What's new
What's new

SB9 Cross slide dial frozen

fgen

Plastic
Joined
Jul 25, 2010
Location
tx, usa
Hello.
I have a sb 9 on which the cross slide dial is frozen in place, presumably by corrosion. Is there any good way to get a grip on this to try and
free it up? So far I've let it sit with blaster like un rust oil all over it but still no luck. Have not yet tried soaking it immersed in penetrating oil.
Have so far resisted wrecking the set screw hole by putting a
pin spanner there. Grabbing with a padded pliers is also ineffective, perhaps because I've not yet grabbed it tightly enough to mar the surface.
What a bother.

Regards,f
 

fgen

Plastic
Joined
Jul 25, 2010
Location
tx, usa
Hey -
I mean the collar with the writing on it is frozen to the shaft it is on so I can't rotate it to set the zero on it as a dial. I'm expecting to touch off on
a part, hold the crank, and rotate the dial to zero to start a turning operation.

I have the crank removed (had to press that off) didn't lose the pin/key that prevents it from rotating on the leadscrew.
I have put the handle back on to try and hold that while rotating the dial (the marked collar) but so far nothing.
I can likely get it off destructively, assuming it is supposed to rotate on the leadscrew and be friction set by the set screw as it is on
other lathes I've run.

I will go look now to make sure there isn't a second set screw - had not considered that but possible I suppose.

Thanks all for the suggestions.

f
 

fgen

Plastic
Joined
Jul 25, 2010
Location
tx, usa
Do you mean the whole dial with handle, or do you mean the bushing that screws into the saddle ?
The bushing into the saddle is not frozen. I was pretty easily able to unscrew the threaded part with a pin spanner. The leadscrew turns freely within
that bushing (that screws into the saddle). The "dial" thing is frozen to the shaft that has the crank/handle keyway (a round pin actually) and the threads that the
handle cap nut. I can't get the dial to rotate independent of the crank.
Regards,
f
 

JBTR

Plastic
Joined
Mar 19, 2020
Location
USA, Northern Illinois
On the printed dial, by "set screw" are you referring to the thumb screw? That should push on a pin which in turn pushes on a tiny brass shoe that protects the shaft.

My dial was really tight too. Strap wrenches would not grip it; they just slipped. So I cut a piece of aluminum flashing, wrapped that around a couple of times to protect the surface, then gripped it with a chain vise grip. That did the job. I will suggest at least 3 layers of aluminum, because I had to tighten the chain enough that it still made a few tiny marks on the dial. (But now I can't pick out those marks from among the 25+ years of action that this lathe had in a high school shop. )
 

jim rozen

Diamond
Joined
Feb 26, 2004
Location
peekskill, NY
It's possible the brass shoe had gone missing and the thrumbscrew has burred up the shaft. Or the brass shoe has gotten thin enough to get caught sideways in there. 1) remove the entire assembly from the carriage by unscrewing the bushing. Take it all to the bench.

2) Undo the slotted screw with a screwdrive suitably modified. Tap the protuding shaft while holding the handle, to remove the handle. Don't lose the dutchman pin that's in there.

3) continue tapping so the shaft passes through the dial and drops out of the bushing.

4) collect all the bits that fall out and figure out where it had locked up. Re-assemble.
 

jim rozen

Diamond
Joined
Feb 26, 2004
Location
peekskill, NY
Harder hitting could be done with a short section of steel with the correct threads in the center - 10-24 I think? Possibly no. 12-24.
 

fgen

Plastic
Joined
Jul 25, 2010
Location
tx, usa
Zow! Excellent insights. I just don't see how to get a grip on the dial/printed collar to drive (or press?) the shaft (leadscrew) out. It is
flush up against the "bushing nut" (thing with the pin spanner hole). I guess I just wrap that with some kind of protective stuff and chuck it in a vise.
I'll look again tonight.

Thanks much!
f
 

jim rozen

Diamond
Joined
Feb 26, 2004
Location
peekskill, NY
In principle if you hold the bushing in a vise so the larger diamter ('dial size') portion cannot slip through, remove the dial lock setscrew and shoe under the setscrew, and remove the nut and handle on the end, tapping the end of the shaft should push the shaft through the dial, and out the back of the bushing. Careful to not bend the leadscrew when it pops out the back....
 

fgen

Plastic
Joined
Jul 25, 2010
Location
tx, usa
Hey - Success last night. I put the bushing shoulder just on the handle side of the threads on a pair of Al bars in the hydraulic press and
used a 5.5mm socket to protect the handle threads (handle removed) on the ram side and with great fear started pumping. Got the usual enormous
WHANG! from the first release and had to keep pressing to get it all the way out, but after a 3 hour liquid wrench bath it all goes together well.
Finally a use for the metric system! If I do this in future I'll machine a socket substitute with square bearing surfaces as the socktet seems to be
rounded enough to slightly mushroom the edges of the shaft - light file work was required after.
Anyway, all this in case someone else goes this way again.
Thanks much for all the help!

Regards,
f
 

fgen

Plastic
Joined
Jul 25, 2010
Location
tx, usa
Don't know for sure but inside the dial there was a copper color deposition for about 1/3 to 3/4 of the way around the dial bore. I assume it has something
to do with the brass shoe being smeared about, but don't see how that is even possible unless the copper colored stuff was dissolved somehow. The thing
did suffer some kind of handle impact in a prior life which is why I has taking handles off (to straighten). Probably just garden variety corrosion from storage in a
barn. Bore and shaft after removal was not pitted that I could see though.

f
 








 
Top