rykk
spending too much on rocks
Member since September 2011
Posts: 428
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Post by rykk on Mar 18, 2012 2:17:00 GMT -5
Hi, y'all - Ok, so the original bearing (Sealmaster L-12 with 3-bolt stamped flanges) in my 20" Lortone vibe lap bit the dust. I replaced it with a 4-bolt pillow block/mounted bearing that started really quiet but lasted only 12 hours b4 it made 2 much racket (it came loose from the block - too much up/down "end thrust" A locking shaft collar would'a helped but there's really no room on the shaft ) and so I finally found a replacement Sealmaster L-12, spent half a day trying to get the rig to spin without binding and.... quiet as a humming mouse.....for 20 seconds. It's nowhere near as loud as the last 2 failed bearings but the rig makes sort of a hammering sound from the eccentric load attached to the motor shaft. I'm guessing this is - to some extent - to be expected but I'm unsure. Does anyone have or used to an older Lortone vibe lap and could you tell me how much noise one should make? I reckon they aren't super quiet at best. There's a low pitched ringing hum from the pan resonating but the hammering is what worries me. I suppose it *might* be from up-down/in-out vibration due to maybe the chunk of metal not being perfectly perpendicular to the motor shaft. Can't imagine a way to help that, though this bearing shouldn't pop out of the mount like the pillow block did. The reason I'm focusing on end thrust noise is that I had to put washers between the two stamped metal flanges to allow the shaft to spin freely. Any slight misalignment caused by clamping the bearing down super tight without them causes binding, friction, HEAT. Anyhow, the bearing seems to be tight enough and hasn't worked loose but that's the only thing I can think of that might cause a hammering noise. This all said, the rig has hammered since i first got it but I've never liked it. What also helps with the free spin on this setup is to adjust the 4 mounting nuts on the motor. A real p.i.t.a.! I've attached a pic of the bearing/flange mounted on like 1/2in standoffs to the motor plate in case anyone wants to look and maybe tell me if this setup is how the Lortones are really *supposed* to be. The gap between the flanges in the pic is much wider than actual as i tried lock washers first since I didn't have to get up (aaargh - work!!) and go to the garage and find them. :-) I ended up using thin flat washers. When I 1st got this vibe, it didn't have the washers. I was able to adjust the motor screws/nuts to get it level and free. This time around, I did that but adding the washers freed it up a lot extra. Thanks - sorry for such a long post, Rick Attachments:
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Post by johnjsgems on Mar 18, 2012 8:37:42 GMT -5
I never worked on the one I had but replaced many bearings in 30 years of HVAC/R work. Main bearing killer was a worn shaft surface. New bearings on worn shaft lasted no time at all. I spent lots of late nights/weekends reversing shafts in units to get a new surface under the bearings when a new shaft was not available. You could call Lortone for advice. They are generally very helpful and replacement parts are reasonable.
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rykk
spending too much on rocks
Member since September 2011
Posts: 428
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Post by rykk on Mar 18, 2012 10:50:00 GMT -5
Thanks - I'd read here that they were the opposite. I tried to call once but the lady couldn't help because the "engineer" took the day off. I'll try again.
The shaft looks ok, though there was a small ding near the end opposite the flat that I had to file down so that the bearing would slide onto the shaft easier - getting it off was a little hard and I certainly needed to take it off a few times whilst tweaking. The bearing on it now is brand new out of the box yesterday.
As I listen today, it IS much quieter than when the last two were going bad. I have no idea how old the one that came with it was; probably years since this is a pretty well used lap. BTW - the sound it makes resembles a diesel truck at idle. Just trying to see if that is the norm for this lap or if I have to dork with it some more. it's like I can get the thing to just purr but only for a short while. The pillow block was quiet for an hour but got louder and the racket was unbearable after a day or two - since the thing had popped loose of the block, I reckon it was slamming up and down. I would have liked to put a much heavier bearing on it but couldn't find a shaft reducer insert bigger than the 3/4" (the bearing's bore size) to 3/8" (the motor shaft size) that's on it now. General duty bearings go no smaller than 1" bore and the heavy duties are even bigger. C-ya, Rick
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Post by johnjsgems on Mar 18, 2012 11:36:00 GMT -5
3/4" bearings are pretty heavy duty. A ding won't matter. I installed lots of bearings over keyways with no problem. Main thing is od must be close tolerance. I sold mine too long ago to remember what it sounded like.
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rockhound97058
freely admits to licking rocks
Thundereggs - Oregons Official State Rock!
Member since January 2006
Posts: 760
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Post by rockhound97058 on Mar 18, 2012 21:53:38 GMT -5
Good Luck! I have the exact same machine I have used for years. Same problem I had a bearing go out... I then found a very close replacement which was a Massey Freguson tractor bearing.. Ran it another several years and then had the motor go out. I for the life of me could not find a exact replacement motor so I rigged another one... since then the machine has been a lemon and have had nothing but bearing issues! - I finally gave up on it and found another machine!
The last bearing I had in the machine was very loud! - However my machine is outside and along side my shop... With neighbors who are up snorting drugs all night I leave it on 24/7 just to screw with them. haha!
From my experience with mine... it should have noise of course, but nothing really loud or hammering sounding.
