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Post by docharber on Apr 25, 2009 17:57:01 GMT -5
I am setting up my home shop and want to build a homemade vibrating lap. I can't do any welding, but I can do most other simple assembly and electrical work. Does anyone know where I can find plans for a simple homnemade machine? I live in a rockhounds wasteland in the Florida panhandle and don't have access to a commercial machine to copy. I would very much appreciate any help.
Mark H.
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Post by geodepat on Apr 25, 2009 18:02:06 GMT -5
;DHey there Florida newby where at in Fl. are you? Here is a web site for a home made one that the guy uses on metal. It should work on rocks. ;DPat boyerfour.com/projects/tumbler/tumbler.htmsorry about that guys it was late and I goofed up but here it is. |
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Post by Doug on Apr 26, 2009 8:57:18 GMT -5
There are lots of different plans out there for a flat lap. Check out: tomaszewski.net/Kreigh/Minerals/Homemade.shtmlA vibrating lap is basically a motor with an unbalanced weight (off to one side) attached to the shaft which transfers motion to the grinding/polishing plate. The motor and shaft are tied together and isolated from the frame through springs. Find your plates and the rest is easy. MUCH easier than a rotating lap with a platen bearing to worry about aligning and contaminating. |
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Post by docharber on Apr 26, 2009 21:38:22 GMT -5
thanks to both of you. I think I might be able to adapt the plans to my needs, especially the first link. I need to keep the vibration in a horizontal plane and that is the challenge. I have see stuff on the RTH board that members have built, and the machines look like something built for a manned Mars mission. Rewally sophisticated. I don't have an engineering degree or a sheet metal/machine shop so I have to keep it simple. The Kreigh site is one I've visited befopre and they have neet stuff, but no vibrating lap. I wonder if I could get muy hands on one of those oscillating solenoid type vibrating devices - I could just boltt one to the perimeter of the plate and that would do the trick. They vibrate at line frequncy. It would sort of work like those old toy football games with a wetal sheet for the field and little plastic players that dance on the surface. If I use a motor driven machine, I think I would like a belt drive to protect the motor bearings from excess wear. this would allow easy positioning of the weight and adjustment of the reciprocating mass . I think that would allow me to mount the weight near the plat, with the other rnd of the drive shaft fixed, maximizing the horizontal motion I would have to figure out what kind of bearings to use, etc. I haev a 3" exercise trampoline frame ringed with springs that could be promising. I think a vibrator assembly from a recliner is a great idea as proposed in the link Pat posted, and should be easy to come by. It should be more of a continuous duty device, too. Anyone else have any ideas? Pat, I live in the panhandle in Niceville, across the bay (north) from Destin. Know any good fossil; hunting sites within a 150 mile radius?  ? Thabnks to you and John, and I'll "see" you ont he RTH board, John! Mark H. |
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Post by geodepat on Apr 26, 2009 22:29:53 GMT -5
Glad I could be of assistance there neighbor. I am in Tallahassee. I like that link using an old tire. I have often wondered if I could attach some kind of drum to the tires on the wheels of my truck and polish as I drive. If I had a tire machine I could fill the inside of the tires with media and rocks and when I got back from a trip they would be polished..LOL crazy thought. Pat
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Post by leonardo on Apr 27, 2009 1:07:23 GMT -5
Pat,,,If you don't try you don't know what will work I think thats a great idea but how do you keep your tires balanced.
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rdk163
Senior Member
Posts: 79
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Post by rdk163 on Apr 27, 2009 6:04:05 GMT -5
Mark,
I have been interested in building a vibrating lap as well. From what I have been able to figure out, one method is to use an off center shaft. This is what is done in the ricipro lap. The portion of the shaft that meets the lap at a bearing is machined down off center. The result is an oscillation in a horizontal plane.
Send me your email address and I can send you a pdf of a vibro-lap manual that includes an exploded view drawing that shows the shaft and counter weight setup. No dimensions or anything, but it gives the idea pretty well.
Next question is what to use for the lap itself. That is the expensive part of the machine, especially in the larger sizes.
