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South Bend 13 spindle size 1 7/8"?

millwrong74

Plastic
Joined
Jun 9, 2018
My 13" SB lathe has a weird spindle size. The serial number is 64754, 13 1/4" swing and 5 ft bed.The cat. number is 186 B according to the serial tag at the time of manufacture.
Closest I can come to it's actual description is on page 19 here from a post here:
http://www.wswells.com/data/catalog/1934_cat_94/1934_cat_94.pdf
My lathe was shipped on 2/25/36, so I am assuming it is still a 1934 Model.?
By my own measurements the spindle OD is 1.86" on the tops of the threads. In between the threads it measures 1.75". The ID is 1.71" or 1.72" from a faceplate and thread protector which screws on.

Here's my question:
What size spindle do I have?
I know it's not 1 3/4" because 2 different backing plates it bought did not fit. Shars Tools told me it was a 1 7/8" spindle based on my measurements, the only problem with that is THERE AIN'T any of those... at least that I can find. The serial tag description I received from South Bend lathes historical records via Grizzly says the headstock is a number 7.

I'm trying to purchase a backing plate to mount a new 6" 4 jaw chuck on this spindle. I already have the new chuck which is a plain back. If I can't find a 6" diameter threaded backing plate with a 1 7/8" thread, my solution of last resort is to use the backing plate off my old 3 jaw chuck which is like 4" Diameter, make an adaptor plate from 3/8" thick steel to fit between the backing plate and the back of the 4 jaw. It's necessary because the 4 jaw mounting holes are at the very outside diameter and the threaded backing plate is only 4" diameter.

Is this lathe a complete one of a kind? :confused:

Common spindle sizes:
Lathe Chucks Technical Information | MSC Industrial Supply Co.
 
That is the normal spindle for the small bore 13"....no commercially available backplates as far as I know... Most just buy cheap 1 1/2"x8 plates and rebore and thread them.
 
source for the old catalogs?

Where do I look for those old catalogs? Is there a source here on the forum? I stumbled upon the 1934 by accident while searching threads on spindle sizes. The search engine on this forum like an other I'm on really doesn't differentiate like I would like, gives you 300 pages to read through each thread or post..... :(

So, based on the reply, backing plates are no longer available, if indeed they ever were. I would need to get a blank 6" plate and thread it to 1 7/8" which is beyond my skill set. My machinist friend has offered to help, so that it a definite possibility. Thanks to you both for your assistance. :)
 
So, based on the reply, backing plates are no longer available, if indeed they ever were. I would need to get a blank 6" plate and thread it to 1 7/8" which is beyond my skill set. My machinist friend has offered to help, so that it a definite possibility. Thanks to you both for your assistance. :)
Did you miss post #2?
 
Not an intense machinist job making a backplate. That is one of the pleasures of owning an older machine. 1 7/8 X 8 tpi can easily be single pointed. I have a tap in like new condition you can have for $40.00 plus shipping. Bore and single point the thread close and run the tap for a perfect fit. I used this tap a few times to make back plates for my 13's series O. PM me if interested. The tap is a Widell.
 

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Not an intense machinist job making a backplate. That is one of the pleasures of owning an older machine. 1 7/8 X 8 tpi can easily be single pointed. I have a tap in like new condition you can have for $40.00 plus shipping. Bore and single point the thread close and run the tap for a perfect fit. I used this tap a few times to make back plates for my 13's series O. PM me if interested. The tap is a Widell.

PM sent. Thank You.
 
tommy1010 your PM box is full. I can't reply to your PM. Sorry, but you'll have to delete a few to make more room. Regardless, I am sending the amount with my address as you requested. In the mean time, I'll PM you when your space is available. Thanks, Pat.

Message:

The following errors occurred with your submission

tommy1010 has exceeded their stored private messages quota and cannot accept further messages until they clear some space.
 
The check is in the mail!

Not an intense machinist job making a backplate. That is one of the pleasures of owning an older machine. 1 7/8 X 8 tpi can easily be single pointed. I have a tap in like new condition you can have for $40.00 plus shipping. Bore and single point the thread close and run the tap for a perfect fit. I used this tap a few times to make back plates for my 13's series O. PM me if interested. The tap is a Widell.

Help!
I don't know how to contact a member whose PM box is full. I thought possibly if I quoted him, he might receive a notice... I donno?

Can Admin or a moderator contact him and have him delete some of his PMs? :confused:

I have mailed the check and included my address as he requested. That's all I know how to do. He was online today, but apparently didn't see my latest post OR get a notification about the mailbox being full.
 
I found my lathe!

It was out in the shop right where I left it! No, just kiddin'. I found this image in the catalog a member linked above. It is a 186B model. It's about 80 years old and still runs great! I am going to try to bore out a 1 3/4" X 8 faceplate I got from Shars and then thread it with the tap from tommy1010 when I receive it. It is going to be very close on the ID, but the thread is the same pitch, so that may help ....I donno? I have no experience threading on the lathe which is why I jumped at the chance to buy the 1 7/8 X 8 tap.

scan (17)

Thanks for the tip on the email john. I did send him one and hopefully we are back on track!

This is a great forum! I am woodnthings on woodworkingtalk.com where I have 23,192 posts. I try my best to be helpful over there and appreciate the help given here! Look me up and check out My Photos.
 
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Here's is what I would start with...these are Decent plates and have plenty of meat to work with...
6.3'' 1-3/4-8 Threaded Back Plates

You are not going to run a tap through without boring and at least partly single pointing first....not gonna happen....you HAVE to bore to the minor diameter...no getting around that....and to go straight to a tap at that size would take a LOT of force to turn that tap.
 
Here's is what I would start with...these are Decent plates and have plenty of meat to work with...
6.3'' 1-3/4-8 Threaded Back Plates

You are not going to run a tap through without boring and at least partly single pointing first....not gonna happen....you HAVE to bore to the minor diameter...no getting around that....and to go straight to a tap at that size would take a LOT of force to turn that tap.

That is exactly the backing plate I bought from Shars. Kevin there was very helpful when I called. I initially was going to return it, but after posting here and finding the tap, I came up with a new plan. My new plan is to bore it out from 1.61" to 1.71" to eliminate the existing threads, which are also 8 TPI. Then start a thread if necessary and use the tap from then on. I may have not stated the dimension correctly above and posted 1 5/8". If so, I'll edit it and change it. I corrected the faceplate dimension. Sorry for the mistake! Thanks!
 
Without doing the math on the differences between 1 3/4-8 and 1 7/8-8 I would think you will not completely remove the threads. Can you pick up the remaining 1 3/4 threads to single point them deep enough to get the tap in and keep it straight?
 
That's my latest plan. The ID of the new faceplate is 1.61" and the ID of the old faceplate is 1.71" leaving about 0.10" to remove. That may leave some of the threads to start the tap in, I donno? But that would be OK with me based on the single point starting advice here. Thanks.
 
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How long is the spindle nose??

ie- how thick does the backplate need to be?


Sorry for the delay. i'll get those dimensions tomorrow. I have a meeting with a lathe hand at a top notch machine shop in the AM to look over the pieces I have. I'll come back with the results. The plan is to bore out the new Shars faceplate and thread it with 1 7/8 X 8 threads. we'll see if that will work. Thanks.
 








 
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