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My five year old is obsessed with dinosaurs (thanks to Dino Dana I'm pretty sure he knows more about them than I do) and earlier this year when we went to a rock show I allowed him to pick out a couple of rocks. He picked out a few coprolite slabs. I decided to polish them as stocking stuffers for Christmas.
I don't have a flat lap so I used a method I read about on Reddit of coating the outside with hot glue then ran it through all the steps in the Lot-O. It turned out really good. I didn't think the saw marks were very visible until after it was polished. They're not super bad, but definitely noticeable at the right angle.
The second slab has much more visible saw marks. I have been trying to use some coarse sandpaper and manually sand them down... omg this is such a pain. I totally understand now why people don't do this. After sanding for about an hour while watching Youtube... the saw marks are about 75% gone. I tried running this one through the Lot-O but the hot glue kept popping off after about 30 minutes. I was thinking about manually sanding the saw marks off with coarse and then smoothing it out with some finer sandpaper and then just running the slab only through polish in the Lot-O. Getting these saw marks off though is taking so long...
Last Edit: Dec 15, 2022 9:14:13 GMT -5 by waterboysh
Post by rockjunquie on Dec 15, 2022 9:40:41 GMT -5
I remember when my son went through the dinosaur stage oh so many years ago. It wasn't popular at the time and was difficult to keep him in Dino swag. He would have loved that polished turd! Your son is gonna freak!
The video sure looks good. Interesting that you used hot glue.
You have a lot more patience than I do...that's for sure!! Don't worry...you've got another 10 days before Santa needs to drop that deuce in the stocking! (I couldn't help myself! LOL)
Favorite Quotes: "It always seems impossible until it is done." - Nelson Mandela "Life becomes easier when you learn to accept the apology you never got." - Robert Brault "You can't wait until life isn't hard anymore before you decide to be happy." - Nightbirde (RIP 2/19/22)
I tried the sanding by hand route on coprolite slabs at one point and quickly gave up. I bought a cheap set of diamond polishing pads and used them with a random orbital sander and life was much better after that. It still took some time to get the saw marks out on the coarsest grit, but once you get the marks out the rest of the grits go very quickly.
For the hot glue, did you reapply the hot glue after each stage? I would be a little concerned about trapped grit. If you only run them in the polishing stage, then it wouldn’t matter.
I tried the sanding by hand route on coprolite slabs at one point and quickly gave up. I bought a cheap set of diamond polishing pads and used them with a random orbital sander and life was much better after that. It still took some time to get the saw marks out on the coarsest grit, but once you get the marks out the rest of the grits go very quickly.
For the hot glue, did you reapply the hot glue after each stage? I would be a little concerned about trapped grit. If you only run them in the polishing stage, then it wouldn’t matter.
I don't have any tools other than my tumblers so I don't usually have slabs to deal with.
I did not reapply the hot glue after each stage. I suspect that even if a little grit does end up between the glue and the rock that it just stays there since it's only running moist and not wet if you know what I mean. There's nothing that will pull the grit back out once it's in. In fact, I'm pretty sure some grit did get in there because I think the back came out slightly more shiny then before I put it in. I didn't think to take pictures before applying the hot glue though.
I tried the sanding by hand route on coprolite slabs at one point and quickly gave up. I bought a cheap set of diamond polishing pads and used them with a random orbital sander and life was much better after that. It still took some time to get the saw marks out on the coarsest grit, but once you get the marks out the rest of the grits go very quickly.
For the hot glue, did you reapply the hot glue after each stage? I would be a little concerned about trapped grit. If you only run them in the polishing stage, then it wouldn’t matter.
I don't have any tools other than my tumblers so I don't usually have slabs to deal with.
I did not reapply the hot glue after each stage. I suspect that even if a little grit does end up between the glue and the rock that it just stays there since it's only running moist and not wet if you know what I mean. There's nothing that will pull the grit back out once it's in. In fact, I'm pretty sure some grit did get in there because I think the back came out slightly more shiny then before I put it in. I didn't think to take pictures before applying the hot glue though.
I've tumbled faced pieces like this in my vibe...but I have a UV-18. I don't know if this would fit in the Lot-O...but if it will, that's an option. If if does, you'd just have to make sure the rough side is cleaned up from grit and slurry before moving it to the next stage...
Favorite Quotes: "It always seems impossible until it is done." - Nelson Mandela "Life becomes easier when you learn to accept the apology you never got." - Robert Brault "You can't wait until life isn't hard anymore before you decide to be happy." - Nightbirde (RIP 2/19/22)
The result looks nice. Just curious: why didn't you do step 1 grinding in a rotary? The flat side would still be pretty flat with slightly rounded edges. I tried removing some marks on some agates by hand or by a nail polisher and gave up easily.
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