Lapidaryforum.net
Gadgets, Gizmos, and Dohickeys => Fixing, Modifying and Refurbishing your Lapidary Equipment => Topic started by: Old Timer on July 14, 2020, 05:53:02 PM
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I am trying to resurrect this piece of equipment I got maybe 20 years ago at a rock club auction. The bearings sound a bit dry but no play. I have removed the wheels and have it down to the allen wrench rings before the bearing dust caps. I can move one of them but the other is pretty tight after backing out the allen screw. So first question is am I wasting my time with this thing? I think all I need is maybe bearings, rubber for the wheels and off course sanding belts and a polishing pad. I will need to mount it, set up a drip and get a motor for it (1/2 HP 1750rpm?). The sanding belts look like the fold into the wheel some how which looks different from the new ones I see. I have an old Lortone 10" saw that I use to cut mainly agatized coral geodes so I thought I could polish them with this. I have a lot of geodes from many years of collecting so I got plenty to keep me busy.
With all this hanging around the house from covid I got a little more time for these projects :icon_thumleft:
Thanks for any advice, help, etc.
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Those bump wheels need to go. New expando drums are the way to go and the polishing pad on the end is fairly useless in reality. A unit with two expando wheels that are easy to change the belts is a fine way to go. Slash guards can be made or bought and you will need a water drip system . A third horse motor is also fine You may want to jury rig a belt guard. You have lots of room to move your work around with these units and if the bearing is fine you will have a great tool.
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Yeah, an old Poly arbor is a great thing to have. The expando drums, trays and spray shields, a small fountain pump, and the 1/3 hp motor would set you up for whatever you want to do. The silicon carbide belts are inexpensive, so no worries there.
For around $300 you'd have a unit that would cost a lot more if you bought one new.
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Thanks for the advice. Do the bearings require any lubrication? Maybe that is all they need from sitting for so long.
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When I was a kid my dad got a 6 wheel set, 1/3 HP worked fine.This was around 1960/1961. It had an end polishing pad, that worked fine, too. If those sanding wheels are 4" wide, good luck finding belts, unless that width sanding belt has come back, the expando wheel will be a smoother ride, although used that old kind for many years. A lot of inprovements since then. Have a good time with it.
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Welcome to the forum Old Timer!
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Those old Poly units were the very best you could get and are still very desirable. I run four of them for eight wheels total but have updated them to expandos. For thunder eggs, bump wheels are fine and you can cut your own wetordry belts. They are the cheapest way to go. For geodes though, I would upgrade to expandos to protect fragile hollows. The polishing pad is still a valid final step. I would keep it. You will get smoother operation using multilink belts instead of a standard v-belt. The bearings are sealed units so there is no way to lubricate them. If they run free with no play, then go ahead and use them until the noise becomes objectionable. If you want to replace them, the number on the race is an easy way to go. Take that to any bearing supplier and they can get new ones. For the stuck collar, you can soak it in a penetrating oil for a few days and it may break loose. For the record, WD40 is not penetrating oil.
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Thanks for all the great advice. When I was about 12 years old in 1972 we had a rock shop in Jacksonville, Fla. run by the nicest folks, Pappy and Dottie Geiss (I probably spelled their names wrong). They would let me and my brother come in a polish our geodes on a set up much like this one. I think they charged us 2 bucks a day, that probably barely covered the electricity. Great people who started me off on a life long hobby. I have been a digger most of my life and just piled the rocks up (as many of us do). Finely my wife got tired of the rocks taking over so she started a gem tree business using what I did not keep for tree bases. She no longer does it but at least it thinned some of it out a little bit. I mainly hunted mineral specimens in the southeast all these years but living in North Florida the agatized coral was close by. Unfortunately as many here know hunting rocks and minerals has gotten really difficult since we were younger. Very sad. So with less places to dig and the hair getting thin thought I would start doing more lapidary stuff. I now live in Western North Carolina and really need to find someone with a big saw. I have some geodes that are over a foot round that I would like to get cut. If anyone knows a rock shop or individual with this capacity in this area let me know as I would not mind paying to get some of these cut. Thanks again for the help.
