dirtsifter
Cave Dweller
Co to za kamyczek?
Member since September 2022
Posts: 402
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Post by dirtsifter on Jan 7, 2023 0:36:58 GMT -5
I completed my first full run of all stages coarse to polish in a Lortone QT 12. To say I was disappointed would be an understatement. I'm writing this post to share what I learned, or think I have learned and invite comments.
Out of a barrel load, only a small handful of stones came out of polish with any acceptable "shine" . A few pieces of chert, a moss agate, a few pieces of lace agate, and an interesting translucent yellow/orange stone. The rest look as though they just came out of a 500 grit pre-polish. As a matter of fact, coming out of 500 they actually looked better.
All pieces of amethyst were bruised, fractured or out right broken. Many pieces of lace agate were rough on one side and many broken
Stone types that came out really nice in a 1.5 pound barrel from an old Skilcraft tumbler, looked like they just came out of 120-220 grit.
Personal conclusions: I had in the tumbler what I think was quartzite, quartz, feldspar, granite, and other Lake Ontario beach cobble, with the before mentioned stones sizes ranging from a couple of tennis ball, several golf ball to dime size stones by the time it reached polish stage with the tumbler just over half full with about 500 cc of ceramic media. I think the there was just too much empty space and lack of cushioning for the larger stones that allowed the smaller amethyst , lace agate, etc. to not be beat to death as they are hard stones but not resilient. I also ended up with about a quarter cup of 5 to 8 mm size pieces
Then lack of shine on the others? Lortone suggests a full 20 Tbs (300cc) for a QT12 barrel, but I went with 12 Tbs (180 cc), the 1 Tbs per lb barrel size measurement. Perhaps this was the problem. IDK. Stones moved from pre-polish to polish were washed in between grits with soap and borax run and rinsed well. I did find an odd stone that had many large pits that I somehow missed that moved on to the polish stage without me manually picking out left over grit. May be part of it. I also used generic rocks for fill to get the level up in the barrel that I know will never polish. AND I discovered I had put a few pieces of sandstone in the mix.
What I think I learned: Not in any particular order
1. While it is important to have different size stones in the tumble, to big is to big. Weight from many stones is superior to weight from a few stones.
2. Add sufficient grit to perform the operation in the barrel size used.
3. Run the barrel at least 2/3 full. In the Lortone instructions it does say at least half full, so I'm not completely sure of this.
4. Be more careful of inspecting each stone before moving it on. It was late at night, wanted to be done, in a hurry, etc.
5. Since sandtone is mainly quartz sand --did that act to sabotage the polish stage?
Thank you for reading. Any comments, advice, ribbing, would be appreciated.
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mgroothuis
starting to spend too much on rocks
Member since November 2022
Posts: 163
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Post by mgroothuis on Jan 7, 2023 7:53:59 GMT -5
Interesting. I'm curious of other experiences and advice. I'm running my first batch on my new QT12 right now. However, I'm using it only for stage 1. I did my first cleanup 3 days ago and it's going well so far. I also wondered about the size/damage from the heavier rocks. I have some in there that are probably 1.5-2lbs (baseball or tennis ball sized), combined with dime-sized and everything in-between. I decided to sacrifice some ceramics in the first stage when I re-ran them for the second week. Mine was closer to 3/4 full.
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dshanpnw
freely admits to licking rocks
Member since December 2020
Posts: 892
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Post by dshanpnw on Jan 7, 2023 8:38:51 GMT -5
Great lessons learned. I think you listed a lot of what would cause problems, contamination from softer rocks deteriorating, not enough cushion and rocks breaking apart, etc. Try not to mix rocks with different mohs hardness, all 6-7 will be okay. Fill the barrel to 3/4 full and not too many large rocks. If you don't have enough rocks to make it 3/4 full, use ceramic media. If possible, use a 12lb barrel dedicated just for polishing, but, with an extra good cleaning the same barrel should work. I have not done a batch through all the stages in a 12 pound barrel, but I have done it with a 3 pounder with great results. I would say the main culprits were, mixing soft rocks with harder ones, and barrel not 3/4 full. Just use your lessons learned and make the changes and try again. I'm glad you shared the experience.
