agatewhisperer
freely admits to licking rocks
Member since May 2020
Posts: 836
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Post by agatewhisperer on Sept 2, 2024 18:56:45 GMT -5
I need some ideas. I need to make a bunch of circle cabs and would like ideas on a jig or tools to assist with this. I went through this last April and needed to make around 20 small circle cabs, and thought using a drill with the rock attached to a nail would work great... But it was more trouble than it was worth. The nails were all a little crooked and the drill got pretty wet which wasn't great. What else could I use instead? I ended up making the other half by hand and I think it took about the same amount of time. Any ideas would be appreciated. Pictures even better 😀 Here's what I ended up with, which worked well for the purpose but I'd like an easier way to crank these out.  |
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realrockhound
Cave Dweller 
Chucking leaverite at tweekers
Member since June 2020
Posts: 4,538
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Post by realrockhound on Sept 2, 2024 19:15:56 GMT -5
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Post by Pat on Sept 2, 2024 19:31:17 GMT -5
stoner used the drill bit in the drill to actually shape the cab on the Genie. I don’t remember, but he must have used a diamond core drill.
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realrockhound
Cave Dweller
Chucking leaverite at tweekers
Member since June 2020
Posts: 4,538
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Post by realrockhound on Sept 2, 2024 19:44:05 GMT -5
stoner used the drill bit in the drill to actually shape the cab on the Genie. I don’t remember, but he must have used a diamond core drill. Thats what I’m essentially saying. Diamond core it. Then I say use the same method in the drill once on dop. Just need to find something straighter than the nails for symmetry. |
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dshanpnw
fully equipped rock polisher
Member since December 2020
Posts: 1,173
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Post by dshanpnw on Sept 2, 2024 20:24:37 GMT -5
It'll be nice if get something figured out, but in the meantime those rounds are looking great!
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agatewhisperer
freely admits to licking rocks
Member since May 2020
Posts: 836
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Post by agatewhisperer on Sept 2, 2024 22:48:04 GMT -5
stoner used the drill bit in the drill to actually shape the cab on the Genie. I don’t remember, but he must have used a diamond core drill. Thats what I’m essentially saying. Diamond core it. Then I say use the same method in the drill once on dop. Just need to find something straighter than the nails for symmetry. I'm liking the core bit idea. Once I have a bunch of circles, I'll need a way to get the dop perfectly centered... Any ideas? If I have a perfect circle but don't center the dop, that would make things challenging getting a nice even dome. |
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realrockhound
Cave Dweller
Chucking leaverite at tweekers
Member since June 2020
Posts: 4,538
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Post by realrockhound on Sept 2, 2024 22:58:29 GMT -5
Thats what I’m essentially saying. Diamond core it. Then I say use the same method in the drill once on dop. Just need to find something straighter than the nails for symmetry. I'm liking the core bit idea. Once I have a bunch of circles, I'll need a way to get the dop perfectly centered... Any ideas? If I have a perfect circle but don't center the dop, that would make things challenging getting a nice even dome. Id get some metal dowels. Something that won’t bend like a nail and sets perpendicular to the preform once dopped. I’d just draw a cross, across the back of the preform and try to center the dop as close as you could get it. Or get a dowel that almost the same diameter of the stone. That should take a lot of the play out. |
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Post by liveoak on Sept 3, 2024 6:47:23 GMT -5
I've made circles on the cabber.
First I cut the round preform oversize - I found it had to be oversize as it's impossible to dop it exactly on center. Then I dop it on an aluminum dop stick that fits in my flex shaft.
My machinist husband made me a set of aluminum dop sticks, with the tops being sized just under the size cab I need.
I found having the dop stick top being JUST smaller than the cab I need was extra helpful, as you can gauge where you are, and it's stuck down to the dop close to the size & doesn't move.
I've found it best to let it sit overnight dopped before grinding, as the tape sticks better.
You have to use the drill or flexshaft going the opposite rotation.
So on my cabber, the drill is on the left side.
I also use a wood rest on the side of the cabber to support the flexshaft or drill.
I found this helps you from bouncing around.
If you really have to have the same size rounds, I'd also recommend a "go-no go" jig.
Basically, you could use a piece of wood & drill a hole in the wood the exact size you want the cabs, then when you're grinding you can quickly check the size. This really saves a LOT of time (Thanks, Lee !)
Works for me  Patty
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agatewhisperer
freely admits to licking rocks
Member since May 2020
Posts: 836
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Post by agatewhisperer on Sept 3, 2024 10:55:29 GMT -5
I've made circles on the cabber.
First I cut the round preform oversize - I found it had to be oversize as it's impossible to dop it exactly on center. Then I dop it on an aluminum dop stick that fits in my flex shaft.
My machinist husband made me a set of aluminum dop sticks, with the tops being sized just under the size cab I need.
I found having the dop stick top being JUST smaller than the cab I need was extra helpful, as you can gauge where you are, and it's stuck down to the dop close to the size & doesn't move.
