What's new
What's new

Remove Large gear from shaft - damaged key

You can't press it out with that key still in there, you'll be guaranteeing the destruction of the bore and potentially the gear. With that small of an item and it being hollow/tubular, probably just torch the inner shaft/cartridge out. I'd give the gear a good preheat first, just to be safe. The gear will likely need the bore cleaned up.
 
You can't press it out with that key still in there, you'll be guaranteeing the destruction of the bore and potentially the gear. With that small of an item and it being hollow/tubular, probably just torch the inner shaft/cartridge out. I'd give the gear a good preheat first, just to be safe. The gear will likely need the bore cleaned up.
Yes I was thinking that. If I cut the shaft close the the gear it'll break into the keyway, so then it will be easy to get that piece of shaft out.
I have a large 4-jaw and I believe it would go into the gap-bed of the lathe, lengthwise, if I have to clean up the bore.
Any idea what size press required to reassemble ?
Bob
 
I set the gear and shaft up in my lathe to take some measurements.
I adjusted the chuck to get that end true, on the bearing surface, and made a plug for the tailstock end, cleaned up the shaft and took some measurements, as shown in the diagram attached.
The chuck end is showing pretty significant ovality in the shaft.
The gear is not running true either, when measured at the top of the tooth.
So clearly a new shaft is required.
Hopefully the bore of the gear is not damaged/distorted.
I've reached out to Bonfiglioli to see if a new shaft is available, the price and delivery.
The shaft is about 12" long, with max OD about 7.50" and a bore about 4.75".
Bob
ps anybody have any idea what size press would be need to get the shaft out of the gear ? (the other option is to cut it out of course).

That was kind of a big waste of time eh?

Cut the shaft out. You'll just fuck up the gear pressing it apart with the key bent up like that.

Like was already outlined for you the last time you asked this same question-

make a print

order material

cut old shaft out

inspect gear, recut bore if required

make new shaft to fit gear

get paid.

Setting that shithouse bent shaft up to get some meaningless numbers was a waste of your time and the customers money.
 
What skin is it off your nose?

He asks questions leaving out some pretty pertinent info. Gets good advice. Ignores advice. Then asks same questions on repeat.

This isn't real big work, but it's pretty far outside hobby shop stuff. Order of operations becomes a big deal when your parts start getting bigger and setups take a large part of the time.

Any repair machinist can look at the pictures of that gear on the shaft and instantly know that shaft is fucked. No reason to spend hours setting it up to find out the bent key has bulged the shaft and nothing indicates right anymore. There are HUGE forces in that bulged keyway acting on the shaft and the gear. No need to measure anything. All you need is working eyeballs to see it's no good.

If the goal is to fix this machine then the very first step is to make sure the gear is OK. It looks OK in the pictures and very likely is. So you need to get the gear off the shaft first, but wait, if you destroy the shaft you can't copy it, so then making a print from the shaft becomes step #1.

It's frustrating because he says his customer is a super tightwad and wants it done cheap, but then he ignores advice to do the job efficiently and costs the customer extra instead. Or he's just going to to eat the time to set that all up and indicate it?
 
No press to reassemble. Heat the gear and slip the cartridge in. We used to do this kind of thing in a big pot of oil with a huge burner underneath. Good even heat and almost no chance of overheating. Have a press on standby in case you need it. It will need to be at least a 50 ton to do much of anything on a decent interference fit that size if it grabs before fully assembled, I'm guessing. Have a short dummy key ready and waiting to align the keyways. Pro tip: do your damnedest to make sure you don't need the press. Apply some anti-seize on the inner part before the fit attempt. In case it starts to bite, you'll need it to prevent/minimize galling. This is not an easy one man job. Get a helper.
 
No press to reassemble. Heat the gear and slip the cartridge in. We used to do this kind of thing in a big pot of oil with a huge burner underneath. Good even heat and almost no chance of overheating. Have a press on standby in case you need it. It will need to be at least a 50 ton to do much of anything on a decent interference fit that size if it grabs before fully assembled, I'm guessing. Have a short dummy key ready and waiting to align the keyways. Pro tip: do your damnedest to make sure you don't need the press. Apply some anti-seize on the inner part before the fit attempt. In case it starts to bite, you'll need it to prevent/minimize galling. This is not an easy one man job. Get a helper.
Long way from that, but thanks for good advice.
The key is "captive" in the keyway in the shaft.

