romo
starting to spend too much on rocks
Member since September 2018
Posts: 104
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Post by romo on Apr 18, 2019 17:41:31 GMT -5
Thank you for starting this! I am also struggling with flat top syndrome and doing flat backs on the wheels along with a host of other things like stabilizers and mixed hardness...the list goes on! Ali, our rock club gives out a 3 page guide with illustrations to all new cabbers, if I can't find mine I'll grab one and upload on Monday. Strictly speaking, you really can not polish a back with a wheel. The center will never polish. UNLESS you rock the stone, but then you won't have a flat bottom anymore. You need to use a flat lap, or settle for a less than perfect polish. If anyone else knows how- then please share. I was always under the understanding that you can't polish a flat with a round wheel. Good to know, guess I'll quit trying, lol! I have used the hand sanding technique for years on Petoskey and always finish the entire piece so was trying to do the same with the cabs. Live and learn! |
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Post by stardiamond on Apr 18, 2019 17:42:32 GMT -5
I've polished a lot of backs and double sided cabs. Your fingers won't like it. At some point the work needs to be done without a dop. If a person uses wax to dop they make be able to remove the wax from a polished face. With superglue that isn't an option. What I do is complete top and sides of the cab, remove the dop sand and polish the bottom. The backside of the cab may have scratches and they show up more when polished I might have to start on a 220 hard wheel. The thicker the cab the less likely I am to grind, sand or polish my fingers. The trickiest part is the polishing wheels. I hold the cab on the edge and slide it on the turning pad and move my fingers to press the cab on the pad and move it the same as when dopped. When I'm done using the pad, I slide the cab toward the outside of the pad and grab with my fingers. I have a lot of practice doing this and haven't lost a cab for a long time. A suction cup on the face might work but a person would have to deal with any defects the cup caused.
I have some laps but with practice a flat back can be ground sanded and polished with wheels. I do a lot of flat top cabs and only use wheel or pads. I can make a lumpy bottom flat also and the work can be checked putting the face on a flat surface. I use a figure eight motion.
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Post by pauls on Apr 18, 2019 17:54:28 GMT -5
Looking at your instruction diagram near the start of the thread.
When I teach cabbing I recommend cutting the first bevel so it goes nearly a third of the way across the top of the cab, so if you look at the top of the cab after you have cut the first bevel going across the cab you will have one third bevel then one third flat spot at the top then one third the other side bevel. Then just take the top ridge off so it almost meets at the centre of the stone. In two cuts you have a pretty good start for a nice even dome.
You can't say use this (whatever) particular angle for your first cut as the angle depends on the height of the dome and the size of the cab, the rule of thirds gets there without worrying what the angle is.
Cut this bevel with the dop stick at right angle to the wheel so you can see the girdle and the bevel angle by looking down and you wont have a problem with girdles or bevels.
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Post by Starguy on Apr 18, 2019 18:28:26 GMT -5
The first bevel needs to go close to the line you draw around the cab’s girdle. The angle only depends on if you like domed or flatter cabs.
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Post by rockjunquie on Apr 18, 2019 18:31:58 GMT -5
Looking at your instruction diagram near the start of the thread. When I teach cabbing I recommend cutting the first bevel so it goes nearly a third of the way across the top of the cab, so if you look at the top of the cab after you have cut the first bevel going across the cab you will have one third bevel then one third flat spot at the top then one third the other side bevel. Then just take the top ridge off so it almost meets at the centre of the stone. In two cuts you have a pretty good start for a nice even dome. You can't say use this (whatever) particular angle for your first cut as the angle depends on the height of the dome and the size of the cab, the rule of thirds gets there without worrying what the angle is. Cut this bevel with the dop stick at right angle to the wheel so you can see the girdle and the bevel angle by looking down and you wont have a problem with girdles or bevels. I lifted that diagram from John Huesler's website. (A master cabber.) He was referring to how a cab should be cut for bezel setting- hence the higher dome. The way you suggest is how I do it. I like a lower dome, So, I don't make as many cuts. But, the same principal applies. You need to make cuts to almost meet in the middle- well sometimes they do meet, if the stone is thick yet not very wide. It was a visual aid for cutting angles towards the center. |
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Post by rockjunquie on Apr 18, 2019 18:34:12 GMT -5
I've polished a lot of backs and double sided cabs. Your fingers won't like it. At some point the work needs to be done without a dop. If a person uses wax to dop they make be able to remove the wax from a polished face. With superglue that isn't an option. What I do is complete top and sides of the cab, remove the dop sand and polish the bottom. The backside of the cab may have scratches and they show up more when polished I might have to start on a 220 hard wheel. The thicker the cab the less likely I am to grind, sand or polish my fingers. The trickiest part is the polishing wheels. I hold the cab on the edge and slide it on the turning pad and move my fingers to press the cab on the pad and move it the same as when dopped. When I'm done using the pad, I slide the cab toward the outside of the pad and grab with my fingers. I have a lot of practice doing this and haven't lost a cab for a long time. A suction cup on the face might work but a person would have to deal with any defects the cup caused. I have some laps but with practice a flat back can be ground sanded and polished with wheels. I do a lot of flat top cabs and only use wheel or pads. I can make a lumpy bottom flat also and the work can be checked putting the face on a flat surface. I use a figure eight motion. I have tried to polish the backs on the 600. I can handle the stone just fine, but the center is never polished like the rest of the cab. |
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Post by Starguy on Apr 18, 2019 18:38:02 GMT -5
When I make the first bevel I check that the flat spot in the middle is the same shape as the preform only smaller. Same with the second bevel. The third bevel is essentially forming the dome.
