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BS0 chinesium semi-universal dividing head problem

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bbaley

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#1
Hi,
I bought one of these (from Precision Matthews, but seems like it's a common device),
and only recently tried to rotate it to the "vertical" position
but cannot seem to get it to do so

The manual contains zero information on how to do so.

When I asked PM they said;
"There are locks on the side, loosen them up and it may be stuck and need tapped to move. . Usually they are pretty sticky from the rust proofing and dried up lubricant that gets on them. "

They did not respond to my question about "please describe the locks - hex bolts? the large slotted screw ? which?"

The only things on the "side" that might be "locks" are;
a) the two bolts going all the way through the "chassis"
b) the locking levers that serve as stops and a pin for the platen with holes behind the chuck (in 10 deg increments)
I know what b) does, not this

I tried the bolts, and whacked the unit with a dead blow, per PM's recommendation, to loosen from any "gunk" or "anti-rust stuff" to no avail.

I cannot get it to rotate.

I am sure I am being stupid or missing something, anyone suggest the next thing to try ?
 

Bob Korves

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#2
You have to loosen the trunnions that squeeze the rotating center section tightly, I think there is a screw with large brass plugs (~1") that clamps it together. It has been way too long since I saw one. Someone else who has one will probably jump in with the "for sure" answer.
 

benmychree

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#3
All the B&S type dividing heads have two hex nuts on the backside that lock the center section in place; loosen them, and the center section should be able to be rotated, a bit of persuasion should do the job. Did it not come with an instruction sheet?
 

JimDawson

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#4
A 50/50 mix of acetone and automatic trans fluid in the hinge area might be helpful also. May be just gunked up.
 

bbaley

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#5
Yes, as mentioned in the post, the documentation contains no such information that I could see.

I did loosen the bolts mentioned, and it would not budge.
I will try some solvent as suggested and see if that loosens up the "gunk"
 

mcostello

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#6
Pictures will help.
 

pontiac428

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#7
The Chinese BS0 has aluminum clamps that are engaged by the two bolts mentioned. If you can get one full turn out of each, and then tap on the heads with a light rap hammer, the divider head should swing free. It takes little more than thumbscrew pressure to keep them in place in the future. To make my life easier, I completely tore down mine, deburred and polished where needed, replaced the bearings with FAG units, and reassembled. Like every Chinese tool kit, the dividing head needs a little bit of love to work like it should.
 

bbaley

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#8
Solved: Thanks all for the ideas!

A combination of the 50/50 mix acetone+ATF into the trunnion "ways" - then some light tapping with a dead blow to the sides around where it gets clamping pressure finally did the trick.

Looks like I'll need to tear it down and go through it to make sure de-gunked.
 

bbaley

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#9
ok, well now I can't seem to get the chuck off of the back plate.

It "seems" like a standard backplate on a chuck. remove the three bolts from rear...
but it won't budge.

I don't see any other bolts/screws...
tried the 50/50 acetone+ATF soak overnight, some tapping with dead blow, twisting/rotating won't budge.

I "gently" tried tapping the bolts while they were threaded most of the way into the chuck from behind - no go, but maybe I didn't whack them hard enough in fear of trashing threads.
 

BROCKWOOD

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#11
The original B&S version used a large center thread to attached the Chuck. Try unscrewing it. Lefty loosy.
 

bbaley

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#12
I ended up making a "bushing" i turned that was ever so slightly smaller than the threads of the head chuck, set down inside and "tapped" with a dead blow that got it loose. then I cleaned up the mating diameter of the plate surface on the lathe to match.

will post a picture of the "bushing" or mandrel or whatever to call it in case interesting to others.
 

BROCKWOOD

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#13
looking forward to your pictures bbaley. In part because I'm not picturing what your solution was & also, I just like to see pics of what others are doing ;-)
 

bbaley

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#14
looking forward to your pictures bbaley. In part because I'm not picturing what your solution was & also, I just like to see pics of what others are doing ;-)
brockwood, ok here they are (or what I actually documented anyway)

Here you can see that there is a "step" where the diameter of the chuck bore is smaller than the bore of the back plate;
https://photos.google.com/photo/AF1QipOekCS2PedxZwUEnF5KsB3GNd8x14fTz4oIPfKN

I took a really thick washer and turned it to fit the back plate threads and the bore of the chuck - really only because there is room down there to slide around - I imagine anything that would fit down there might have worked.
https://photos.google.com/search/_tra_/photo/AF1QipOnCn_0emK3x1T9bTq2ajVe5iG0nlJQdZiH7qua

I tap-tap-tappy-tapped with a piece of wooden closet dowel/rod that was about the right size.
I could tell by the screws down there there was a backplate on the chuck - and looking at my other cheap-o chuck it didn't look very robust, so I was a bit afraid I'd break it being super high quality Chinesium cast crud.

once I got it loose, I put it in the lathe and trimmed it up a tiny bit - it really just needed to be kissed on the OD of the backplate "step" because it wasn't perfectly round and pretty rough. I could test it in the lathe chuck by carefully holding the (other) chuck up to it each light pass until it fit but no wobble or excessive play. i tested this when I first took it out by tapping the backplate when it was in the back of the chuck to listen for any play/rattle and it sounded and felt solid but I could still put them together and remove easily enough.

After that - which was the purpose of all of this, I drilled three new holes in an extra face plate I had - to mount to the dividing head backplate so I could mill some circular cutouts and recesses in some large rectangular stock - and also use the same setup to drill and tap some holes for some pieces that fir in the same holes/recesses.

https://photos.google.com/search/_tra_/photo/AF1QipM-SuMf1KKGxRKI-wxom3FEoiCWV1uYIWrrRfc9
https://photos.google.com/search/_tra_/photo/AF1QipPiljACrCMcuyUM0QpTsAY0PPLmhc1joi1kVd_4
https://photos.google.com/search/_tra_/photo/AF1QipOuA4At5NPTc5ngdQhG3gxxzioHP5gGHwbSUx0N

and then mounted it to the dividing head
https://photos.google.com/search/_tra_/photo/AF1QipPWYaReQWp1J2YIxVS6f5RTSaW7Dzkc3AT829RW

I then learned what an extremely trying and patience testing operation trying to tram this monstrosity is going to be every time I use it.
I'll have to learn the tricks and tips, if there are any for that. what a PITA. Not to mention I need to find someone with a bigger lathe to true of the face plate which is definitely not flat enough....

https://photos.google.com/search/_tra_/photo/AF1QipO4X1rrUaPNjOICYUr73gpjOXPdBFefftMfTk7p

The purpose of all of this was a bunch of stepped holes in some rectangular pieces;
https://photos.google.com/search/_tra_/photo/AF1QipNh95sTU5oygHNP2i6pyqU6rHt6PbnsznVCdSW_

And that exercise is teaching me it ain't easy getting the front and back side of a stepped hole to match up, especially with matching parts through those holes that have drilled/tapped holes that can bind it up when put together and it's only off 0.002"... I expect the order of operations has a lot to do with how well all of that turns out...
 

BROCKWOOD

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#15
All those links & I can't open any of them :-(

Nice write up just the same!
 

bbaley

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#16
All those links & I can't open any of them :-(
Nice write up just the same!
bummer. I'll see if I can just upload them directly since you can't reach the links
 
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