Vm Cutaway modif?

I agree with zed1015 on the suggestion of doing this modification by hand with a file.

If you give that to a machinist there is the slight chance that however they are going to approach the material removal that the slides could be damaged either by the cutter, clamping, or any other such mishap.

I would suggest blueing and scribing the area for material removal then taping the full length of the slide to protect the surface in case its inadvertently dropped.

0.5mm with a file will be so tricky dont you think to remove all the material perfectly for all 4 slides? If I tell to the machinist to scotch  the slide before using his cutter or other machine?   Have you a suggestion to trace them perfectly ..

There are several methods you could use.
One would be to modify one slide then use that as a comparison gauge to transfer the profile to the others.
Offer the modified slide face to face with an unmodified slide and either scribe the new arc as you roll around or just slowly remove material until it matches.

 

You can use a tube of cardboard as a gauge (mark the cutout on the cardboard with the start of the taper as a reference mark on both sides then use it as a template to mark the other three) you will spend a lot of time and money going to and from a machinist to take a little at a time from each!! 

Doing it with a file is not going to be "perfect" especially from slide to slide. I doubt being over or under the width of a scribe line would make a massive difference in air flow either. Taking that into account I also doubt that you will "feel" any discrepancies between one slide and the next.

I think having the ability to control the process and trying the modifications is key. Your going to want to "sneak" up on the sweet spot for your tune up.