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dillonf
fully equipped rock polisher
Hounding and tumbling
Member since February 2022
Posts: 1,583
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Post by dillonf on Jan 7, 2023 8:55:16 GMT -5
I completed my first full run of all stages coarse to polish in a Lortone QT 12. To say I was disappointed would be an understatement. I'm writing this post to share what I learned, or think I have learned and invite comments. Out of a barrel load, only a small handful of stones came out of polish with any acceptable "shine" . A few pieces of chert, a moss agate, a few pieces of lace agate, and an interesting translucent yellow/orange stone. The rest look as though they just came out of a 500 grit pre-polish. As a matter of fact, coming out of 500 they actually looked better. All pieces of amethyst were bruised, fractured or out right broken. Many pieces of lace agate were rough on one side and many broken Stone types that came out really nice in a 1.5 pound barrel from an old Skilcraft tumbler, looked like they just came out of 120-220 grit. Personal conclusions: I had in the tumbler what I think was quartzite, quartz, feldspar, granite, and other Lake Ontario beach cobble, with the before mentioned stones sizes ranging from a couple of tennis ball, several golf ball to dime size stones by the time it reached polish stage with the tumbler just over half full with about 500 cc of ceramic media. I think the there was just too much empty space and lack of cushioning for the larger stones that allowed the smaller amethyst , lace agate, etc. to not be beat to death as they are hard stones but not resilient. I also ended up with about a quarter cup of 5 to 8 mm size pieces Then lack of shine on the others? Lortone suggests a full 20 Tbs (300cc) for a QT12 barrel, but I went with 12 Tbs (180 cc), the 1 Tbs per lb barrel size measurement. Perhaps this was the problem. IDK. Stones moved from pre-polish to polish were washed in between grits with soap and borax run and rinsed well. I did find an odd stone that had many large pits that I somehow missed that moved on to the polish stage without me manually picking out left over grit. May be part of it. I also used generic rocks for fill to get the level up in the barrel that I know will never polish. AND I discovered I had put a few pieces of sandstone in the mix. What I think I learned: Not in any particular order 1. While it is important to have different size stones in the tumble, to big is to big. Weight from many stones is superior to weight from a few stones. 2. Add sufficient grit to perform the operation in the barrel size used. 3. Run the barrel at least 2/3 full. In the Lortone instructions it does say at least half full, so I'm not completely sure of this. 4. Be more careful of inspecting each stone before moving it on. It was late at night, wanted to be done, in a hurry, etc. 5. Since sandtone is mainly quartz sand --did that act to sabotage the polish stage? Thank you for reading. Any comments, advice, ribbing, would be appreciated. Hi dirtsifter I also have a QT12 I am not an expert, but I have learned a few things related to your post. I have only been tumbling a little over a year - rotary only. 1) tennis ball size pieces are likely too large - I've never run anything that big and I still get bruising occasionally particularly with quartz/amethyst. I have used golf ball sized stuff (2-3) with no big problems. 2) I use 15 tblspns of grit. I started with 18 and worked my way down to what seems to work well. I tested it in groups of 3, 18-15-12, and 15 seemed about right? 3) I no longer use the QT12 for polishing (not that it can't be used for that) I find it isn't the best. I try to do my 80 grit and 220 grit stages in the QT12/QT6 then use my 33B for 500,1000 & polish since polish is thinner I run this in the rotary at 3/4 full for 1-2 weeks. If I was running polish in the QT12 I'd actually run it 3/4-7/8 full for 2-3 weeks (more gentle action for a longer period of time). 4) I only use ceramic filler, so I cannot comment on the filler stone. I also have a variety of barrel sizes, so I can shift barrels instead of using excessive amounts of filler. QT12 to QT6 to 45C. I don't lose much mass by the time I get to 500 grit in the 33b. 5) I never run quartz/amethyst type material with agates, jasper or chert in a 12lber they tend to get beat up. When I do run them I start rough grinding about 3/4 full then add ceramic as space opens up keeping it 2/3-3/4 full the whole time. I agree running it 1/2 full is probably no good. By the time I move Quartz/Amethyst from 80 to 220 grit it is about 50% ceramic to 50% stone. With cherts and agates I don't do this. I keep it about 2/3 full and I add more stone, or move to a smaller barrel to compensate for lost material. I never have more than 1/4 ceramic filler in a chert/agate/jasper mix. 6) Sometimes I do 2 runs of the 220 grit not one - if the stones aren't perfectly smooth after the first run. Looking at each stone is very tedious, but necessary. Hope this helps! I just got a 45C and I moved a quartz mix into it (for more 80 grit rough grinding), and after the first run it came out all chipped and cracked I think I just wasn't paying attention and didn't have it filled high enough?? Also, I think I didn't have enough ceramic in there. We will see this weekend if I made the correct adjustments. Happy tumbling.
