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Help ID'ing a dividing-head with an MT3 spindle

VtSlowLearner

Plastic
Joined
Oct 6, 2019
Location
Vermont, USA
Newbie here, please try to excuse my ignorance. I've owned an Emco Maximat 7 for almost 50 years mostly for hobby purposes, now in retirement am trying to expand my tooling and skill sets.
This week I have been cleaning up an old dividing head that has no manufacturer's name, trademarks, or anything else. Its basic design and overall size resemble a Brown & Sharp Model 0, including the ability to rotate it from horizontal to vertical or any angle in between. However, there is no sign at all of a direct indexing plate, the spindle thread is 1 1/2" x 10 tpi (not 8), and a #3 Morse taper seems to fit the spindle bore perfectly.
The only indexing plate that I have is 5" diameter, 1 1/4" bolt circle, and has ten sets of holes: 17,19,21,23,39,48,56,60,66, and 72.
I have been trying to disassemble for through cleaning and rust removal; have been able to dismount the gear box from the circular-dovetail base but so far cannot get inside the gearbox. The second photo illustrates the rear of the spindle. Everything in that cavity rotates with the spindle, but I was dismayed to find what looks like a driving key after managing to unscrew the threaded collar (shown on the workbench.)
Beyond simple curiosity, I hope that identifying this unit will lead to some ideas on how to finish disassembly, cleaning, and reassembly. It might also help in tracking down other index plates, and possibly work-holding options.
Is there a series of collets that fit into an MT3 taper?
Thanks very much...
 

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I have seen a few copies of the B&S heads,most have mfg ids.
I have a Rockford h-mill with what I believe to be the original DH.It does not have any mfg name on it.It's quite possible that other old m- machine mfgs made their their own dh's or subbed them out and did not have their name on them.
I have a B&S O import copy also but since I don't have an original to compare I don't I have no idea how faithful it is to the original.My guess is that the design would be the same so see if you can get a copy of the B&S manual.I will see If I can find the manual for mine if that will help.
 
When I bought mine it was covered in black paint as part of a telescope mount and I could not see a makers mark. I kept looking at dividing heads on eBay until I found one that looked like mine and finally found it was a Brown & Sharpe.
 
To answer the actual question the OP asked, you can buy MT collets, but they are pretty limited in sizes; usually they would be used for toolholding so standard shank diamters are what you will find.

You can also buy ER-series collet chucks with MT3 arbors.
 
More Pics of Mystery Dividing Head

I would imagine that additional photos would help in possibly arriving at both identification and disassembly process
Unfortunately I didn't take overall shots of the unit, nor become aware of this forum, before starting disassembly for rust removal. However, the next 4 photos were taken during step by step removal of the crank, index plate, etc.PreCleaning1.jpgPreCleaning2.jpgPreCleaning3.jpgPreCleaning4.jpg
Next I managed to ease the gearbox out of the circular-dovetail base, and soaked everything but the gearbox in "EvapoRust": CleanedParts1.jpg
 
I have seen a few copies of the B&S heads,most have mfg ids.
I have a Rockford h-mill with what I believe to be the original DH.It does not have any mfg name on it.It's quite possible that other old m- machine mfgs made their their own dh's or subbed them out and did not have their name on them.
I have a B&S O import copy also but since I don't have an original to compare I don't I have no idea how faithful it is to the original.My guess is that the design would be the same so see if you can get a copy of the B&S manual.I will see If I can find the manual for mine if that will help.
I did find a copy of the B&S manual on this forum, and now realize that the unit I have is much simpler than even the B&S "0".
Here are some more photos. Because I still haven't figured out how to "open" the gearbox, I haven't wanted to immerse it in rust remover.
The last photo, with index plate and crank reassembled to the gear box, shows what a difference that stuff can make. But of course this isn't true reassembly since the gear box still hasn't been fully cleaned or reinstalled in the base. And it does need further disassembly, because the spindle does bind somewhat, at one point when being put through a full rotation.
 