I've found it best to let it sit overnight dopped before grinding, as the tape sticks better.
You have to use the drill or flexshaft going the opposite rotation.
So on my cabber, the drill is on the left side.
I also use a wood rest on the side of the cabber to support the flexshaft or drill.
I found this helps you from bouncing around.
If you really have to have the same size rounds, I'd also recommend a "go-no go" jig.
Basically, you could use a piece of wood & drill a hole in the wood the exact size you want the cabs, then when you're grinding you can quickly check the size. This really saves a LOT of time (Thanks, Lee !)
Works for me Patty
Very helpful Patty, thank you! Couple questions come to mind... - once you have the circle, do you finish the cab while it's still on the flex shaft or do you take it off and finish by hand? - what kind of flex shaft tool / hand piece do you use for this? It's one I've been looking to add to my tool list but haven't had a strong reason yet... - how fast do you run the flex shaft while grinding it down to a perfect circle? It seems like a nice thing about your method is that when you're done making the preform, it's already perfectly centered on the dop stick. Oh yeah... And how could I find a husband to make some dop sticks?? 🤣 Thanks! |
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Post by liveoak on Sept 3, 2024 11:20:59 GMT -5
My flex-shaft is a Foredom Industrial version (we got used a number of years ago) that takes collets - the collets allow you to use a larger "bit" (or in my case a 1/4" stick).
Some flex-shafts, like the one on my jewelers bench (cheaper, no name) doesn't take as large of a bit. And I think the 1/4" stick works well.
The 1/4" stick was made from a long sawed off 1/4" bolt & the tops of the stick were made from drilling/threading, & cutting off the end of an aluminum bar, in a lathe.
But maybe you can improvise. I suppose you could try a 1/4" wood dop stick with wax. But starting with an approximately round oversized shape, would help a lot (I have a bandsaw as an advantage there).
I'm certain that people have used a cordless drill to do the same thing.
Speed is a good question - There is a sweet spot, but I couldn't tell you exactly how fast.
I mean a little faster than the wheel, but I couldn't possibly tell you how much, with the variable speed pedal on the flex shaft - but you'd know.
The main thing is to turn the drill, so the cab is rotating opposite, against the direction of the wheel, and also, the rest to hold it all steady, is very important.
That and leaving the tape to "set" overnight. If it's not set enough, it moves & you'll never get it round.
That, and don't put a lot of pressure on it when you're just shaping it.
When I was making them, I HAD to have them an exact size, which is where my gauge came in. If you're just wanting to make a lot of round shapes, the gauge wouldn't be needed.
I've done it both ways, completing the cab all the way in the flex shaft to 3000 OR only on the first 3 wheels and then by hand.
Kind of depends on the stone, my mood, etc. Obviously, you have to keep it on the same dop.
Give it a shot with what you have on hand - there was a little leaning process- it wasn't magic, but once you get it, it can go fast.
Let me know if I can help,
Patty
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agatewhisperer
freely admits to licking rocks
Member since May 2020
Posts: 836
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Post by agatewhisperer on Sept 3, 2024 22:38:53 GMT -5
Thanks liveoak, I'll see what I can get set up. Probably going to try to get some better/straighter dops first since that was a point of frustration. |
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Post by Rockoonz on Sept 4, 2024 17:56:07 GMT -5
I machined a couple centering jigs out of some high density plastic for the specific size of round I cut for wine stoppers, there is maybe .010" variance. They were made for dopping with epoxy, so no relief for the top of the dop. If I ever get the little lathe out I'd like to make a stepped one. A couple degrees of draft and they might be even tighter.
I switched from the rubbery thick picture hanging tape to spectape ST501, it's about as thick as masking tape so it doesn't flex under pressure.
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agatewhisperer
freely admits to licking rocks
Member since May 2020
Posts: 836
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Post by agatewhisperer on Sept 4, 2024 19:20:08 GMT -5
I machined a couple centering jigs out of some high density plastic for the specific size of round I cut for wine stoppers, there is maybe .010" variance. They were made for dopping with epoxy, so no relief for the top of the dop. If I ever get the little lathe out I'd like to make a stepped one. A couple degrees of draft and they might be even tighter. I switched from the rubbery thick picture hanging tape to spectape ST501, it's about as thick as masking tape so it doesn't flex under pressure. Cool! What does a jig like that look like? Sounds like it comes in handy |
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Post by Rockoonz on Sept 4, 2024 22:43:28 GMT -5
I made it for 1/2" dopsticks. I faced both ends of the plastic round bar, drilled and bored a slightly over 1/2" hole through it, then cut about 1/8" deep on one end slightly over the diameter that I get from the diamond hole saw plugs and chamfered the end of the 1/2" hole for a place for the epoxy to squirt out into when I put a little on the end of the dopstick and push it through. The epoxy doesn't stick to plastic so after 5 minuted I can take it out and do another one.
I made 2, I think I know where they are, but with the double stick tape and tee shaped dops they would have to be modified.
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