Remove Large gear from shaft - damaged key

[Overland]

Some good suggestions here some bad. Drilling out a captured key is ridiculous . The shaft is extensive, having a grinding element past the bearing and the whole thing in some sort of housing .
Does the customer want repairs done in place or tear down?
I would bar over the grinder and measure run out of gear now.
I would advise that in place removal will likely leave shaft in an unusable as is condition, requiring a time consuming and expensive in place repair of the fit for the gear.
Typically a grinder like I think you’re talking about will have circuit protection to kick out the motor in a jam and require an Operator to reset and manually hit reverse to clear.
If this is a hammer- mill, more often seen handling scrap wood and metal, it may well be a tapered fit for the gear.
I really need more info on the problem, Will it not run as is?

The gearbox is disassembled now. The grinder is a drum with teeth on it that cut against an anvil, I believe. Apparently PLC controlled; the PLC senses load and auto reverses to protect system. Obviously something dropped in and stalled the grinder.
It might be possible to just reassemble the gearbox and run it. Would need to ensure this shaft is running true first, and be sure no other damage.
If everything is running true this might be a viable option. However, the system will reverse from time to time, so there is a concern the gear may move on the shaft.
The PLC control system can probably be programmed to run slow speed in reverse and limit torque, assuming VFD's etc. I doubt there is much risk of the gear moving on the shaft.
Bob

 

[eKretz]

Whoever said that, there's no way in hell something like this is getting repaired in place unless it's a hack quickie fix just to hold out until it's torn down. Some disassembly required...

If they want to just run it, run it and quote them a new shaft, gear and key. Swap when they're done. Lots of places that make a lot of dollars per hour running the equipment like that option better.

 

[implmex]

Hi eKretz:
You wrote:
"there's no way in hell something like this is getting repaired in place unless it's a hack quickie fix just to hold out until it's torn down."

You mean like just weld the gear to the shaft and stop worrying about it?
Let the next guy break his head about taking the whole shebang apart if it ever even needs taking apart?

May be a viable solution if the customer is cheap and you can hold your nose long enough to break out the stinger and make a noise with it.

If the shaft's not badly boogered it may even work.

If the shaft IS boogered, and you were really willing to hold your nose, you could weld up and re-turn the shaft journals after you weld the gear to the hub.

Cheers

Marcus
www.implant-mechanix.com
www.vancouverwireedm.com

 

[eKretz]

Hi eKretz:
You wrote:
"there's no way in hell something like this is getting repaired in place unless it's a hack quickie fix just to hold out until it's torn down."

You mean like just weld the gear to the shaft and stop worrying about it?
Let the next guy break his head about taking the whole shebang apart if it ever even needs taking apart?

May be a viable solution if the customer is cheap and you can hold your nose long enough to break out the stinger and make a noise with it.

If the shaft's not badly boogered it may even work.

If the shaft IS boogered, and you were really willing to hold your nose, you could weld up and re-turn the shaft journals after you weld the gear to the hub.

Cheers

Marcus
www.implant-mechanix.com
www.vancouverwireedm.com

Yes sir, exactly what I mean. I've seen some very interesting "get by" fixes over the years in the steel mills so that the million dollar an hour machinery can keep spitting out product until a scheduled shutdown.

 

[William Lynn]

If the gear isn't timed, verify that nothing is bent, then run it. From the picture, the assembly is probably more secure than original. If later it frees up, then fix it. It's not like a big fan, so vibration shouldn't be an issue.

 

[just Dave]

The gearbox is disassembled now. The grinder is a drum with teeth on it that cut against an anvil, I believe. Apparently PLC controlled; the PLC senses load and auto reverses to protect system. Obviously something dropped in and stalled the grinder.
It might be possible to just reassemble the gearbox and run it. Would need to ensure this shaft is running true first, and be sure no other damage.
If everything is running true this might be a viable option. However, the system will reverse from time to time, so there is a concern the gear may move on the shaft.
The PLC control system can probably be programmed to run slow speed in reverse and limit torque, assuming VFD's etc. I doubt there is much risk of the gear moving on the shaft.
Bob

Sounds like you are not dealing with a bull gear on a grinder shaft but rather a separate gear box?Did you or your customer make a move? What brand gearbox?

 

[Overland]

Bonfigliori Riduttori Reducer TA125
So now you know !
Waiting for guy to come back to me.
Bob

 

[neilho]

Possible to just fill in the gap between the key and keyway? Assuming everything still runs true....

 

[Overland]

Possible to just fill in the gap between the key and keyway? Assuming everything still runs true....

I was thinking that. Maybe no need, but .......
Bob

 

[just Dave]

Bonfigliori Riduttori Reducer TA125

I haven’t delt with them in larger gear box’s , however I have been involved in many of there small units used in high speed packaging machinery. They were pretty much throw away box’s. Any decisions?

 

[Overland]

I haven’t delt with them in larger gear box’s , however I have been involved in many of there small units used in high speed packaging machinery. They were pretty much throw away box’s. Any decisions?

It's all gone quiet for now.
Bob

 

[Overland]

Well I have the offending gear, and shaft, so some more pics attached.
I'm thinking I have to somehow try to measure this assembly to see if there is any runout.
The bore in the shaft is 4"+. I don't have a tailstock center anywhere near that size.
I have a 12" "set-true" chuck on my lathe, so I'm thinking to set it up in the chuck and try to get the shaft on center, both sides of the gear, then see if I can see any runout on the gear.
The key is about 1" wide, and movement is shown in the 1st pic. There were bearings on the diameter on each end of the shaft, that were torched off.
It's all a bit dirty with some rust in places, which should clean up, I believe (hope).
Open to suggestions.
Bob

 

[eKretz]

That thing looks like an old doorstop, Jesus. Are they averse to making a whole new cartridge? If not, just torch the old one completely out, re-bore the gear and make a new cartridge.

 

[Overland]

That thing looks like an old doorstop, Jesus. Are they averse to making a whole new cartridge? If not, just torch the old one completely out, re-bore the gear and make a new cartridge.

Not a lot of money in the pallet repair business .......

 

[Garwood]

Runout of what in relationship to what?

This is like the blind leading the blind kinda thing from the sound of it. Company who doesn't know what they need has hired a guy to fix it, but the guy doesn't know what fixed looks like.

OP- Please state exactly what you are doing here. The "measuring runout" statement makes me go huh? Why would you give a shit about runout on that fucked part? Make a print. Cut it out. Clean and check the gear. Then make a new part. How the hell does measuring runout in that mangled state do anyone any good?

 

[Garwood]

Not a lot of money in the pallet repair business .......

Bullshit.

Richest old WWII vet Jew I knew growing up built a pallet empire $3 at a time. There's a ton of money in pallets.

 

[Overland]

I can clean up the bearing surface on the "shaft". And clean up the gear.
I can, I think, set it up in my lathe to see if the gear is running true to the shaft.
I have not seen the main shaft that this sits on, so I don't know the fit, or how it's secured to the main shaft.

 

[Overland]

Bullshit.

Richest old WWII vet Jew I knew growing up built a pallet empire $3 at a time. There's a ton of money in pallets.

If you say so.

 

[William Lynn]

The bore in the shaft is 4"+. I don't have a tailstock center anywhere near that size.

Take a piece of something that's a couple inches thick, flat or round, and turn a short hub that is a tap in fit to the gear bore. Drill a small thru hole in the same setup. Then turn around and put a center using the small drilled hole as a locator.

 

[ronf]

That looks like a taper that fits on the main shaft, i think just make a new insert the gear should be okay, if anything i would worry about the shaft it goes on.