Post by rykk on Nov 4, 2013 15:30:10 GMT -5
Hi, all. Finally getting around to putting this up. I've had a 20" Lortone FL-20 jiggle pan (vibrating lap) for a little over 3 years. Worked pretty well but had problems with its propensity to hop the pan up and down along with its horizontal wiggle.
So I set about to do something about it! I hatched a plan right here (hollow sound as the boy raps his cranium) in my own quasi brain-ish type matter to turn the Lortone into something resembling a Reciprolap.... at a mere fraction of the price. Not counting the original lap that I bought very cheap - and VERY used - I have about $90 in this mod.
First, I got a shaft with one end offset by 3mm made by an awesome member of this list who lives in Georgia. I'm really sorry I can't remember his handle - the history seems to only go back to the date this board was updated to version 5. Something "dad" was/is his handle. It's super well made and I really appreciated him machining it for me at such a reasonable price. It was over a year ago. Anyhow, here be pix with some verbage:
Ok, so here's the top view. Been using it a lot, as y'all can tell.
I installed two lengths of angle iron across the top of the Lortone base shell so as to be able to mount an angle bracket to which 2 1" bearings and the offset shaft are mounted, along with a 120Vac fan to cool the motor beneath it. (Florida = Brutal heat!) You can see the offset at the end of the shaft.
The 3 thingies sticking up where the balls used to be are 2 1/4" tall by 1 1/2" diameter rubber shock mounts. There's a 1/4-20 threaded stub that holds them to the base and 1/4-20 threaded holes on the top that I screwed down the pan base to.
The pan holder base now has a 3/4", 4-bolt pillow block bearing mounted to the underside that the offset end fits into - no need for the set screw, just lifts off the rubbers after taking out the 3 screws.
And I made a counterweight installed directly opposite the shaft offset to smooth things out. Not as big as the Reciprolap counterweight because the Lortone pan is aluminum, not heavy steel.
And here's a view from the bottom. I mounted a new, 1/7hp motor - 2 screws to the lip of the base and one to a length of angle iron I had to install across the bottom for the motor to attach to. Its angled to allow for the shaft and pulley, which are dead centered... ish. :-) The original 1/15hp was too wimpy to spin against the 3 rubber shock mounts.
You can see the motor and, also, a spring loaded tensioner pulley for the belt. (spring not pictured... because I didn't even think of having one until it became apparent I couldn't keep the tensioner from creeping during operation)
You can also see the big angle bracket and bearings. I cut the bracket from a steel computer holder that they threw a few out where I worked - freebie!
And a couple more pix:
The wooden hexagon with padded feet was to stabilize the unit and also so that the various shafts and pulleys wouldn't grind against the floor. I did add a counterweight opposite the offset shaft to minimize walking but still had to prop two sides with some big, heavy chunks of schist/pegmatite covered with quartz crystal points to keep it still.
The thing works a whole lot better than the original design and rough grinds go (sorta - I'll explain...) much faster as the rocks now can't hop and spend 100% of their time in horizontal motion with no wasted vertical motion.
Now, as to it being faster. As some members have said about their reciprocal jiggies, yes it is much faster than the spinning weight design. At least nominally on paper the manufacturers supply. HOWEVER. I soon found that 6 hour per grit grinds produced very unsatisfactory polish results.
Here's why: While the reciprocal action is more efficient and eats rock away faster, it still requires much longer grind times to break the grit down to smaller sizes to smooth out the rock enough. Yes, you can remove all saw slashes in no time flat, but the 60-90 grit may only have worn down to maybe 110 in 4 to 6 hours. If you then go to 220 for 4-6 hours, that grit breaks down quickly to where it can't make up for what was left undone by the rough grind. And this "error term" increases linearly as you progress until, after a "short" 600 grind, the rock isn't even near "pre-polish".
Once I figured that out and went back to the old 16 or so hour grinds, the polish was very noticeably better than anything the old design had achieved and I'm one happy, Cyborg Sammy the rock-droid!
C-ya,
Rick
So I set about to do something about it! I hatched a plan right here (hollow sound as the boy raps his cranium) in my own quasi brain-ish type matter to turn the Lortone into something resembling a Reciprolap.... at a mere fraction of the price. Not counting the original lap that I bought very cheap - and VERY used - I have about $90 in this mod.
First, I got a shaft with one end offset by 3mm made by an awesome member of this list who lives in Georgia. I'm really sorry I can't remember his handle - the history seems to only go back to the date this board was updated to version 5. Something "dad" was/is his handle. It's super well made and I really appreciated him machining it for me at such a reasonable price. It was over a year ago. Anyhow, here be pix with some verbage:
Ok, so here's the top view. Been using it a lot, as y'all can tell.
I installed two lengths of angle iron across the top of the Lortone base shell so as to be able to mount an angle bracket to which 2 1" bearings and the offset shaft are mounted, along with a 120Vac fan to cool the motor beneath it. (Florida = Brutal heat!) You can see the offset at the end of the shaft.
The 3 thingies sticking up where the balls used to be are 2 1/4" tall by 1 1/2" diameter rubber shock mounts. There's a 1/4-20 threaded stub that holds them to the base and 1/4-20 threaded holes on the top that I screwed down the pan base to.
The pan holder base now has a 3/4", 4-bolt pillow block bearing mounted to the underside that the offset end fits into - no need for the set screw, just lifts off the rubbers after taking out the 3 screws.
And I made a counterweight installed directly opposite the shaft offset to smooth things out. Not as big as the Reciprolap counterweight because the Lortone pan is aluminum, not heavy steel.
And here's a view from the bottom. I mounted a new, 1/7hp motor - 2 screws to the lip of the base and one to a length of angle iron I had to install across the bottom for the motor to attach to. Its angled to allow for the shaft and pulley, which are dead centered... ish. :-) The original 1/15hp was too wimpy to spin against the 3 rubber shock mounts.
You can see the motor and, also, a spring loaded tensioner pulley for the belt. (spring not pictured... because I didn't even think of having one until it became apparent I couldn't keep the tensioner from creeping during operation)
You can also see the big angle bracket and bearings. I cut the bracket from a steel computer holder that they threw a few out where I worked - freebie!
And a couple more pix:
The wooden hexagon with padded feet was to stabilize the unit and also so that the various shafts and pulleys wouldn't grind against the floor. I did add a counterweight opposite the offset shaft to minimize walking but still had to prop two sides with some big, heavy chunks of schist/pegmatite covered with quartz crystal points to keep it still.
The thing works a whole lot better than the original design and rough grinds go (sorta - I'll explain...) much faster as the rocks now can't hop and spend 100% of their time in horizontal motion with no wasted vertical motion.
Now, as to it being faster. As some members have said about their reciprocal jiggies, yes it is much faster than the spinning weight design. At least nominally on paper the manufacturers supply. HOWEVER. I soon found that 6 hour per grit grinds produced very unsatisfactory polish results.
Here's why: While the reciprocal action is more efficient and eats rock away faster, it still requires much longer grind times to break the grit down to smaller sizes to smooth out the rock enough. Yes, you can remove all saw slashes in no time flat, but the 60-90 grit may only have worn down to maybe 110 in 4 to 6 hours. If you then go to 220 for 4-6 hours, that grit breaks down quickly to where it can't make up for what was left undone by the rough grind. And this "error term" increases linearly as you progress until, after a "short" 600 grind, the rock isn't even near "pre-polish".
Once I figured that out and went back to the old 16 or so hour grinds, the polish was very noticeably better than anything the old design had achieved and I'm one happy, Cyborg Sammy the rock-droid!
C-ya,
Rick