Requesting advice on motor/pulley setup for Sears 109 21270

Keep us posted , he has a sleeve type spindle for my lathe I'd like to ask him about .
Mark .
 
Well he replied and said that he did not have a countershaft unit.
 
aoresteen said:
The biggest problem with the 109 is not the spindle, it is the speed. It is just not slow enough. If you have just a plain pulley in the headstock you need to get the "planetary" backgear set with a 3 step pulley. Like this one:

View attachment 408282

This will reduce the spindle speed to 1/5 of the speed when engaged. It is a must on the 109. My 109.0703 didn't have one (although it came with one from the factory when it was made in 1941) when I got it. I bought the best one I could find off of eBay (I am in the process of replacing the bearisngs in the backgear - they have a reputation for being noisy).

You can see one being pulled apart at 9:42 in this video:


With a regular pulley & motor, the 109 can have speeds of 580 to 2040 RPM which is way to fast to cut gears or work with steel. Even with the planetary backgear unit, with a 1750 RPM motor your lowest speed will be around 116 rpm. Better, but it needs to be down in the 55 RPM range to be truly useful.



To control the speed of a 109, options are:

1) DC motors with VFD, or

2) Countershaft setup, or

3) a slower AC motor of say 900 RPM and forgo high speeds altogether.

I've decided on building a countershaft, option 2.

I found an esoteric mention of a Craftsman countershaff for the 109 on the British website www.lathe.co.UK. It reads:

"...Obviously aware of the limitations imposed by this arrangement, the Company (Craftsman) offered later versions with the option of a double-step pulley on the motor and a proper countershaft assembly, thus doubling the number of speeds and giving, according to the handbook, a range from 55 to 465 rpm in backgear and from 380 to 3050 in direct drive - a very much more satisfactory arrangement."

AA109, Craftsman 80, Dunlap, Simpson & Courlan Lathes

History and development of the Craftsman, Dunlap, Companion, Metalcraft, Metalmaster, AA109, 109, Simpson and Courlan and manufactured by the American
www.lathes.co.uk

This is the only reference that I have been able to find about the existence of a factory countershaft setup for the 109. I'd just like to see a photo of it so I could start making one. Perhaps they are wrong but I hope not.


Bent shafts on the 109 are due to worn bearings, too fast speeds and improper tool alignment (operator error).

For $120 You can get a new replacement spindle made from 4140 steel that is far stronger that the original ones made 70 years ago. I bought one and opted for the original 1/2" x 20 TPI thread but they are available with a 3/4" x 16 TPI. Look on eBay.

My need for a lathe is to make 7/8" x 2" round parts out of aluminum which the 109 can do very well.
Click to expand...
Thanks. Mine does have the planetary setup, Still in the disassembly and cleaning/discovery phase. Just wanted to know my options and get familiar with this little guy. Unfortunately its gonna be on the back burner for while, but will pick at it when I can, while getting list of what I need and compiling some resources! Will post some pics soon. Any and all help is certainly appreciated. Thank you for the info, and for taking the time!
 
Deepcover said:
....Still in the disassembly and cleaning/discovery phase. ...
Click to expand...
While it is torn apart, I highly recommend that you replace:

1. The headstock bearings

2. The spindle with a 4140 steel one. You can get a new 4140 spindle with the original 1/2" - 20 chuck size or a stronger 3/4" - 16 chuck size (Sherline).

Starting new with known good bearings & spindle will ensure starting fresh from a good baseline.
 
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