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Post by Jugglerguy on Feb 12, 2015 12:18:27 GMT -5
A while back, I bought a used cab machine from a friend. You may remember me asking some questions when I was refurbishing it. It's been all together for a while now, and I found a motor for it. It came with two hard wheels, and I bought four others. I bought 280 and 600 Nova wheels and Chuck (Drummond Island Rocks) sold me a couple cheap import wheels that he's had good luck with. Those were 1200 and 3000.
I'm finding it impossible to remove scratches from my cabs. I have a flat lap that I've never had problems with scratches on and I can't figure out what the difference is. I keep thinking it's because the wheels aren't broken in yet, but they should be by now. The directions with the Nova wheels say that it only takes a few minutes running an agate cab on the wheels. I have been running an agate rock on all of them, but I keep getting scratches. Chuck recommended using a sharpie to completely cover a cab, so I did that with a unakite cab. I removed all the marker and then some on each wheel, re-coating with sharpie in between. There were still scratches.
At first I was using fairly light pressure on the wheels, but the Nova directions said to use more pressure, so I pushed harder today. Still no luck. I'm really frustrated. Can anyone give me any advice?
Thanks!
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Post by Jugglerguy on Feb 12, 2015 12:49:01 GMT -5
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Post by Drummond Island Rocks on Feb 12, 2015 12:57:52 GMT -5
Those sure look like scratches that should have been removed at the 220 hard wheel. I find that I need to spend a majority of my time on the 220 hard wheel and the 280 nova for scratch removal. I would normally tell you to paint the cab with a sharpie between stages for nice solid agate/jasper cabs but for unakite, pudding stone, petoskey and our Michigan beach stones that's probably not a good idea do to the texture.
Actually if that is an Unakite cab your new nova 280 wheel should have had no problem removing scratches.
Are you drying off the cab and inspecting (under magnification) after each wheel?
Your refurb on that machine came out great!
Chuck
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Post by Drummond Island Rocks on Feb 12, 2015 13:05:23 GMT -5
I just re-read and seen that you did use sharpie.
I guess now I don't understand because the sharpie should fill the scratches which means you cant remove the all the sharpie without removing all the scratches. I guess make sure you coating the cab real good so the sharpie penetrates into the scratches. When I do this on an agate cab after the 220 hard wheel I can take off the majority of the marker with light pressure on my 280 nova then when I look at the cab there will just be a bunch of faint black lines that show the scratches that require more pressure to remove.
Chuck
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Post by Jugglerguy on Feb 12, 2015 13:48:44 GMT -5
I'll give the Sharpie trick another try with an agate. I'll also go back to the 220 hard wheel.
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Post by phil on Feb 12, 2015 13:53:08 GMT -5
Please take a new stone and start at the beginning. After each wheel, and before you use the next, please wash it off with clean running water, dry it off, and inspect. Are the scratches there after every wheel, or are they gone then return? We're looking for a contaminated wheel this way. Been there, done that. Then let us know the results. The scratches should be mostly gone at the 280 soft, definitely the 600 s oft wheels. Are you spending enough time on those 2 wheels? The human eye cannot see 600 scratches per inch, but 280, maybe. Pressure should be just enough to make a slight (slight!) indention in the soft wheels while polishing.
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Post by deb193redux on Feb 12, 2015 14:10:56 GMT -5
I think one of the lower wheels may have some contamination. It would not hurt to use a fine grained dressing stick on them. Another possibility is cross contamination - this sometimes happens with water from below.
Also, this particular rock may have some larger loose crystals in its seams. Possibly it is shedding as you grind. You could test this by taking that rock to the flat lap.
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Post by Jugglerguy on Feb 12, 2015 14:22:20 GMT -5
More things to try. Thanks.
