rewdownunder
spending too much on rocks
Member since March 2012
Posts: 357
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Post by rewdownunder on Sept 19, 2021 19:41:05 GMT -5
I just received a box of stabs as a club donation which almost all have break off nubs at the end of the cut. What is the best way to clean up the slab. Do I cut them off with a trim saw, grind them away with a wheel or just break them off with a tile nipper. I have good access to equipment but have never had to deal with this before. I plan to keep some of them as slabs so I can't just cut them off.
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Post by stardiamond on Sept 19, 2021 20:23:33 GMT -5
I'm not sure what you are taling about without pictures. Slabs are simple for me. I don't collect them. They are just inventory to make cabs and I work around issues. If they stick up above he surface. I grind them off with a flat lap.
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AzRockGeek
has rocks in the head
Member since September 2016
Posts: 703
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Post by AzRockGeek on Sept 19, 2021 20:52:57 GMT -5
If the slab is for display, use a saw or grinder and trim/grind it off. If the slab is for cabbing or sitting in a box in your shed use a tile nipper or slide your rock hammer along the slab and bust it off. (Depending on price of slab, expensive slabs I would grind it off).
When I use to sell slabs at shows, people would want them removed, I would point at something the opposite direction to distract them and smack it off with a hammer. LOL
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Post by hummingbirdstones2 on Sept 19, 2021 21:43:09 GMT -5
Yeah, if they're thin - near the edge of the slab only - tile nippers are great.
Bigger slabs often break off an area extending farther onto the face of the slab. Then it's time for the trim saw or grinder.
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Post by stephan on Sept 21, 2021 0:40:22 GMT -5
If the slab is for display, use a saw or grinder and trim/grind it off. If the slab is for cabbing or sitting in a box in your shed use a tile nipper or slide your rock hammer along the slab and bust it off. (Depending on price of slab, expensive slabs I would grind it off). When I use to sell slabs at shows, people would want them removed, I would point at something the opposite direction to distract them and smack it off with a hammer. LOL Seriously? People asked for that? That’s too funny. Never would have occurred to me. They’re just often part of the slab. I used to grind them down if they got in the way of the templates, but since I now make more free forms, it’s less of an issue. |
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rewdownunder
spending too much on rocks
Member since March 2012
Posts: 357
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Post by rewdownunder on Sept 21, 2021 9:36:55 GMT -5
I understand that a slab is nothing but raw material for most lapidary people and that a nub on the end of the cut is no big deal. I polish slabs for geologic examples and for display as full slabs and of course the nub is always on the best side of the slab. In this case I was give 60 or 70 slabs for the club and about half had sharp nubs on the ends from the slab saw. I do not want to put them in the shop and have students grind them on new wheels. I can only think of the damage some of these sharp points could do to the wheels. My plan was to clean them up quickly before making them available to everyone. Some of this is very good material so using the hammer is out. I have setup the old tile saw and will mount an old SC to the end of my combo unit and clean them up.
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Post by stephan on Sept 21, 2021 14:35:43 GMT -5
I understand that a slab is nothing but raw material for most lapidary people and that a nub on the end of the cut is no big deal. I polish slabs for geologic examples and for display as full slabs and of course the nub is always on the best side of the slab. In this case I was give 60 or 70 slabs for the club and about half had sharp nubs on the ends from the slab saw. I do not want to put them in the shop and have students grind them on new wheels. I can only think of the damage some of these sharp points could do to the wheels. My plan was to clean them up quickly before making them available to everyone. Some of this is very good material so using the hammer is out. I have setup the old tile saw and will mount an old SC to the end of my combo unit and clean them up. Of course they are on the best side. That is the way the Universe works. I can't imagine that quickly grinding down a bunch of nubs on new wheels would cause a lot of damage, if you have hard, sintered wheels (especially 60 or 80 grit -- they are MADE to eat rock). In fact, if they are brand-spanking-new, it might be a good way to break them in. If you're worried about it though, consider beating the students to the punch, and grinding down the nubs before you put them out. It should take less than a minute per slab. If you're really, really worried about it, swap in an old wheel and do it on that. A bigger worry with newbies is probably more that they'll take it down too far. |
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Post by victor1941 on Sept 23, 2021 10:21:37 GMT -5
I use a 8" flat lap 60 grit to remove the nub at medium speed. I place the slab nub at a 45 degree angle and lower the slab as the nub is ground off and the slab is flat on the surface. Surface irregulars or kerf marks are removed on the 60 grit flat lap. Sometimes I use a less aggressive grit for the first step for better control if the slab is large. I also have a number of petrified wood display pieces that have the nub that need to be removed before I polish them.
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