Southbend Screwcutting clutch

[Mike OConnor]

Hi Gray,

Just thought of something else... On the 9" and 10K under drive lathes with the motor and countershaft in the cabinet, there is a safety interlock that prevents the end and gear guards from being opened while the countershaft has tension on the spindle belt. It has a vertical rod that is in the vicinity of the area we are talking about here for the trip rod. I took a photo with a 1/2" dowel pin centered on the boss of the bed foot in the approximate location where this would be. Because my 10K is a horizontal drive model, the bed foot casting does not have the hole drilled for the rod, so it is a guesstimate. This interlock was the first thing that I removed when I had one of these under drive lathes. That would easily solve the problem. It is a mechanical interlock only, no electrical interlock.

My guess is a 3/8"- 1/2" diameter rod with its centerline approx. 2" from rear of bed. Based on central location of boss on casting and the cam on my end gear guard (which is present).


Dowel pin representing approx. location of guard safety interlock.

Maybe someone with an underneath drive SBL can provide some more information. Sorry to add more complications to your design. I think this will be an extremely popular modification to the 9" & 10K SB Lathes and this problem would come up eventually.

Mike

[steamer]

Mike,

Checked the dimension again last night.....got 5.1875 actual.   I don't think the 1/16 is too important though for this situation.

Dave

[Mike OConnor]

Hi Dave,

Thanks for the double check. I just checked my other 10K headstock and got 5.547" compared to 5.536" on my original one. Was just surprised it wasn't closer to the 1/2" difference in the center heights of our lathes than .151" .

Thanks again!

Mike

[steamer]

You are measuring to the top of the V''s ...which is the leveling reference surface ...correct?

Oh and I took a picture of it...but I'll post it tonight...costs money to do it with the phone....

Dave

[Graham Meek]

Hi Dave/Mike,

I have managed to find away around the problem, moving the trip rod drop arm away from the bed as I originally intended would I feel bring a fouling condition with the bracket that holds the change wheel guard as I can see a definite curve in the bracket towards the drop arm.

However moving the trip rod drop arm closer to the lathe bed and making an "L" shaped bracket to attach the trip rod to the drop arm means we pass beneath the bracket for the change wheel guard and then go up to the trip rod centre-line which passes over the casting protrusion for the under belt drive and brings us to a position that is below the carriage keep plate. This position means we are also clear of the taper turning attachment.

Details of the rear inverted Vee way on an original machine would be good. Also what is the thickness of the clamping plate that locks the taper turning attachment to the rear Vee way, I estimate it at 0.625".

Finally how far is the cast protrusion from the change wheel end of the bed, this will give me the maximum length for the "L" shaped bracket, and just for good measure can you give me the width of the bracket that holds the change wheel guard where it actually attaches to the bed.

My best regards
Gray,

[steamer]

Sounds good Graham.   I think there is a bit of leeway with the actuator rod length as the case maybe.

Just sent you an email.....

Dave

[Mike OConnor]

Hi Dave and Gray,

Attached is a drawing with the dimensions of my 10K rear vee way.

Mike

[steamer]

Thanks Mike!

Dave

[Mike OConnor]

Hi Gray,

Good eye on the T/A Bed Clamp Bracket thickness! It is indeed 5/8".

The protrusion on the bed foot for the spindle belt is 1-3/4" from the END of the lathe bed.

Mike

[Graham Meek]

Hi Dave/Mike,

Thanks for all the dimensions, I just need one more and that will be it, how wide is the bracket that holds the change wheel guard where it clamps to the bed? This will set the minimum length of the "L" shaped bracket.

My best regards
Gray,

[Mike OConnor]

Hi Gray,

The end guard bracket casting is 1-5/16" wide where it clamps to the bed, but the bracket may need to be positioned another 1/8"- 1/4" from the end of the bed in order to align the face of the guard parallel with the headstock. So, you may want to add a bit of length to that dimension.

Mike

[Graham Meek]

Hi Dave/Mike,

This is something I was afraid of, the position of the bump out in the bed casting combined with the width of the bracket, the movement of the bracket on the bed for adjustment, plus the travel of the drop arm to trip the clutch in either direction means the one arm of our "L" shaped bracket now has a negative thickness.

Back to the drawing board as they say, there is a way around it, but it's complex.

My best regards
Gray,

[Graham Meek]

Hi Mike.

Can you tell me the maximum thickness of the rear wall of the casting on the bump out for the under drive and the over-all length please.

Finally laying a straight edge across where the tumbler gear fits to the headstock, what is the largest drill shank that can be inserted between the straight edge and the rear face of the headstock, currently I need 0.375" to clear a boss for the selector spigot.

My best regards
Gray,

[Mike OConnor]

Hello Gray,

The wall thickness of the bump-out for the belt in the bed foot is max. 7/16" and that is in the rear corner near the end of the bed.

Laying a straight edge across the boss for the tumbler bracket, I assume you are interested in the lower corner of the headstock casting, that clearance is:

My original 1978 horizontal drive H/S with plastic guards: 3/8"
Older 1950- 60's style horizontal drive H/S with cast guards: 1/2"

Sorry for the delay in response. Will be back in the shop in 2 hours if you need anything else.

Mike

[Graham Meek]

Hi Mike,

Thanks for the dimensions, things are starting to come together at long last.

I have worked out a way around the problem I just need the over-all length of the bump out now to complete the "detour" for the trip rod.

My best regards
Gray,