Robert
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Post by docharber on Apr 27, 2009 9:46:08 GMT -5
YES!!!!! My eMail is Docharber@cox.net. Thank you very much- I hadn't thought of generating horizontal motion that way. I think I understand that the end of the shaft is machined down to an off center circle that fits in a bearing on the plate. You could use such a system to both maintain the horizontal motion you want while stabilizing the shaft with another bearing. that would mean having a friend with a machine shop, of course. Less than 1/16" would be enough of an offset. A T-bushing would be adequate for the underside of the plate, I think.
The plate could be made of a number of materials. In Knoxville, TN there was a p[lexiglas plant that sold defective sheets at a really low price and this stuff could be 1/2" thick or more. Dead flat, and heavy too, especially if you mount it on a board. You can drill a recess in it to hold a bearing with ordinary tools like a FOrstner bit used for woodworking. I think I have some of this stuff at my parents' house. I would love to get my hands on a sheet of mild steel or aluminum. Even a stainless panel from an appliance glued to wood and scored might do. Keep thse ideas coming, guys! Has anyone here considered a separate board for homemade equipment? The one on the Rock Tumbling Hobby goard is always interesting reading.
Mark H.
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rdk163
Senior Member
Posts: 79
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Post by rdk163 on Apr 27, 2009 15:06:29 GMT -5
I have sent you the pdf.
Robert
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Post by docharber on Apr 27, 2009 19:54:25 GMT -5
Got it- snet an email- thanks again!
Mark H.
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Post by jpolk123 on Apr 28, 2009 9:40:58 GMT -5
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Post by arappaho on Apr 28, 2009 14:35:38 GMT -5
I have a homemade rotary flat lap. I didn't make it, but bought it because the man had a huge supply of peel-and-stick discs to go with it. Works great on rock under Mohs 8, but takes forever on agate and such. I know this is not the type of lap you are talking about building but here are a few pics incase they will help in any way.    Okay, so here's my question. What about building a flat lap that moves back and forth? Kind of like a motorized shaker/sifter box. Seems like it would be easier to construct, but I don't know if it would work as well. Someone with a Lortone Vibralap ought to be able to answer your question about the grits, Jim. |
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Post by docharber on Apr 28, 2009 16:07:38 GMT -5
The manual Robert sent me shows the vertical drive shaft as having a milled end with an eccentric round pin that inserts into a bearing (thrust bearing?) that lies in a circular collar fixed to the bottom of the plate. When the shaft spins, the off-center pin in the bearing causes the plate to gyrate in a sort of orbital motion. Speaking of which, I was thinking my old orbital sander might be adaptable to the job of powering a small lap. The motion would be in a flat plane and that was a big concern.
About grit, I understand you use graded grit, that is NOT the grit used in tumbling, which contains a wide variety of sized particles, but a much more uniform product. The graded grits are designated with a single size, such as "400" rather than as, say, 60/90. Thjey cost more. Most lapidary suppliers will carry these products.
The idea of a jiggling plate would not be an orbital motion, so there would be a relatively dead area in the center, and much more abrasion on the periphery. That could cause uneven grinding. Using the eccentric pin, thet whole plate is in the same uniform motion.
Your lap machine looks plenty serviceable. How do you get it going fast enough with that huge drive wheel on the shaft and the little pulley on the motor? You need at least 2000 RPM capability for most grinding. I have tried using my 600RPM no load faceter to grind flats and it just doesn't hack it. So, I just ordered a new Ameritool flat lap grinder. If you rearrange your pulleys, you might get much better speed and performance. If the platen is wooden, though, beter make sure its well balanced.
Mark H.
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Post by arappaho on Apr 28, 2009 17:47:37 GMT -5
Thanks for the info, Mark.
And thanks for the advice on my lap. The performance has been poor.
I'll definately have to work on that.
Joe
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Post by rockphil on Apr 4, 2015 12:02:01 GMT -5
Hi to all of you. I am Phil and I live in UK at present where it is very very hard to buy any lapidary equipment unless you import from the US and then there are huge carriage charges and taxes here on arrival. All the British companies have gone out of business as there is so little demand here. It's like a complete desert even to buy saw blades and simple things. I have managed to source everything I need via the internet except a vibrating lap. I saw some guys on your forum had also been asking about this and it seem a home made system is available. One of your members kindly offered to send a pdf of the plans of how to build one and if these are still available I would love to hear from you. If anyone can help with this it would be great as I hope to get this done this summer. Hope you all keep on enjoying the rocks!
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