Grinding wheel & belts 101...

[AlainTernet]

Hello !
I am new to thw lapidary word and before making or buying a lapidary grinder
I would like to be able to understand the pros or cons of each kind of grinding wheel.

What kind of wheel you use and why? The diamond wheels seem to be verry good
but are very expensive. The Expanding drum is a option not too expensive to build a
simple and "cheap" grinder, but what kind of belt using ? (and why?).

I make a little inventory of what is available (this may help other beginners).
Feel free to add those that I forgot and give me some feedback on what you prefer
and where it is cheapest to buy.



Expanding Drum (~$50 to $100)
The drum expands as the wheel rotates, holding the belt firmly in place. Slightly cushioned
sanding surface makes smoothing and shaping of contoured surfaces quick and easy



Textured Diamond Grinding Wheel  (~$140 to $200)
The interrupted surface texture improves the rate of stock removal and  keeps the cutting
action clean and free.



Diamond Wheel (~$100 to $200)
This wheel is evenly electroplated with diamond to provide a smooth finish.



Diamond Resin Wheel  (~$60)
No more wasting time changing belts! This ready to use diamond resin wheel is ideal for
lapidary applications.  Put on any wet arbor or cabbing machines. Take advantage of the
softness of this affordable wheel compared  to metal bonded wheels, as it will allow you to
contour your piece



Silicon Carbide Grinding Wheels
Made with the finest quality graded silicon carbide grit, these grinding wheels are bonded
especially for lapiday work. Important: For your safety, always run silicon carbide wheels until
they're completely dry. Residual moisture will drain to the botton of the wheel and can create
an imbalance in the wheel weight that could cause spontaneous, high–velocity fracturing
on startup

------------------------------


Silicon carbide belt (~$1 to $2 by belt)
Use silicon carbide sanding belts wet or dry for excellent results in lapiday and metalworking
applications. Carefully graded silicon carbide abrasive is resin–bonded to durable backing



3M IMFF Aluminum oxide Sanding Belts (~$3 by belt)
Long-wearing flexible film backing with aluminum oxide abrasives for fast repeatable results.
These belts are suitable for both; lapidary and metalworking applications, use them wet or dry



3M Diamond Belts (~$30 by belt)
Use for all lapidary finishing as well as for cutting, shaping and smoothing;just about any
material. Belts should be run wet for best results. • Cloth-backed diamond abrasive graded
from .5 micron to 15 microns produces an ultra-high finish on most materials



3M Diamond Micro-Finishing Film Belt (~$15 to $40 by belt)
This long-wearing, flexible film backing with diamond abrasive for fast, repeatable results
is suitable for Lapidary or metal working applications



3M Trizact Belts
Advanced technology called Microreplication makes these aluminum oxide abrasive belts a
time saver - as much as 50% reduction in buffing time along with unprecedented consistency
and precision is provided.

[akansan]

The hard diamond wheels (or hard SiC wheels) work best on removing stone - the grinding stage.  The expanding drum or resin wheels work best in the sanding stage - where you smooth out the dome - and can be used in the polish stage as well.  The softer back helps eliminate flat spots.  At the very least, I'd recommend two wheels - a hard wheel and an expanding drum.

I've used the expanding drum, the resin wheels, diamond belts, SiC belts, SiC grinding wheels, and electroplated diamond grinding wheels.   I have not used the sintered diamond wheels yet, but would really love one.  What I can tell you is this:

• Diamond wheels grind (and sand) faster than SiC.

• Resin wheels last longer than belts.

• Diamond belts last longer than SiC belts at that grit level.

• Grit on SiC belts break down to smaller grits - a 600 SiC belt will become a 1200 SiC belt with use.  (I'm not certain if this is true for diamond as well)

I'm sure there are other pros and cons of each, but these have been my observations.

[Taogem]

You did a great job in researching.. Think you covered every possible option..

I use the 6" textured diamond wheels. Although.., if I could afford it, would go with an 8" setup.  I start with a 100 grit, then 220, 400 for grinding and prepping for the silicon carbide belts.

Then almost always start off with a 100 grit SC, 220, 400, 600, and finally a worn 600.