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dirtsifter
Cave Dweller
Co to za kamyczek?
Member since September 2022
Posts: 402
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Post by dirtsifter on Jan 7, 2023 9:11:10 GMT -5
Thank you for your time dillonf. So bummed, and just on the heels of recovering from covid. It was sickening to see the amethyst so fractured and bruised, not to mention all the lace agate pieces and fragments.
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dirtsifter
Cave Dweller
Co to za kamyczek?
Member since September 2022
Posts: 402
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Post by dirtsifter on Jan 7, 2023 9:18:44 GMT -5
A nagging suspicion is the quartz particles from the sandstone shedding and being much larger than aluminum oxide polish sabotaging the polish stage. Let alone the stone with the deep 2-3 mm pits that I missed in the cleanout. My gosh, there were even small pieces of ceramic media in those pits. Doh! Just sloppy.
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stefan
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Member since January 2005
Posts: 14,095
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Post by stefan on Jan 7, 2023 11:56:22 GMT -5
Polishing in those big barrels is difficult for sure. It can be done, but you really need to cushion the load and make sure EVERYTHING is really the same hardness and CLEAN!. Tennis size ball rocks are fine if you limit it to just 1. 2 (plus the golf ball sized rocks) would be a literal wrecking ball(as you discovered). I think you pretty much figured out where things went astray. I often learn a lot more from my errors than my successes.
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chris1956
fully equipped rock polisher
Member since July 2022
Posts: 1,204
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Post by chris1956 on Jan 7, 2023 12:58:59 GMT -5
Great information. I have had a QT12 running for about 6 months. I am happy with the results but have not yet used it for final polish. I have used it mostly for 80 and 220 stages and then typically switched to Lot-O. Recently, my Lot-O motor died so I extended one run on the QT12 to 600 grit and it seemed to work well. I did put some ceramic pellets in the 600 stage. I typically fill it to about 2/3 full and so far I have always used the recommended 20 tablespoons of grit.
I also try not to put more than one real large (baseball sized) rock in a run. And limit the golf ball size ones also.
Running material at the same hardness or all of one material if you have it is a good idea. I am lucky enough to have creeks on my property where I can get banded chert, jasper, quartz, quartzite, and a couple other rocks I haven't figured out what they are yet, that are all about the same hardness. So far I have been learning on these rocks and they seem to polish well.
A few times I have added what I think is brown obsidian and it hasn't polished well. But I have read other people say they have the same issue with obsidian. Sometimes you will get soft quartzite also which won't polish well.
Keep experimenting and try to change only one variable at a time so you know what causes what.
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pebblesky
fully equipped rock polisher
Placed another order in rockshed. Happy 2024 everyone!
Member since September 2022
Posts: 1,391
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Post by pebblesky on Jan 7, 2023 14:49:10 GMT -5
This post and the replies are very informative. Thanks all for sharing.
I have read somewhere in RTH that it is fine to have one or two large rocks in the grinding stage, but for polishing you'd better work on one large rock at a time, with a lot of fillers that are just "fillers", and take care of the smaller rocks in a separate batch.
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dirtsifter
Cave Dweller
Co to za kamyczek?
Member since September 2022
Posts: 402
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Post by dirtsifter on Jan 8, 2023 1:35:16 GMT -5
Thank you all for taking the time to add input to this thread!
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dirtsifter
Cave Dweller
Co to za kamyczek?
Member since September 2022
Posts: 402
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Post by dirtsifter on Jan 10, 2023 23:44:01 GMT -5
Thank you all for taking the time to add input to this thread! More is better! Pitfalls of tumbling. Everyone who wants to learn....can. Pet peeve: If one already knows everything, no new learning occurs and one's knowledge remains within the confines of wee little box of lead. .
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dirtsifter
Cave Dweller
Co to za kamyczek?
Member since September 2022
Posts: 402
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Post by dirtsifter on Jan 11, 2023 0:41:56 GMT -5
Alrighty then 12 lb barrel loaded with rough self collected over time and 5 lbs of medium rough from the rock shed that came with the QT 12. Lot o tumbler mounted and filled with it's maiden load of rough. --will see in am if the dowel rod needs to be repositioned, 3lb barrel running a coarse run of stones not ready to move to medium and 3 lb barrel prepping ceramic for the lot o. Don't know why I'm nattering on about it. Just needed to tell some one who may care.
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