|
Post by Jugglerguy on Jan 21, 2013 14:41:37 GMT -5
I'm trying to make circular cabs to fit inside magnetic necklaces my daughter and wife have. They're called "Magnabilities" and have cheap little inserts. I'm trying to make stone inserts on my ancient flat lap. I've made very few cabs and it's pretty slow going because I'm using S.C. laps. I'm going to upgrade to diamond one of these days, but it's a little too close to my latest Rock Shed order to make that order now. I'm having trouble making the cabs the correct size or shape. Here are some of my attempts: The first problem is that I don't have a template the correct size. I attempted to trace the inserts that came with my daughter's necklace, but it's rounded on the bottom and it's difficult to hold the pen perfectly vertically. I bought a set of the Lortone templates, but none are the correct size. I drilled a hole in a board, but I didn't have the exact size bit. Does anyone know where to get a template that is just a hair smaller than a quarter? Should the template be slightly larger than the finished cab or the exact same size? Does anyone have tips for making the cab perfectly round? I think if I had the right size template, I could use that to check for size and roundness as I worked. What I have been doing is working to my line, then keeping the cab spinning the best I can by hand as I grind it. Any advice is welcome. Thanks, Rob
|
|
|
Post by Pat on Jan 21, 2013 15:05:55 GMT -5
Rob, somewhere on this forum, stoner posted how to make a round cab using a rotary drill. I've never used the Search function successfully on this forum. If you could learn metalsmithing, you wouldn't have to worry about the precise size of the cab to fit the finding. You would make the bezel and plate to fit the cab.
|
|
|
Post by Drummond Island Rocks on Jan 21, 2013 15:21:39 GMT -5
Making calibrated circles is a lot harder than it seems. I have a metric and english set of drafting circle templates and I always grind to be stock safe then very slowly and evenly remove material till its almost fitting on the 100 grit that way I can clean up the fit on the 220 where its a little safer without hogging away too much too easily. The drawer pulls I did recently I just took the existing stock ceramic inserts that I removed and matched them to the proper size on the templates and started there so if you have a purchased insert that fits good I would use that as your guide. If you get a nice snug fit then how do you plan to get the cab out to interchange it if you have no gap to pry it out? here's the templates I was talking about www.staples.com/Staedtler-Mars-Combo-Circle-Template/product_242594Chuck
|
|
|
Post by Jugglerguy on Jan 21, 2013 15:38:46 GMT -5
Those templates look like just the thing I need. I'm headed to Staples as soon as I'm done with this message.
I have managed to make a couple cabs that fit ok. The magnets are smaller than the back of the insert, so if you press down on an edge, they pop right out.
Pat, I know how to search this site using Google. Just type "site:http://forum.rocktumblinghobby.com" before your search term and it searches for that term on only the RTH site. I thought about using a drill to rotate the cab, but I'm not sure i can get the nail I glue on centered perfectly. I'll check out Stoner's post.
Thanks!
|
|
NDK
Cave Dweller
Member since January 2009
Posts: 9,440
|
Post by NDK on Jan 21, 2013 15:51:01 GMT -5
Rob, do you have a compass? Draw your own circle. Thanks for the cheat on how to search this site. The search on here is terrible!
Nate
|
|
|
Post by Jugglerguy on Jan 21, 2013 16:05:13 GMT -5
Yep, I have a compass. The problem is, a compass doesn't help check your progress along the way. I just got back from Staples and the template Chuck suggested has a hole the exact size I need.
|
|
|
Post by Drummond Island Rocks on Jan 21, 2013 16:16:07 GMT -5
Cool idea by the way. I used these same pendant bases before but I epoxied the stones in, never thought about magnets at the time but I see they are all over etsy now with fancy glass and ceramic style inserts.
Chuck
|
|
QuailRiver
fully equipped rock polisher
Member since May 2008
Posts: 1,635
|
Post by QuailRiver on Jan 21, 2013 18:39:45 GMT -5
Rob, are you marking your circle on the back side, or top side of the cab? It's always easier to keep the correct shape if you mark your shape on the back side of the stone and preform to the marked line allowing just a hair thickness extra for the stock that will be removed when sanding. It's nearly impossible to keep a stone the correct size and shape if it has been marked on the top surface.
|
|
|
Post by Jugglerguy on Jan 21, 2013 19:28:55 GMT -5
Nope, I was marking the front. I had no idea that was the wrong way to do it. My line disappears as soon as I start doming the top. Marking the back will make it harder to get the exact part of the rock I want in my circle, since my rocks are opaque.
Thanks for the tip!
|
|
Geoff
spending too much on rocks
Please add 1074 to my post number.
Member since December 2012
Posts: 446
|
Post by Geoff on Jan 21, 2013 19:51:11 GMT -5
Making calibrated circles is a lot harder than it seems. No it isn't :-p I mass produce circles with a 1.125 inch diamond core. Cab-o-John the top, throw em in the vibe.
|
|
|
Post by Jugglerguy on Jan 21, 2013 19:58:50 GMT -5
Wow, that's a lot of circles. I've seen pictures of your bottle caps on here before, but I forgot all about them today. I don't have a drill press yet, but it's on my list. I have a few questions about the core drill:
Is the diameter measurement of the drill the diameter of the circle it makes or the hole it leaves? About how long does it take to drill through a 1/4 inch rock? How long does the bit last? Where do you get your bits?
|
|
Geoff
spending too much on rocks
Please add 1074 to my post number.
Member since December 2012
Posts: 446
|
Post by Geoff on Jan 21, 2013 20:22:15 GMT -5
They are sold by outside diameter usually. I actually cut my first 25 or so with a cordless drill and a plastic bin with a half inch of water. With the drill press it takes ~45 seconds for agate, ~30 seconds for "rocks", and 5 seconds for calcite or epidote. The worst is Brazilian agates. Damn things might as well be Kryptonite! I'm still on my first bit. Been through over 100 slabs. It's slowing down, but it just needs dressed. According to the manufacturer, I should expect 300+ circles. These are pretty high end though. www.ukam.com/thinwall_diamond_drills.htm You can get cheaper ones from many lapidary shops. Kingsley has some for ~$50 I think.
|
|
|
Post by Jugglerguy on Jan 21, 2013 20:47:11 GMT -5
Thanks Goeff. Your circles do look a lot more circular than my circle wannabes.
|
|
NDK
Cave Dweller
Member since January 2009
Posts: 9,440
|
Post by NDK on Jan 21, 2013 21:04:45 GMT -5
Yep, I have a compass. The problem is, a compass doesn't help check your progress along the way. I just got back from Staples and the template Chuck suggested has a hole the exact size I need. I thought the circle would be drawn on plastic (milk jug or similar) to make a template. I suppose circles are somewhat difficult to cut out too though. To check the progress, just eyeball it up on the finding. Good to hear you found the template you needed. Let's see the progress, I like the look of those settings. Nate
|
|
drjo
fully equipped rock polisher
Honduran Opal & DIY Nut
Member since May 2008
Posts: 1,581
|
Post by drjo on Jan 21, 2013 21:48:36 GMT -5
You could just cut the backing out of one of the findings. DrJoe
|
|
|
Post by stonesthatrock on Jan 22, 2013 9:44:13 GMT -5
ralph also uses the hole saw diamond bit to make circles, its his favorite thing to cut out
|
|