My last bearing attempt I ash canned the original lortone design and had my buddy machine a aluminum plate with a pressed in bearing... It worked good, however the side to side motion with the off balance shaft started making noise after a fair period of time.
Anyrate I expect to get my new "used" machine here this week... I'll see how loud a original one is for ya!
Jason
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rykk
spending too much on rocks
Member since September 2011
Posts: 428
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Post by rykk on Mar 19, 2012 14:58:20 GMT -5
Thanks, rockhound. I'm starting to think that at least part of the noise might be the pan whacking against the pan base. It seems to "modulate" depending on how the 3 thumbscrews are tightened or over-tightened. I had put some rubber sheet in a few strategic looking spots when I saw something on the 'net about it but it wasn't a magic bullet. I used a drill and made a pattern of 3/16" dimples in a grid kinda like a Reciprolap to try to get the rig to flatten rocks faster. Maybe that made the bottom a little wimpier and flexible? Maybe not but I'll look into that. C-ya, Rick
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rykk
spending too much on rocks
Member since September 2011
Posts: 428
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Post by rykk on Mar 20, 2012 0:38:23 GMT -5
Hot dang, I think I got the problem whupped!! Looks like the problem WAS the shaft slamming up and down. Or, maybe more likely, the entire magnet/winding/commutator assembly. It's a property of used electric motors called "end thrust" or "end play". I'd read that there were old-timers (careful, son - you ain't exactly easter season poultry, yerself!) who used to fix them by adding "wave washers" inside the motor under the top and bottom bearings. I gather that these are sorta potato chip bent washers that can flex. Even brand new motors have a small amount of end play which allows the motor to find its "center" where the electromagnetic fields are balanced and the motor will run smoothly. Over time, the washers in the motor flatten put and the bearing races wear making for an excessive amount of up/down play in the shaft. This is a used original equipment motor i found on ebay - the Grainger/Dayton crapped out after 9 months of nearly constant use. Anyhow, couple that with an inherently unbalanced load on the end of the shaft that you also can't get absolutely perfectly perpendicular and the shaft will bang up and down or at least whack the heck out of the big 3/4" load bearing.
So, since Grainger didn't have - nor had they ever heard of - wave washers when I'd asked them last month, here's what I did: I loosened the set screw that holds the big load bearing to the flat on the motor shaft, grabbed the shaft with a pair of pliers, pulled it up while holding the bearing down, and then re-tightened the set screw effectively keeping the shaft at the upward side of its range of play/slop like a locking collar would. VOI - freaken - LA! I mean this rig is so quiet when it runs that you can hear even the taped rocks clattering against each other! (which, now, bugs me - lol) I have to get really close to the sliding glass door that the lap is only 4ft away from to even hear from inside the house.
I'm still gonna have to keep an eye on it (especially since I can't HEAR it - lol) because I was a little worried that restricting the shaft might cause the motor's bearings - especially the top one - to maybe get hot and wear out sooner than normal. It's been purring right along for over 3 hours but we'll see what happens over the course of a couple of days especially in this unseasonably hot weather down here in Florida right now. I don't even venture out of the house b4 7PM from May-October! And working in the garage is downright brutal hot then. I'd set up on the back lanai but.... moss-kwee-tows!
I'll probably post this "fix" in a new thread after I see if it's gonna hold up as I would imagine that, though most here are tumblers, sawyers, and cabbers, I'm sure it would be of great help to someone with a vibe lab like this Lortone who might be googling like crazy trying to find some info.
C-ya, Rick ("cyborgsam" on ebay)
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rykk
spending too much on rocks
Member since September 2011
Posts: 428
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Post by rykk on Mar 20, 2012 17:12:09 GMT -5
Ok, after about 16 hours, the rig is a little bit noisier. Not very much but I can tell that it's a few dB. We'll see if it gets any worse over the next day or 2. Maybe I pulled the shaft up too far and the motor is trying to pull down to balance the electromagnetic fields and has developed a little slop.
Or, maybe more likely, the set screw has slipped just a tiny bit from being hammered half the night and all day. If it continues to increase - and it doesn't seem to be right now - what I will do is drill a small dimple into the flat of the shaft for the screw to seat into. That oughtta keep it from moving.
More on the developing "drama" later.... I'm sure everyone is just riveted by this thread - lol Rick ("cyborgsam" on ebay)
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Post by johnjsgems on Mar 20, 2012 20:50:21 GMT -5
They are called thrust washers. If you have a motor repair place in your area they should have them. On small motors they are just very thin shims. An industrial hardware like McMaster Carr may have them.
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rykk
spending too much on rocks
Member since September 2011
Posts: 428
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Post by rykk on Mar 23, 2012 3:17:33 GMT -5
Thanks, John.
And now the latest news flash from Rick's back porch. When I went to start a new grit, I discovered that the slightly louder noise from my "fixed" vibe lap was a couple of the thumbscrews had worked just a little loose. To some extent, you can sorta modulate the amount of noise the pan makes by loosening one of the screws. When I started the next batch it was just as quiet as when I first cranked it up after raising the motor shaft. WAY cool - I mean this rig just whispers when it runs! You can even hear the water splash between rocks. Three days plus and still "maintaining low tones" as the Coneheads used to say. I reckon the reason I didn't investigate after it got louder was that I assumed it wasn't going to last and expected the thing to fail. C-ya, Rick
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