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Post by stardiamond on Jul 31, 2014 18:56:47 GMT -5
After reading the thread on slab price. Some questions came to mind.
I have been slabbing small rough using my genie trim saw attachment. The uses 8" mk303 .032 blades. I know that slabbing uses up a blade a lot faster than trimming.
The slabbing is done by pushing the rough through the blade freehand and for larger pieces rotating the piece through the blade. I'm not forcing the material, but I am pushing and a 2x2 slab is created fairly quickly 5-10 minutes. Cutting freehand has some advantages; no vice and less waste. The disadvantage is sometimes the slab is a little uneven.
1. Would my blade last significantly longer if I did less pushing and let the blade sort of work it's way through the material? In other words, be more patient.
2. A large part of slabbing is the labor, but what is the wear factor on the blade. I know there are other costs like oil and electricity. In other words, how many slabs can you get from a blade? I know it depends on he size of the slab and the hardness of the material. If someone sells an 18 square inch slab on ebay for $5 are they losing money? How much blade cost for cutting an 18 square inch jasper slab? I naively thought that the blade cost per slab for a 16" saw was minimal, even though I could see the blade cost using my trim saw.
I do understand that if you cut a slab the money is spent and it is better to get some money than having a slab that you don't need in your inventory.
3. I posted a picture of some starburst rhyolite on the id board. Once I got an id, I took a look on ebay to see what similar quality slabs went for. The material is a sunk cost, but how do I know if it is worth slabbing it without knowing the blade cost? Maybe it is better to sell it as rough. Some of the rough I have would be surely worth slabbing because I know the slabs would be worth significantly more than the rough.
These the kind of things I'm thinking about when I start to use my slab saw.
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Sabre52
Cave Dweller 
Me and my gal, Rosie
Member since August 2005
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Post by Sabre52 on Jul 31, 2014 19:23:04 GMT -5
1. Yes, a rock saw blade essentially grinds it's way through the workpiece. Harder you push, more chance of dishing the blade and faster the wear. Patience is good!
2. If the 18 square inch slab was cut on a larger saw, they probably are losing money even without the cost of the rough. That's under 30 cents per sq inch for the cut and for hard jasper, more wear on the blade and a slower cut so more time spent cutting. If the rough was pricy and purchased, even worse.
3. That was a nice looking hunk of starburst. However, it is a rhyolite and often problematic to polish past a satin finish. Therefore , it usually does not demand real high prices. Some rhyolite really drags on the saw blade too as it tends to run dry in the cut due to porosity. I have had some types be real saw stoppers, especially if your blade is not new and very sharp and your oil is dirty. I've got a few starburst slabs in my collection and none were in the "expensive" category. Probably paid less than 50 cents per square inch cut. When I did E-bay, and I did very little, I found it pretty much non profitable except maybe in the instances the material was premium and self collected so my only cost was the cutting. You do have to bear in mind that the larger the blade kerf-wise used to cut your material, the more waste too. I figured my old 20 inch saw ran a blade so thick that I lost one slab from three to the blade kerf....Mel
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Post by stardiamond on Jul 31, 2014 20:02:39 GMT -5
Thanks for the answers. I don't think I am dishing but will try a lighter touch. Here's the kind of rough I like to bid on ebay.  I haven't received it yet. The total weight is 1.2 pounds. I can see 5 to 10 single cab slabs and the only way to cut these would be with a trim saw. I like working with heels so there may be more. I hate to waste blades. |
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Sabre52
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Me and my gal, Rosie
Member since August 2005
Posts: 20,504
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Post by Sabre52 on Jul 31, 2014 20:52:50 GMT -5
Yeah, I'm with you. I'm enjoying the hobby more since I decided to go with the smaller saw and stick too smaller hunks of rough. One cab wonders are faster and more fun to cut, less trimming, less waste and for me, easier to get a solid cut too. Morrisonite is hard. That will take some patience but a fine material and very rewarding.....Mel
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Post by rockjunquie on Jul 31, 2014 21:57:08 GMT -5
Great thread! I have a 7" trim saw and find it to be pretty much useless. I need to practice more, but I have a hard time finding rock freaking small enough for it. I would like to get a 10" and do a lot of cutting by hand. I would be slabetting for myself and not for sale, though. I have purchased rough in anticipation of getting a bigger saw, but it just sits and mocks me...
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Post by stardiamond on Jul 31, 2014 23:09:45 GMT -5
I learned some techniques here regarding slabbing larger pieces with a smaller saw. One I use a lot is when the piece is too large to cut straight,I roll the rock and cut in a circle. I also try cutting a small piece of a bigger rock (if I can) and then slab the smaller piece. My problem is that it wears the blade out too fast and that isn't cost effective. I'm going to try to do the same things I'm doing but push less and let the blade dictate the pace.
