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Post by tims on May 23, 2020 12:50:47 GMT -5
My latest tumble got chewed up. Rolled in QT12 rotary and finished in Viking VT14 vibe. I ran the rotary stages (rough through pre-polish) with more padding and for longer than usual, and everything looked better than normal after pre-polish with few dings or fractures. After the polish stage in the Viking it looked like someone had dropped the whole batch off a cliff and I'm not sure what went haywire. The Viking did break a belt (well, both belts) but the pros assure me that a blown belt shouldn't cause hopping or any violent motion in the vibe, but I've used the Viking before with no change in settings or method and have never seen such extreme damage to a load of rocks.
Here are some Chinese garnets that had no visible fractures after pre-polish that just shattered:
Some chert / jasper / quartz that looked fine after pre-polish:
Not sure what happened but I destroyed nearly the entire load. Here are a few "survivors" but almost everything shows at least minor damage:
Suggestions welcome, I really like the results I've gotten from the Viking in 2 previous loads but something went terribly wrong this time.
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jamesp
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Post by jamesp on May 23, 2020 17:18:00 GMT -5
Those garnets fractured in a way similar to poorly annealed glass.
Garnets are one of the most impact resistant rocks known.(Yes, questioning your corona garnets ho ho).
The rare times I found mine running on one belt it was barely moving Tim.
Take the cover off and make sure the set screws on one of the counterbalances did not loosen and allow the counterbalance to wander.
Their function is to tighten down a counterbalance = prone to coming loose.
Better check every fastener on your top section. These fasteners secure vibratory components ! Broken/loose springs ?
For the 12/14 pounds it should be set at 1.2 to 1.8. I use crap o-rings and they break every single batch I run once and I never had an issue. Most batches were glass to boot.
One breaks and shortly after the other breaks. I am well into my 2nd bag of 50 cheapo o-rings.
How did it sound when running on one belt ? Violent ? Smooth ? If a vibe is heavily damaging rocks it is usually apparent.
Were your belts glued/heat welded ? Do they have a stiff spot in them ?
Check for play in the motor shaft, are the bearings loose ?
Did you once run it on top of soft cushioning and move it to solid surface ?
The cherts look OK, I don't see much frosting on the edges and points at all.
The 1st 5 photos in the link show a setting of 1. Not easy to read their scale. Setting 3 does 35 pound hoppers.
Good luck.
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Post by tims on May 23, 2020 20:31:46 GMT -5
Thanks for the reply James. I ran a short burnish (90min) after replacing the belts and everything looked / sounded normal then (except for the rocks they were obviously fubar). I run it on a thin, stiff doormat sitting on the sidewalk; the mat doesn't have any give at all but it seems to muffle the sound a little bit. The belts are o-rings with no visible seam and no stiff spots. The vibe was unattended for ~ 2 hours when the belt(s) broke, and when I checked it both belts had broken and the it was just sitting still with the motor spinning. I couldn't find anything loose and nothing broken but did find some abrasion I hadn't noticed on one of the counterbalance weights, it was jumping hard enough that the weight was making contact with the motor case. The photos are poor but it ground down the counterweight probably 1/16" in that spot and left a little scar on the motor. I believe both sides are set to 1.2 and neither has moved from that position.
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Post by tims on May 24, 2020 13:12:34 GMT -5
Those garnets fractured in a way similar to poorly annealed glass. Garnets are one of the most impact resistant rocks known.(Yes, questioning your corona garnets ho ho). I missed the implication on first read, but I'm certain they're garnet. Pre-tumble they're big clunky lopsided dodecahedrons ... if you were gonna make glass imitations they wouldn't be this ugly (or heavy).
Total guess here but I think that when the first belt broke on the Viking, the second one managed to hold together for several revolutions before it broke causing the hopper to ... hop. Violently. I'll babysit better next run.
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jamesp
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Post by jamesp on May 24, 2020 16:05:31 GMT -5
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EricD
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Post by EricD on May 24, 2020 18:06:38 GMT -5
Looks to me like that one offset weight is wayyyy further from where it should be judging from some pictures of jamesp's unit. Perhaps when the belt broke it hit the motor and spun, creating HUGE vibration before the other belt broke? I'll have to go look at his pictures again |
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EricD
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Post by EricD on May 24, 2020 18:13:20 GMT -5
Looking at james' pictures I don't see how the weight could hit the motor unless something very very bad happened. Also even with the fuzzy pic your weight doesn't seem like it moved.
