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I've seen the 48 inch ones Joe Cota has down south, wish I had the room and the money for one of those.
Joe's is nice for sure. You always have the room and if you don't spend your money rocks, it will just get spent on something else.
The last quote I heard for a 48 inch one was north of 9000. too much for my blood.
Buddy in southern ca built a 6 footer.
The club does a "field trip" down to Rock Castle annually, it's the 27th this year, pretty sure I'll go. Joe feeds us lunch and all the rock on the huge pile is 50 cents a lb, and he donates an equal weight to the club, Found some decent large wood chunks last tima and a member found a nice fire agate piece.
“If history could teach us anything, it would be that private property is inextricably linked with civilization.” - Ludwig Von Mises
How large of a piece can you polish with that beast?
Can you remove an arm of the sweep to do larger pieces?
Once you have had it up and running for awhile, it would be interesting to know the grit steps you use and how long it takes.
The sweep can come off to do larger slabs, but I have 30 inch flat lap with no sweep on it. NOw I will only use it for larger pieces. I will only use this to get rid of saw marks and such. I use grade 180 grit. Once i am happy with the surface it goes a texas rocks bull wheel, starting with 100 grit bellt, then 200 grit, and finially 400 grit. From there it will go to a 24 inch flat polishing machine with a cerium oxide slurry on a wool pad.
I haven't measured it very close but with the sweeps on it will hand 12 inches maybe more.
Last Edit: May 12, 2017 19:20:53 GMT -5 by woodman
woodman, your machine looks like a Bob Strayer machine (he has passed- Joe Cota knew him well). I also have one like that, not made by Bob but by a fabricator in central Oregon. I cannot understand why these machines are not more popular. Sounds like we process our stuff the same way; grinding lap, bull wheel, flat polishing lap.
You machine was designed by Bob to be a grinding lap. Grit range used on the lap from people I know that use them is 120-220. Some of you who may have noticed the counter-rotating top platter is not centered over the bottom plate. This was by design, to help avoid wearing the plate in one place. The centerlines of the top shaft and plate are the same- the oscillating motion is achieved by making the angle iron arms on the top platter different lengths. This moves the rocks 2-3 inches back and forth across the plate.
My machine has an upgrade over Bob's original design- I had the plate fabricated from AR (abrasion resistant) steel. I actually do not need to turn on the upper motor at all. The upper rotating system is only to move the specimens back and forth across the plate, not to reduce grind time. I run my pieces the same amount of time either way. My next grinder will not use the upper motor assembly at all.
The nice thing about this machine is how much quicker the bull wheel sanding goes when you start with a flat specimen. I do not waste time trying to remove scratches or grooves on the bull wheel. After a few seconds on the bull wheel with 100 grit, I can tell if the sanding process is going to be too much work- if so, back to the grinder it goes. It also makes apparent how sharp and well-aligned your saw blade is.
Next to my polisher, this lap was the best lapidary $ I've spent. When I think of the hours I've spent on vibrating laps trying to get them working, keep them from marching around my shop smashing up everything in sight, cleaning the splatter off everything within ten feet, these laps are a dream. I can grind on this machine in one hour what took eight hours on the vibrator. Polishing is even faster- it takes about 30 minutes to polish whhat took eight hours on the vibrating lap. I can final polish 100 pieces a day easy on the polisher.
If you intend to stay in lapidary or just want to ramp up your production I cannot recommend these machines too highly. They are quiet and reliable. Don't say you don't have space- nix your dining room table, and just throw a sheet of plywood over the machine when you have company. You wife can hang pots and kitchen doodads from the top part. Yes, I am married.
I have some friends using the aR steel, works good and like you say you can probably get away with out turning on the top motor. But I would still have the sweep to hold the slabs. I recon it could be stationary alright.
"Some of you who may have noticed the counter-rotating top platter is not centered over the bottom plate. This was by design, to help avoid wearing the plate in one place. The centerlines of the top shaft and plate are the same- the oscillating motion is achieved by making the angle iron arms on the top platter different lengths. This moves the rocks 2-3 inches back and forth across the plate."