Recently I opted to try some of these diamond smoothing pads for following up after the 600 SC belts. They go on a larger flat lap.

I use these in 1000, 2500, and 5000 mesh.



If I had it to do all over again, or when can afford to set up.. Will go with the diamond belts.

Would probably go with the 3M belts or maybe even these Rez belts. Resin impregnated canvas belts (shown below on a drum-not included) for use with diamond compound.



Never have used the Silicon Carbide Grinding Wheels.

With all this in mind, one of our finest cabbing members Bobby, does excellent with just using the silicon carbide belts. I do a-ok with just coming off a 600 SC grit belt and straight to a polish, but have seen big differences with some minerals using the diamond pads mentioned above.

Here is a neat thread.., silcon carbide belts versus diamond belts - advice please

[bobby1]

I use the SiC belts exclusively. I like the adaptability in being able to use them dry and enjoy the speed at which they work. I also like the feature where they get more flexible and soft with useage thus they work great with removing flat spots. They also last a long time. I've got some that I have been using (almost abusing!) for 5 years or more of nearly constant, hard use. Diamond grinding wheels are a must. I use a  1 1/2" by 8" 120 grit Chinese plated wheel ($95.00) for all of my coarse grinding. I also have a 220 grit SiC  - almost worn down to nothing  - grinding wheel for doing touch up prior to sanding. I've taught classes on all diamond wheel machines and they work well for working smaller (up to 2") cab but they are not my personal preference. I grew up with SiC machines (going on 52 years of cabbing) so I do have a personal bias.
Bob

[woodyrock]

For my two cents worth, I found little actual cutting difference speed wise between SiC wheels, and diamond, but the constant dressing of the SiC wheels was a pain. I never could keep the wheels square, and did not like working on a dished out wheel. My last SiC course wheel had a soft spot in it that was a royal pain.
Woody

[AlainTernet]

Thanks all for your reply !
I am knifemaker and normally I grind on a knifemaking belt grinder
(vertical wheel) but I dont like to grind cabs on the horizontal flat diamond
disc of my small Inland swaptop machine. Second thing, the finest grit on
the inland machine is only 1200 grit, I found that is not enought to go
on polishing directly after... Now,  I think it's time to upgrade my setup.

I thought to build a small lapidary grinder, but I lack of space (my shop is small and full)
and money I look for a alternative: I already have a knife belt grinder with a big variable speed motor,
a "lapidary attachement" will be easy to build.
I can remove platten, belt and wheel and put a Expanding Drum with a housing and water mist.
This solution is not the best (only one wheel at time) but it think this is the cheapest solution for now.

Therefore, what is the best kit to start for this scenario (at low cost). 
I think to a 6" x 1.5" diamond wheel for the initial grinding and a expanding drum
with 220-400-600 sillicon carbide belt. 

But after 600, what kind of belt is the best ? RioGrande have some stock, but I do not
find a lot of belt  for 6" x 1.5 drum in high grit (more than 600). SIC it is available on finner grits ?
Diamond belt are verry expensive and diamond paste on canvas belt seem quite expensive too...

And last question: Where do you buy your belts and wheels ? Where is the best place (choice and price)

Thanks for your help !

[Taogem]

Can you post a pic of your vertical unit that you would like to attach a lapidary set up too?

Just curious what it looks like.

Bobby changes his belts out using just one expando drum. Seems to work great for him.

For myself, using just one diamond sintered/textured grit wheel for initial shaping does not work. I like going through all 80, 220, and 400 prior to getting to the silicon carbide belts.

Even then, quite often I start right off on an 80 grit silicon carbide for most agates and jasper's before moving through the 220, 400, and 600 belts. So you may want to consider adding an 80 grit to your arsenal of silicon carbide cabbing belts.

I can't offer much more help about the belts than what I posted earlier except that I might choose to try the Rez belts sometime.

[redrockrods]

I'm using 60 and 220 grit diamond plated wheels (Chinese fmg) and then 3m diamond belts 220, 320, 400, 600 on an 8" drum. I polish on a crystal belt charged with Tin Oxide. If I feel that I need to take the cab higher than 600 grit, I have diamond pastes 1200 - 50,000 that I will apply with a dremel tool and felt disk.

