# Bolt Hole Circles on Acu-Rite DRO

• posted
I have an Acu-Rite Micro Line DRO on my mill. I am trying to use the
bolt hole function but am having some problems. I zero the workpiece
which is a chuck backplate and then enter the appropriate numbers into
the the DRO.
It is not working. The first bolt hole is 60.6218mm from the center of
the backplate on the X axis and 35.000mm on the Y axis the bolt hole is
30 degrees off of the X axis in a counter clockwise rotation. The
radius of the bolt circle is 70mm. There are 6 bolt holes on this
circle which means that there are 60 degress between each bolt hole.
How should I program this into the DRO? The first question it asks is
the number of holes, which is 6. It then asks for the center of the
first bolt hole in X and Y coordinates which is X = 60.6218mm and Y =
the start angle which is 30 degrees.
Should I use the DRO to drill the first hole at the above X and Y
coordinates and then program the DRO? Would I still use 6 bolt holes
and just use the starting hole as the one I just drilled? From the
instructions that is what I am gathering but I just want to make sure.
Any help greatly appreciated.
Thanks, Steve
• posted
I too have an Acu-rite. That bolt hole function don't seem to work. (at least for me) It just takes a minute to calculate the X and Y coordinates in a speadsheet like Excel and then print them out.
If you're not a trig kind a guy, describe what you need. Someone here will chime right in.
Karl
• posted
The dro must be in absolute mode for bolt holes it won't work in inc. mode. Also position the drill in the center of the bolt hole circle first so when it asks you x amd y , x0 y0
• posted
Steve, I just checked the manual for my Acu-RiteVRO-300M to make sure. I'm not sure if your DRO works the same, but it sounds like it does. I assume that your mechanical zero is the center of the backplate. With the mill centered over that, you set the DRO's ABS. X and Y to 0.000.
You then setup the bolt circle. Enter the number of Holes (6), the Center of the circle (X=0.000mm, Y=0.000mm), the Radius (70mm) and then the Angle. This is the angle the first hole is rotated counter clockwise from the X axis. If you want two opposite holes to be lined up along the X axis you enter 0.000 degrees. The 1st and 4th holes will be located on the X axis. If you want two opposite holes to be lined up along the Y axis you enter 30.000 degrees. This will rotate the hole positions 30 degrees so the 2nd and 5th holes will be located on the Y axis.
You can start with the drill at any X-Y position. The DRO now knows where your ABS X-Y zero is. When you run the program it will have move the table to zero out the INC. X and Y numbers, putting you over the first hole. You drill that. Stepping throught the program will move you to each successive hole position.
If you were doing a bolt circle on a square or rectangular plate you could set the ABS zeros to a corner of the plate. When setting up the program you would enter the X and Y position on the plate where you want the circle to be centered, insead of X=0.000 and Y=0.000.
I hope this helps.

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