Grinding wheel & belts 101...

[AlainTernet]

Ok, it seems that I must buy at least one 80 grit and one 220 grit
diamond wheel  and I should not go below 1 1/2 "wide.

- Do you think that a 60 grit diamond wheel would be better than 80 grit ?
It would be better to remove material and make the basic shape but is it too
agressive to make the top of the cab (dome?) and can leave deep scratch ?

I think to buy one of those wheel sequences. This is very expensive for me,
thus, I want to make good (and durable) choice. What do you think?

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Choice #1 (6 wheels)

- 80 grit (or maybe 60 grit ?) hard diamond wheel
- 220 grit hard diamond wheel

- 280 grit soft diamond resin bond wheels (220 to 280 is not a big step and 400 is not available... 220 to 600 it is possible?)
- 600 grit soft diamond resin bond wheels
- 1200 grit soft diamond resin bond wheels

- Expanding Drum with 3M Diamond Belts (3000 grit, 8000 grit and 50 000 grit)

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Choice #2  (same as above but with three hard diamond wheel)

- 80 grit (or maybe 60 grit ?) hard diamond wheel
- 220 grit hard diamond wheel
- 400 grit hard diamond wheel

- 600 grit soft diamond resin bond wheels
- 1200 grit soft diamond resin bond wheels

- Expanding Drum with 3M Diamond Belts (3000 grit, 8000 grit and 50 000 grit)

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Choice #3 (cheaper setup: only 4 wheels)

[Taogem]

I am not absolutely sure about the difference between a 60 and 80.. I use a 100 as my initial shaping wheel. From using a 100 grit, I would say that an 80 would be fine for sure.. Just not sure about the 60.

I do see your dilemma for sure ! 

Not an uncommon one.. Your certainly doing your research and carefully considering the options.

Don't believe I am the best person to comment on your options that include the soft resin wheels. As I have no experience on them.

I can tell you that option #3 sure works for me. Except I think mentioned before..

For hard Jaspers, and Agates, I come off the 400 grit diamond wheel straight to a 80 grit silicon carbide belt. Then go on through the 220, 400, 600, and a worn 600.. Then straight to an oxide polish.

I do on occasion us a few diamond mesh pads prior to the oxide polish.

Someone else can comment better on your choice of 3M Diamond Belts (1200 grit, 3000 grit, 8000 grit and 50 000 grit). I would like to know if such big jumps in the diamond mesh works well..

I am thinking that a jump from the 8000 to 50,000 would likely be a bit of a jump.. Maybe even the 3000 to 8000 also..

Lets see what someone else says..

Overall ...... From my limited experience, I like your choice #3.

Also..... I can't help but always want to point out a very experienced cabber here... Bobby.. He strictly uses silicon carbide belts.. No diamond belts at all..

I too get very nice results doing the same.. I rarely use the few diamond mesh pads I have.. Only on a few off the wall mineral types.

A nice hard good quality Jasper and agate will come of these silicon carbide belts quite nicely !

Your other choices are considerably more expensive too... You can always upgrade or add to your cabbing arsenal.

Ok... I am done rambling ! 

[johnjsgems]

If using Chinese low cost wheels use 80 grit.  The 200 or 220 will remove the scratches.  Lowest cost alternative would be the two wheels and one drum with silicon carbide belts.  I learned on an old machine with silicon carbide wheels (100, 220) and then silicon carbide 400 and 600 belts, wet.  I saved a worn out 600 and used dry it gave a nice prepolish.  From there I polished on a hard felt wheel with cerium oxide.  I'd never go back to silicon carbide wheels.  The belts are very inexpensive but only available to 800 grit from my suppliers.  You could either use 320, 400, 600, and 800 and then go to 1200 and 3000 diamond belts and then to a polish belt (14,000 or RezBelt with 14,000 diamond paste).  Or wait until the 800 is wrn down and go directly from there to polish.  The choices are practically endless and intermediate steps reduce time in each step and can speed up the process but if finances are an issue start simple and expand as you can.  The "old way" worked just fine until diamond technology reared it's expensive head and yes it works much faster and in many cases better but have you seen Bobby's work?

[Taogem]

  The belts are very inexpensive but only available to 800 grit from my suppliers. 

Did not know there was an 800.... Could you post a link to your supplier for me ? 

[johnjsgems]

If I could post links I would not have to pay a web person to help with my web site.  I buy them from Covington Engineering, Redlands, CA.  Best prices I've found on S/C belts are Indian Jeweler Supply.  Last time I looked their price was about what my wholesale, 50 unit price from Covington or Johnson Brothers.  I don't know if they carry 800 or not. 

[AlainTernet]

This can probably interest others newbies like me:
I do some calculations to compare prices (without shipping and custom fees),
and there is no a big difference between the 3 choices above.

