Dave Austin
starting to spend too much on rocks
Member since January 2008
Posts: 104
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Post by Dave Austin on Jun 5, 2009 3:00:38 GMT -5
Morning all, we have started getting into making flat display pieces and have realised that it’s going to take forever on our 8” flat lap so after some reading on the forums it seems that a vibrating lap is the way to go.
Now due to the general lack of lapidary equipment here in the UK and the high cost of shipping from the USA I have decided to see if I can build one.
My initial problem is getting head around the mechanics of these machines like how do they make the lap pan vibrate, any pictures of a machine showing the way its driven and constructed would be very much appreciated.
Cheers
Dave
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Post by Hard Rock Cafe on Jun 5, 2009 8:52:45 GMT -5
I don't have any pics for you, but I believe I have a general idea of how they work. One approach has a central motor driven shaft with an off-set weight that causes the pan to vibrate. The pan rests on relatively stiff springs. This is the same method used by most vibrating tumblers (if not the Lot-O).
Hope that helps! Chuck
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Dave Austin
starting to spend too much on rocks
Member since January 2008
Posts: 104
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Post by Dave Austin on Jun 5, 2009 17:02:50 GMT -5
Hi Hard Rock Cafe,
thank you for your input, it's much appreciated.
Have a good one
Dave
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Post by kap on Jun 5, 2009 18:17:54 GMT -5
Hi Dave here are some pictures of my 24in lap This is the pan on top for the rocks This is the plate that the pan and the shaft hooks to the pan is setting on the rubber pads and is held in place with set screws at the corners This is the shaft with the pulley and the weight attached the top bearing is mounted to the plate and the bottom of the bracket is mounted to the frame with springs at the motor end Hope this helps Keith
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Dave Austin
starting to spend too much on rocks
Member since January 2008
Posts: 104
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Post by Dave Austin on Jun 6, 2009 2:38:40 GMT -5
Hi Kieth,
you are a real gem, thanks very much for this, from the pictures you have posted I now have a decent understanding of how this set up works.
Just a couple of more questions if I may please:
Your pulleys appear to be of a similar size on the motor and the weighted shaft. do you know what size these are and at what RPM your motor runs at.
You have certainly got my grey matter working overtime now.
Thanks again and have a good day
Dave
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Post by kap on Jun 7, 2009 11:38:58 GMT -5
Dave the motor is a 1/3 hp, 1750rpm and the pullys are 3 1/2 inch on the motor and 3 inch on the shaft. Keith
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Post by kap on Jun 7, 2009 19:21:21 GMT -5
I have 4 pans for this one and use it from rough to polish changing pans with each grit with out any problems running the same speed. Keith
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Dave Austin
starting to spend too much on rocks
Member since January 2008
Posts: 104
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Post by Dave Austin on Jun 8, 2009 2:50:19 GMT -5
Hi Kap,
thanks for answering the extra questions, I think I have all I need now in terms of knowledge for building this machine, now all I need to do is source the hardware, I think the pans are going to be hardest thing to find over here.
When I have evrything together I will make a post about how I built it so others can benefit from your help.
Now I have to head over to Holland for an early pick tomorrow morning for a same day delivery back in the UK - bet it rains!
All the best
Dave
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scottyh
starting to spend too much on rocks
Member since November 2007
Posts: 181
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Post by scottyh on Jun 8, 2009 19:50:37 GMT -5
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Dave Austin
starting to spend too much on rocks
Member since January 2008
Posts: 104
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Post by Dave Austin on Jun 9, 2009 10:02:20 GMT -5
Hi Scott,
this is one hell of a piece of kit you have built here, fantastic and its really inovative the way you have made the wieght on the shaft. I also like the way you made your own pan, how well is it working for you because most of the commercially available pans I have see have some sort of pattern in the bottom to help spread the grit.
Did you say you had plans for this baby, if so would you be willing to share them?
Once again thanks for posting this it's really helped me a lot.
Cheers
Dave
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garrett
having dreams about rocks
Member since August 2008
Posts: 62
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Post by garrett on Jun 9, 2009 11:51:54 GMT -5
Scott,
I’m also very impressed with the pic’s of your vibra-lap. That’s one to be proud of.
