2 axis or 3?

M

Maplehead

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Hi All
I'm looking to purchase a new Grizzly G0678 on Monday. I will purchase a DRO for it as well. Should I buy a 2 axis or 3? I don't really get how the z axis would connect so I don't know how to move forward with which DRO. I feel I would like and use a z axis DRO though.
Any help is greatly appreciated.
 
I used a 3 axis on a Bridgeport. The Z I installed on the column and knee. It was a little tricky, but it works well.
 
My preference is to have a scale on each axis. Where you have the z axis scale depends upon how you use your mill. You can place it on the knee or on the quill. There are some who have a scale on both. There are some systems that can algebraically sum the knee and the quill.
 
The quill would seem like the logical place to put the DRO. However, since the quill is what slides in and out of the mill head, I can't see that being possible. I see the knee only being used for large/general movements. The DRO would be for fine z axis readings via the quill movements. So I still don't get how to do it.
 
i have had a 2 axis readout and a Mitutoyo Quill kit on my BP for 20 yrs. back then the kit was $100

Mitutoyo 053906B, Quill Kit for Bridgeport Type Mills, 0- 6" Travel inch/mm, with Mounting Brackets: Micrometers: Amazon.com: Industrial & Scientific

Mitutoyo 053906B, Quill Kit for Bridgeport Type Mills, 0- 6" Travel inch/mm, with Mounting Brackets: Micrometers: Amazon.com: Industrial & Scientific
www.amazon.com

i have seen where others have used a 6" digital calipers and made their own mounts.
 
There are import versions of the quill readout as well. I have one from Shars. It works well, my only complaint is the same as all the import calipers, it eats batteries. My Mitutoyo batteries last a long time. These are good for about 6 months, on or off. I only really use the quill readout when drilling or boring blind holes. I set milling depth using the knee, so having the main DRO there made more sense to me.
 
I have a DRO on the quill, and a power feed for the knee. I use the quill more than the knee
 
You can mount a scale onto the quill to read directly into the DRO or some will put the Z axis on there knee and use one of these on the quill. Just depends on which way you want go. I have seen a lot of people use 2 Axis DRO (X & Y) and then this separate unit on the quill.

DRO.JPG
 
You might consider a 4-axis for the Grizzly G0678, you have lateral, longitudinal, knee, and quill--all of which move.
You can "get by" with a 2-axis and just use the dial* on the knee with a locked quill,
But you really should not go less than 3-axis.

(*) I have the same sized G0730 brother of the G0678 (no VFD,...) and the dials on the knee are the most repeatable set of dials on the entire machine. I think this has to do with the weight on the knee forcing the knee and everything riding on it to one side of its leadscrew.
 
Hi All
I ended up buying the 3-axis DRO that Grizzly offers.
Mitch, what do you mean by "most repeatable set of dials"?
 
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