At first I used  SiC wheels and belts, but became so frustrated with the slow/poor cutting and constant dressing of wheels  that I took the plunge and bought diamond equipment. With the diamond, I can do in minutes what used to take me hours on SiC. I'll never go back.

I bought my diamond wheels from http://jadecarver.com/ and everything else from www.sfjssantafe.com/.

I haven't seen any SiC belts for sale above 600 grit.  SIC belts break down over time and eventually a 600 g belt will become a 1200+ belt.  Diamond belts are avaliable from 1200 - 50,000 but they are expensive as you know.

[Freeform]

I work a metal bonded diamond wheel in 80 grit and 220 grit. If you plan to cut hard stone, you need a metal wheel for rough shaping.  Then I use sil belts on expando drums ranging from 100 grit to 1200 grit. As Bob notes, sil belts do last a long time and under heavy use. I’ve gotta a few I still use that are 5+ years old too. They only turn into a less grit stage and unless they break, can be used well for general and final sanding.  I then use diamond compound on resin belts.

If you can manage a way to rough shape your cabochons on the grinder you got, allot of people then finish then by tumbling the sanding and polishing stages. Another piece of equipment, but tumblers can be made allot easy than grinders I say.

I don’t think you will find sil belts in high grits, I don’t know of any makers of them. They stop at 600 grit as far as I know.  The diamond belt route is the only route, weather compound on canvas, or straight diamond resin belts. (They are worth it). If you use compound there is cross contamination you can to worry about, depending the stone and how experienced you are at proper sanding stages. I would recommend diamond belts over resin until you experienced enough to understand how certain materials can cross contaminate your resin/canvas belts.

Now this happens in most cases when sanding, but is not an issue when under 1200 grit.

[AlainTernet]

Ok, It seems like I'll have to buy more than one Diamond wheel...

The web site given by redrockrods have verry good prices on diamond wheel (only 39$ for a 1" x 6" and 63$ for a 1.5 x 6") this is much less than RioGrande ! (Thanks for the link!).

This brings me another question:  Can you give me your advice about wheel width and diameter ? I imagine that larger and wider the wheel, it will last longer.  But a wide wheel it is  really necessary to make normal size cabs ?  The surface in contact with the wheel is very narrow: cabochon is rarely in contact with the entire width of the wheel ? In your opinion, is that the 1" x 6" wheels is usable or is too narrow? (for the same price as 1 or 2 big and large diamond wheel I could have a complet set of 4 to 6  small 1" x 6" diamond wheel)

Taogem: Ok, I will take some pictures of my knifemaking belt grinder.

[Taogem]

I would love to have 8" diamond wheels..

The 6" are pretty standard although.., you will want the 1 1/2" wide.. Trust me  :)

[AlainTernet]

you will want the 1 1/2" wide.. Trust me  :)

Why ?  1" is not enought wide to work ?

[Taogem]

No it is not.. take at least an 1/8" off both sides of that 1" because if your cab hits the edge of the wheel you will be either reworking or reshaping the cab to get rid of the big notch/scratch that resulted.

I also like to be able to move in strokes across the wheel.. I would just not be able to move freely across a 1" wide wheel.

Many of my cabs are very low domed as well. Most a good 1" one way or the other. It would be impossible for me to work a 1" low domed cab on a 1" wide wheel.

Kind of hard to explain.. Probably hard to understand, but once you start cabbing on a 1" I think you will be pretty disappointed. Mainly because of the limited ability to move freely over more surface of a 1 1/2" without fear of hitting the edge of the wheel.

[AlainTernet]

Where do you buy your lapidary stock ?
Anyone have other good internet link to buy diamond wheels,
belt and lapidary supply ?

[idrockman]

Hello,

I use Kingsley North, they are great to work with and will help you.  I have dealt with them for the past 10 years.

Their internet site is:  http://www.kingsleynorth.com/

I am a dealer for Inland Lapidary Supply, that has mainly wheels and flat laps, as Kingsley has belts, grits, everything that you need.

Take care,

Brad