llanago
fully equipped rock polisher
Member since January 2004
Posts: 1,714
|
Post by llanago on Sept 28, 2004 0:22:18 GMT -5
I put on my 220 belt a while ago and started playing around with it. It broke and flew off the drum! Needless to say, scared the crap out of me! Anyhoo, gotta order a new belt. Does this happen often? This was suppose to be a new belt. I have discs in all sizes also, so waiting on a new belt won't slow me down any! When I start using the 220, 400, 600, and 1200 diamond disc, how long should I use those grits on the stone? It would seem to me that it wouldn't be very long cause it doesn't take very long on the 100 grit wheel to shape the stone. Or should I just get a loupe and look at the stones as I go? Of course, I really don't know what to look for, so I am not sure that would help! llana
|
|
|
Post by sandsman1 on Sept 28, 2004 0:43:00 GMT -5
llana as i go i just dry the stone and look at it you can se the scratches when its dry and when there small and only a few i move to the next stepyou will see the depth of the scratches with each grit change so you can kinda tell when its ready for next gritsome time you cant get a couple out just go back a grit ---i find that an easy touch after 100gt works best for me it takes alittle longer but in the long run you dont hafta go back as much and reshape when i first started i was pushing too hard on the 220 grit and it was changing the shape and i had to go back alot to 100gt
i necer had one pop yet but it was prob old and the glue gave out
|
|
|
Post by stoner on Sept 28, 2004 21:13:50 GMT -5
Hi llana. Grinding rocks is just like sanding wood. If ya think along those lines, you should be ok. Use rough for shaping, then go on to finer grits and eventually to polish. Actually, it's just like tumbling stones, except you're doing it manually. And it's more fun! So go have some fun and grind away.
Ed
|
|
llanago
fully equipped rock polisher
Member since January 2004
Posts: 1,714
|
Post by llanago on Sept 28, 2004 21:45:05 GMT -5
Hmmmm, I never thought of it as like sanding wood. Have done alot of that, so I should be able to do alot of sanding rocks! LOL!
Another question here. I put on my 220 disc and it works great. Put my 400 belt on the expanding drum and tightened down the nut. The drum is on tight and doesn't wobble or anything, but the belt is loose. Seems like the drum didn't expand or something. I can just slip this belt on and off without untightening the nut. The 220 belt was really hard to get off, then back on. Was it just too tight and that's why it broke, or is this one too loose?
llana
|
|
|
Post by stoner on Sept 29, 2004 2:01:37 GMT -5
Hi llana. I don't know what kind of grinder you have, but I was under the impression that the expandable drums made for lapidary grinders use centrifigual force to hold the belt in place. As the motor gets up to speed, drum expands and holds the belt, and when the drum stops turning, the belt is loose enough to remove. Is it a variable speed grinder? Maybe it's running too slow to push out against the belt. If you have another belt, try it too. Could be that one belt is just a wee too long.
Ed
|
|
|
Post by sandsman1 on Sept 29, 2004 2:33:20 GMT -5
there is another kind of expanding drum ive not seen one in person but it tightins with a bolt or screw as you turn it it expands and holds the belt i think its an old style drum but i dont know much about them maybe someone else knows better
|
|
llanago
fully equipped rock polisher
Member since January 2004
Posts: 1,714
|
Post by llanago on Sept 29, 2004 8:57:27 GMT -5
I was under the impression that the expandable drums made for lapidary grinders use centrifigual force to hold the belt in place. As the motor gets up to speed, drum expands and holds the beltThanks Stoner. After I posted this question, I wondered if that might be the case. I did a bit of grinding with it last night and the belt didn't slip off to the side or anything, so that must be what happens. I will try another belt, though, and see if it is tighter. I don't have a variable speed sander, but I do have three wheels for the belt. Have to admit, thus far, I am not sure how that works yet, so any info you have to depart on that will be appreciated. My logic, which sometimes ain't so logic, tells me that the small wheel would be the fastest speed. That is what I have been using for the initial grinding. I have a book, Gem Cutting, A Lapidary's Manual by John Sinkankas, that the guy I got the grinder from recommended and I keep hoping I will come across something in it that explains the wheel thingys but so far haven't found anything. I have the same kind of grinder Sands has, a Lortone AS8, and I think he told me he uses the smaller belt wheel for everything. I may never get past the 220 stage! I put the 220 disc on last night and in the process of sanding the cross, the rubber pad the disc sticks on flew apart! Surprisingly enough, the disc wasn't damaged, but the rubber pad is sure a mess. It looked like it needed to be replaced when I got the grinder and I should have bought a new one when I ordered the discs, but I didn't. So now I am hold on the 220 until I get another one. Ordered one and another 220 belt last night, so I can just keep grinding out new ones til I get them. Or, I could finishing painting the bathroom and get the tile down. A project I started over the weekend, but pushed aside to sit at the grinder. Grinding is alot more fun! llana
|
|
|
Post by BearCreekLapidary on Sept 30, 2004 9:45:08 GMT -5
Hello Llana,
Check your sanding drum ... on some types, if they are put on backwards ... they will not expand to conform to your belt and keep it in place. You might just have the drum on backwards ... and yes, it is a common situation.
There are drums that have slots in the rubber that expand when turned on, there are drums that have a slot cut into the drum that an aluminum dowel holds the sanding paper in place with and there are some older drums that have two small bolts in this inside of the drum that holds the paper ... which kind do you have?
Are you using pressure sensitive discs (which use an adhesive to keep them in place) for your polishing/sanding pad?
Hope this helps, send me an IM if there is anything else that I might be able to help with.
Take care,
John
|
|
llanago
fully equipped rock polisher
Member since January 2004
Posts: 1,714
|
Post by llanago on Oct 1, 2004 23:20:02 GMT -5
Bear, I have the kind of drum with the slots in the rubber. One of the first things I did was make sure I had it on correctly.
I guess my disc is pressure sensitive. The pad that flew off appears to have been glued on. The guy I bought it from included a polishing pad that has to be glued on, if that helps any! I used contact glue to glue the disc on and it was on there pretty firm. I think what happened is that I didn't get the disc on the pad evenly. I was sanding on the cross I made and I think I must have missed grinding a spot completely smooth and it caught the edge of the rubber pad. The disc was not damaged at all and was still glued firmly to the half of the pad that was still there.
Anyhoo, got the new pad I ordered today, along with a new 220 belt for the expanding drum, so I am ready to go again. Before I start grinding again, I HAVE to cut some splash guards and get them on. I bought a small piece of plexiglass to make them with, just haven't gotten around to getting out the jig saw, cutting it and putting it on the grinder. Need to do that so I can stop wearing my garbage bag shirt. LOL!
llana
|
|