Source for 1.75 module change gears?

[Galane]

I need a 28 tooth gear, flat sided, 1.75 module, face width 13mm, 20 degree PA. Max OD across teeth tops is right on 76.99mm every which way I measure. Definitely a metric lathe because the gear chart shows a 127 tooth in the train for imperial threads and feeds. The 28 tooth gear goes onto the output shaft from the headstock. Could also use a 44 tooth but that's for module and some other odd thread spec the lathe will never be used to make.

The problem is, I don't see 1.75mod offered by stock gear shops.

Lemme guess, 1.75mod is the obsolete metric cousin of 14DP? One day the tool industry decided they were no longer going use 1.75mod, as they had done with 14DP after WW2, as they've done with 35mm keyed shafts for 3HP variable speed drives, and...

 

[johnoder]

Lots closer to 10 DP

I.E., 3.031" OD divided in to 30 = 9.898.

2.57 Module if you will

 

[Zahnrad Kopf]

You've got something else going on. 1.75M gears are common enough that we stock that size Hob at all times. But the dimensions you give are not for 1.75M. Assuming stock geometry, if it were it would be 2.0669" in diameter. 2.5M would be 2.9527" and 10DP would be 3.000". So, one has to assume that you have a gear with some Addendum Shift. It's a fairly safe bet that this gear and its mate are not on adjustable center distances. You are going to need to work backwards to figure out what it actually is. Are there any of the gears in the same train that are on adjustable centers that you can measure? If not, you've a little more work ahead of you.

 

[CalG]

I need a 28 tooth gear, flat sided, 1.75 module, face width 13mm, 20 degree PA. Max OD across teeth tops is right on 76.99mm every which way I measure. Definitely a metric lathe because the gear chart shows a 127 tooth in the train for imperial threads and feeds. The 28 tooth gear goes onto the output shaft from the headstock. Could also use a 44 tooth but that's for module and some other odd thread spec the lathe will never be used to make.

The problem is, I don't see 1.75mod offered by stock gear shops.

Lemme guess, 1.75mod is the obsolete metric cousin of 14DP? One day the tool industry decided they were no longer going use 1.75mod, as they had done with 14DP after WW2, as they've done with 35mm keyed shafts for 3HP variable speed drives, and...

There is one of those gears on the bed of every milling machine large enough to hold a dividing head. ;-)

 

[Finegrain]

77mm OD is "perfect" for 1.75 module 42 teeth ...

Regards.

Mike

 

[Galane]

Ahhh, now I realize my goof. 76.99mm is the diameter of one of the other gears (42 tooth) that is on the lathe, not the 28 tooth one which is missing.

The other gears in the train to the gearbox are adjustable, and all are double stacked so switching between metric and not requires only moving the drive gear to the inner or outer position.

What would make it easier is if anyone had any information on a Takang TK380L. It's a very nice, heavy, smooth operating lathe but somewhere in its lifetime somebody decided to remove and dispose of the gears on the output shaft.

 

[Zahnrad Kopf]

Ahhh, now I realize my goof. 76.99mm is the diameter of one of the other gears (42 tooth) that is on the lathe, not the 28 tooth one which is missing.

The other gears in the train to the gearbox are adjustable, and all are double stacked so switching between metric and not requires only moving the drive gear to the inner or outer position.

What would make it easier is if anyone had any information on a Takang TK380L. It's a very nice, heavy, smooth operating lathe but somewhere in its lifetime somebody decided to remove and dispose of the gears on the output shaft.

Okay, so a 28T 1.75M gear would be 2.0669". If you cannot find a stock one that can be modified we can Hob one for you. But start by trying to find a stock one to modify first as it will be a more economical solution.

 

[Galane]

I've yet to find any stock gear manufacturer in the USA that has ready made 1.75mod gears. Found HPC Gears in the UK and another outfit in Bulgaria, and some companies that make the hobs and cutters.

What kind of price would you charge for a 28T 1.75M gear, no hub, 13mm face width? I'd have to take the parts off the output shaft to find the bore size and if it needs a keyway.

 

[Zahnrad Kopf]

I've yet to find any stock gear manufacturer in the USA that has ready made 1.75mod gears. Found HPC Gears in the UK and another outfit in Bulgaria, and some companies that make the hobs and cutters.

What kind of price would you charge for a 28T 1.75M gear, no hub, 13mm face width? I'd have to take the parts off the output shaft to find the bore size and if it needs a keyway.

Not to be evasive, but it all just depends on the details. Bore and Keyway, Post Process, Blank, Speed, etc... Hobbing one of anything is never economical. However, I will say this - you can mitigate some of it by doing everything else yourself and being patient. If you want to turn the blank ( and be responsible for getting it right ), do the Heat Treatment, and are able to be willing to wait for another run of 1.75M gears for someone else you could save some money over having someone else do all of that and requiring it in three days. Shoot me an e* or PM when you have all the details and we'll be happy to give you a firm Quote.

 

[Galane]

I don't expect it to need to be too hard. Cast iron works on gears to drive gearboxes on lathes, so any steel with similar properties ought to do and shouldn't need hardened.

The lathe isn't going to see 24/7 duty. Its owner rebuilds pellet mills and builds other support equipment for them like blower fans, rotary valves, material feeders, rebuilds hammer mills and whatever other jobs come along.

I've been wanting to get my hands on an old AAMCO disc and drum brake lathe (or any other of similar configuration), dirt cheap. I have some ideas about using one as the basis for a CNC controlled gear hobbing machine, but anyone who has one for sale seems to think they're super valuable. Except for old cars for which brake discs or drums are unobtainable new, nobody turns them anymore because it's cheaper to replace with new rather than pay for the shop labor to run the brake lathe.