mikeinsjc
spending too much on rocks
Member since June 2010
Posts: 329
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Post by mikeinsjc on Feb 9, 2011 10:51:50 GMT -5
I am considering purchasing a vibrating flat lap to remove the deeper saw marks that can't practically be removed on my sanding wheel. It would dedicated to this purpose only, only using one grit.
I would appreciate any recommendations or experiences from members regarding this idea, and any specific models or sizes you might or might not recommend.
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Post by rocklicker on Feb 9, 2011 13:11:33 GMT -5
I can't really speak from experience because I only just started using a vibrating flat lap. I imagine it takes a long time to remove saw marks. I have found that you need to run it for at least 5 hours per grit to get results, probably more if you want to remove more material. If you are using an autofeed saw then I would suggest figuring out why you are getting saw marks in the first place. If your feed is smooth, the carriage straight, and your blade is not dished then you should have very few saw marks to begin with. If all is well, then a flat lap should work if you are patient. Steve
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Post by deb193redux on Feb 9, 2011 14:03:56 GMT -5
I agree the best approach might be to avoid the marks.
But, I have taken a 7lb piece of Maury Mountain moss agate and put it in a 10" vibrating pan with the flattest part down and 60 grit. I wanted to see how long it would take to remove enough material to get a flat face like it was cut. Also, I needed a good demo for a lapidary equipment display at a kid's science show.
I needed to remove about 1/4" of material over about 6 square inches of the total 12 square inch face.
I used it three years running and have done 27 grit changes. It is very slow.
A cut face would likely only need to remove 1/32 inch, so it would be faster.
You didn't say if you were talking about faced rough or slabs. I do NOT recommend this for slabs, except possibly very large slabs. You have to weight them. The thinner material is more prone to chipping/breaking. It is a messy machine to boot. For slabs I would overwhelmingly recommend a belt sander. I often clean up slabs on my Covinginton vertical belt sander.
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Post by jakesrocks on Feb 9, 2011 14:32:51 GMT -5
Your choice of flat lap will depend on how much you want to do at one time. I have an old H.P. 20" vibro - lap that I use. As already stated, for slabs, you're going to have to weight them down. You can make lead weights dopped to the backs, or T-egg halves dopped to them. To prevent chipping, I cut rubber bands out of old inner tubes to stretch around the slabs. Depending on how deep the saw marks are, it can take anywhere from a few hours to a couple of days. The lap plate has to be wet at all times, but not flooded with water. Keep a squirt bottle near the lap, and give it a squirt every hour or so, or set up a very slow drip system. Vibrating laps are noisy, so if you're going to run it over night, set it up in a shed away from the house. Vibrating laps also have a habit of walking all over the shop, so if you have a wood floor, fasten wood strips around the outside of the laps feet.
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Post by Jack, lapidaryrough on Feb 9, 2011 21:53:27 GMT -5
Mike;
I run two 27" HPs. i only use 220 grit in the pans. with a IV drip system about a drip every few seconds. depends on the weather outside.
Face sand your piece`s and grid the break off - off.
for slabs i use rounds of ply-wood that cover the outside edge of the slabs. this way i can stick a large heel our weight on the slab.
for large rocks i set on the lap, i use flat hose to make bumper rings. using a strip copper pushed into each end of the hose wedging the ends together.
The plate on my laps are aircraft aluminum, costing $500.00 now. both sides are grooved. I use a Furmer 20" for polish only, with 1/4" lamb wool carpet. glued in.
When you lap stones and go to polish you`l see that they are frosted looking.
You`l need to belt sand them with a drum or flat disk. then to polish phase - on the lapping polish.
If grit dry`s on the stones it like cement to remove. I had Mexican Coconut dry out on the lap. i tried soak them, scab with brush, still on them to this day.
Acid won`t work - Calcite formations in the Geodes.
loose chips leave cork screw grooves in the face.
lap drys out the wild dance of stone walking over each other.
And as said above, a lap well walk where it damn well wants to, and push a lortone 18" saw up against the wall.
my laps have adjustable legs, they need to be level. and i made a ply-wood base for the legs to fit into.
this has stoped it from walking around the shop. one thing i have found out - they're like a young kid, don`t leave them home alone running!
Jack
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rockhound97058
freely admits to licking rocks
Thundereggs - Oregons Official State Rock!
Member since January 2006
Posts: 760
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Post by rockhound97058 on Feb 9, 2011 22:57:23 GMT -5
I run vibra-laps all the time and it's one of the main machines I use in the business. My experience is depends on what type of machine you have. I have a 20" Lortone and a 20" Highland Park. The Highland Park works great for smoothing down a face, while the lortone works much better for polishing. The HP has a very aggressive shake, and the lortone is a very fine vibration. These work great for many stones, however certain Thundereggs such as your course grained matrix's like Lucky Strike Mine will undercut on a vibra lap. Also your moss agates will tend to undercut as well. For these I use a 20" solid rotating flap lap, which is actually much faster than the vibra-lap and Mike this is something I'd look into if all you want to do is remove saw marks. I bought a machine, but yet to go pick it up and it's a 20" Rociprolap. Never used one, but everyone I know who has one say this is the cats meow. Works on a different principle than normal laps. Problems with the laps walking about.... I know these are very touchy to leveling them - but once you get it exact it should calm down greatly, but to help with them walking around, we actually take machine leveling pads and replace the small feet HP uses. Seems to really help out - here's a link - Keep in mind this isn't the exact units we use, but a photo just for your info. www1.mscdirect.com/cgi/NNSRIT2?PMAKA=86435005&PMPXNO=5368251&cm_re=ItemDetail-_-ResultListing-_-SearchResults
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mikeinsjc
spending too much on rocks
Member since June 2010
Posts: 329
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Post by mikeinsjc on Feb 11, 2011 10:02:54 GMT -5
Actually, my saw cuts pretty smooth. It's the stuff I have gotten from others and still do occasionally obtain from collections that is sometimes a problem.
From the input thus far, it sounds like the vibrating lap is probably not for me. It sounds like it needs a bit much attention. I need something that works quickly.
The machine I really want is a rotating lap that is made by a guy in Oregon, but it's $4k. Removes saw marks in a matter of minutes.
My saw cuts good enough that I can take the pieces to my bull wheel, run them through the sequence of 100/220/400/600 belts and end up with an acceptable "tourist" shine, but not a "collector" shine. I have not had any luck with cerium oxide on the leather wheel that came on the bull wheel, so I am looking for other ways of obtaining my "collector" polish.
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Post by Jack, lapidaryrough on Feb 11, 2011 12:43:48 GMT -5
picasaweb.google.com/lapidaryrough/WebPageShop?authkey=Gv1sRgCIS5gpjWko3dkgE# Rotary 18" cast iron, i only use 220 grit on it. And the 24" lamb wool 1/4 inch nap. charged with cerium oxide. i know a few people around here that use 48" steel plate laps. good saw cut, and the saw marks are gone in 30 minutes, using 220 grit. then as you said off to the Bull wheel, and the polish lap. Mike; in a few hours of 220 grit on my 27" Hp, i have removed all saw marks, though my saws are kept in great cutting order. main thing about running vibra-laps is fill them up, of 3" - 5" half's i run about 25 -27 on the 27" lap. Then i finish with glued grit pads or drum sand with a worn out 600 grit belt.
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Post by Jack, lapidaryrough on Feb 11, 2011 19:52:12 GMT -5
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