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Need Help Identifying Spur Gears

metalpyro

Aluminum
Joined
Nov 10, 2017
Location
Sacramento
Good Day Everybody, Part of the secret to my success is knowing what I don't know and when to get help. This is one of those times and I'm confident that there will be some helpful information forthcoming. At least I hope so.

I have a great customer that has a machine that I have been helping him keep running for years. The machine makes an insulating bubble wrap product with an MPET film on one side. The gears in question are on the end of one of the two inflatable bladder mandrels that applies tension to the MPET film as it is fed into the process. The latest phone call, I'm told that one of the tensioners stripped the gears and no longer holding tension of the film. He sends me a photo of the gears and they are tore up. For a quick fix until I could get there, I told him to slide the gear over (outboard), to keep the machine producing. That's what you see in photo 1.


DSC00432.JPG


Once on site, diagnosing the problem was easy. The mandrel is bent. The bearing is inboard of the gear, so the end of the shaft is oscillating. They have spare mandrels so I told them to change it out and what to look for in the future. The job in front of me now is to replace the big gear that was damaged. After doing a couple hours of searching the webs, I realized I am clueless about A) how to identify what I have in front of me, B) where to look for replacement gears, and C) are the gears available bored with ketways, and bored for bearings? The machine was designed & built in China, so I'm probably safe assuming that it is metric. This was a one off machine from the factory and as such, actual documentation has been non existant. The factory doesn't even have part specifications on the buy out items (like these gears). The next photo shows tensioner #2 that has no damage, so I got measurements, but I am unable to remove it from service for any long length of time.

Mandrel Gear: 23 teeth, 50 mm OD, 30 mm bore, 50 mm wide
Tensioner Gear: 63 teeth, 130 mm OD, 47 mm bore, 20 mm wide


DSC00433.JPG


Whatever help I can glean from those smarter than I, shall be much very appreciated
 
For metric module gears the formula is
od / 2+number of teeth
130mm / 2+63 = 2
50mm / 2+23 = 2

So your Gears are 2 module and They could be either 14 1/2 or 20 degree pressure angle. I would guess at 20 degree but not sure. Im not sure you can buy one that wide for the small one. You may have to have them made.
 
From the teeth counts and the OD's these are "module 2" metric gears. Pressure angle is probably 20 degrees, but is not critical in this application.

You can buy module 2 gears from stock. In a pinch, you can get ones with a bore too small or too large, and bore it out or bush it. The 50mm face width on the mandrel/pinion might require some hunting. The 63 teeth on the tensioner is going to definitely need some hunting, as catalog stock M2 gears in that size range jump from either 60 or 62 to 64 teeth.

[Added in edit] Completely in agreement with cuttergrinder, he just types faster.
 
Send a napkin sketch of the gear you need to rushgears.com. Tell them how fast you have to have it and they will ship you the gear. Just be sitting down when you get the quote and have a cardiac specialist standing by. But if you need gears tomorrow you can have them.
 
Thank You for your help. I do have some wiggle room to work with. The wide mandrel/pinion gear doesn't need to be that wide. Notice they drilled and tapped the gear for a set screw, or in this case, a socket head cap screw. A narrower gear with an extended hub with set screw would work. The big gear has a bearing, and its held in with an internal C clip.

I will begin my search for Module 2 @ 20 degrees If I don't find an off the shelf 63 tooth gear, would I be better with a 62 or a 64 tooth? I can adjust the location of the mandrel to correct the mesh clearances

Thanks again
 
Thank You for your help. I do have some wiggle room to work with. The wide mandrel/pinion gear doesn't need to be that wide. Notice they drilled and tapped the gear for a set screw, or in this case, a socket head cap screw. A narrower gear with an extended hub with set screw would work. The big gear has a bearing, and its held in with an internal C clip.

I will begin my search for Module 2 @ 20 degrees If I don't find an off the shelf 63 tooth gear, would I be better with a 62 or a 64 tooth? I can adjust the location of the mandrel to correct the mesh clearances

Thanks again
It looks like that gear also meshes with another gear under it. If thats the case I think you will need 63 and you will have to get the same pressure angle as that lower gear.
 
If I don't find an off the shelf 63 tooth gear, would I be better with a 62 or a 64 tooth?
Better check with the customer. This would change the gear ratio, so might have an effect on the machine's operation. They can tell you whether a slightly lower (62 tooth) or higher (64 tooth) mandrel speed would be acceptable, and if so, which would be better.
 
From the teeth counts and the OD's these are "module 2" metric gears. Pressure angle is probably 20 degrees, but is not critical in this application.
I'm not sure there even is a 14 1/2* mod series. I've never seen one. Module came along after 14 1/2* was pretty well obsolete, so it's very unlikely you'll ever see that.

