Cutting granite makes stone dust. Will sliding a ring across the dirty surface make scratches in the polished surface?

I think that is a very good point.

An air jet or vacuum to clear the stone debris (before it reaches the ball bearings set in the ring) may be good.

Cutting granite makes stone dust. Will sliding a ring across the dirty surface make scratches in the polished surface?

A dust chute for the auto pressure foot may help.
(This I made myself)

That's it, just the thing 

The sliding ring may not work for all applications. Sometimes the background may be cut away leaving the lettering. Then there may not be enough supporting material for the ring.

Agree.
"Horses for courses"

 

Hi,
I imagine the tool would be flood cooled. Water cooling vastly extends the tool life, poly crystalline diamond tools
are expensive.

Craig

Maybe think of other ways if Diamond bits are very costly
FYI
A small factory in Sydney invested in a 10 feet x 20 feet 5-axis CNC waterjet and was able to replace a hugh CNC DIAMOND circular saw, a huge diamond wheel CNC grinder, 3 SKILLED craftsman using air powered diamond circular saws/grinders.
Business is dealing with large
Marble slabs, Granite slabs, fake granite slaps, terracotta  etc.
5-axis CNC waterjet use just pressurized water + fine sand to cut, chamfer or roundover the cut edges, and can even engrave (which 3-axis waterjets can't).
He even contracted a sign maker opposite his factory to cut metal and plastic signs for them - replacing their CNC routers.
I was there for two weeks when the waterjet was being installed and tuned up.
A small suction (fork) lift and a suction crane load and transport the slabs on/off the CNC waterjet. Little off leveling is automatically compensated by the waterjet auto probes before the g-code actually start cutting.
Computer is embedded industrial Win XP with 3 parallel ports controlling servos and pumps etc. etc.

Hi,
I bought a Harvey Tools (high quality if pricey brand, superb selection) 0.5mm PCD endmill.

If memory serves it cost about $78US but by the time it was shipped to New Zealand it cost me $250NZD.
You can be sure that when I use it I KEEP IT COOL. Of course being so small its very tender anyway.

The point is that you can turn a $300US PCD tool into a few dollars worth of scrap by letting the tool overheat.
On the other hand that same tool will last hundreds of hours if you do keep it cool.

OP has obviously been using these tools for a while and presumably making money doing so. For the sake of
a $20 home made probe and some time to experiment with Autoleveller, Gcode Ripper or Surface Map (Mach4 only)
he can improve what he is doing WITHOUT spending big bucks.

Craig

Hi.
About the cooling, well yes I use pcd, vacuum brazed, electroplated, sintered diamond tools. They all need a lot of water to "stay cool".

On the topic for the auto pressure foot spindle mount. I was thinking about buying one. There will be no problem for the bearings sliding on the material, if they are aluminium or poliamid. BUT as MN300 wrote, there is the problem with removing the background around the letters, which is the main method for engraving in my region. I believe that the engraving will mess up when it starts to work on area where all the background is removed and also the marble pieces that will be left behind from the material will be carried around from the bearings on the polished surface.

About the surface mapping. This is an interesting topic. I will try do some next week. From what I saw on the hundreds of videos that I watched, I think that the mach 4 feature will be most suitable.
The reason behind my thoughts, is that most of my projects are made by few different tools. For example, I use pcd for the clear contour of the letters - this is one g-code, and after that I use vidium tool to remove the background - second g-code. So if I need to make the scan over and over with each tool (each g-code) it may cause differences and loss of time.
What I am saying is that I haven't tried autolleveler or g-code ripper yet. And I am not sure if there is a way on both of them to make a tool change without having to re-scan, the surface.
The g-code ripper has a nice feature - the offset of the probe from the tool. Not sure if the others have the same function.
https://www.youtube.com/watch?v=QN8yPjy6uTk

This video gave me the idea to make a permanent mount for the probe on the machine. So if I don't need to change the tool between the different jobs, I will not need to put the probe on the spindle. The probe will stay there on the machine and will wait for doing what its made for.

Thank you all for the ideas, it is really great to get some advice when you do something you haven't done!

Peter