Maybe I can help, I fabbed glass for 15 years. First, thats a pretty big tool
you got there. We used 4" ish diamonds on bridgeports to bevel on side at a
time on a rectangle/square one side at a time and then set up radius jig to do
radius by hand. No fun. Then we got a milltronics cnc with a 50k spindle, and a sabre500 with a spindle similar to yours.Too bad the milltronics rarely went above 12k. Too much runout on tooling. After that we ran MANY parts just like yours on the cnc. Glass was usually cut .125 " over. Used a 80 grit(+/- 20) bonded to metal form for rough typically .5 or .375 diameter tool at between 8 and 12k rpm to rough it to . Finish tool usually same diameter 120 or 180 grit if chip spec/finish not critical, 220 grit bonded to metal form for tight specs,very rarely above 220. Bevel tools usually 1" diameter at the top 220 grit. Usually left .03 to .05'' for the finish pass depending on chip specs for O.D, bevel would have been one pass. As far as coolant water works in a pinch but there are (expensive) coolants specifically for glass. As you probably know grinding with no coolant returns glass to its elemental form . coolant placement was tricky. you need fair amount of pressure right in there at diamond glass interface but nothing unreasonable. Spray was never a problem but you will get a little misting. After 15 years of it I'm pretty sure the inside of my lungs are white but then I did a lot of hogging with a blanchards and lathes too but cnc was never too bad with spray/mist/mess. Your 4" tool might throw some coolant around though. Used coolant filters in some apps due to scratct/dig specs but they are problematic. 10 to 40 micron typically. Funny, we ran out often and skipped the filter and it doesn't make a big difference. Swarf will settle to the bottom very quickly and harden like cement. Thats when you call a chip sweeper over to dig the tanks Particle size will inform your decision. 60 grit will make what almost looks like chips of glass. A 220+ grit will make baby powder and will stay suspended a longer. Spray the chuck off before and after every part and rinse part and you won't have any problems. Avoid sliding glass like the plague. Used to stack them on a cart horizontally and shake a little of what looked like fine sawdust between each part. I used to use my finger to push up on finished part to brake seal and spray water into chuck glass interface and part will sort of hydroplane up then lift off. Feedrates: wish I could give you exact numbers but that's the one thing that is a little fuzzy for me right now. It's been 8 years. Fuzzy probably because there is a lot of tweaking and variables. I think I remember doing a 4x6 1/4" thk part with a small 45 degree chamfer on the four corners and a 45 degree bevel on top in about 6 minutes or so. Thats three passes. rough OD, fine OD and bevel. Manual tool changes. Only took 10 seconds per tool. Sabre was full auto and more robust spindle so shave a minute or two off time for that.
Your only taking off .025 on the OD and .05 bevel. Don't quote the job on this but i would think you could do this part in under six minutes. You could save time with a two or four part chuck. Did two parts per load on the milltronics. four parts in a load on the sabre. Vacuum will limit feed rate. Part will push off
chuck if you feed to high ( tell you something you didn't already know right )
Used something that looked like electrical tape but was more of a static cling,
comes in wide rolls, covered aluminum vac chuck and used a razor blade to make appropriate cutouts for vac. This stuff seemed to help both seal and slip. Want something with high enough C. of Friction but not scratch or dig glass. Segmented tools are usually bad news on mills. Work great on a blanchard though. diamond bonded to metal form tools go quick. rate will have to be tweaked as it wears. Much cheaper than the big resin bonded diamonds that your looking at though. Resin bonded usually needs dressing. Brownstone if you can find it. I think I've gone on too long and yet haven't even scratched the surface. If I find an old tool I'll post some pics.