rixrocks
having dreams about rocks
Member since September 2019
Posts: 50
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Post by rixrocks on Jun 21, 2020 9:33:54 GMT -5
I'm not sure anyone could help without actually working with this flat lap. I am a beginner with using a flat lap so I don't have the experience to draw on. I can find nothing wrong with the machine and I clean the disks under water with a toothbrush, then dry it and inspect it under a magnifying glass. I find nothing wrong with them. However, I have a serious problem trying to get scratches out even after long periods of time on each disk. I can actually feel something "grabing" as it spins. Yet I can find nothing protruding from the disks to cause it. My questions are: Has anyone else experienced this and did you find what is causing it? Also, say you're working with jasper, what would your average time on the metal cutting disks be until you could move on to the next? I don't have these problems when using my Genie and I'm a little frustrated because it seems like operator error but I can't see what I could be doing wrong.
Thanks!
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Post by opalpyrexia on Jun 21, 2020 9:53:13 GMT -5
How did you break in your diamond disks? It sounds like you might have to do some additional breaking in if you're getting scratches.
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rixrocks
having dreams about rocks
Member since September 2019
Posts: 50
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Post by rixrocks on Jun 21, 2020 10:11:50 GMT -5
I thought they were broke in by now though I couldn't say how much time has been spent on the disks. I did use an agate at first on the disks to break them in but I didn't spend a huge amount of time doing that. I've also done about 10 flats to completion by now and started several others but couldn't see much improvement getting scratches out.
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billdean
starting to spend too much on rocks
Member since April 2020
Posts: 153
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Post by billdean on Jun 21, 2020 10:28:06 GMT -5
I am assuming your using diamond disks but I don't recall you saying so? Progressively go up in grit steps to remove scratches from the previous grit. Don't move to the next grit and until the scratches are gone from the pervious grit. 600 grit tools are designed to remove 400 grit scratches, 400 grit tools are designed to remove 220 grit scratches, 220 grit tools are designed to remove 120 grit scratches. Skipping a grit will cause the finer grits to wear out prematurely. Cleaning the disks with a tooth brush and storing them in zip lock bags is a good practice. No contamination that way. After a 600 grit diamond wheel I will usually move to a 600 grit silicone carbide disk or a 600 silicone carbide stick to remove any tooling marks left. There is know time period to move from one disk to another. You move when the scratches are removed from the pervious disk.
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herb
spending too much on rocks
Member since November 2011
Posts: 444
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Post by herb on Jun 21, 2020 11:14:06 GMT -5
If you are feeling "grabbing" maybe you need more water to wash the ground material away? Another possibility is maybe you are pressing too hard? I've never used a flat lap for grinding/polishing, so these are just guesses.
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rixrocks
having dreams about rocks
Member since September 2019
Posts: 50
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Post by rixrocks on Jun 21, 2020 11:41:37 GMT -5
I am assuming your using diamond disks but I don't recall you saying so? Progressively go up in grit steps to remove scratches from the previous grit. Don't move to the next grit and until the scratches are gone from the pervious grit. 600 grit tools are designed to remove 400 grit scratches, 400 grit tools are designed to remove 220 grit scratches, 220 grit tools are designed to remove 120 grit scratches. Skipping a grit will cause the finer grits to wear out prematurely. Cleaning the disks with a tooth brush and storing them in zip lock bags is a good practice. No contamination that way. After a 600 grit diamond wheel I will usually move to a 600 grit silicone carbide disk or a 600 silicone carbide stick to remove any tooling marks left. There is know time period to move from one disk to another. You move when the scratches are removed from the pervious disk. Thanks, billdean,I understand that. I use a Genie for cabbing so I know the progression. As far as the metal cutting diamond disks, I have a 180, 260 and 600. Not a 400. I have a difficult time getting the scratches out going from 260 to 600. Is a 400 grit neccessary, in your opinion? I do have a wide assortment of the soft diamond polishing pads but the problem seems to be going from 260 to 600 on the metal disks.
