# Pm-25mv Import Dro Installation



## PaulF2 (Apr 5, 2016)

Hey everybody,

I recently bought an import glass scale DRO set for my PM-25MV.  I'll try to remember to post some pictures as I proceed.  I'll start with the X axis, I plan to mount it to the front of the table.  For the Y axis, I'll be doing something very similar to what brav65 did.  I'll cross the Z axis bridge when I get there. 

My plan for the X axis is to mount the scale using the front T-slot.  It lines up in a good position, so no trouble there.  The plan is to clamp some 123 blocks to the table surface, use the aluminum guard as a spacer, and some clamps to pull the scale up tight to the blocks.  That should put the surface of the guard perfectly aligned with the top of the table.  I'll screw the guard down to the scale ends using some button head screws.  They'll stick up a little, but only one at each end.

I tried to find a good way to attach the read head using existing holes, but I didn't find a layout that I liked.  My next thought is to drill into the saddle and screw the read head directly to it.  The head has a pair of M5 threaded through holes facing the right direction.  An M4 screw will slip right through, so I bought some M4 screws and tap.

I won't lie - I'm afraid of drilling into my machine and breaking off a tap.  I've tapped a few things, and I've broken a few taps, so I don't have the best track record.  Would I be better off drilling out those M5 threads to a clearance hole and using a larger screw and tap, which would hopefully be more robust?

Questions:
1) Does the mounting plan for the X axis seem reasonable?  Any problems that I'm not seeing?
2) What do you think about the screw and tap size?
3) Any tips on drilling and tapping into the machine?  I would be mightily disappointed if I screwed it up.  It would be repairable, but I'd still be ****** at myself.

Many thank!

Paul


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## markba633csi (Jun 13, 2016)

Why can't you just use the M5 threaded holes as is? Get some M5 screws and done.  
Right? 
Mark S.


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