I too would be interested in a copy of the plans you mentioned.
I’ve wanted one for quite a while and will eventually get one (or build it). But so far I’ve never even seen one close up yet.
I was wondering about the motor and drive pulley being mounted solid to the frame and the driven pulley on the shaft being suspended by springs. Does the belt tension tend to pull the lap surface out of level?
Now that you’ve been using it, is there anything you would change?
Great machine.
Garrett
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scottyh
starting to spend too much on rocks
Member since November 2007
Posts: 181
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Post by scottyh on Jun 9, 2009 19:04:21 GMT -5
Hi Dave and Garrett, The vibra-lap is going really well , the only thing that I would do differently is that I would construct the lap so that the pan sits closer to the ground. That would make it easier to get it in and out of the fame for cleaning. Due to the pans weight I don’t remove it to clean it. I just mop the used slurry out of it then dry it. Once the pan is dry I vacuum it. I then scrub the pan out again with out with fresh water and a scrubbing brush and dry it. This is followed by another vacuuming and one last wipe done with a very clean cloth. If you are scrupulous about doing this then you will have no problems with stray grit. I have had no problems to date and hey if you do it’s just a day or so lost. Other than that I am very happy with the way it performs. I can supply a PDF of the rough plans you should have no problem following them (you just need to make some decisions on bearing sizes etc). Just drop me you email address and I will get them to you and answer any questions you have to the best of my ability. A couple of things you can't see from the pictures 1) You can't see the bumper ring in the pan.- for that I am using a ring of garden irrigation pipe (polythene), 2) I did put in a bracket in case the tension of the drive belt tilted the pan too far out of level (this unit does have adjustable feet to take care of a small amount of tilt). The plan was to use a spring and turnbuckle to take care of this should it happen but the unit runs so well I have decided just to leave things alone…. If it isn’t broke don’t try to fix it. 3) The amount of weight on the shaft: I have had to experiment with this but in short I filled the pan with water then just kept adding weight to the shaft in the form of brass washers then switching the unit on and watching the surface of the water in the pan for a 10-15 seconds until I had a nice even ripple over the whole surface. I then put some agate in the pan and watched for a couple of minutes to make sure that they would circulate around the pan evenly. Then we were off. Now to answer the questions you asked. The pan: None of the pans that I have seen on homemade vibra-laps in New Zealand have been milled and they all seem to work very well. So I don’t think that you need them. Milling the plate may speed things up somewhat but I am happy. It takes me about 7 days to complete the grind (see below for the methods) and have the butt ends/slabs ready for polishing. However, it is critical that the surface of the pan is dead flat. When the pan was made it was initially clamped to a flat welding bench with a 51 mm (2 inch) thick surface and the welding was done in very short runs to avoid warping (remember this is a 12 mm thick piece of plate) the plate. Each month when I have down time I run a straight edge over the pan to make sure there are no high or low spots. If there are (and there haven’t been to date) the hammer comes out and some flattening takes place (that’s what others do). Tension on the drive belt: See point 2 above. Initially this was a concern for me but then looking at this from a practical point of view the there shouldn’t be a lot of tension on the belt. If you think about it you are just driving a weighted shaft at approx 1440 rpm (in my case) so there isn’t a lot of movement there to cause the belt to jump off. So when the unit was assembled I had just had enough tension on the belt to make sure the shaft was driven (no weights at this point) without any slippage. This arrangement seems to have worked very well and I haven’t had any problems with belt tension. But just in case (and its included on the plans) I had a plan B but haven’t needed it. Methods I have one main method (method 1) that I use to prepare agate and petrified wood slabs and butt ends. I have also tried a second method (method 2) that appeared to work just as well but I am just not that comfortable with it so I stick to number 1. Method 1) pour approx 1-1.5 l water into the pan, switch lap on and place ¾-1 cup of 80 grit silicon-carbide into the pan. Place agate and their protective rings into the pan and watch to make sure they circulate freely. Leave for 3-4 days (in hot weather may need to add some more water). After three days I take the agate out and wash it and check to see that it is flat and all saw marks etc have been removed. If slabs or butt ends aren’t flat or still have saw marks etc repeat aforementioned process. If the agate etc is ready