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billdean
starting to spend too much on rocks
Member since April 2020
Posts: 153
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Post by billdean on Jun 21, 2020 12:05:17 GMT -5
I believe 260 to 600 is to big of a jump, especially if you're having trouble removing the 260 grit scratches. I move from 260 to 360 or 400 and then to 600 grit and it works out well. Is a 400 grit necessary you ask? Did you not answer your own question? If you are having trouble going from a 260 to 600 because you can't get the scratches out, then yes I would say it is necessary. I also find by adding more water to the disk, the stone does more hydroplaning than cutting. Like a waterboarder water boarding. I usually use less water as I like the slurry it leaves as I am lapping the stones.
Other people may and will have different approaches to this. If it works for you great, if it doesn't move on a try something that does. There seems to be more than one way to approach this.
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rixrocks
having dreams about rocks
Member since September 2019
Posts: 50
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Post by rixrocks on Jun 21, 2020 14:15:21 GMT -5
The maker of the flat lap doesn't offer a 400.grit metal cutting diamond disk. Just goes from 260 to 600. I have soft diamond polishing disks that include a 360 disk but I am not sure that would be the one to use between the 260 and 600 metal diamond cutting disks. I could look around for a metal diamond disk from a different supplier I guess. However, it does feel like something is "grabbing" the stone as I am operating it. This just doesn't make sense to me.
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Post by Drummond Island Rocks on Jun 21, 2020 14:48:56 GMT -5
When I first started out cabbing I was using an 8" flat lap. I started by getting a whole set of diamond plates in good progression but soon realized the contact point on a hard diamond plate is so minimal that getting scratches out would be too tedious. All of the horizontal cab machines use two hard wheels then 4 or 5 soft wheels. That is because the cab can be pushed into the wheel creating a much larger contact point. So on my flat lap I did the same thing. I used an 80 grit plate then a 120 plate. After that I out on an 8" diameter dense piece of foam and and on top of that 8" wet dry sandpaper in a progression of grits. That allowed me to bush the cab into the sandpaper much like a soft diamond wheel works. My final polish was done with a 1/4" thick x 8" diameter felt disc with polish on it.
Chuck
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billdean
starting to spend too much on rocks
Member since April 2020
Posts: 153
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Post by billdean on Jun 21, 2020 14:54:19 GMT -5
Keep using what you have then. If it is grabbing the stone, it is cutting. Going back to what I originally told you "Skipping a grit will cause the finer grits to wear out prematurely". If you are happy with that so am I.
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billdean
starting to spend too much on rocks
Member since April 2020
Posts: 153
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Post by billdean on Jun 21, 2020 15:17:02 GMT -5
When I first started out cabbing I was using an 8" flat lap. I started by getting a whole set of diamond plates in good progression but soon realized the contact point on a hard diamond plate is so minimal that getting scratches out would be too tedious. All of the horizontal cab machines use two hard wheels then 4 or 5 soft wheels. That is because the cab can be pushed into the wheel creating a much larger contact point. So on my flat lap I did the same thing. I used an 80 grit plate then a 120 plate. After that I out on an 8" diameter dense piece of foam and and on top of that 8" wet dry sandpaper in a progression of grits. That allowed me to bush the cab into the sandpaper much like a soft diamond wheel works. My final polish was done with a 1/4" thick x 8" diameter felt disc with polish on it. Chuck I do a similar thing but I start with 120/260/360/600 grit on the diamond wheels and then use this arrowheadlapidarysupply.com/products/8-diameter-14-thick-foam-rubber-disc/2246/c40/ with finer grits of sand paper starting with 600 grit to accomplish very good results. I mostly just polish jade though.
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rixrocks
having dreams about rocks
Member since September 2019
Posts: 50
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Post by rixrocks on Jun 22, 2020 0:20:05 GMT -5
I'm not cabbing, I'm trying to polish flats.Thanks for your thoughts though. I will get one of my club members that has experience to come over sometime and see it working in person. It's difficult without being there.
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