Lapidary equipment purchased.......long

[inbtb]

Labor Day weekend I purchased some older used lapidary equipment. A Rock Rascal 6” trim saw that needs work. A B&I 6” Gem Maker flat lap that is running now but more on that in a little bit. A tumbler with no label so have no idea what it is. Tumbler came with 2 plastic barrels that are yellow and have removable rubber liners but only 1 lid. Tumbler needed a new belt which I had, so in went some rocks and grit and water and we off to the races, will check in a couple of days. Set-up of saw and lap is on a cabinet with the motor between the 2 running both only problem was could not keep belts tight. Purchased a motor on ebay ¼ hp, 1725 rpm frame has a hinge on one side so I figured I could put a long bolt on the other side so I could adjust belt tension. All good and run fine. Ordered some diamond disk laps from Jade Carver, ad stated disk needed to be placed on a metal blank, 1 of those came with the gem maker. Ready to grind filled water cup put a short piece of plastic tubing on spigot and turned on the water, but not sure as to how much water I should be using. Should I use a steady drip or a small steady stream. I then rigged a 2 liter Pepsi bottle to the water cup and a hose to the drain and now I can grind away and shape my stones and clean up some of the saw marks.

As far as disk speed the pulley on both motor and gem maker are 2.9”, Good, bad, do I need a different pulley on the motor end? Also how much pressure should I put on stones while grinding?

I tried the trim saw, blade is not very good. I found instructions for using the saw and they called for deodorized kerosene and light machine oil. I read some one recommended baby oil for small saws which I just happen to have. Oil in table back on saw, grab a rock turn on power and oil everywhere, over filled oil tank but it smelled good. Took quite awhile to cut a 1” rock. Cleaned up oil and started again oil leaks from between tank and saw table looks like it might be be warped. So for now I won’t be worrying about the saw. Sorry this is such a long read.
Les
Now some pictures.

lap


lap and drain


motor


saw 1


saw 2


Thanks for looking.

[captbob]

Looks like you made a good find there. Ought to keep you out of trouble for awhile!

Doesn't make sense that the saw "leaks" between the tank and table. Any oil slung around there ought to go to the back and that looks fine. Blade has seen better days.
You should only have a quarter inch or so of oil touching the saw blade. A half inch would probably be slinging oil everywhere.

When you can rustle up a new blade for that saw there will be nothing stopping ya!

[inbtb]

Hi Bob I think the leaks are at the dents in the top of the tank, where the red circles are. Also the saw table only has 1 screw and it does no tighten very tight. May have to make some kind of gasket to try and fill up were the dents are. Also need to work on the belt tension.

[tims]

I picked up the 10" version of the Gem Maker recently and it came with the cast iron lap plate. Is that what you've got with your 6"? How do the Jade Carver laps affix to your plate, are they magnetic?

Regarding rpms, does your 6" have a 4-step pulley on the shaft? I found a pdf copy of the owner's manual for the B&I 10" and it says to use the slowest speed for grinding, but states that it's to avoid throwing the grit off the plate. Since you're going to use a metal lap that shouldn't be an issue, but those run at 1000rpm max so you don't want to use it at a 1:1 pulley ratio from your 1700rpm motor. I'm not expert on pulley conversions but i think (get a second opinion) you'd want the pulley on your Gem Maker to be about twice the diameter of the pulley on your motor to run at a safe speed of ~850ish rpm.

[inbtb]

The diamond disk fit a 1/2" arbor so the nut and washer that hold the plate on is used to hold the diamond disk on.

As far as the pulleys go I have no idea if the pulley on the Gem Maker is the original but it is only a single step. The motor that came with this set-up when I bought it has a smaller pulley that I could probably move to the motor I am using. I'll check the pulley size later today. I found that pdf also and there is some stuff on the 10" that is not on the 6". I did get the clamp for use while cutting stones but no saw blade.

[tims]

No saw blade with mine either ... I picked up a 5/8" to 1/2" arbor bushing and will probably try an MK 303 when i get some spending cash.

I like your 2L bottle coolant expansion. For water flow and pressure while grinding you'll probably need to experiment but too wet is probably better than too dry. Good luck and i hope to see some of your results.

[inbtb]

Thanks. All my equipment is outside or in unheated space so if I'm lucky I'll have about 2 months before it is to cold to play in the water. I have 3 diamond disk now a 80 grit a 180 and a 360, need to buy some of their finer grit disk but that purchase is going to have to wait for awhile. Should be able to get some preforms cut for the tumbler before it is to cold. Good luck with your 10". Post some pics here if you get a chance. Use this thread if you want.

[quartz]

My Rock Rascal has a cast extension much like a sleeve about an inch long on the underside of the table that fits the machine base quite closely, eliminating leaks. Does yours not have the extension?

[inbtb]

Sept 22, 2016 0:20:54 GMT -5 quartz said:

My Rock Rascal has a cast extension much like a sleeve about an inch long on the underside of the table that fits the machine base quite closely, eliminating leaks. Does yours not have the extension?