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Post by Jugglerguy on Feb 12, 2015 15:26:36 GMT -5
Ok, here's what I just did. I got a piece of jasper (I think) that I had rough tumbled. There were no holes or anything that could lose rock fragments when grinding. I started at the first wheel and then inspected with a 10x magnifier. There were scratches, but I expected there to be. I colored it with a sharpie, dried it, and went to the second hard wheel (220). Scratches were there when I was done, but they seemed smaller than the first scratches, so that seemed alright. I repeated this procedure of coloring with a sharpie, drying, going to the next wheel and inspecting again. Each time, I could see scratches, but they were all uniform. Each wheel seemed to leave smaller scratches than the previous wheel. No scratches seemed deeper than others and there was never any black sharpie in the scratches. The 1200 wheel was different. The stone started getting shiny, but when I looked at it under magnification, there were scratches that looked bigger than before, at least I think they did. Some scratches were deeper than others. I think this may be the source of my frustration. Now I just need to learn how to decontaminate it. I have a blade dressing stick that's brand new. I'm guessing that this is not the type of dressing stick I need. Here's the description from the Rock Shed:
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Post by deb193redux on Feb 12, 2015 15:32:28 GMT -5
if it is a fine grain dressing stick it could work. I used a porcelain-fine white one on some diamond wheels I had get gunked up.
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Post by Drummond Island Rocks on Feb 12, 2015 15:46:27 GMT -5
Just for fun try skipping the 1200 and go straight to 3000 and see what the results are? My genie is set up for a drip water system so I have never had any contamination problems. If I remember right a few months ago Tommy had any issue trying to track down a bad wheel. chuck
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minerken
Cave Dweller
Member since August 2013
Posts: 466
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Post by minerken on Feb 12, 2015 16:23:11 GMT -5
The scratches look to be all in the same direction are you turning the stone and sanding in all directions? think of it like polishing your car wax on wax off grasshopper.
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Post by Jugglerguy on Feb 12, 2015 16:49:49 GMT -5
They're in different directions.
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Post by broseph82 on Feb 12, 2015 19:32:56 GMT -5
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Post by phil on Feb 12, 2015 20:09:29 GMT -5
If you use that dressing stone, you're doomed. Think about it. You want to use a 600 grit stick to dress a 1200 grit wheel, and risk embedding 600 grit into it... take it off the unit, and scrub the heck out of it with a bristle brush and dawn dishdetergent. UNLESS it's a new wheel. Then you contact the dealer, tell him what it's doing and let them replace it with a good one. If you're determined to "dress" it, use a piece of jasper with a sharp edge and CAREFULLY scrape (like you're shaving your face) the wheel while running it as slowly as you can. maybe that will loosen the bad grit, maybe not. Then again, wash it off with fresh water and dawn. Are you using a spitter or fresh water drip system? Could be your spitter is throwing up grit from your coarser wheels. From your pic, it looks like you move the spitter back and forth.. Maybe wash it between moves? When/if you scrub,. scrub hard.. that grit is embedded, and it might take a couple tries to get it dislodged. First, maybe try scraping the wheel while running using a credit card and lots of water will do it, there's many ways to try.....
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Post by Jugglerguy on Feb 12, 2015 20:55:03 GMT -5
@broseph, no my marks are different. phil, that's exactly what I was thinking about that dressing stick. I'll try what you suggested. Would reversing the wheel be a good idea? Drummond Island Rocks, I was unicycling tonight and haven't had a chance to try skipping the 1200 wheel, but I will try that. Good idea.
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Post by Drummond Island Rocks on Feb 12, 2015 21:11:03 GMT -5
So you have a studded snow tire on that unicycle?
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Post by Jugglerguy on Feb 12, 2015 21:43:26 GMT -5
No, have keys to the school. We had the day off today because it was so cold, before last year, I never remember having school canceled for cold. It's supposed to be -13 tonight, but not as much wind as last night,
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Post by phil on Feb 12, 2015 21:53:25 GMT -5
@broseph, no my marks are different. phil, that's exactly what I was thinking about that dressing stick. I'll try what you suggested. Would reversing the wheel be a good idea? Drummond Island Rocks, I was unicycling tonight and haven't had a chance to try skipping the 1200 wheel, but I will try that. Good idea. Reversing wouldn't hurt. Skipping the 1200 is a good test too!
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Post by orrum on Feb 12, 2015 22:03:43 GMT -5
Are your wheels broken in? Fresh wheels are hard to work with until a few big hard agate cabs have taken the aggresion out of the diamonds.
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