Large(ish) spur gears RFQ or recommendations

Hello ladies and gents.

I'm currently trying to get a couple of quotes for one of each of three gears for a 1920s skid mounted winch used to move rail cars into loading stations.

The large gear is a ring gear, 36 3/4" in diameter, 72 teeth ( appears to be) 14 1/2° Pa, and was told that makes it a 2 DP. With about a 30" bore. ( Forgot to bring the dimensions home and can't remember this one) 4 3/8" face width.

The other gears are 15 tooth, drive and sliding engagement gears mated to the large one.

I've made quite a few phone calls with little luck finding a shop interested in the job.

If need be I can make the smaller ones on my horizontal Cincinnati no3, but that 36+ gear is just too big for my mill and I don't recall seeing a way to cut gear teeth on a lathe.

Any information would be appreciated. If anyone here is interested in quoting I can add more info and... pictures.... ( Still trying to learn this new format)

Thanks
Jacob.

What do you think this job "should" cost?

I don't have an expected cost number, but my customer probably wouldn't ok it if the price resembled his SSN.

The problem here is not cost as nearly as much as gear shops tell me they're just too busy for one offs and I don't need two of each.

You want to pay shipping from Montana??...Phil

Shipping is no problem, I'm sure no matter who builds them, they'll have to be shipped.

The price will be shocking......my end of the big gear market try to weld up teeth profiles first,if thats not possible ,i suggest you get the large gear plasma or laser cut ,and the small ones you can cut yourself......Ive saved the gears out of every friction crane Ive scrapped,generally the big gears,the smaller ones are often well inside the guts and hardly worth cutting out.

Maybe possible, and cost effective.....
Could this be fabricated ?
Fairly easy to do the turning, but design it such that you can attach the gear as segments of a size to suit your available machines. Maybe welded or bolted.
Lots of ways to cut the segments.
There's certainly a lot more than a "on-off" when you're talking to gear shops, lol.
A shaper comes to mind the cut the gears.
Bob

Gear teeth are less than 50% remaining, welding and re shaping would be a big job. The shaper idea has been considered, but the trouble comes along the route of mounting to a dividing head, I've got 2, 16" shapers but no good way for indexing or clearance.

Can plasma or laser produce real gears??

This ring gear is mounted by shrink fit with dowel pins installed to prevent slipping.

[Added in edit] When I wrote this, I was assuming a ring gear with internal teeth. If the ring has external teeth, this isn't going to work very well unless you can clamp the gear blank to the end face of the shaper table and use a tool that reaches the full table depth and gear width.

hvnlymachining, if you can't find a gear shop to do this with a proper gear shaper, you can probably improvise something with one of your 16' shapers.

Turn a recess on your gear blank concentric with the bore and PD. Turn a disk that mounts on your dividing head with a spigot concentric with the DH axis. Make at least four bars that fit precisely between the gear blank recess and the DH disk spigot, and drill/tap to secure them in place to each. If I had a really big lathe, I'd bolt them to a faceplate and turn their ends to precisely fit the blank recess and the disk spigot, but you could get by with milling a nice radius (smaller than recess radius) on one end and precisely trimming the other end square to length. After you double check concentricity, drill/ream and dowel (slip fit) the bars to the disk and blank so you can remove and replace them. (Label the bars and their mounts on both pieces. DAMHIKT.)

Then improvise a stand for the DH (and maybe a step for the operator) to get the blank to the right height and sufficiently centered on the shaper. Since I never weld straight, I would probably put the DH on a hinged platform with a screw to adjust pitch (to set the blank vertical), and maybe short slide to fine tune the centering of the blank w.r.t. the shaper ram.

Let the shaper vise take all the cutting force, so your indexing arrangements don't need to resist it. Unclamp to index, obviously, and reclamp for each cut. If the outside of the blank is smooth, you can support the weight when unclamped with a parallel. As one of the bars indexes into interference with the shaper tool, remove it and then replace it when you have indexed enough more. This is similar to hand-over-hand clamping on the mill when working around a full perimeter.

Have any of you guys ever seen a 2DP gear tooth ? Can I watch while you try to cut it with your cute little shapers ?

Any of you guys want to tell me what an elephant looks like ?

The OD or the DP is wrong. With 2DP, the OD (and pitch diameter) will be in wholes or halves.

David_M said:

The OD or the DP is wrong. With 2DP, the OD (and pitch diameter) will be in wholes or halves.

Click to expand...

A 36 pd would be right for 72 t 2dp gear, 36.75 od would also be right...Phil

I get 36 for the pitch diameter and 37 for the outside diameter unless they shifted the addendum(s) and kept the center distance.

David_M said:

I get 36 for the pitch diameter and 37 for the outside diameter unless they shifted the addendum(s) and kept the center distance.

Click to expand...

Yep 74 divided by 2 is 37 ... and 72 divided by 2 is 36
That 37 1/2 burn out 5 " thick is going to be 1564 Lbs

A neat thing about 72 teeth is the tooth centers are exactly 5 degrees apart

old hoisting winch, the mfg could shift center distance or gave more backlash for open grease, or the 36.75 could be flawed...dont know until all the sizes are posted...Phil

small gears are 15T 8-1/4" Dia. 4-5/8 face width, could be made as one continuous gear and I can part and finish machine as needed. Or as mentioned before, I can make these myself, if needed.

I'm fairly sure someone about 40 years ago now made an indexing plate for one of the lathes at my work to shape new gears for a local clock tower. I suspect this because I remade them about 4 years ago. I used our WEDM which was not in the shop at the time. (Damn thing is a 1990 model, so close, but the shop bought it used.) I had always wondered why there was a nicely made indexing fixture on the back the shops "big lathe".

After struggle bussing my way through burning out those gears I thought to count the holes on the indexing plate and wouldn't you know it, I have a solid guess as to how those gears were made.

That said they weren't gears anywhere near that big but it might be an option if you have a lathe big enough and a few months to burn trying to manually shape gears on a lathe.

Indexing for the big ring gear may not be that difficult, because you don't need very high precision. The pitch could probably be marked out with dividers, etc, on the pitch circle.
Then with a carefully made template, the tooth form could be marked out.
Puts you one step closer, perhaps.