Unless you imbedded a small piece like I pictured above in mortar. I can't see how you could cut it with a 16" saw. I generally buy small rough, but I have may be 10 very good rocks that require a big saw.
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Post by deb193redux on Aug 1, 2014 9:26:08 GMT -5
the "prices" discussed where when someone wanted you labor/wear for a rock they needed/wanted cut.
we cut a lot for ourselves just because we want to see inside, and plan to trim up any nice slabs ourselves. rolling can be done in that case. You try selling a slab on ebay with saw marks and a nub in the middle, and you won't get squat. You will also get a lot of smaller slabs that don't have much in them. And then there is larger trim saw scraps. Unless you are cutting for the pleasure of it, you need to discard the boring bits. (Maybe they can be tumbled and sold to wrappers).
A lot of slabs at shows and on ebay are the ones the cuter did not want. They end up in the $1 bin, or sold for 50cents each.
When slabs are sold individually, a lot more than wear and time matter. The "cost to cut" questions really only applies once someone has something they want cut (prospectively) and they need to hire someone to do it.
The do "it for a slab" arrangement possible wen a hobbyist is involved, really depends on the material. I would not cut 4-5 slabs of hard Brazilian agate for a single slab, because I am not that excited about this common material. If it was an amazing pattern amy sage, I might cut 6-8 slabs for keeping one (my pick). The point is the value of my time is fixed, but the value of a slab is variable.
In the end, a fair price is something you are willing to take, and the other guy is willing to pay.
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Post by stardiamond on Aug 1, 2014 11:53:51 GMT -5
I've only had one piece of rough cut by someone else. It was primo horse canyon that I got very reasonably. The deal was 50/50 split which was acceptable.
I understand the cost to cut for someone else, I was trying to get an idea of cost to cut for yourself. For material you intend to cab yourself, it isn't as relevant.
if the slab cut is intended for sale then slabbing cost is relevant.
Regarding slabs on ebay. There are at least two kinds of buyers; slab collectors and buyers who are looking for cabbing material. They bid against each other even though they have different objectives. A slab collector is looking for a clean beautiful example of the material. I buy for cabbing material and look for how many good scenes are available in s slab. I don't care if it is a heel, has fractures, saw marks or a nub as long as I can work around them. A slab that has a beautiful scene might not be as nice when cut into small pieces.
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Post by johnjsgems on Aug 1, 2014 13:50:18 GMT -5
Mel pretty well covered it. With trim saws, heavy handed cutting will dull the blade faster requiring more frequent dressing (dressing open new diamonds) which reduces blade life. If you draw a line across the rock you can get a pretty straight cut for cabbing with a gentle feed rate. On the larger MK/BD blades (.085" and .100" you lose maybe one slab every two or three. A good slab saw blade will last a long time unless a rock is improperly vised or breaks in the vise while cutting. This never happens when the blade is nearly worn out.
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Post by stardiamond on Aug 1, 2014 14:38:20 GMT -5
The trim saw blades I used aren't dressed. There is about 3/8" band of exposed diamonds on the perimeter. The more I cut the narrower the band becomes. The rate is slower when trimming and faster when slabbing. If I only use the blade for trimming they last a while.
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Post by cobbledstones on Aug 2, 2014 14:57:42 GMT -5
Pushing a little cobble through the 10" saw is one of the things I enjoy most. Instant gratification! I never did a complete cost analysis as this is my hobby, but it seems to me you should compare 12 and 14" blade prices and blade life to the 10" 'push through" method. Then consider that the push through allows you to slab the whole stone and has a thinner kerf so there is less waste on the back end. The price of the saw should not be discounted either. 10" saws are 3-4x cheaper out here on CL. As material price goes up, the push through looks more and more attractive.
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Post by stardiamond on Aug 2, 2014 18:04:20 GMT -5
I guess I should kick myself for throwing one away. I bought something like a Highland Park or the like saw from someone on another rock board. It was suppose to be 10" but was actually a 8" saw with a 9" blade. I had it mounted on a board and used a motor from some other lapidary equipment I was no longer using. It was gravity feed and had a regular rock saw blade not like the kind I use now. It was slow and didn't cut very well. It did have a vice. If I still had it I could use a mk303 blade and push through.
My genie saw cuts with water but has no guide or vice and I have to slab freehand. Sometimes I get nice even slabs and sometime I don't. The saw I tossed would be another alternative.
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Post by Deleted on Aug 2, 2014 18:35:44 GMT -5
So here is my question/suggestion.. and seeing how my hands are no longer able to hold these smaller caps etc.. I've found ways around this.. thou your stones are rather large.. One might get away with doping the stones with several dop sticks on different locations of the stones.. thus allowing the freedom to move and cut at whatever angle.
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The Dad_Ohs
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Post by The Dad_Ohs on Aug 2, 2014 19:38:53 GMT -5
dopping does not work very well and can be disastrous to the stone and the person cutting when it pops off the dop stick!!