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Hey Old Timer. I have 3 Poly grinders and am in the middle of tearing them all down to clean up. I need to polish the shafts, replace the belts, file some battle scars off the pulleys as well. I am attaching a pic of the shaft to show where you will have problems with the bearing removal. It will show you the damage that's done from the set-screws. Take a very fine (maybe a nickel titanium) file and very gently remove the burr from the shaft. There are times you may need to "drive" the shaft, & caution you if that's something that you have never done before. Removing the shaft completely Will give you a chance to inspect it & polish it up before re-installing it. You need to remove at least one bearing in order to replace that old worn out belt. Be careful with those pulleys, mine have some dings in them probably from Someone years ago prying on them. The nicks on a pulley will tear apart a belt faster than you can imagine! Good luck with your venture.
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So with Christmas around the corner the wife said she will get me the expando drums I need. Are there different sizes, shaft sizes, etc.? Different brands? What do you get the most bang for your buck with? In other words looking at what I got exactly what do I need? I have been running my Lortone 10" saw cutting agatized coral geodes and need to get to polishing :grin:
Oh thanks for the advice too GeoTech. I will keep all that in mind.
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Measure the clearance between center of shaft and mounting surface. That is the absolute maximum radius of drum without a riser. Check the shaft diameter. Now look at expandos and see what sizes are available for that shaft. Shaft size, IE bearing size, is the real limiting factor. For that reason you will not find ten inch wheels with 1/2" bore. The poly arbors were thicker castings than the competition so whatever drum you can find to fit the shaft will be fine.
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OK I think I understand what you are saying and that makes sense. Thanks for the help.
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So it looks like I can use a 8" X 3" expando drum. I have a 3/4"arbor. There are quite a few manufacturers for these and I want to make sure I can get the silicon carbide belts, etc. easily. There is one out there made by a company called Hans. Anybody have any experience with these or are the ones say from Kingsley and the like better quality since they are quite a bit more expensive. The Hans one runs a bit over 70 bucks and the Kingsley North are 115 bucks. I am mainly polishing geodes. Excuse my stupidity :Worthy:
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I've been using Hans neoprene backed belts for years. They last far longer than the more expensive variety and they have enough stiffness to put a 3" wide belt on a 2" drum. One caveat. They tend to run small ID. It makes them very difficult to change. In my case, not a problem since I have dedicated wheels.
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Never heard of Hans. Will check it out, if you can save money, always good.
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Hey GeoTech,
I finally got my Poly unit apart as I had to put a new belt on it. Man it was tough. It has sat for probably 30 years. I think the combination of soaking everything down with PB-Blaster and leaving it out in below freezing temps helped. I did bugger up the first 2 threads on the shaft and a bearing. I think I can work on the shaft but can't seem to find anything online about the bearings. My bearings do not have set screws. They have a number 88 A 3/4 with the letters ND also on them. Any idea on how I can find these? As I said can't seem to find any online with these numbers. I may need to go somewhere with lots of bearings and see if they can match them.
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OK correction here. The bearings do not have set screws but there is another piece (collar) between the bearing and the drum that does. I really had practically given up on this thing. The pulley has a set screw but even after taking it out that pulley was froze on that shaft pretty good. I guess if I could provide some advice on this thing again I would say soak it down with PB Blaster and let it set for awhile and then maybe put the whole thing in the freezer :thumbsup:
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Hans is in China so it can be a while to get your order filled. I use Johnson Brothers in California. I have compared a few of the expando wheels and they all look identical so they are all probably made in China. I have been doing a lot of lapidary over many years and I use the expando wheels and silicon Carbide belts. I never throw one away because it is worn, only when the seam fails. I have a homemade lapidary machine with two 8" diamond grinding wheels and one expando wheel.
Bob
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Thx,
I saw a few of the Hans wheels on amazon. Still may need to come from China but heck I have had this thing for 25 years sitting so what's a little more time.