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jamesp
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Post by jamesp on May 24, 2020 19:01:31 GMT -5
This is the 3rd type of bearing i have seen on the shaker shaft. Mine are Sealmaster with a grease fitting. Another machine had a larger squarish bearing. Tim's bearing looks as if it has no grease fitting. No matter, just pointing out differences. This machine has been in production a long time.  Some of the cast iron counterweights have been ground shiny in some spots for some reason. Perhaps to balance them. |
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jamesp
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Post by jamesp on May 24, 2020 19:10:52 GMT -5
Looks to me like that one offset weight is wayyyy further from where it should be judging from some pictures of jamesp's unit. Perhaps when the belt broke it hit the motor and spun, creating HUGE vibration before the other belt broke? I'll have to go look at his pictures again I can't tell by the photo. On setting 1 the counter weights are at 2 o'clock from being directly opposite each other. at max vibration both lobes are on one side off the shaft making obvious maximum off balance. |
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EricD
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Post by EricD on May 24, 2020 19:12:25 GMT -5
That looks really fresh, and looks like aluminum on the cast iron. If the bearing has play, do you think it could be hitting the deck jamesp? |
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Post by oregon on May 24, 2020 20:15:34 GMT -5
Imagine you've checked the four springs.
Was the load extra dry when you found it? Wonder if things dry out enough and the action on a big 'solid' mass could make for interesting happenings? certainly seems like it was violently shaking for some reason. Might be worth loading it up and turning it on for a few seconds with one belt on to see if the first belt failure might have caused it. Mystery indeed.
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jamesp
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Post by jamesp on May 25, 2020 12:44:33 GMT -5
That looks really fresh, and looks like aluminum on the cast iron. If the bearing has play, do you think it could be hitting the deck jamesp? Without opening it is hard to say Eric. I would think that if the bearing is wallowed to that extent there would be some serious noise and clanking happening. That shaft spins close to 1:1 speed of the 3450 rpm motor. I am not fond of pillar block bearings without grease fittings. No better pillar block bearing than Sealmaster brand which is what my machine is fitted with. An off-balance shaft should have high grade even oversize bearings to offset the forces it generates. But IMO my Sealmasters are 1/2" bearings and seem to have undersized castings. Another Sonic I looked at had giant 1/2" pillar block bearings. May have been oregon's unit. Note that the o-rings have to slip over the counterweights to be put on the small sheaves/pulleys. Note high tensile star head bolts to hold all vibratory components in place.  |
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Post by tims on May 25, 2020 14:50:46 GMT -5
Imagine you've checked the four springs. Was the load extra dry when you found it? Wonder if things dry out enough and the action on a big 'solid' mass could make for interesting happenings? certainly seems like it was violently shaking for some reason. Might be worth loading it up and turning it on for a few seconds with one belt on to see if the first belt failure might have caused it. Mystery indeed. The springs look fine. The load was drying out on top when i found it but seemed plenty wet except for the stuff sitting right on top. The shaft doesn't seem to have any play in the bearings. Nothing looked or sounded odd when i replaced the belts and ran a short burnish after this incident.
I'll try it with one belt just to see what happens and report back.
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Post by oregon on May 25, 2020 18:56:56 GMT -5
mine doesn't have the high tensil bolts on the pillow blocks...
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Post by tims on Jun 1, 2020 15:11:54 GMT -5
Sorry for the delayed reply. I did run it with one belt attached and there was no hopping, it ran fine with one belt and I couldn't see any obvious difference from running it with both belts. I'm baffled. I got some better pics but they don't show any obvious problems (that i can see anyway).
This is the side where the counterweight got ground down. I'm 99% certain this wear wasn't there before this failed mystery run:
Circled here is the side that didn't show damage to the weight. Some black rubber baked on / around the pulley. The belt from that side shows some obvious scuffs and abrasions like it did some skidding around before it broke.
This is the motor pulley on that side, same black rubber
Here's the motor case on the side with the damage to the counterweight. It looks like the bottom lid of the hopper would need to move a couple inches laterally at least for the counterweight to align with the side of the motor there which makes me think the abrasions on motor and weight can't be related, but I don't remember seeing those abrasions before. Maybe I just overlooked them before and they've always been there ...
A little clearer shot of the weight again
The more I look the less I understand what happened, so I think I'll call it a one-off failure until proven wrong. Both counterweights are set securely at 1.2 and haven't budged. Springs are fine. No indication that running on one belt would cause crazy hopping. I dunno.
