C to B to A Conversion


gorvil
 

Hi All,

Well I am half way through the conversion process. I milled a keyway
in the leadscrew for my 9" x 4' C and changed out the apron to a
clutch type with power cross feed that I got on E-bay. I had the
leadscrew here at work for several weeks waiting for our machinist
to help me but he could never get around to it. I finally took
matters into my own hands. I made a milling attachment from a Taig
headstock, a DC motor from a treadmill and a dimmer switch with a
full wave rectifier bridge. The Taig headstock is just the right
height to match the center of the SB when mounted on the cross
slide. Not having a steady rest, I made one out of a 2 x 4 mounted
on the base for the tailstock. I drilled for a tight fit with a bit
mounted in the lathe chuck. I cross drilled the 2 x 4 for a setscrew
to keep the leadscrew from turning when I had to rechuck it to take
another pass with the mill. The chuck was clamped to the lathe bed
by propping a piece of scrap steel under one of the lathe jaws. I
took the precaution of unplugging the lathe motor. It is just too
much of a conditioned response to grab the F/R switch when you want
to start cutting.

The next step is to cut down the length of the leadscrew, thread it
and cut the keyway for the drive gear. Does anyone know how the
sleeve is affixed to the leadscrew? The documentation from SB says
there should be a pin, but I can't find one.


frankblack67401 <frankblack@...>
 

It's taper pinned on there, it's just a b***h to find. Apparently
they drive in the pin and then file it flush. A good light and a
magnifying glass helps.

Makin chips

Frank

--- In southbendlathe@y..., "gorvil" <Gorvil@a...> wrote:
Hi All,

Well I am half way through the conversion process. I milled a
keyway
in the leadscrew for my 9" x 4' C and changed out the apron to a
clutch type with power cross feed that I got on E-bay. I had the
leadscrew here at work for several weeks waiting for our
machinist
to help me but he could never get around to it. I finally took
matters into my own hands. I made a milling attachment from a
Taig
headstock, a DC motor from a treadmill and a dimmer switch with a
full wave rectifier bridge. The Taig headstock is just the right
height to match the center of the SB when mounted on the cross
slide. Not having a steady rest, I made one out of a 2 x 4
mounted
on the base for the tailstock. I drilled for a tight fit with a
bit
mounted in the lathe chuck. I cross drilled the 2 x 4 for a
setscrew
to keep the leadscrew from turning when I had to rechuck it to
take
another pass with the mill. The chuck was clamped to the lathe
bed
by propping a piece of scrap steel under one of the lathe jaws. I
took the precaution of unplugging the lathe motor. It is just too
much of a conditioned response to grab the F/R switch when you
want
to start cutting.

The next step is to cut down the length of the leadscrew, thread
it
and cut the keyway for the drive gear. Does anyone know how the
sleeve is affixed to the leadscrew? The documentation from SB
says
there should be a pin, but I can't find one.


strictlystainles@...
 

Would you have an extra pair of half nuts? I could use a pair so I dont have
to repair mine.

Gerald
Iowa


strictlystainles@...
 

LOL Yep I found that out when I did my conversion form C to A. I will see if
I can find the wore out set.

Gerald
Iowa

ps what is a "perjoggin"


gorvil
 

Thanks Frank,



I spent about a half hour looking for the pin under a 40 power stereo microscope with a fiber optic light source and I still couldn't find it. I tried magnetizing the shaft and dipping it into a pile of filings to look for anomalies in the flux lines. I tried soaking it in vinegar to see if the pin would etch differently than the collar. I think that the pin healed itself into the collar. I ended up making a new collar and a new pin.



The good news is that I finished the conversion. I now have a 9" x 4 foot A as well as my original 9" x 3 1/2 foot A. I also have a some leftover C parts (apron, leadscew, etc.) that are available to whoever might have a need.



Glen Reeser

--- In southbendlathe@y..., "frankblack67401" <frankblack@h...> wrote:

It's taper pinned on there, it's just a b***h to find. Apparently
they drive in the pin and then file it flush. A good light and a
magnifying glass helps.
Makin chips
Frank
--- In southbendlathe@y..., "gorvil" <Gorvil@a...> wrote:
Hi All,
Well I am half way through the conversion process. I milled a
keyway
in the leadscrew for my 9" x 4' C and changed out the apron to a
clutch type with power cross feed that I got on E-bay. I had the
leadscrew here at work for several weeks waiting for our
machinist
to help me but he could never get around to it. I finally took
matters into my own hands. I made a milling attachment from a
Taig
headstock, a DC motor from a treadmill and a dimmer switch with a
full wave rectifier bridge. The Taig headstock is just the right
height to match the center of the SB when mounted on the cross
slide. Not having a steady rest, I made one out of a 2 x 4
mounted
on the base for the tailstock. I drilled for a tight fit with a
bit
mounted in the lathe chuck. I cross drilled the 2 x 4 for a
setscrew
to keep the leadscrew from turning when I had to rechuck it to
take
another pass with the mill. The chuck was clamped to the lathe
bed
by propping a piece of scrap steel under one of the lathe jaws. I
took the precaution of unplugging the lathe motor. It is just too
much of a conditioned response to grab the F/R switch when you
want
to start cutting.
The next step is to cut down the length of the leadscrew, thread
it
and cut the keyway for the drive gear. Does anyone know how the
sleeve is affixed to the leadscrew? The documentation from SB
says
there should be a pin, but I can't find one.


gorvil
 

Hi Gerald,



The model "A" apron I bought on eBay had excellent half nuts, so the ones I refurbished are not needed. I spent about 6 to 8 hours building the holding fixture described in the HSM article and learning how to braze cast iron. I found that furnace patching cement is useful in building a dam to keep the brass from running out of the area to be repaired. If you send me your old half nuts I will send you a "renewed" set for $25.00 S&H included. I tried them out on my lathe while still in the "B" configuration and the only play I could detect was due to the leadscrew shifting in its bracket.



There is a difference between model "C" halfnuts and those for B or A lathes. The interlock mechanism that prevents the clutch drive from being engaged when the half nuts are engaged and vise versa depends on an adjustment (filing or grinding) of a perjoggin on the side of the bottom half nut. These "C" half nuts would need to be fitted to your "A" or "B" lathe.



Cheers!



Glen Reeser

--- In southbendlathe@y..., strictlystainles@a... wrote:

Would you have an extra pair of half nuts? I could use a pair so I dont have
to repair mine.
Gerald
Iowa