I got a response back from Bonfigliori, USA; apparently replacement shaft not available.
We need to assess the state of the whole gearbox before we start spending money.

Thanks again for the good advice.
Bob
 
He asks questions leaving out some pretty pertinent info. Gets good advice. Ignores advice. Then asks same questions on repeat.

This isn't real big work, but it's pretty far outside hobby shop stuff. Order of operations becomes a big deal when your parts start getting bigger and setups take a large part of the time.

Any repair machinist can look at the pictures of that gear on the shaft and instantly know that shaft is fucked. No reason to spend hours setting it up to find out the bent key has bulged the shaft and nothing indicates right anymore. There are HUGE forces in that bulged keyway acting on the shaft and the gear. No need to measure anything. All you need is working eyeballs to see it's no good.

If the goal is to fix this machine then the very first step is to make sure the gear is OK. It looks OK in the pictures and very likely is. So you need to get the gear off the shaft first, but wait, if you destroy the shaft you can't copy it, so then making a print from the shaft becomes step #1.

It's frustrating because he says his customer is a super tightwad and wants it done cheap, but then he ignores advice to do the job efficiently and costs the customer extra instead. Or he's just going to to eat the time to set that all up and indicate it?
The reason I did the measurements is to fully understand the level of damage. The "customer" has become a friend as well as a customer, so I don't mind putting some time in to help him.
 
At one job I worked at in early life we had two straightening presses, a 250 ton and a 500 ton, we used to straighten the kinks out of drill collar bar before it was trepanned. I recall a similar situation at least the key wasn't kinked as it is here. The small press was 250 ton and pushed out the damaged shaft without putting a bleep on the pressure gage.. The shaft wasn't near as large, too. Ever seen a oak 4 x 4 stood on end and pressed on with 500 tons of pressure? Lots of tooth picks created.
In this situation, as one said, that shaft is gaulded to the gear. You will never get that shaft to move by pressing on it, even with heat applied. More than likely, the hub will bust out of the gear. If your good with a scarfing nozzle on your oxy-acetylene rig, you may get lucky and gouge most of the shaft out to a point that if becomes loose and knock it out with a sledge. I know I'm not good at doing things like this with a torch.
You need a real lathe like a 25" HD or 36" Monarch or Lodge & Shipley, better yet a old Axelson lathe. Dad had a 22" Springfield that wouldn't have an issue tackling this in a heart beat.
If you can bore out enough of the old shaft, the interference stresses should relax enough to allow the rest of the shaft with the key drop out, if the key is not welded to the keyway in the gear.
 
If I was going to try to machine this out, I think I would just pick out 2 or 4 spots that were diametrically opposite and cut right down through to the gear bore. I'd likely cut it out with an indexable endmill by plunging. From both ends if necessary. Doing it that way would save a lot of time compared to trying to machine the entire hollow shaft out.
 
Long way from that, but thanks for good advice.
The key is "captive" in the keyway in the shaft.

I got a response back from Bonfigliori, USA; apparently replacement shaft not available.
We need to assess the state of the whole gearbox before we start spending money.

Thanks again for the good advice.
Bob
If you are doing the whole gearbox job, contingent on salvagability, I would focus my attention to he high speed end and work your way back to the bull gear. High speed end will not stand much error. The output end is much more tolerant of imperfection. The gear PD and OD may not necessarily run true to each other. If the hub of the gear is well supported with a ring of significant wall and a clearance just enough to clear the key; You would generally be able to push that out with a 100 to 150 ton. I don’t like to heat unless necessary, hot metal galls easier than cold. If you reach a point where the support appears to start to yield, hold pressure and add a rose bud.. It will POP.
You have hundreds of things to consider in a typical simple reducer and we are just looking at a snap shot here.
Good luck
 
