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What trade?
Some grinders have plane bearing ways (which require no precautions), others like the Norton have cylindrical rollers. The table is held down by gravity so the issue is there is no preload on the bearings - On a grinder you can literally walk over to it and pick the table up. Without a preload, when you hit a bump, the table might lift a tiny amount and come back down with an impact. Bearings don't like impacts and brinnelling can result. While many machines are moved with air ride suspensions etc to minimize risk, I've not heard of precautions taken for preloaded bearings such as spindles, (as the whole assembly will move so there isn't the impact). I think its just the gravity attached SG tables that are high risk.
How I was taught to move surface grinders is to to take the table off, carefully store the bearings, throw a couple of blocks of wood where the bearings were, table on top and strap it all down.
Eons ago when setting up my shop thats what I did, built a RPC. Then I got a 600-220 volt transformer and ran it in reverse. Gives me 240 and 600 3P. It served me well, but there are two issues, fairly minor, but they nag at me. First is the drone. Silence is golden and it does take away from the shop Zen thing. Second is doing the acrobatics to get form one side of my crowded shop to the other to turn it on. I could add an infrared start or some sort of remote control, but life would be easier if it was step up to a machine and go.
The difference between then and now is the low cost of VFD's. So I've started using VFD's to supply 3P and have used 1P transformers to get the household 220 to 440 (or 600). they (1P transformers) are available fairly often on kijiji, at least around here (TO)
So, several things are important to know.
I was one of the guys who worked on this problem when the industry realized that it was only a far east and far west problem. I was sent to the Maritimes to try and figure out why. It was one of my first major assignments. You would not believe how many roads I looked at until I found a problem vehicle that had never been on the road. Then the light bulb went on.
In the old days, vehicles were cinched down tight with chain cranks. Tires were heavily loaded as a result. YES, tires did reduce the problem. But they couldn't save a bearing that was constantly being pounded in the same position when it was not turning. Tires do provide some damping but not enough against the mass of an entire constrained vehicle.
Box car'd is a great term.
Wearing due to lack of lubrication is partly true. But it wasn't just wear it was also permanent deformation in the surface metal treatment of the race. Micro analysis by Timken showed that the bearings were wearing but were also being deformed (minor metal displacement) as well as being worn.
Changes were made to both the bearings and to the tie-down system. The problem went away industry wide.
The phenomenon is well understood today. It's called Bearing Brinelling. I believe @Mcgyver is spot on with his observation and advice.
Edit - I guess we are all easily scarred by our life experiences. Every time I whack a chuck or a draw bar with a plastic hammer, I cringe. In my minds eye I see a bearing taking a beating. It's not the same cuz it's always a different position, but I just can't help myself from thinking about it.
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I would have thought that transformers like that would be everywhere. But I've been looking and have not found any. Maybe I'm searching for the wrong thing.
My preference would be a big one with multiple taps for different voltages to accommodate all the different motors out there. I remember seeing a really big one with a variable tap in it. It was free for the taking, but at the time I just couldn't see how I would ever use it. But it sure was a thing of beauty! Hind sight is always 20/20.
Please let me know next time you spot one.
DPittman
Ultra Member
Interesting stuff. According to Wikipedia it looks like the transportation style damage might be called False Brinelling or Fretting.
Brinelling - Wikipedia
Interesting stuff. According to Wikipedia it looks like the transportation style damage might be called False Brinelling or Fretting.
Brinelling - Wikipedia
en.m.wikipedia.org
Very cool!
They call it false brinelling because the bearings are only polished not deformed. The reference to transportation is parts shipping.
There is no doubt that the wheel bearings were permanently damaged and I think there is no doubt that this is what happened to the surface grinder bearings too.
But it's cool to see that there are cases where damage might be apparent on inspection but not actually present. Very cool and good to know
I saw that video. Apparently its a couple grand to grind a bed, plus shipping costs. I believe this lathe would be worth doing, if it needed it, but its looking pretty good so far. I'm going to have a better look soon. Might have to make some tools to accurately guage the bed wear, and do some test cuts.
I recently ordered a pair of front hubs/wheel bearings for an 06 Canyon. On the ABS wheel speed sensor harness, there's a pre-attached metal bracket. On both hubs, the bracket had cut through the harnesses like a razor blade during shipping, despite being fairly well packaged. Of course I didn't find this out until I was back at the shop, 30km's from the parts store....
Ouch! I feel for you!
Thankfully, I'm retired from that business now. I can't help you anymore....... I tried pulling some strings for a friend last month. The response on the phone was basically "Susquatch who?" Apparently all traces of my career have been erased and I don't exist there anymore.
I'm a farmer now. Wanna buy some corn? LOL!
BTW, that's a bad place for a wire connection repair. If you do repair it, make sure you solder the wires together and use a good quality shrink wrap with internal sealer. No crimp on connectors allowed.
Its all good, my supplier takes care of me. They had a new set sitting on the counter by the time i got back there. Shit happens.
I wasn't about to repair them, at 30 minutes old....But i've repaired many of them when thats all that was needed.
Found a bit of time to finish up the DRO install on the Emco V13 lathe. I'm not entirely happy with the guards the way i set them up, and will be changing a few things, but for now they will work. I really like having the RPM readout on the display all neat and tidy. With the VFD, its variable from 6 rpm in low gear to over 3500 in High gear, so its nice to know. I still have to do some compensation on the X axis, as its off about 0.001 over 2", and these are all 1 micron scales, so it should be able to be bang on.
Here's some pics:
Here's some pics:
yes it does. The switch is in the cover plate for the QCGB, it has a common, and fwd/rev contacts that would normally go to the fwd/rev contactors in the cabinet at the back. They now hook up to the VFD and tell it what to do.