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Post by rockjunquie on Apr 18, 2019 18:39:46 GMT -5
When I make the first bevel I check that the flat spot in the middle is the same shape as the preform only smaller. Same with the second bevel. The third bevel is essentially forming the dome. Aha! Great tip! I hadn't even thought of that, but you're right.  |
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Post by stardiamond on Apr 18, 2019 18:42:43 GMT -5
I've polished a lot of backs and double sided cabs. Your fingers won't like it. At some point the work needs to be done without a dop. If a person uses wax to dop they make be able to remove the wax from a polished face. With superglue that isn't an option. What I do is complete top and sides of the cab, remove the dop sand and polish the bottom. The backside of the cab may have scratches and they show up more when polished I might have to start on a 220 hard wheel. The thicker the cab the less likely I am to grind, sand or polish my fingers. The trickiest part is the polishing wheels. I hold the cab on the edge and slide it on the turning pad and move my fingers to press the cab on the pad and move it the same as when dopped. When I'm done using the pad, I slide the cab toward the outside of the pad and grab with my fingers. I have a lot of practice doing this and haven't lost a cab for a long time. A suction cup on the face might work but a person would have to deal with any defects the cup caused. I have some laps but with practice a flat back can be ground sanded and polished with wheels. I do a lot of flat top cabs and only use wheel or pads. I can make a lumpy bottom flat also and the work can be checked putting the face on a flat surface. I use a figure eight motion. I have tried to polish the backs on the 600. I can handle the stone just fine, but the center is never polished like the rest of the cab. Figure eight motion, otherwise the middle is missed. |
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Post by Starguy on Apr 18, 2019 19:22:34 GMT -5
I have tried to polish the backs on the 600. I can handle the stone just fine, but the center is never polished like the rest of the cab. Figure eight motion, otherwise the middle is missed. The biggest mistake I see on new people’s cabs is a flat center with rounded sides. It’s easy to do because it is quick. You need a dome. I tend to take a pretty flat angle on my first bevel. I’m guessing my first bevel is around 30 degrees from the bottom of the cab. The second and third bevels are much flatter. Stock removal with the 80 grit wheel is important. It saves time and money. You don’t want to make corrections with finer wheels. It really sets you up for the cab you want. |
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Post by rockjunquie on Apr 18, 2019 19:38:13 GMT -5
Figure eight motion, otherwise the middle is missed. The biggest mistake I see on new people’s cabs is a flat center with rounded sides. It’s easy to do because it is quick. You need a dome. I tend to take a pretty flat angle on my first bevel. I’m guessing my first bevel is around 30 degrees from the bottom of the cab. The second and third bevels are much flatter. Stock removal with the 80 grit wheel is important. It saves time and money. You don’t want to make corrections with finer wheels. It really sets you up for the cab you want. I agree, but the quote was referring to doing the backs. I'm still not so sure it can be done- by me, at least. |
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Post by stardiamond on Apr 18, 2019 20:07:53 GMT -5
I had a one hour cabbing lesson including using dop wax, grinding, sanding polishing. I bought a pamphlet with a diagram similar to posted on this topic. I'm basically self taught and that may part of the reason I have trouble with girdles. My process is.
