docharber
has rocks in the head
Member since October 2008
Posts: 693
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Post by docharber on Sept 23, 2009 16:02:20 GMT -5
;D I just picked up my Barranca GP8 I bought from JS GEMS and this beautiful, 150 lb powder-coated stainless steel beast of a machine has me confused. The very brief 3+ pages) unillustrated owner's manual is a little confusing and not very helpful. In fact, it's written on a fourth grade level (by a fourth grader?) and not even proofread or spellchecked. So, I'm confused. The unit has the standard 80 and 170/200 mesh grinding wheels and 2 expandable drums. There are two polishing hubs, one on eiyther end of the unit. the instructions say to use the four grinding belts in sequence swapping belts once on each drum. There are 400, 600, 1200 and "6 micton" belts- I calculate the latter to be around a 2100 mesh though the instructions reference a 300 mesh belt. It came with 8,000, 14,000 and an unlabelled syringe which per the instructions should be 50,000 mash diamond compound and 3 polytex pads. I have always used 100 or 180 , 360, 600, 1200 metal laps, and resin disks followed by aflted fiber pad with 14000 mesh diamond for final polish. on my Ameritool. The machine came with a leather disk as well, and a recommendation to use it dry without additional abrasive for a final high luster polish. I had always thought the leather was used with some sort of polish. I have 2 extra stages of polishing here and I am unsure when they are appropriate. I aso don't know when to use the 8000 diamond compound or on what. Does the substrate the abrasiv eis on make a big defference in the finishing results? I work mainly with hard materials (Moh's 6 and higher). Help?!?
Mark H.
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rallyrocks
fully equipped rock polisher
Member since November 2005
Posts: 1,507
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Post by rallyrocks on Sept 23, 2009 17:36:39 GMT -5
Relax Doc, this will all seem like child's play after a few days of messing with it. You should know the drill on the hard wheels, rough shaping on the 80 then smoothing and more final shaping on the 200, from there go to the 400 belt on an expando drum and work your way through those stages- 600, 1200 and 2400 is a pretty standard progression on a rig like this. With the flat lap we usually will skip wider ranges when progressing through he stages, but the more aggressive nature of cutting on a convex surface compared to a flat makes these seemingly "extra" steps worthwhile. After that you have some options, I've been using an 8000 belt and really liking is as a pre-polish prep stage, I've also used 8000 compound on a resin belt ( bottom of the page at www.kingsleynorth.com/skshop/search_results2.php?catID=177&keys=&start=5&count=10) but other times skipped from 2400 or 3000 straight to 14000 and 50,000- sometimes even 100,000. In my experience almost nothing shines before about 8000, most things look pretty good at 14,000, but different materials give different returns from going beyond that- to the 50 and 100K. There is also the option of using an oxide polish in lieu of anything in the 14000 and up range. I prefer the resin belt for using compound over the end disk polish pads, although the resin belts do tend to wear out, they are inexpensive, and I find them easier to work with than the end disk- but that's just a personal preference. As for the leather- you could certainly charge it with polish, but left clean it works nice to remove polish residues and give a final buffing. There is generally no harm in experimenting, (provided you don't do something silly like running a belt that needs to be wet while it's dry, or contaminating a polish pad with coarse grit or something along those lines), so try a few things out and decide what works for you- there isn't any set procedure that "must" be followed. Whatever you decide to do, I expect you will be very pleased with the increased speed and ease of working compared to what you could do on the Ameritool.
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Post by Bikerrandy on Sept 23, 2009 17:57:22 GMT -5
I've had some cabs shine like a new Corvette after the 3,000 grit Nova wheel, and others that didn't have any shine until after the 14,000. That looks like a really great machine, looking forward to the stuff that you do with it. Don't limit yourself to ovals like I did for the first two years, freeforms are much more fun to do and more fun the wire wrap as well. As the pads go, just keep on experimenting, you'll figure it out. Nothing can replace personal experience!!
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Post by johnjsgems on Sept 23, 2009 18:16:08 GMT -5
Mark, the 6 micron belt is 3000 per Eastwind. Agates will look pretty good at 3000. I go from there to an oxide polish on leather. If you use the polytex pads label somehow to not mix up. Coat the polish pads with the 3M glue so you can remove and reinstall pads. You can skip the 8000 but I'd try it. Generally any steps will shorten the overall time. Kind of like sanding. You can sand at 400 and jump to 1200 but you will spend a lot longer than using a 600 and then 1200. Try the 8000, 14000 and 50000 and see what looks good at what polish. In most cases you won't see much of a difference from 14000 to 50000 without magnification so you can decide which polish works for you. Most competing companies provide14000 and one polish pad. 4 polish pads an 3 diamond compounds are overkill I guess but why complain about them giving too much?
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Post by kap on Sept 23, 2009 19:11:32 GMT -5
Hey Mark you will love the unit! I have a favor to ask would you send me a copy of the parts list? I need to get some things and am having a hard time getting any info from them. I sent you a pm THANKS!!! Keith
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docharber
has rocks in the head
Member since October 2008
Posts: 693
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Post by docharber on Sept 23, 2009 21:06:44 GMT -5
Thanks all. I see the point abou t the more aggressive action of a a vertical wheel compared to a flat lap and why that allows skipping some steps. I was under tghe impression there was a bit of overkill. i've done enough on the flat lap to appreciate the way different materials respond or don't to the diffenent grits. I can also see that the media the abrasive is in would make a difference in the amount of an abrasive particle exposed and available for grinding. A harder medium might be more agressive as it doesn't give, forcing contact with the material being cut. A finer polish might be had with a softer surface of the same mesh size. I have to recheck the mesh size/microm chart again. I thought the mesh size was based on the number of particles that could be lined up in an inch or cm or whatever, not allowing for actual mesh hole sizes- the holes being sized to allow passage of a particl of that size. Wikipedia states 10 micron is about 1250 mesh, 5 microm 2500, etc. I based my calculations on that simple arithmetic. i couldn't find a standard for the size of the mesh fibers that might actually be useed in a screen to separate p[articles of different sizes. It sounds like lots more work going through all these steps compared to the flat lap, though. So, I have my homework asignment...
Mark H.
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Post by frane on Sept 24, 2009 7:45:48 GMT -5
Sounds like when you get the hang of it, you are going to be putting out some fantastic cabs and most likely, in better time! I will look forward to the results and can only hope to be in your current predicament one day...until then, I am on the swap top and tumblers. Fran
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