Not that it's impossible - people do anything you can imagine to gear teeth, the so-called 'standards' are really only suggestions - but still. If you find one, stick it up on the bulletin board as a curiosity.

I'd kinda like to know how you guys plan to change the number of teeth without changing the center distance ?

Our guy is in sacratomato ? I happen to know a gear shop nearby that can make a new one, same as the old one (possibly better), in a reasonable amount of time. I would be going that direction before I'd butcher what is there.
 
He doesn't need to worry about that. He wrote in post #5 that he can adjust the position of the mandrel shaft.
Ah. If he'd put a bit of sex in there I'da paid better attention :D

(I normally don't think of a gear running on a mandrel, probly went in one ear and out the other. btw, getting a new part made is by far the better solution here. It's a simple part, no idea why people are scared to death of gear shops, this is what they do, it's kinda like removing your own appendix, yes it's possible but wouldn't it be easier to have a guy that does this for a living do the job ? I used to take all my welding to the welding shop down the street because they'd do a nice job and I was just going to fuck it up, but to each his own I guess.)
 
Thanks again. In thinking it out some more, I think I am going to have to match the 63 tooth. I do have adjustability at the mandrel interface, but if I change the tooth count, I don't know if can adjust the idler gear to the drive gear below it. I did find a couple of websites that offered 63 tooth with the 47 mm bore for $125 or so. The tensioners are adjustable. so If I have to change the ratio, I can change the RPMs to accomodate.
 
I'm not sure there even is a 14 1/2* mod series. I've never seen one. Module came along after 14 1/2* was pretty well obsolete, so it's very unlikely you'll ever see that.

Not that it's impossible - people do anything you can imagine to gear teeth, the so-called 'standards' are really only suggestions - but still. If you find one, stick it up on the bulletin board as a curiosity.

I'd kinda like to know how you guys plan to change the number of teeth without changing the center distance ?

Our guy is in sacratomato ? I happen to know a gear shop nearby that can make a new one, same as the old one (possibly better), in a reasonable amount of time. I would be going that direction before I'd butcher what is there.
They do make module hobs that are 14 1/2 degree but probably rare. We make a few gears at work but we don't have any metric hobs.
 

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They do make module hobs that are 14 1/2 degree but probably rare. We make a few gears at work but we don't have any metric hobs.
That's gotta be Ash ... all the dimensions are inch except for the module :D

I can see someone who wants to make a very quiet gearset on metric dimensions doing this but haven't ever seen it in real life. You just don't see module on really old stuff, which is where the 14 1/2* teeth are common.

Maybe in yurop ? But even there, old pieces like from pre-war Alfas tend to be a strange combination of inch and metric.

Anyway, you generally don't have to worry about which pressure angle a module tooth is; unless you came across an unusual situation it'll be 20.
 
You can buy a 20mm wide 2 mod 63 tooth gear on eBay for 67$ right now and the 23 tooth gear is 12$ from the same seller.

Supposedly 1045 steel, teeth are induction hardened.

They will come a little banged up, but will give you enough time to find a better solution.

Given how malleable the existing teeth appear to be, i think they will work for a long time.
 
Send a napkin sketch of the gear you need to rushgears.com. Tell them how fast you have to have it and they will ship you the gear. Just be sitting down when you get the quote and have a cardiac specialist standing by. But if you need gears tomorrow you can have them.



Yowsa!!!! You ain't just whistling dixie.

48 hour delivery $ 16,950.00
 
You can buy a 20mm wide 2 mod 63 tooth gear on eBay for 67$ right now and the 23 tooth gear is 12$ from the same seller.

Supposedly 1045 steel, teeth are induction hardened.

They will come a little banged up, but will give you enough time to find a better solution.

Given how malleable the existing teeth appear to be, i think they will work for a long time.

Thanks,

I'll check it out
 
I know that everything in the first photo is badly worn, but it looks like a gear running against a spline. Wouldn't that be different tooth forms?
JC
 
Looking at the hammer tracks on the end of the pinion shaft and the SHCS in place of a set screw, I would say you have a lot of job security helping keep the machine operating.
 
You can buy a 20mm wide 2 mod 63 tooth gear on eBay for 67$ right now and the 23 tooth gear is 12$ from the same seller.

Supposedly 1045 steel, teeth are induction hardened.

They will come a little banged up, but will give you enough time to find a better solution.

Given how malleable the existing teeth appear to be, i think they will work for a long time.


Those parts are unfinished. I would need to increase the bore on both gears.
The price is attractive though. The stress on the gears is minimal, probably 5 psi or so.
 








 
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