Thread: I Found It Over There

Originally Posted by Ranzor

Will do......if I ever get the damn thing lapped.

If it is Sioux Quartzite, it is a hard, hard rock! Good luck with it.

All quartzites are very hard. They are even hard on the diamond abrasives - just like Arkies. If you're using a diamond cut off wheel at all you should use oil lubricant to cut them - otherwise the wheel will glaze over pretty quick. This has to do with the metal bond holding the diamond getting very hot and plastically flowing over the diamond, preventing it from cutting properly. Using a plain diamond lapping plate you are still good with water though. And a lot of elbow grease.
I recommend loose grit lapping with SiC abrasive, much faster.

Really, when you are doing any lapidary work you should be using some kind of lubricant as you cut or grind.

Yep, most use water for everything though - quartzite and novaculite will glaze a metal bond diamond wheel over in seconds if water is used though. They can be unglazed by using a"dressing stick " on the wheel or just cutting through some old crappy synthetic SiC honing stones a few times. Using oil slows this glazing down considerably but still won't stop it.

Most heavy duty lapidary saws use a gravity feed device and if I recall correctly our large saw in the Geology Dept used a combination of oil and diesel. We could cut through quartz all day with no issues.

The gravity feed is the key meaning slow cutting, very slow with the diamond saw.

I picked up a couple pieces of rock last week. I had our tile installer slice one. He got some twist in the cut so its far from flat. I would like to get it lapped but I am having a bear of a time getting that done. It is very hard. I can hardly even raise a slurry on 120 wet or dry. I went after it with my DMC but even that is going to take forever and a day.

What do you guys use to do the preliminary flattening? The stone does have some promise, as the small area that I did get lapped put a shiny chamfer on a file end.

Hardness is a big issue for me. There are some rocks that I have abandoned due to simply being to hard to work with easily, and my hones are generally fairly hard for hones. I have a piece of rubber that goes down in the sink then my DMT lapping plate and then water to cover and a lot of elbow grease. I think If it wasn't for the work of lapping I would be able to turn out hones with a great deal less labour. I am going to guess that lapping and finishing is at least half of the effort of making hones. It is also where some get culled because it is simply too much effort for a variety of reasons. I have not yet figured out how to cut a warped hone flat. Once they get there I give it one shot to make it straight on the saw and if it doesn't work I chuck it. Sad but true. Sometimes correct that takes forever. You may be having to take and 1/8 or 3/16 off of most off the hone. On a very hard hone that is a lot of lapping.

Shaun get an angle grinder and a diamond cup wheel. Get closer with that then go to the lapping plate - or, as I prefer, loose SiC grit. That 1-2 punch makes pretty short work of even the hardest stones I've tried.

I have one it I always make a mess with it. I keep planning on doing mount for it with a guide and table but between my work schedule and my brothers it hasn't happened. He has all the steel and steel tools at his shop and I'm wood and rock.

Gotcha - here's an easy way to make it work without the guide: take a can of cheap spray paint or something and coat the stone really lightly, then use your lapping plate to give it a few scrubs. Hit only the spots that get the paint removed lightly with the grinder, then repeat a few times. Having had some practice at it now I can usually get flat enough to go to the lapping plate with loose grit in 5 minutes.