If you are doing the whole gearbox job, contingent on salvagability, I would focus my attention to he high speed end and work your way back to the bull gear. High speed end will not stand much error. The output end is much more tolerant of imperfection. The gear PD and OD may not necessarily run true to each other. If the hub of the gear is well supported with a ring of significant wall and a clearance just enough to clear the key; You would generally be able to push that out with a 100 to 150 ton. I don’t like to heat unless necessary, hot metal galls easier than cold. If you reach a point where the support appears to start to yield, hold pressure and add a rose bud.. It will POP.
You have hundreds of things to consider in a typical simple reducer and we are just looking at a snap shot here.
Good luck
Thanks Dave.
The customer is chewing on his options right now. He has a chipper that's currently in use, but it's old and well worn, so looking for a backup / replacement.

The bearings for the bull gear are "6034", deep groove ball bearings, 170 x 260 x 42 mm. The specified shaft tolerances and fit are a whole lot different to the state of the current shaft !

There's probably a lot more required to put this gearbox back together again, so the job will probably go cold for a while as he figures out what he wants to do.
Attached parts drawing - this is the 3 shaft double reduction version, I believe.

Thanks for all the good input.
Bob
 

Attachments

  • spare-parts-list_parallel-shaft-gearmotors---units_ta_i-uk-de-f-e_r00_0.pdf
    655.9 KB · Views: 15
Last edited:
Heat the gear and slip the cartridge in. We used to do this kind of thing in a big pot of oil with a huge burner underneath.
I love it! What could go wrong with a big pot of oil with a huge burner underneath. Just be sure to clue in your insurance company on this technique when the policy comes up for renewal. They will love it too.
 
I love it! What could go wrong with a big pot of oil with a huge burner underneath. Just be sure to clue in your insurance company on this technique when the policy comes up for renewal. They will love it too.
If insurance companies were told of everything that happens in every shop, none would be insured for less than their annual gross income. Many not at all.

As far as oil with a large burner... I believe they are perfectly legal for even home consumers and insured ones at that, they're called turkey friers. And yes, in the hands of the right nincompoop, they do result in catastrophic failure.

But then spinning multiple tons of steel between two much smaller retainers, the operator within inches of 500 degree steel chips flying in multiple directions, while not wearing thermally protective clothing, and having no "institutional" training for this obviously incredibly dangerous situation also seems ludacris to many.

It's all in how you look at it.

I used to regularly find myself sandwiched between 18 wheelers with just inches between my face and a truck doing interstate speeds, (though motor homes were the worst offenders) and my back against the broke down truck I was there to tow. Occasionally having to superman dive to avoid looking like a woodland creature recently aquatinted with low hanging drivetrain components.

Safety is only what each person puts into it. Knowing what works, what don't and what to do when what does usually work, somehow doesn't.
 
I love it! What could go wrong with a big pot of oil with a huge burner underneath. Just be sure to clue in your insurance company on this technique when the policy comes up for renewal. They will love it too.

This was a huge job shop that had been doing business for decades... It burned down exactly zero times. There was also the lid nearby to cover the oil pot should it perchance ignite. No chance of knocking it over, it was a fully fabricated steel pot that weighed hundreds of pounds empty.
 
As far as oil with a large burner... I believe they are perfectly legal for even home consumers and insured ones at that, they're called turkey friers. And yes, in the hands of the right nincompoop, they do result in catastrophic failure.
I have seen multiple news stories of guys burning down their decks and setting their house on fire frying turkey's in hot oil.

My only experience with hot oil was back in the mid 1960's at Boy Scout summer camp. We were given a cast iron Dutch oven, a quart of vegetable oil, flour, and some raw chicken to fry. None of us had ever fried chicken before but we had all seen our mothers do it. Remembering the oil bubbling around the chicken when our mothers cooked, we tried to get the oil in that Dutch oven to boil, not knowing it only bubbles when the chicken goes in.

We kept throwing wood on the fire and fanning the flames trying to get that empty pot of oil to bubble. Eventually it burst into flame and splattered out making the fire flair six feet high. I learned a lot that day but I have never again tried to fry chicken.
 








 
Back
Top