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Post by rockjunquie on Dec 29, 2017 10:42:16 GMT -5
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Post by MsAli on Dec 29, 2017 10:52:47 GMT -5
I want to know what everyone thinks as well
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kevin24018
spending too much on rocks
Member since February 2012
Posts: 284
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Post by kevin24018 on Dec 29, 2017 11:23:15 GMT -5
I would say at some point before the final stages, once you can tell what the end shape will be seems like a good point to drill. The coarse steps might enlarge or misshape the hole depending on the hardness of the stone etc. In the end you want the hole to be blended and shiny as the rest or at the very least so you don't notice it. My initial thoughts would be to drill before the last 2 stages generally, but it may require experimentation.
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Post by MsAli on Dec 29, 2017 11:30:08 GMT -5
I would say at some point before the final stages, once you can tell what the end shape will be seems like a good point to drill. The coarse steps might enlarge or misshape the hole depending on the hardness of the stone etc. In the end you want the hole to be blended and shiny as the rest or at the very least so you don't notice it. My initial thoughts would be to drill before the last 2 stages generally, but it may require experimentation. This was my thought as well. I am going to drill a few before the polish stage......I would also think that if I drilled before the last 2 stages the rock might break down at the drill point and be lost completley?
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kevin24018
spending too much on rocks
Member since February 2012
Posts: 284
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Post by kevin24018 on Dec 29, 2017 11:57:28 GMT -5
I would say at some point before the final stages, once you can tell what the end shape will be seems like a good point to drill. The coarse steps might enlarge or misshape the hole depending on the hardness of the stone etc. In the end you want the hole to be blended and shiny as the rest or at the very least so you don't notice it. My initial thoughts would be to drill before the last 2 stages generally, but it may require experimentation. This was my thought as well. I am going to drill a few before the polish stage......I would also think that if I drilled before the last 2 stages the rock might break down at the drill point and be lost completley? I see that as a potential concern as well, especially in a rotary tumbler, how close to the edge you drill it, several variables.
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fvpty
noticing nice landscape pebbles
Member since July 2017
Posts: 95
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Post by fvpty on Dec 29, 2017 12:33:48 GMT -5
I drill before but I always pray on the drilling process some have break when everythin is all ready done ! 😓
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Roger
fully equipped rock polisher
Member since January 2013
Posts: 1,487
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Post by Roger on Dec 29, 2017 12:43:57 GMT -5
rockjunquie - I always drill after I cut the rough shape with the trim saw and before I start grinding the preform. If the stone cleaves or fractures, I want it to happen before I spend any real time on it. I don't use tumblers or vibes anywhere in my cabbing so I don't need to worry about a stone breaking that way. After I drill; I grind the preform to shape and make any adjustments needed if I missed my mark for the hole. Next I grind bottom of the cab to prep it for polishing. After the bottom is prepped I start grinding the cab dome and girdle. If it doesn't break in the first three steps, it probably won't break at all.
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Post by rockjunquie on Dec 29, 2017 12:49:24 GMT -5
rockjunquie - I always drill after I cut the rough shape with the trim saw and before I start grinding the preform. If the stone cleaves or fractures, I want it to happen before I spend any real time on it. I don't use tumblers or vibes anywhere in my cabbing so I don't need to worry about a stone breaking that way. After I drill; I grind the preform to shape and make any adjustments needed if I missed my mark for the hole. Next I grind bottom of the cab to prep it for polishing. After the bottom is prepped I start grinding the cab dome and girdle. If it doesn't break in the first three steps, it probably won't break at all. I was thinking along the same lines. I ordered some diamond bits and will give it a shot after I get them. I'll post them when I get them done. I was thinking it would be way easier to drill a hole on a flat surface like the preform.
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Tommy
Administrator
Member since January 2013
Posts: 12,652
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Post by Tommy on Dec 29, 2017 14:29:35 GMT -5
Background information: I typically just drill flats that I've VIBE tumbled for gifts - if the tumbling is nice and the drilling is successful I will sell them as pendants. Once in a while I will drill a hand made cabochon if I've tried unsuccessfully to sell it as a cab. Not my favorite thing to do because starting a hole on the slope of a dome is problematic.
With that in mind I tried drilling *before* tumbling, and I also tried drilling at the middle steps of tumbling and I stopped both for a variety of reasons. First and most annoying is almost without fail the holes become so impacted with debris that it can't be picked out and has to be drilled out which screws the hole up because the debris is never symmetrical with the hole.
(Edited to add: AND the impacted holes have to be cleaned at every grit step or it becomes a potential carrier of lower grit - multiply that by 20-30 drilled stones in a batch - it's a real pain in the patootie)
Secondly and most importantly I found that I was wasting a lot of time (and expensive drill bits) drilling stones perfectly then having to throw them away in the "island of lost cabs" jar because the tumbling went to hell for whatever reason...cracks, undercutting, broken at the hole, etc. For these reasons I now only drill only when it's finished. I have a diamond burr that I taper the hole with after drilling and so far so good, haven't had any complaints about the hole quality.
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Post by vegasjames on Dec 29, 2017 17:37:34 GMT -5
I would think in part it depends on the tumbler you are using. If a rotaty tumpbler I would say afterward since the rounding of the stone could break the hole. A vibratory tumbler though would not likely break the hole so I would drill before.
If drilling after tumbling I suggesting backing the stone where you are going to drill with a layer of epoxy to prevent a blowout on the back side. Same principle as taping a piece a wood before cutting on the table saw to prevent breakage and splintering on the backside. Same for drilling after cabbing. Then you can just grind off the epoxy, which does not require a lot of pressure and polish.
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grizman
freely admits to licking rocks
Member since July 2011
Posts: 878
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Post by grizman on Dec 29, 2017 17:56:56 GMT -5
rockjunquie - I always drill after I cut the rough shape with the trim saw and before I start grinding the preform. If the stone cleaves or fractures, I want it to happen before I spend any real time on it. I don't use tumblers or vibes anywhere in my cabbing so I don't need to worry about a stone breaking that way. After I drill; I grind the preform to shape and make any adjustments needed if I missed my mark for the hole. Next I grind bottom of the cab to prep it for polishing. After the bottom is prepped I start grinding the cab dome and girdle. If it doesn't break in the first three steps, it probably won't break at all. I was thinking along the same lines. I ordered some diamond bits and will give it a shot after I get them. I'll post them when I get them done. I was thinking it would be way easier to drill a hole on a flat surface like the preform. The other factor to consider is that a polished cab will have a very slick surface...making the start of your drill hole difficult at best. It is still a good idea to start your hole in the unpolished cab with a burr to give the diamond bit a place to get a bite into the stone. Otherwise the bit wants to skate all around.
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cobbledstones
spending too much on rocks
Member since January 2014
Posts: 482
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Post by cobbledstones on Dec 30, 2017 0:38:14 GMT -5
I drill before cabbing because I like to incorporate the hole placement into the cab's design, and it is too hard to get a hole perfectly placed in a finished cab. I drill from the back side of an slightly thick slab, that way any blow-out will be removed in the doming process. If the hole needs to be centered, I even bust out the callipers to check placement. Maybe I am fussy, but a misplaced/offcenter drilled hole really bothers me. I also tumble-finish drilled pieces and haven't had the amount of problems cleaning holes that others have pointed out. I did have some clogged holes once upon a time but that stopped when I switched to ceramic media as my only filler. Clean the holes with compressed air or an old waterpick. easy peasy.
last benefit of the vibe tumbling is that the edges of the hole, where it intersects the face of the pendant, get cleaned up and polished.
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