for the next stage then clean the pan out as described above. I then change the bumper ring (I have separate rings for the two stages) pour approx 1-1.5 l water into the pan, switch lap on and place ¾-1 cup of 600 silicon-carbide grit into the pan. Place agate and their protective rings into the pan and watch to make sure they circulate freely. Leave for 3-7 days (in hot weather may need to add some more water). I say up to seven days because I have just left them but the material is usually ready to go after 2-3 days. I then polish the material on a flat lap with a carpet pad and tin oxide because I feel that I get better control over the end product compared with using the Vibra-lap with a polishing pad. Method 2) pour approx 1-1.5 l water into the pan, switch lap on and place ¾-1 cup of 80 grit silicon-carbide into the pan. Place agate and their protective rings into the pan and watch to make sure they circulate freely. Leave for 2-3 days (in hot weather may need to add some more water). Check and if ready i.e. no saw marks etc then do the following pour approx 1-1.5 l water into the pan, switch lap on and place 1-1.5 cups of 80 silicon-carbide grit (yes that’s 80 grit) into the pan. Place agate and their protective rings into the pan and watch to make sure they circulate freely. Leave for 7-8 days (in hot weather may need to add some more water). Remove the agate etc wash then polish. This method works due to the 80 grit breaking down and I know at least 2 people that use it exclusively. I am still not too sure about it but they swear by it and their results do speak for themselves. Well I hope this helps all and am quite happen to answer any questions and pass on plans Cheers Scott
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Dave Austin
starting to spend too much on rocks
Member since January 2008
Posts: 104
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Post by Dave Austin on Jun 10, 2009 11:53:12 GMT -5
Hi Scott,
well first of all I would like to express my thanks to you for such a detailed post, all of this information is really helping me.
I would really love to see a copy of your plans, although I may have to scale the dimensions down a bit to fit the finished item into our workshop.
I also read the two methods with interest and I guess I will try both once we have this machine built and running.
Anyway I will PM you with my email address now.
Best regards and thanks once again
Dave
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Dave Austin
starting to spend too much on rocks
Member since January 2008
Posts: 104
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Post by Dave Austin on Jun 11, 2009 10:29:33 GMT -5
Hi Scott,
thank you very much, the plans are super and easy to follow, as I said I will need to scale the dimensions down some for the unit to fit into iur workshop, will keep you posted.
Thanks again
Dave
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docharber
has rocks in the head
Member since October 2008
Posts: 693
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Post by docharber on Jun 12, 2009 22:41:05 GMT -5
Hi Dave- i have wanted to build a flat vibrating lap, too. Lacking an engineering degree from MIT or a machine shop, I solicited advice from this and the Dirty Rockhoumnds forum and received a schematic of a commercial lap. i had considered using the base of my vibe tumbler and mounting a metal baking pan on it with a plywood base (for flatness) and a flat plastic sheet cut to fit the interiotr to protect the metal pan from degradation, that could be swapped out for each grit stage. I was concerned, though, that the orbital motion of the tumbler would not give me good flat faces andf that keeping the pan moving in a flat plane was important- not having it make the wobbling motion vibe tumblers use to circulate the rock. An expanded partds draweing of a commercial machine revealed the secret. The drive shaft was securely fixed to the frame and the end inserted into a bearing mounted on the bottom of the pan. The end of the shaft was milledto a smaller ccircular diameter that was slightly offset to the center of deive shaft. Inserted into the bearing, it would move the plate/pan in a single plane in an orbital motion where all parts of the plate/pan are in motion. It was suggested to me that the vibrator from an old recliner might serve well. I thought that was a neat idea but there were two problems- mounting the vibrator to the pan/plate would give the desired planar motion but it would oscillate around the center, with relatively litetl motion in the middle. Using two vibrators at 90 degree angles, their axis of vibration centered in the pan/plate, would work. The vibrastors in recliners and other such devices are usually not motor drivben, but use a coil and magnet solenoid. Rapidly oscillating AC current changes the direction of magnetic force generated 100 times a second for 50Hz current and the magnet is alternately attracted and repelled by the magnetic field thus created. It moved in a single axis creating the single plane motion.
Let us know what you come up with. i lovbe to see what the other members are building.
Cheers, Mark H.