Yes mine has the extension, but either the top has been dropped or the roughness of the tank top does for some reason not allow the top to seal very tight. Or as captbob said I overfilled with oil.

[tims]

Sept 20, 2016 8:09:08 GMT -5 inbtb said:

Thanks. All my equipment is outside or in unheated space so if I'm lucky I'll have about 2 months before it is to cold to play in the water. I have 3 diamond disk now a 80 grit a 180 and a 360, need to buy some of their finer grit disk but that purchase is going to have to wait for awhile. Should be able to get some preforms cut for the tumbler before it is to cold. Good luck with your 10". Post some pics here if you get a chance. Use this thread if you want.

Here's a dry run with the lap plate:


I got an MK-303 blade and did one cut last evening; it took about 90 minutes to cut through a 1.5" x 3" chert. Thinking maybe i need more weight on the gravity feed. Does yours have a weight setup attached to the clamp for an auto feed? Are you planning to use it as a saw or just stick with the lap?

A minute of cutting:


I definitely need to buy a 2L bottle of something, had to fill that cup about 20 times for the 1 cut

Hope your machines are coming along, and am looking forward to seeing what you do with them.

[inbtb]

Mine is not set up for any kind of mechanical feed, hand feed only. I did get a 5 inch saw blade but have not tried to cut anything with it, the angles just did not look right to me so I decided to wait until later to try cutting. Right know just using as a lap but I did some grinding Monday and water sat in garage over night and after about an hour fingers started getting stiff so probably am about done for the year but will keep eye open for warmer days. Got a new blade for the Rock Rascal and had to turn motor around so I would not have put a twist in drive belt. Saw cuts better with new blade and looks like it will work a lot better know. Not getting all the oil splash now so must have had to much oil in before. I think things are in pretty good shape now so should be able to do some cutting and shaping as I get the time.

Les

[barclay]

90 min for a 1" x 3" piece if chert is way too long. I would also check the tension on the belt.

[Peruano]

Its almost a given that you had too much oil in the Rock Rascal. Fire it up with coolant at the lowest level and then add slowly until the blade begins to hurl enough to form a detectable line of oil in front of the saw blade. Or as stated no more than 1/4" up on saw blade. Oh did I say place it in an area where you can afford a bit of oil spray and to buy Oil-dri at Walmart (cheap and works like a champ).
I have the same 6" antique gem lap and have never conceived how to effectively cut with it even though I have the vice that came with it. When lapping I have to slow it down to keep it from hurling the stone across the room. If I sawed at speeds that would not sling the rock, it would take 90 minutes or longer. At saw blade speeds it would be slinging water, oil, and the finished slab. So I'd use the Rock Rascal (or any other real saw) for cutting and the lap for polishing. I may be polishing at too slow speed, because I'm still not satisfied with my results but at least the stone is under control.
You don't need much water for lapping. I use an irrigation sprinkler valve to regulate a gravity feed source, Yes a constant stream but a 2 uart supply should last longer than you want to hold the stone on the disc. I'm presuming that the vertical mounting of a motor designed to be deployed horizontally will be ok for light duty, but I've always heard the the vertical position will cause excess bearing wear in the long run. I rigged mine with a long twisted belt allowing the direction of rotation to go from vertical to horizontal.

[inbtb]

I'm new to this stuff so am always open to tips, hints, and corrections. I guess I'll have to keep an eyes open for bearing problems, thanks for the tip.

[tims]

Mounting my motor horizontally seemed weird but with a decent length belt it seems to work fine.

barclay I think my belt tension is ok --- it doesn't seem to slip or anything, but i'm new to belts and pulleys so if you see an obvious problem please let me know. I had a couple interruptions but the saw ran continuously for at least 40 minutes and nothing seemed to get hot.

[barclay]

Sept 30, 2016 21:16:58 GMT -5 tims said:

Mounting my motor horizontally seemed weird but with a decent length belt it seems to work fine.

barclay I think my belt tension is ok --- it doesn't seem to slip or anything, but i'm new to belts and pulleys so if you see an obvious problem please let me know. I had a couple interruptions but the saw ran continuously for at least 40 minutes and nothing seemed to get hot.

Belt tension is a funny thing. Too little and the saw slows down while cutting. Too much and you start pulling things out of alignment. I am not sure how much tension you are supposed to have. i guess when the blade starts to cut the stone does it sound like the blade is slowing down? I am not familiar with this device so I don't know how much pressure the stone is putting on the blade. An old timer told me once, "we don't cut stones. we sand over very small surface areas".

[tims]

Hey barclay, there's no noticeable change in speed when the blade contacts the stone. My belt is brand new so i have it pretty tight but i don't think it's enough to do any harm, the rod on this runs through a 3" or so brass bearing sleeve so i think you'd really need to torque on it to pull it out of alignment.

I've been too busy to try another cut but next time will try more weight on the feed (5# or so) and see if that makes a difference. I've got myself convinced it's just feeding to lightly / slowly.