Broken Gear teeth - how do I get this gear off?

[JamesW84]

I haven't been around in a while, and I thought there used to be a talk section that I would have posted this in. Not sure where else to put it.

Any idea how to get this bevel gear off? The teeth are in bad shape, so I need a new gear. The "top" (short end of the shaft" has a key in the keyway that I haven't been able to remove. There appears to be a slot cut in the gear to go around the key. I've tried pounding from both ends, but it hasn't moved yet.

Where would be the best place to get a gear? I found rushgears.com, but haven't looked much further.

 

[BillK]

You might have to put it in a press to get it off.

As far as getting a replacement, what is it for ?

 

[strutaeng]

Shop/hydraulic press ideally.

With a combination of heat maybe, depending on how tight it was pressed in...

 

[Jeff Ivers]

Is that a cluster gear - small and large diameter one assembly? Check the diameter of the shaft on both sides. You may need to push that towards the small diameter gear to remove.

 

[finn]

Shop press and a gear splitter.

Pounding is likely futile.

 

[The Cobbler]

shop press
with that gear being bad it's likely that the gear it mates to will be worn or damaged too.
if part's aren't available you may have to go to a machine shop & have it(them) made
Keith Rucker ( I'm just a viewer , no affiliation to him) on You tube makes gears . it will probably be pricey if it's not an off the shelf item

 

[JamesW84]

Thanks. It's for an Advantco MX20 stand mixer (20 qt commerical). The mating gear is bad also. The gear below the bevel gear appears to be separate.

The manufacturer sells similar gear assemblies (center axle) for other models, but they don't have it listed for this model. I sent them a message to see if they have it.

Looking further at rushgears.com, their minimum order is $4750, so that's out. I guess I'll part it out on eBay if I can't get a gear.

 

[alfadan]

Is the smaller gear bad too? If you don't care about it, you could use a cutoff wheel down the center of it just into the key or just shy and split/wedge it with a cold chisel.

 

[JamesW84]

Is the smaller gear bad too? If you don't care about it, you could use a cutoff wheel down the center of it just into the key or just shy and split/wedge it with a cold chisel.

The smaller gear below the bevel gear is good. Fair point. If I cut the key I'd just have to find another key. Shouldn't be that hard, but finding a similar gear with the keyway will probably be a challenge.

 

[mm08822]

Before any pressing, measure the shaft to verify if any taper exists. If there is a taper, you want to press the gears toward the smaller shaft diameter.

 

[nadogail]

making a replacement key is not difficult if you have Key Stock, a hacksaw and decent files

 

[BurtEggley]

press and bearing splitter. Follow the suggestions on the shaft taper that others have suggested. Looking at the threads, you will need a new shaft too so not sure what you will gain by pressing it off at this point. Its scrap metal. Next time if you must hammer, at least use a lead hammer so it deforms instead of the steel.

Another trick is to throw it in the freezer for a few hours, then heat the gears a little with a torch before trying to drive or press them off. That can help. Too hot and the temper will change.

 

[Grant Gunderson]

A splitter and press as others stated is key for this. You can also heat it a bit first too. Sometimes it’s easier if you use a punch to tap the machine key out first. Also check all of the gear teeth sometimes you will see a small bore with a set screw in it.

 

[Firebrick43]

Thanks. It's for an Advantco MX20 stand mixer (20 qt commerical). The mating gear is bad also. The gear below the bevel gear appears to be separate.

The manufacturer sells similar gear assemblies (center axle) for other models, but they don't have it listed for this model. I sent them a message to see if they have it.

Looking further at rushgears.com, their minimum order is $4750, so that's out. I guess I'll part it out on eBay if I can't get a gear.

Have you looked at boston gear?

https://www.bostongear.com/ecatalog?page=search&cid=bevel_miter_gears_straight_spiral&filter=Material_And_Condition%3A2%3ACast%20Iron#

Might have to have a machinst enlarge the bore and cut a different keyway but thats a lot cheaper than 4750

 

[PWC Repair]

There are places now that 3D print with various metals. You should be able to get that gear made.

 

[larry4406]

No first hand experience, but I’ve seen on forums where crashed head stock gears on lathes are repaired using brazing methods if I recall correctly.

 

[Stuart in MN]

To elaborate, this is a food mixer, used in a commercial kitchen or restaurant (I didn't know if it was a cement mixer or what, until I looked it up.)

 

[larry_g]

Have you been on the PHONE and talked to the company that sells this product?

 

[zimman]

Clamshell and a press if you want to only remove one.
Zim

 

[Firebrick43]

No first hand experience, but I’ve seen on forums where crashed head stock gears on lathes are repaired using brazing methods if I recall correctly.

I have done this on several special gears when a blank wasn’t available. Mill a slot where the teeth were, and silver braze with 56% a 4140 prehard piece in. If one has a mill, rotary table, and the correct involute gear cutter it works. Bevel gear would need a sine plate or 45 degrees angle plate as well. Easier if you have a horizontal mill.

One can even use a fly cutter holder and grind the involute pattern into a HSS tool blank but that ***** both in grinding the involute precisely and how slow you have to cut.

 

[npp]

Like most of the suggestions definitely a press, if you don’t have access to one I’m sure a machine shop could do it at a reasonable price.

 

[JamesW84]

press and bearing splitter. Follow the suggestions on the shaft taper that others have suggested. Looking at the threads, you will need a new shaft too so not sure what you will gain by pressing it off at this point. Its scrap metal. Next time if you must hammer, at least use a lead hammer so it deforms instead of the steel.

Another trick is to throw it in the freezer for a few hours, then heat the gears a little with a torch before trying to drive or press them off. That can help. Too hot and the temper will change.

This is Garage Journal - some misshapen threads don't stop us! Fortunately, the nut still goes on with my fingers. Point taken about being careful around the threads, though.

Have you been on the PHONE and talked to the company that sells this product?

I have messaged them, and got a reply. They linked all of their replacement parts, which does not include this. They recommended I call around to food service equipment techs and see if they have a generic or know where to get one.

One of the gears has 47 teeth, and one has 36. I think I'll just run by a machine shop tomorrow and see what they say.

I checked Boston Gear and they don't have 47 tooth that I can find.

Nice call on the shaft also, the shaft is different sizes with the smaller being the top where that key is.

Thanks for all of the help.

 

[alfadan]

Something seems amiss to me. I don't see how the cluster is held in place, I don't see a set screw and the keyway is much longer than needed, implying the cluster can move up and down. I suppose the matching gear can keep it from sliding down, and the nut on the shaft keeps it on?

 

[wssix99]

There are places that can repair that gear for you: (it doesn't look specialized or exotically hardened...) https://illinoispulleyandgear.com/blogs/blog/repairing-gears

It looks like you have more than one tooth missing. Before doing anything, I would make sure you have zeroed in on the root cause for this. If more than one tooth, it probably isn't a random break. (The actual problem is, or was, elsewhere.)

 

[BOHICA8]

Another avenue that may assist ... https://www.baumhydraulics.com/

 

[alfadan]

One of the pics looks like the key is riding up on the end of the slot, which is very thin. I think it's jamming the gear to the shaft. Try punching the key back down.

 

[LXCam]

I wonder if the key or keyway is tapered. I’m with the guys that recommended pressing them down, then remove the key and press off. And why I say that is because the keyway isn’t fully slotted so it’s trapped on the shaft. If you have a caliper, get a measurement next to the gear and at the end and see if it increases a few thousandths.

 

[racecougar]

If you don't want to use a press...