I saw the three threads on polishing granite with a cnc, but no responses, plus they were old so I'm putting it out there again...

I have an EGAR 450n. We have the usual diamond wheels, the dreaded clay wheels, and yay! guiness wheels. I had the same problem as other users, the horizontal lines left after polish. I am a very new user to this kind of cnc, my background is in metal, so bear with me.

With the stock r-values given and suggested by our trainer we got a fairly shiny polish but those lines were there on Vyara Gold, did some Carrera and it was better but still there. I scratched my chin and thought hmmmm.

I think the FIRST segment wheels left them there... (I'm not at the machine and no notes so I'm giving rough numbers here)

If my sawyer gives me 1/8 extra material to my drawing line like suggested I have about 3mm. My first segment has r of 1.3 or so, Anyone ever measure the crevice depth on one of those wheels?(I don't have the tools) I BET that some of those grooves are bigger than 1mm. AND if your presetter gives the machine tool table a tool radius taken from inside one of the grooves, more material goes away. The second segment is at like .7mm, third diamond at about .2, last at .0 then on to guiness.
That presetter rocks to the side a bit when measuring so it HAS to catch a groove right?
SO I decided to use my last two diamonds twice and bump out the r value of segments. I kept the last segmented wheel at r=1.2 or so mm and ran it. TA FRIGIN DA:) I saw a huge improvement on those lines. But alas still not perfect...but wait a sec.... what IS perfect?

Now I think of course it's up to the boss to decide what level of quality to sell from the shop, not me. I DO think however that at first we got a must touch up finish and now at least with fresh tools we may go straight out the door.

Has anyone else a similar setup and experience? I'm a very newbie on this machine but i'm not a total idiot:) And has anyone ever dared putting an r value on the last diamond wheel to squeeze the guiness a bit, very interested in that, but I think it would misshape the wheel if not just destroy it.

Anyone do a large variety of stone that can clue me in on various spindle speeds and feed rates for mills, segments and convex saw?
Another question, is the convex saw worth it? saw vs. fingerbit
How well does your laser piece scanner work? laser vs. mechanical
Would guiness wheel alignment be better if bottom of tool was measuered of table for all three tools or does the core of the tool vary in position?

THANKS FOR READING!!

Try using a black marker on the diamond wheels (position 2,3,4). Run the position 1 diamond, draw a line on the profile of position 2 diamond in four spots then run the diamond, check the lines to see where the diamond is hitting, make adjustments (radius or length) draw lines on diamond again and run that same diamond again until it is lined up with position 1 (lines are removed from running the diamond on the pc. of stone) then go to the next diamond and repeat the process until all the diamonds are aligned and removing the black lines. you can do the same thing with the clay polishers. This can be done on a scrap pc. and when you are done you have samples. It should only take an hour to complete the setup.

We are running a brembana that has dynamiic compensation for the radius of the tools. we use this for the clay polishers, as the tool runs the controller reduces the size of the radius to compensate for tool wear. We are using ADI tooling and have had great success with the caly polishers.

Our machines do not have a presetter or "probe" for measuring tool size. ADI tools come with measurements, we set these measurements in the control and go from there.

Does your machine have automatic cutter comp.?

What brand of tools are you using? We had an ADI tech come to our shop form Italy and explain how to set up the diamonds and supplied us with the speeds & feeds.

I also run the position 4 diamond and the pos. 5&6 clay polishers 2 passes. We get a excilent shine on black granite.

We do not have a convex saw so I have not comment but have heard good things from freinds.

We have a laser scanner but it is a 3d scanner for relief carving. place a 3d object on the bed of the machine, scan it, make changes (size, mirror, reverse, ect.), porgram the scan in software, and cut a new pc. it is made by Scantech.

I have not used other brands of tooling but I do know ADI works for us.

good luck.

I will try the marker trick, sounds good. All of our tools are Bavelloni tools except the polishing heads wich are called Guiness wheels, wich have diamond strips glued to a rubber backing, not sure how much I like em since we already wore a groove in the bottom of em. BUT my counterpart set all the tools up. and uneaven wear on the tools suggests they were not aligned correctly. Now it's up to me to take up where he left off.

Have you ever tried bumping out your first segments to get rid of those lines? Or do you not have that problem at all? Sounds like you have a great setup.

My Egar also has dynamic radius adjustment for clay tools but the rubber wheels don't use it.

Yes I have bumped out the first diamond whatever it takes to remove the line, this may be more than recommended by the manufactuer.

I tried the rubber wheels a few years ago with not great success. Try the clay wheels with tool comp I think you will be satisfied.


Be a active member in the tool setup with your operator. It may take a while but you only have to do it once and you will understand what has to be done with the offsets.

again good luck and be patient.

Unfortunately I am the only operator, drawings, machine setup, hand polishing etc. We have an extremely small crew right now, only 3 guys full time in the shop 1 cnc, 2 bridge saws, 1 inline machine, 1 wizard, 1 manual router.
We are just moving into a new building while trying to keep our loaded schedule. Been a real challenge that has only now (today we moved in) starting to pay off. But oh boy when we find the right help to join our team, we will kick out some stone!
Enough whining....
I can already see the rubber wheels have drawbacks, have you stayed with given values for your clay wheels? I suppose if they are set up a tiny bit off they would wear in pretty quickly.
Ever tried Marmo's wheels? Longlife I think they were called? looks like a fairly good design from the web page...

Thank you very much for your replies!!!

I have to let the clay polish wheels wear in, I have never had a set hit perfect all around. I install the given values and run to see where they are hitting, adjust, and just let them wear in, you may have to run them seveal times on the setup pc. to break them in.

We have never tried marmo's wheels. ADI came out with a three step clay wheel polishers, we have a set but so far the same result as the two step clay polishers.

Congradulations on your move. What do you consider the right help? Might be interested.