes a HUGE difference when drilling holes. I've tried adjusting for this in one of the ATC files that holds Z-zero offsets, but each time you run any alignment routine, with the ATC, it resets these values. Not sure how to work around this. If anyone has any suggestions I'd love to hear them.