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Author Topic: Grinding wheels  (Read 2609 times)

glot

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Grinding wheels
« on: June 30, 2017, 05:17:00 PM »
Are the textured coarse grit diamond grinding wheels more or less aggressive that the standard electroplated ones?

Shivan

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Re: Grinding wheels
« Reply #1 on: June 30, 2017, 06:34:35 PM »
I have a 220 textured wheel, it acts the same as the normal wheels, only difference is it leaves a textured finish, this does come out for me in later stages.

Aussie Sapphire

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Re: Grinding wheels
« Reply #2 on: June 30, 2017, 06:38:57 PM »
The advantage of the textured wheels is that the surface pattern allows water to cool more effectively and flush debris during cutting. They are not designed to be more aggressive - just to work more effectively.

Dont go too coarse if you dont need to - it might grind off material quickly but often you lose that time saving in later steps taking out the scratches.

cheers
Leah
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glot

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Re: Grinding wheels
« Reply #3 on: June 30, 2017, 07:15:27 PM »
I have a worn 80 grit. I am looking at a new 80 grit to grind the outline shape. Sounds like the textured wheel might be the go.
Shivan, what do you mean it leaves a " textured finish"? Do you mean just deeper scratches?

glot

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Re: Grinding wheels
« Reply #4 on: June 30, 2017, 07:22:50 PM »
Another question on said wheels. Manufacturers often state maximum speed or RPM. What speed or RPM is generally a best compromise for common use such as silica based stones.

Shivan

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Re: Grinding wheels
« Reply #5 on: July 01, 2017, 01:31:14 AM »
Its not so much that the scratches are deeper, but less uniform i guess.... Hard to explain. If i get a chance i will try to get a photo of what i mean.


Aussie Sapphire

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Re: Grinding wheels
« Reply #6 on: July 01, 2017, 08:10:19 AM »
I have a worn 80 grit.

Are you sure you need an #80.  Even a #100 wheel is pretty aggressive.  I repeat:  coarse wheels in first stage may appear to save time by grinding quickly but you usually waste that time and more by taking longer on subsequent steps to sand down those deep scratches.

We sell coarse wheels because people insist they want them but often going a bit finer is a better idea.

cheers
Leah
Aussie Sapphire - The Lapidary Warehouse

Shivan

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Re: Grinding wheels
« Reply #7 on: July 01, 2017, 10:50:42 AM »
I hear what you are saying Leah, but if grinding harder stones like agate, wont you just burn through wheels trying to pre-shape on anything over 100 grit? Softer stones i can understand.

So long as you are not taking the stone back to a finished levels on the 80-100 wheels there is still plenty of stone that still needs to be ground away on 200-600 wheels and so you are not trying to get scratches out just finish grinding the shape, if that makes sense.

MakkyBrown

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Re: Grinding wheels
« Reply #8 on: July 01, 2017, 01:36:46 PM »
I hear what you are saying Leah, but if grinding harder stones like agate, wont you just burn through wheels trying to pre-shape on anything over 100 grit? Softer stones i can understand.

You sure will, I got sick of wasting time on 80/100grit. Might work ok when the wheel is brand new but that doesn't last long. Best thing I ever did on my cabbing machine is my 5 inch saw blade wheel, rips the stone to shape, then onto 60 or 120grit soft wheels soon removes sub surface damage etc. I'd spend all day trying to cab large stones without it.  I made it with 18 5inch turbo concrete cutting blades bolted together.  Got them cheap off ebay for $3.50 a blade. Also need to wear safely glasses as it's pretty rugged less than 20grit imo :) Have to take care not to chip edges on smaller stones.

Aussie Sapphire

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Re: Grinding wheels
« Reply #9 on: July 01, 2017, 05:09:08 PM »
I hear what you are saying Leah, but if grinding harder stones like agate, wont you just burn through wheels trying to pre-shape on anything over 100 grit? Softer stones i can understand.

Yes - you do need to be sensible but we get asked for #30 and #60 grit wheels and I really dont think these are necessary.  Even an #80 compared to a #100 - just go the #100.

If you are grinding a LOT of material away, then maybe consider trimming it closer to size with a saw.

It will always be a series of steps from coarse to fine.

However, lots of ways to skin that cat as Makky as shown with his different method.

cheers
Leah
 
Aussie Sapphire - The Lapidary Warehouse

FlashGP

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Re: Grinding wheels
« Reply #10 on: July 01, 2017, 11:59:18 PM »
Macky, Bruno the Qld based rough merchant was telling me how he uses 6 worn trim saw blades to do the same thing.

Regards
Flash
Yours Sincerely
Flash (Gordon)

MakkyBrown

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Re: Grinding wheels
« Reply #11 on: July 02, 2017, 08:19:39 AM »
Small world flash, I met Bruno(if the same one) at agate creek a few years ago.  ;)

FlashGP

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Re: Grinding wheels
« Reply #12 on: July 02, 2017, 12:58:54 PM »
Makky,

you may have, he is originally from France, but now does the circuit  selling slabbed rough.  We see him at most SE Qld gem shows.  He was at the Gold Coast show yesterday and will be at the  Bundaberg and Hervey Bay shows in the comming weeks.


regards
Flash
Yours Sincerely
Flash (Gordon)

glot

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Re: Grinding wheels
« Reply #13 on: July 02, 2017, 03:32:36 PM »
Why not trim close with a band saw instead of using something akin to using a thermal lance?

MakkyBrown

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Re: Grinding wheels
« Reply #14 on: July 03, 2017, 10:55:25 PM »
Why not trim close with a band saw instead of using something akin to using a thermal lance?
I nice cabbing curve over a broad area  :)

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