1920 Dort w/ Brown-Lipe Differential: Who can cut me a new spider gear?

[Nate Dort]

Somebody finally responded to one of my RFQs. $3000 to make two new gears.

I'll keep looking. Welding and filing back to shape is looking more and more likely if my potential source for some good used ones isn't able to locate his.

[human-potato_hybrid]

On 4/23/2024 at 7:56 PM, Rod P said:

According to Master interchangeable parts service Vol 1, 1925-1930, if I am reading it right, section DF has other models that used same spider gear.

 

Not that this usually helps much, as most are rare as hens teeth. 

 

Yes, the Dort's are by far the most common there I think. Only one Geronimo left and not sure if any Bradley's.

[human-potato_hybrid]

On 5/2/2024 at 2:36 PM, Nate Dort said:

Somebody finally responded to one of my RFQs. $3000 to make two new gears.

I'll keep looking. Welding and filing back to shape is looking more and more likely if my potential source for some good used ones isn't able to locate his.

I think 3D printing from stainless steel would give a useable result. However the finish is like sand casting. So first, you would need to replace all 3 gears. The 3D printed ones would need to have the bores machined and you'd have to get in with a needle file and clean up the teeth. Then ideally install them and use some sort of lapping compound to help the gears mesh. Though that compound might tear up the other diff parts. Lastly I would not plan on a long life for these gears...

 

But you could do it for only a few hundred.

[edinmass]

A printed gear will fail………

[mechanician]

The price is driven by the set-up.  I would have expected it to be a little lower but not substantially lower.  It is one of those fields that has not a huge demand but yet the equipment and know-how to use it is expensive.  Most of the customers are industrial users whose real expense is the downtime of their equipment, prototyping work, and aerospace/defense, all of which operate on different budget levels.  Even an off the shelf generic gear from McMaster Carr (probably Boston gear) is not even a factor of 10x cheaper despite being more or less mass produced.

 

You could re-machine the rear end internals to operate with some more widely available gears.  An option but perhaps not a good one, and if that was sent out it would be more than the gears.

 

Maybe, one could be investment cast to tolerable tolerances, machined, and heat treated, maybe, but that is going to be a lot of development work, probably end up around the same cost with a great deal of uncertainty around the result.

 

Printing would give a finish more like sand paper than sand cast.  It would take so much finishing that the result would essentially be a gear with already worn teeth.  That presumes the material properties are sufficient.  Stainless which seems to be one of the strongest easily available printed metals wouldn't be as strong and isn't suitable for the heat treatment usually done to gears of that type.

 

Your best bet might be to solicit more bids, and let them know that you understand that it is going to be expensive.  My guess is that most of the no-bids that had the capability didn't want the hassle of paying their staff to quote it because they figured a hobbyist would never bite on the price. I need to have a couple done myself for a long term project...I feel your pain.

[Nate Dort]

Guess what I got today?

 

 

Situation averted. I'll post more about it in my main thread, but I took a little jaunt over to Canada today to pick these up, along with some other goodies.