mikeinsjc
spending too much on rocks
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Member since June 2010
Posts: 329
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Post by mikeinsjc on Apr 19, 2012 10:47:03 GMT -5
I was curious what techniques you folks use to weigh down thin slabs for polishing. I have attached big lead fishing weights to the back of slabs with silicone, but they either vibrate loose, or, if you use enough cement to hold them through the cycle, are a real booger to get off. Feel like I'm missing something here.
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Post by jakesrocks on Apr 19, 2012 11:35:08 GMT -5
Try using dop wax. When it's time to take the weights off, just pop them in the freezer for a few minutes. Be sure your slabs are clean and oil free before using dop wax, or any other method.
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Post by catmandewe on Apr 19, 2012 11:38:54 GMT -5
I have heard silly putty works. Have not tried it yet but plan to.
Tony
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Post by gr on Apr 19, 2012 11:58:08 GMT -5
For the unusal dome shapes, I use plastic baggies with lead fishing sinkers.
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rykk
spending too much on rocks
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Member since September 2011
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Post by rykk on Apr 19, 2012 14:33:47 GMT -5
I use good ol' Duct Tape to attach weights to my slabs and end cut nodules. Works great and they stay on for as long as you need them to 99.9% of the time and even in a bucket of water. Back when I was getting a little lazy about contamination, it wasn't uncommon for me to tape a weight rock (can't find any lead) to a slab or nodule and just leave it on thru all 3 grind phases in my vibe lap, 120/220/500-600. Using rocks for weights, you pretty much have a weight-rock that's selected for it's size and shape to match up well with the rock you're polishing.
Here's what I do: 1) First, I wrap the weight with a half-wide strip of duct tape. This gives a good surface to stick to. Duct tape LOVES to stick to itself! If someone is using rocks for weights, like me, I suggest completely covering the weight-rock. This will keep any bits that might chip off when it bangs against some other rock from getting into the pan slurry and prevent the (imho) #1 cause of those dang corkscrew "squiggly" scratches.
2) Then, use 1/2 wide strips of duct tape to wrap around the edges of the slab at least twice. I usually will put a third strip on with part of it folded over to make a double wide strip.
3) Take yet another strip of tape and cover the top of the slab or at least a 1/2 wide one. This serves 2 purposes. First, it provides a great surface to stick to and, secondly, will serve to protect the top of the slab from getting dinged if someone is using weight-rocks that might not be flat and have some edges or projections sticking out on the surface that is attached to the slab.
4) Then take a strip of duct tape and roll it over some on each end and stick the side that is sticky between the two ends to the bottom of the lead weight or weight-rock and place it onto the slab or nodule in whatever position evens out the weight applied to the top of the slab. Sometimes you might have a nodule or end cut that is markedly thinner/lighter on one end/side and so you might want to add extra weight there so that the rock grinds level/flat. Occasionally - actually often from some rock sellers - you might have a rock where the saw blade wasn't shimmed properly or maybe too small of a flange and there's a sorta low "step up" on one end of a slab. Or maybe it got there from lapping off the groove that always precedes that dang "nub" that many sellers leave on their slabs when they sell them. I've had good results from adding extra weight to that end of the slab for one 120grit grind, then taking it off after that.
5) And lastly, wrap duct tape around the slab/weight assembly to cover the gap between the weight-rock or lead weight and the slab/end-cut. This adds even more sticky stability to the rock and you have no idea how much grit/polish can get wasted when it splashes into the gap and is trapped atop the the slab. If it's set up so that there is a "downhill" slant to the last wrap of tape and it is fairly smooth and unwrinkled, what little grit/polish that does stick can just be squirted back into the pan with a spray bottle every now and then during the grind.
c-ya, Rick
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kevin24018
spending too much on rocks
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Member since February 2012
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Post by kevin24018 on Apr 19, 2012 15:35:58 GMT -5
lots of times you can get lead weights for free from a garage that balances and rotates tires etc.
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isellwood
starting to spend too much on rocks
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Post by isellwood on Apr 19, 2012 20:37:50 GMT -5
I bought a block of lead from the plumbing store, cut it into aprox 1' chunks and used plumbers putty to stick it to the slabs. Pat
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snuffy
Cave Dweller
Member since May 2009
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Post by snuffy on Apr 19, 2012 20:43:34 GMT -5
Good idea.
snuffy
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ulstergeki
starting to spend too much on rocks
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Member since April 2012
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Post by ulstergeki on Apr 27, 2012 18:34:59 GMT -5
i got wheel weights from a garage, melted them down in my casting ladel,(a small cast iron pan would worktoo ) and pulled out the steel, and poured the molten lead into a cast iron muffin pan i got at a thrift store. This will give me uniform shapes and i can vary the thickness for diffrent weights.
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