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bobrocks
off to a rocking start
Member since April 2008
Posts: 9
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Post by bobrocks on Jun 14, 2009 10:20:44 GMT -5
Hi Dave, I have not built a vibrating lap, but I did try to build a vibe tumbler. It failed in short order. here is what I did wrong. To save time and money I mounted the motor directly to the pan or bowl in my case and suspended the whole works with cables and springs. For the vibration I attached shaft collars to the mortor at either end. it was double shafted one north and one south. Instead of set screws fot the shaft collars I used machine screws of about 2 inches in length for eccentric weights. Simple, cheap, and infinitly adjustable. In short Brilliant! Less than 12 hours later that motor, half horse, heavy duty... tore herself apart. SO lesson learned direct drive will not work. It Was a Fun Project. It sounds like Scott knows what HE is doing. Have fun Bob.
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scottyh
starting to spend too much on rocks
Member since November 2007
Posts: 181
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Post by scottyh on Jun 14, 2009 19:50:39 GMT -5
Hi Bob... You definitely can have a direct drive type of machine..... I know of at least two of them (home built) and they work very well and have been running for years. The secret behind them is getting the right motor. If you have big bucks you can buy a shaker motor. It is essentially an electric motor with adjustable eccentric weights on the shaft already built into the unit. They are used on industrial shaker tables/screens etc. However, they are really expensive. I looked at buying a nice new ¼ hp unit that would do what I wanted and it was up around the 4-500 US dollar mark.... The second option that I have seen in use is a pool pump motor with a flange on it. This was for a smaller lap so didn’t have the biggest of weights on it. The owner had been using it for 20 odd years and had very few problems.
Basically the unit was a smaller version of mine with a suspended frame that held two plates. Top plate was the grinding plate made out of steel with the edges of the bowl being made out of the sides of a plastic 44 gallon drum that was glued and screwed in place. The second plate was held on the frame approximately 100 mm below the first. This was made out of ply wood with a 40-50 mm hole in the centre of the plate that the electric motors shaft went through. The motor was bolted to the plate via its flange. The weights for this unit were attached directly to the shaft. Just remember with this design you probably don’t need a whole lot of weight.
So yes a direct drive vibra-lap can be made however you need to get the right electric motor. I have seen them made with 1/4 motors out of old style washing machines... but these don’t last (weeks maybe months if you are lucky).
Cheers Scott
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garrett
having dreams about rocks
Member since August 2008
Posts: 62
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Post by garrett on Jun 18, 2009 3:12:27 GMT -5
Great information and instructions thanks for sharing it with the rest of us.
I sent you a PM.
Garrett
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daryl
off to a rocking start
Member since June 2012
Posts: 8
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Post by daryl on Dec 24, 2012 21:29:43 GMT -5
If anyone still has the plans could you send them to me. Please and thank you
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cherdarock
starting to spend too much on rocks
Member since December 2012
Posts: 140
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Post by cherdarock on Jan 6, 2013 4:42:21 GMT -5
;D ;D ;Done other method for direct drive is a vibro lap I want to build. Absolute simplicity. It is based on the COMBS GYRATORY FOUNDRY RIDDLE. The original design is for sifting foundry sand, (also handy since I cast metals) BUT! with a solid bottom pan, I don't see it NOT able to lap as well. The unit is suspended, the 1/2hp motor is mounted at the top, shaft down. There is the cross brace plate that supports it. Two arms extend downward, and there is another cross brace. A shaft runs from the motor to this cross brace, and under the brace an off center weight, disc shaped, is rotated (1725rpm) the arms continue down and terminate with the pan, (or riddle) To see one, click on the link. It is an old foundry catalog. Scroll up to page 125 books.google.com/books?id=JPFYAAAAYAAJ&pg=PA393&lpg=PA393&dq=combs+vibratory+sand+riddle&source=bl&ots=BU6OnvsGyO&sig=YiTL236uYE1Hcfqlw-5LpShKCxA&hl=en&sa=X&ei=ujvpUMXzMYGWiAK3-YCYAQ&sqi=2&ved=0CEQQ6AEwAg#v=onepage&q=combs%20vibratory%20sand%20riddle&f=falseTwo of these and a set of pans, you would have slabs piling up to your ears in a couple days... ;D ;D
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