Does not your statement contradict itself? The sweep shaft is not centered over the center of the lap plate. It is offset to give back and forth motion. The angle iron arms on this machine are all the same length, 17 inches. I can vary the amount of back and forth motion by whee the sweep shaft is placed in relation to the center of the lapping plate.
woodman, your machine looks like a Bob Strayer machine (he has passed- Joe Cota knew him well). I also have one like that, not made by Bob but by a fabricator in central Oregon. I cannot understand why these machines are not more popular. Sounds like we process our stuff the same way; grinding lap, bull wheel, flat polishing lap.
You machine was designed by Bob to be a grinding lap. Grit range used on the lap from people I know that use them is 120-220. Some of you who may have noticed the counter-rotating top platter is not centered over the bottom plate. This was by design, to help avoid wearing the plate in one place. The centerlines of the top shaft and plate are the same- the oscillating motion is achieved by making the angle iron arms on the top platter different lengths. This moves the rocks 2-3 inches back and forth across the plate.
My machine has an upgrade over Bob's original design- I had the plate fabricated from AR (abrasion resistant) steel. I actually do not need to turn on the upper motor at all. The upper rotating system is only to move the specimens back and forth across the plate, not to reduce grind time. I run my pieces the same amount of time either way. My next grinder will not use the upper motor assembly at all.
The nice thing about this machine is how much quicker the bull wheel sanding goes when you start with a flat specimen. I do not waste time trying to remove scratches or grooves on the bull wheel. After a few seconds on the bull wheel with 100 grit, I can tell if the sanding process is going to be too much work- if so, back to the grinder it goes. It also makes apparent how sharp and well-aligned your saw blade is.
Next to my polisher, this lap was the best lapidary $ I've spent. When I think of the hours I've spent on vibrating laps trying to get them working, keep them from marching around my shop smashing up everything in sight, cleaning the splatter off everything within ten feet, these laps are a dream. I can grind on this machine in one hour what took eight hours on the vibrator. Polishing is even faster- it takes about 30 minutes to polish whhat took eight hours on the vibrating lap. I can final polish 100 pieces a day easy on the polisher.
If you intend to stay in lapidary or just want to ramp up your production I cannot recommend these machines too highly. They are quiet and reliable. Don't say you don't have space- nix your dining room table, and just throw a sheet of plywood over the machine when you have company. You wife can hang pots and kitchen doodads from the top part. Yes, I am married.
Can I ask you guys why you use this 3 machine process to face polish a specimen (grinder, bull wheel, flat polishing lap)? I recently purchased a covington vibrating flat lap, and using 150 grit, 500 grit, and AO polish, I've used solely this machine to polish the specimen, and although the polish is okay, it is not a mirror polish.
Hoping to get some advise on why you use a bull wheel for the middle of the process, and what kind of machine you are referring to for the polishing lap?
doublet, I use the sequence of machines for productivity. The bull wheel is very fast, particularly when sanding a ground slab. I get a super polish on the big flat lap, which I like to have because selling the rocks is my business. The vibrating lap is capable of a nice polish, but it requires a lot of babysitting and is not suitable for production work.
doublet, I use the sequence of machines for productivity. The bull wheel is very fast, particularly when sanding a ground slab. I get a super polish on the big flat lap, which I like to have because selling the rocks is my business. The vibrating lap is capable of a nice polish, but it requires a lot of babysitting and is not suitable for production work.
Ah ok sounds like its mostly for speed.
I just leave the vibrating lap on the original card board box that it came in when its running, which seems to stop it from moving around or making a mess.
"Hoping to get some advise on why you use a bull wheel for the middle of the process, and what kind of machine you are referring to for the polishing lap? "
The lapping machine leaves a pretty rough surface, I use 180 graded grit, friends use 120. By using the bull wheel with 100 grit and 200 and then 400 you can do a lot of material pretty fast. I am not a production shop but I can be lapping while i am sanding the last batch and while having the polisher running at the same time. I had a vibe lap and it was one step on one piece of rock and it took forever.
video is my 24 inch polisher running, only one chunk of petrifed wood but you can load it up pretty good.
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Welcome to the Rock Tumbling Hobby Forum where we share a love of rocks and a sense of community as enduring as the stones we polish.
The RTH Forum of www.RockTumbling.com is an Amazon Associate site and we earn money from
qualifying purchases you make after clicking on our links such as this
Rock Tumbling Supplies on Amazon
link for instance, or any of our various product ads and banners. By clicking our links every time you begin your Amazon shopping
experience, you are generating a bit of revenue for the forum which helps us cover our expenses. Thank you for your support!