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Post by Bob on Apr 12, 2021 21:41:37 GMT -5
I believe 80 grit is way less than 1mm in dia so I don't see how it could make a 3mm deep scratch. I've used grit as large as 30 and even it can't do that.
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Post by Bob on Apr 13, 2021 10:15:18 GMT -5
I can't comment on barrels smaller than 6lb. I only have some of those, some 12lb, and 20lb and 40lb. A few years ago, I started testing grit going down from 80. 80 had been my coarse grind for a couple of years. 70,60,50,40,30, and it seems like I did one larger 26 or 20 maybe it was. I saw improvements from 80 to 70, and from 70 to 60, and from 60 to 50 maybe. But so little that I think 60 or 50 is about the same.
But going below 50, I didn't see any improvement and felt just the opposite was happening.
So I buy, for coarse grind, 50 or 60, whatever deals I can find, and think I end up with 60 most of the time.
In case it matters in the above impressions, I do a lot of large rocks, more than most people. Lemon, orange, grapefruit, and some larger.
I never use grit larger than 80 through on delicate things such as crystal quartzes, feldspars, obsidian, etc.
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Post by As I in does tries! on Apr 13, 2021 19:25:34 GMT -5
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Post by Bob on Apr 14, 2021 10:46:55 GMT -5
I don't know how much applicability that article has to rock tumbling before the polish stage but I sure enjoyed reading it. It's title is a bit silly. As a former cabinetmaker, I'm often invited when at friends' homes to see this or that project they have built. And there is always the "whaddaya think?!" at the end and of course it's always beautiful I say.
So many people underestimate the art and sequence of proper sanding, and maybe this is why the tumbling grit sequence is something I don't take a chance with. For instance, sometimes my rocks feel just great to the hand coming out of 60 or 80, and look great. And a pile of them that just finished 220 maybe looks the same and feels the same--at least to my calloused fingers. But no way would I skip 220.
In cabinetwork, with paint this matters not near as much, but with staining boy does it matter. Some cabinetmakers will say that surface prep before finish, which is mostly but not all sanding, is the hardest part of cabinetmaking. I would probably say that and designing the cabinet is equal, but certainly agree that building the thing is less that either of those most of the time.
This is one of the reasons why I am so careful to avoid grit contamination from one stage to the next. Actually, I think a particle of 80 going into 220 matters not too much, 220 into 600, matters not, etc. due to it being at the beginning of a week and having a whole week to break down. But still I go to lengths to avoid it. What I really worry about though is a particle skipping one step. For instanced, a 80 grit particle accidentally getting in a 600 batch is going, in my opinion, to make a scratch in the first few minutes which--although I think it would have self-repaired in 220--can't be fixed in 600.
So I never let a barrel do one grit stage, unless it has just before completed the prior grit stage. For instance, last night I had a 12lb start 600. The week before it was running 220. I don't even bother rinsing or cleaning the empty barrel at all. There is one exception to that. Before I seal up a batch, I have cleaned the sealing lip well. But if something when wrong, and that sealing lip got some grit particles in it that weren't ground down to dust in that week--in that case, I will thoroughly wash the barrel before going to next finer grit. Going to polish though, I go all out with cleaning and even wear a clean hat and even don't hold my barrels under lampshades on my workbench that have dust on them.
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Post by Rockindad on Apr 14, 2021 18:16:34 GMT -5
I don't know how much applicability that article has to rock tumbling before the polish stage but I sure enjoyed reading it. It's title is a bit silly. As a former cabinetmaker, I'm often invited when at friends' homes to see this or that project they have built. And there is always the "whaddaya think?!" at the end and of course it's always beautiful I say. So many people underestimate the art and sequence of proper sanding, and maybe this is why the tumbling grit sequence is something I don't take a chance with. For instance, sometimes my rocks feel just great to the hand coming out of 60 or 80, and look great. And a pile of them that just finished 220 maybe looks the same and feels the same--at least to my calloused fingers. But no way would I skip 220. In cabinetwork, with paint this matters not near as much, but with staining boy does it matter. Some cabinetmakers will say that surface prep before finish, which is mostly but not all sanding, is the hardest part of cabinetmaking. I would probably say that and designing the cabinet is equal, but certainly agree that building the thing is less that either of those most of the time. This is one of the reasons why I am so careful to avoid grit contamination from one stage to the next. Actually, I think a particle of 80 going into 220 matters not too much, 220 into 600, matters not, etc. due to it being at the beginning of a week and having a whole week to break down. But still I go to lengths to avoid it. What I really worry about though is a particle skipping one step. For instanced, a 80 grit particle accidentally getting in a 600 batch is going, in my opinion, to make a scratch in the first few minutes which--although I think it would have self-repaired in 220--can't be fixed in 600. So I never let a barrel do one grit stage, unless it has just before completed the prior grit stage. For instance, last night I had a 12lb start 600. The week before it was running 220. I don't even bother rinsing or cleaning the empty barrel at all. There is one exception to that. Before I seal up a batch, I have cleaned the sealing lip well. But if something when wrong, and that sealing lip got some grit particles in it that weren't ground down to dust in that week--in that case, I will thoroughly wash the barrel before going to next finer grit. Going to polish though, I go all out with cleaning and even wear a clean hat and even don't hold my barrels under lampshades on my workbench that have dust on them. As someone who once made a living doing custom woodwork from design to finish I can attest to the truth in the above post. I really believe I have had an easier time, and a much shorter learning curve, tumbling because of that experience with finishing and the necessary prep work to really end up with a great product.
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Post by Bob on Apr 14, 2021 22:39:12 GMT -5
Wow, you understand me and I understand you. Nothing like screwedup face sanding of rail/stile joints in oak before dark oil stain to show what grit can make happen. Our grit was on paper. Now the grit is loose, but it's still grit in sequences, making new scratches all the time.
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