Choice #1 - 475$
Choice #2 - 479$
Choice #3 - 371$

"Cheap" Hard diamond wheel 6" x 1 /12"  (63$)  http://jadecarver.com/DiamondTools.htm
Soft diamond resin bond wheels (59$)  http://www.riogrande.com/MemberArea/ProductPage.aspx?assetname=203306&page=GRID&free_text%7c1267331556089=lapidary&first_answer=61
3M Diamond Belts (30$)
http://www.riogrande.com/MemberArea/ProductPage.aspx?assetname=201684&page=GRID&free_text%7c1267331556089=lapidary&first_answer=31
6" x 1 /12" Expanding Drum(52$)  http://www.riogrande.com/MemberArea/ProductPage.aspx?assetname=201086&page=GRID&free_text%7c1267331556089=lapidary&first_answer=1
Silicon Carbide belts (5.45$ for 5) http://www.riogrande.com/MemberArea/ProductPage.aspx?assetname=201789&page=GRID&free_text%7c1267331556089=lapidary&first_answer=31

[Mark]

Here's my 22 cents worth.  I have a Genie and i have an extra spindle and several used wheels so i have a lot of variety.  I use an 80 HEX which is more aggressive than a regular 80 grit wheel.  I believe 60 HEX or even 60 regular, may be too aggressive unless you have been doing it for awhile and know what stone can take what pressure/stress.  A 60 grit wheel can break a preform, especially softer or composite stones, a lot easier than a 100 grit.  If you are careful, you can go with an 80 HEX or maybe even a 60 regular.  These wheels will really grind stone quickly and you have to be very careful you don't end up with a pile of rubble instead of a cab.  Next in line would be the 220 grinding wheel.  After the 220 wheel, you move into the sanding wheels.  Most cab machines start have a 280 "soft" wheel next, followed by a 600, 1200, and finally a 3000.  Now you can use belts on expando drums for the sanding through polishing as other have pointed out.  I am not familiar with that stuff but you need to somewhat gradually decrease your grit size as you progress.  I saw some posts where the order jumped from like 8000 to 50000, that is probably too big a gap and the 50000 probably will not do much if anything after an 8000.  Many stones turn out perfectly well at 3000 grit and anything more will not make a noticeable difference.  I had that set up for several years and was happy with it.  I did find on occasion that it looked like i needed a bit more polishing and i bought a cheap pad and just sprayed Cerium Oxide on it to complete cabs that needed it.  I eventually got an 8000, 14000, and 25000 wheels as I purchased an extra spindle and needed to fill it up.  So now after hitting the 600, 1200, and 3000, i swap the second right hand spindle and put on the 8000, 14000, and 25000.  I have a 50K diamond spray, but i don't use it.

As you can see, there are many different approaches and styles and you'll learn as you get into it more.  Try not to make too big a gap between adjacent wheels or belts and for the most part, you don't really need to go to 50k, or often even 25K or 14K.  If you do, try Cerium Oxide for that final polish.

Mark

[AlainTernet]

I am thinking that a jump from the 8000 to 50,000 would likely be a bit of a jump..
Maybe even the 3000 to 8000 also..

I thought that this grit progression (1200-3000-8000-50 000 grit) was ok because
the 3M Diamond belt seem to be available only in these grits...

[Taogem]

Your right !

Just goes to show you that I obviously do not have any experience with using diamond belts !!

Sorry about that !

[Jane101]

Get a JOOLTOOL, I got mine recently and I  have ground and polished more than 40 stones in last two days!!! 

dancer121

Talk about instant gratification!!!

I found some cool stones on the beach, can't wait to find out what they are!!! 

yippie24

[novice]

Hi all! New guy here. I have been "self teaching" (with the help of the internet) to learn how to cab, etc. One thing I have found out, one diamond wheel is not the same as another, by manufacturer. I have already been doing a little research on recoating diamond wheels, with some of the "newer" resins that cure in sunlight, or UV light, so they cure in seconds, instead of hours. One thing I've found, the epoxy and other resin manufacturers aren't really all that helpful when they find out you're not planning  to buy resin in fifty five gallon drums, or tanker trucks full. Imagine that! So far, I've been able to get diamond abrasive in various "grits", or micron sizes, at reasonable prices if I shop around a little. At this point, I can resurface a wheel for about $7 or less, with more diamond in the matrix, and they cut as well as factory made. I am particularly hard on my wheels because I cut a lot of hard stuff, like Yellow Feather jasper lately. I don't know if it is the manganese dendrites in it, or what, but it is somewhat harder than the Montana Agate I've cut before. It does take a most beautiful polish though, and the patterns are so varied, depending where on the hillside it comes from. Sometimes, only a foot or two makes a big difference in color and pattern, but they're all gorgeous! You're all probably thinking , "Boy, does that new guy ever have a lot to say!". Yeah, probably.