Help identifying/making gear for my DSG lathe

[BPence310]

I could really use some help figuring this out. I have a DSG 4AV lathe that I acquired and I've figured out (partially) why my power feed isn't working. It seems I'm missing a change gear (several actually, but only one that I NEED). In the pictures, I attached the plate that has the setups, and a picture of the gears with them labeled how I believe is correct. It seems I'm missing the gear on "C". I took the gear from "D" and moved it to "C" and now I can get my power feed screw to spin. My problem is that I cannot seem to get the correct information for the gear that I need to either make or buy.

The O.D. of the gear on "D" is approximately 105mm, and the gear on "B" is approximately 112mm. I know a Mod 2 gear is 100mm and a mod 2.25 gear is 115mm. These are 48 tooth gears but I'm unsure if they are 20 deg, 14.5 deg, or some other PA. I have some 14.5 deg gear cutters, but they are the wrong mod, so I don't know any good way to determine which gear cutter to buy.

Right now I'm just trying to get smooth sliding and surfacing cuts, but I would like to be able to make all the threads also, so any insight into what gears I need would be helpful.

If anyone has any insight into what these gears are and how I could make them (which PA/Module cutter to buy) I would greatly appreciate it. I have an arbor and dividing head and milling machine, so I can make them if I just could figure that out.

Thanks for any help!

 

[markba633csi]

You might want to invest in a manual for that beast: (I would)

Dean Smith and Grace Type A & B Lathes (from the 1940s) | store.lathes.co.uk

store.lathes.co.uk

 

[Ischgl99]

Are you sure your gears are metric? The measurements you state for the 105mm gear comes out very close to a DP of 12.

 

[Larry$]

I know a Mod 2 gear is 100mm and a mod 2.25 gear

The Module or DP defines the shape of the gear teeth and should be the same for all gears in a gear set. Module is measured in mm OD/(# of teeth+2). Diametral Pitch is just the inch system which is the inverse of the module. Numerator & denominator switch places and use inches. I think a Module 1.25 and a DP of 20 are the same tooth form. That machine was built using imperial measurements, lead screw. So, the gears were probably defined using the DP system. Doesn't matter which measuring system you use. The 127 tooth gear is used to convert to metric pitch screws. 127*2=254, 25.4mm/"

 

[BPence310]

Are you sure your gears are metric? The measurements you state for the 105mm gear comes out very close to a DP of 12.

I'm not sure of anything about this lathe to be honest. I actually had a recommendation to check out Boston gears catalog and about 10 minutes ago came to the same conclusion that I think it's a DP12 gear.

I'm just a little baffled that one gear is almost 10mm bigger than the other and they are supposed to be (I think) the same gear profile.

It was also mentioned to be that it is probably a 14.5 degree PA since most British gears were 14.5 back in the WWII era. Does this sound correct? I'm probably going to order a 14.5 degree DP12 gear cutter today and see if it works. I just hate to spend the money on the wrong cutter.

Brian

 

[BPence310]

That would be very strange if they need to run in the same gear train! The Module or DP defines the shape of the gear teeth and should be the same for all gears in a gear set.

I agree. I don't know what module it/they are. I am beginning to be convinced that these are actually DP12 14.5° gears based on the measurements and a few recommendations I received.

 

[BPence310]

You might want to invest in a manual for that beast: (I would)

Dean Smith and Grace Type A & B Lathes (from the 1940s) | store.lathes.co.uk

store.lathes.co.uk

I would love to have a manual but looking at various pictures and sizes of machines, I haven't seen one that looks like mine. The only thing I have that it's a 4AV is from one of the plates on the lathe.

 

[markba633csi]

They sell one there that supposedly covers your model for 39 pounds (about 47$ US)
The Rolls Royce of lathes!

 

[BPence310]

They sell one there that supposedly covers your model for 39 pounds (about 47$ US)
The Rolls Royce of lathes!

I just ordered the manual. I hope it really does cover my lathe so I can get some good info about it!

Thanks!

 

[Larry$]

14.5° gears

You should be able to tell 14.5° gears from 20° visually. Look for photos or drawings at about the same scale to compare. One is more "pointy" than the other.