1. Rough shape with trim saw.
2. Follow the shape on the bottom leaving a little extra outside the lines 80 hard through 220 soft.
3. Mark the girdle and center lines.
4. Grind from above the girdle line toward the center line with 80 grit repeating the process moving toward the girdle line and up to the center line.
5. Grind down from the center line toward the girdle line getting the dome even.
6. Refine the dome and work toward the girdle line with the 220 hard.
7. Grind from the girdle line toward the center line with the 220 soft.
8. When I am satisfied with the dome and the girdle line is reached, I rotate the cab and remove the excess material outside the line on the bottom.
9. I sand from the girdle line to the center line with the 600 and 1200 grit. I make sure the dome is completely sanded and then rotate and sand the girdle line.
This approach worked reasonably well on the girdles with and without a dop. A couple of problems with the girdle may be attributable to having dop sticks that are too long so they get too close to the adjacent wheel. I made the dop sticks and the dops are not 90 degrees to the face of the cab.I 'm going to cut and try to square the dops. I have bad feet and when my feet aren't steady it impacts my hands. I have trouble keeping the dop aligned and even pressure as I rotate the cab with the dop.
I try to stay away from touching the girdle line until the 220 soft because material can be subtracted but not added without lowering the gridle line. I went past the girdle line with the 80 grit when I started cabbing.
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Post by pauls on Apr 18, 2019 20:59:56 GMT -5
The absolute best way to do backs is to get very manual with them. No machinery at all until polish.
Get a piece of flat steel plate reasonably thick so it doesn't flex, you should be able to pick something to do the job at a sheetmetal shop for free, you only need a smallish scrap, several for different grits is even better.
Put loose tumbling grits in salt shakers or spice bottles, and you will need a squirty bottle of water.
Sprinkle a small amount of coarse grit on the steel plate with a squirt of water then just rub the back of your cab on it around in circles and figure eights until all saw marks are gone and the surface is a nice even matt finish. Wash everything thoroughly then do the same with 220 600 1000 grits. wash thoroughly again and take to your polish wheel, you will need to use the very edge of the buff to get into the middle of the flat.
While this seems like a lot of bother and frankly pretty old hat it works and does so very quickly. really only a few minutes to get a back done.
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Post by parfive on Apr 18, 2019 21:25:04 GMT -5
Polishing backs is so easy it’s pathetic.
• cut preform and ease back edge.
• lap the back perfectly flat on glass to 500. It’s small, only takes a couple of minutes.
• dop it, cut and polish the cab.
• take it off the dop and polish the back on the wheels – 1200, 3k, 14k, done in a minute. Two at the most.
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gemfeller
Cave Dweller 
Member since June 2011
Posts: 4,064 
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Post by gemfeller on Apr 18, 2019 21:54:46 GMT -5
Now you mention it rockjunquie, what IS the correct angle for girdles? I've done silversmithing for years and I habitually cut angles I know I can bezel or prong set, even the ones with low spots. But is there a sweet medium angle to satisfy both smiths and wire wrappers? FYI, I cut my girdles the same way you do: by eye. I can do most of them freehand but occasionally dopping is necessary. |
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Post by rockjunquie on Apr 18, 2019 22:16:25 GMT -5
Now you mention it rockjunquie , what IS the correct angle for girdles? I've done silversmithing for years and I habitually cut angles I know I can bezel or prong set, even the ones with low spots. But is there a sweet medium angle to satisfy both smiths and wire wrappers? FYI, I cut my girdles the same way you do: by eye. I can do most of them freehand but occasionally dopping is necessary. That's a good question. I have seen anywhere from 10 to 20 degrees. I think Pat knows the "official" number. I shoot for about 12-15. As for wrapping, it seems most wrappers prefer it straight up and down. I don't care either way. They do like them thinner, too. |
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Post by rockjunquie on Apr 18, 2019 22:25:14 GMT -5
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Post by rockjunquie on Apr 18, 2019 22:25:54 GMT -5
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Post by Pat on Apr 18, 2019 22:35:44 GMT -5
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gemfeller
Cave Dweller
Member since June 2011
Posts: 4,064
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Post by gemfeller on Apr 18, 2019 23:55:06 GMT -5
rockjunquie and Pat , The controversy over bezel angles reminds me of the old joke about a young man who asked Abraham Lincoln how long a man's legs ought to be. "Long enough to reach the ground, son" Lincoln replied. Men's and women's legs come in a wide variety of lengths and so do opinions about bezel angle.
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