And it will pop off.... the vibration combined with liquid will cause the stone to release and may get thrown, at worst, or destroy the blade, at least. I would never dop anything I was going to run through a saw. you can glue it to a piece of wood using an epoxy , I use Elmer's Wood Glue Max and let it sit for 24 hours b4 I try to pull it off the board, if it stays on I will cut it.
When I use my trim saw to cut small slabs I hols the pieces in my hand as you cannot cut yourself on a diamond blade unless there is a piece of metal sticking out of it. I also have a piece of 2x4 1/4" away from the front of the blade to act as a guide so all my cuts are about the same thickness.
Cutting rough on a large saw should never be faster than 5 minutes/inch, so if you cut a 2 inch thick stone on your trim saw in less than 7 minutes you are probably going too fast. I kept a battery operated clock next to my sw to help me adjust my pressure when I cut. Now I can tell when I push too hard by the sound of the saw and the pressure of the rock against my hand.... I still check the clock from time ti time too!!lol!
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Post by stardiamond on Aug 2, 2014 20:38:53 GMT -5
I got started cabbing when I got some used equipment from a local lapidary/knapper. I got my Star Diamond machine with two worn Galaxy wheels, a belt sander and a trim saw. The trim saw was slow and was cooled using a wet sponge. When I got my Genie they were just about giving away the trim saw attachment. It cut slabs faster than cutting wood on a jigsaw. There is no resistance or sound. It just goes right through quickly. Small rough cuts rather quickly and the only consequence is blade wear.
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Post by stardiamond on Aug 3, 2014 13:30:06 GMT -5
dopping does not work very well and can be disastrous to the stone and the person cutting when it pops off the dop stick!! And it will pop off.... the vibration combined with liquid will cause the stone to release and may get thrown, at worst, or destroy the blade, at least. I would never dop anything I was going to run through a saw. you can glue it to a piece of wood using an epoxy , I use Elmer's Wood Glue Max and let it sit for 24 hours b4 I try to pull it off the board, if it stays on I will cut it. When I use my trim saw to cut small slabs I hols the pieces in my hand as you cannot cut yourself on a diamond blade unless there is a piece of metal sticking out of it. I also have a piece of 2x4 1/4" away from the front of the blade to act as a guide so all my cuts are about the same thickness. Cutting rough on a large saw should never be faster than 5 minutes/inch, so if you cut a 2 inch thick stone on your trim saw in less than 7 minutes you are probably going too fast. I kept a battery operated clock next to my sw to help me adjust my pressure when I cut. Now I can tell when I push too hard by the sound of the saw and the pressure of the rock against my hand.... I still check the clock from time ti time too!!lol! I hate dopping. I have memories being burned by dop wax and the dops keep coming off. The tape in the picture below was recommended and I made some dop sticks. On the other hand, if I work thinner slabs, my fingers take a beating. The good thing about the tape, is it warns you when it is about to come off. It start to get loose rather than coming off suddenly.  |
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Post by stardiamond on Aug 3, 2014 14:09:46 GMT -5
I posted on this thread about two types of ebay slab buyers, slab collectors and cabbers. I got both of these Blue Mountain slabs very cheap. The one on the left is twice as big as the one on the right. The left one has a fracture so it turned off the slab collectors and the pattern is too big so it didn't attract cabbers. The seller usually gets premium prices for their auctions. I bought it because it was Blue Mountain and the cabs might attract someone. The piece was big enough that I could create some moderately interesting scenes. The one on the right has smaller more interesting scenes, is dark and I would need to work around the fracture. I optimistically thought I could get one or two interesting cabs from it.  |
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Post by Deleted on Aug 3, 2014 18:25:17 GMT -5
@the Dad_Ohs I understand the whole principle of cutting just never attempted doing any because of my hands.. Thou I fell it the saw was more of a shaping wheel where I could rest the stone and my arms on a stand and simply turn or rotate (while on a flat surface) the stone to remove the rough or sharp edges. I would suspect this is one means or form of capping..
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Post by johnjsgems on Aug 4, 2014 12:28:05 GMT -5
"8" saw with 9" blade" was likely one of the old 9" Highland Park saws. Very common back in the day. Most people run 8" blades in them as the only 9" blade available is really thick. The Genie saw is labeled as "trim saw only, not for slabbing" by the way.
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The Dad_Ohs
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Post by The Dad_Ohs on Aug 4, 2014 18:04:07 GMT -5
@the Dad_Ohs I understand the whole principle of cutting just never attempted doing any because of my hands.. Thou I fell it the saw was more of a shaping wheel where I could rest the stone and my arms on a stand and simply turn or rotate (while on a flat surface) the stone to remove the rough or sharp edges. I would suspect this is one means or form of capping.. sounds like one of the older craftsmen units where the shaping wheel was used as a saw too, the wheel sat flat and if you wanted to cut sometrhing you laid it flat and cut across. |
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