Anyway, on an unrelated note, is there a "correct" way to orient the hopper (front and back)? The feet on the base of the hopper are different shapes on the front and back but the hopper appears to be centered ok regardless of which way the feet are pointing. Does it make any difference? Pic for reference:
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jamesp
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Post by jamesp on Jun 2, 2020 4:50:49 GMT -5
I believe the hopper can go on either way Tim. The only way I see those damages occurring is if some one turned the machine on accidentally with the top unit displaced a few inches. The damage/scrapes on the counterweight look old and oxidized. Could you have missed seeing it early on ? Sure looks like counterweight hit motor which would require the top unit to be off set inches as you mentioned. It would only take a second to cause such damage since the countershaft rotates so fast. Any way, the damage is odd and not obvious as to cause. Perhaps a foreign object got caught inside the machine at one time. Has this locking collar been scratched up too ?  |
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jamesp
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Post by jamesp on Jun 2, 2020 4:56:48 GMT -5
The star bolts and Fafnir bearings sure look new.
Could the past owner had the bolts vibrate loose and the whole counterweight system dropped down and cause a catastrophic crash ?
Maybe those bearings are the new retrofit from Diamond Pacific ?
The Vibrasonic has been around a long time and apparently had several different bearings over the years.
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Post by tims on Jun 2, 2020 14:01:04 GMT -5
The star bolts and Fafnir bearings sure look new. Could the past owner had the bolts vibrate loose and the whole counterweight system dropped down and cause a catastrophic crash ? Maybe those bearings are the new retrofit from Diamond Pacific ? The Vibrasonic has been around a long time and apparently had several different bearings over the years. I've never had it running without everything set in place first, but as to past owners I can't say. That locking collar does have a scuff on one side, I hadn't noticed that. And yeah it's very possible the scuff on the weight was also there previous to this incident and I just didn't notice it. And again when I found it running after the belts broke the hopper was sitting square on the springs and nothing looked out of place.
I got this machine second hand, as did the previous owner, and I don't know its history beyond the guy I bought it from who'd never even used it.
Thanks for looking and for the advice and suggestions, I'll just keep running it and try to keep a better eye on it while it's running.
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Post by oregon on Jun 2, 2020 17:25:06 GMT -5
Thanks for looking and for the advice and suggestions, I'll just keep running it and try to keep a better eye on it while it's running.
So what would you guys' guess be if the rock tub solidified, dried out, or got wedged in such that the rocks could no longer move. Could a solid mass start the thing oscilating wildly? too hot & too much mowing to think about all the F=ma vectors and whether loose rocks would really behave differently. than a concrete chunk. 2c. Actually when you vibe your large rocks, if I recall lots of smalls, worked better than a mix with mediums? I can't remember exactly, but maybe that's an illustration of a large chunk being able to do more damage? |
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jamesp
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Post by jamesp on Jun 3, 2020 5:17:37 GMT -5
Thanks for looking and for the advice and suggestions, I'll just keep running it and try to keep a better eye on it while it's running.
So what would you guys' guess be if the rock tub solidified, dried out, or got wedged in such that the rocks could no longer move. Could a solid mass start the thing oscilating wildly? too hot & too much mowing to think about all the F=ma vectors and whether loose rocks would really behave differently. than a concrete chunk. 2c. Actually when you vibe your large rocks, if I recall lots of smalls, worked better than a mix with mediums? I can't remember exactly, but maybe that's an illustration of a large chunk being able to do more damage? Truth be known glass(w/sugar) gets 100% solidified/concreted quite regularly when running SiC 500 and sometimes AO 200 since those two abrasives skin off a lot of 'mud'. Sugar is not like Borax in that a concretion can be loosened with water and a bit of mechanical prodding. When I step outside in the morning and get within 50 feet of the Vibrasonic it sounds like the hopper is in a rubber vice. In this case it the batch is concreted. I just turn it off and spritz the batch with water and wait an hour then turn it back on pushing my finger into the batch and working the semi-concretion loose till it rolls again. I try to avoid this situation but I am busy at times. Try to hold the hopper from vibrating when it is running. It is impossible to stop it from vibrating but it can be greatly dampened. No matter, the springs still serve as padding enough to prevent the motor from over heating. If the vibrations were generated by say a direct drive mechanical cam and the hopper was locked down or restricted it would overload the motor. The springs serve as a 'shear pin' or a point of give. The motor can not be overloaded in the Sonic for this reason. Those Sonics will vibrate a 70 pound capacity hopper. Rumor of 100 pounds. That is a lot of weight to shake at such a high frequency; certainly more resistance than a man trying to hold it in place. But the forces are greatly increased because a 35 pound hopper setting is with counterweight at mark 3 of 5. The setting for 14 pounds is only 1.2 of 5. At a setting of '3' the off balance is way more violent.(try it sometime on a load of trash rock) At a setting of '5' the off balance weights are 100% opposite each other and the vibration is off the chart.(off balance is on logarithmic scale for sure). Blah blah blah, this still does not explain what happened in your situation tims. |
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