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Could be a Brown & Sharpe product or an imported clone. Some of the features on this dividing head are different from the catalog version.
ie: a singular frame clamp and the spring loaded plate stop.
Attached are specs for comparison and a LeBlond image that has a plate stop.
Brown & Sharpe.JPGB&S Dimensions.jpgParts.jpgLeBlond section view.jpg
John
 
Departures from the B&S design

...Some of the features on this dividing head are different from the catalog version. ie: a singular frame clamp and the spring loaded plate stop.
Attached are specs for comparison and a LeBlond image that has a plate stop.
View attachment 267446View attachment 267444View attachment 267447View attachment 267448
John
John,
Thanks for pointing out the frame clamp and especially the plate stop, which I hadn't yet recognized as another significant difference. Here's a list, so far.
Indexing
Ten hole circles, 17 to 72 (B&S plate "C" has 49 holes max)
Spring-loaded plate stop and set-screw on the hand-shaft
No sign of any direct-indexing plate
No handle on back side corresponding to B&S part "1-39"
No backlash adjustment that I can find
Frame
One 1/2" diameter clamping bolt, no tilt-assist handle on back face of gearbox like B&S part "1-43"
Spindle
1 1/2" diameter nose, 10 TPI instead of 8
Interior taper: 22 mm ID at front, 19 mm ID at rear, MT3 seems to fit perfectly
At tail end of spindle: What appeared to be a bearing retainer threaded onto the spindle end (1 1/4 x 20 TPI) seems after removal to be merely a very solid cover - similar to B&S "1-15" but not held by separate screws.

Also unlike B&S, there is an external keyway cut into the threaded end of the spindle, with no obvious way to remove key from it; but it's hard to believe the gearbox could have been "irreversibly assembled." (Keyway and key can be seen in one of the first photos I posted.)


As I have mentioned, a noticeable bind does occur once in each full revolution of the spindle, and that is what makes the disassembly puzzle more than idle curiosity: how can I get in there for cleaning and (re-)lubrication???

Thanks, everyone...
 
I'd like to revive or restart this thread. Discussion dried up when the forum's algorithms decided that my Oct 17 reply to John Hruska's comment might be "spam", and shunted my posting into the "moderation queue" where it sat until reviewed and released from Purgatory on Oct 21.
BTW from correspondence with "Jessica" in the front office, I now understand that I probably triggered the spam-trap by neglecting to delete images when quoting John's comment. YMMV.
Thanks in advance, again, for anyone who sees useful clues in my Oct 17 summary of the mystery div-head's properties. I still haven't figured out how to disassemble the gearbox itself.
 
You definitely have an odd ball one there. I've notice a few sold on eBay that do not have the quick index plate on the front of the spindle. I have a B & S-0 clone and had a real B & S-2 many years ago. As for getting the spindle out of it, you must get the worm shaft or indexing shaft out first. Then the spindle should come out. May have to bump it gently to get it to move, but should drop out. But it's not going to come out before the worm is removed first. If you don't do this the bull gear on the spindle will get damaged. Don't force anything, be gentle. As for the No. 3MT and the odd spindle thread, well lets say, these clones did not always follow exactly what B & S did years ago. My No. 0 has a No. 2 MT and a odd ball spindle nose that is 10 TPI.

Ken
 
Check the thread pitch of the spindle nose. If metric then likely imported.
Drill a pair of holes for a face spanner to remove the cap on the back side of the head-see the attached photo.
Face Spanner.jpg1.jpg2.jpg3.jpg4.jpgThe last four photos are of a scrap B&S head after electrolysis. Just there for comparison.
John
 
As I have mentioned, a noticeable bind does occur once in each full revolution of the spindle, and that is what makes the disassembly puzzle more than idle curiosity: how can I get in there for cleaning and (re-)lubrication???

I would not. Disassemble it.

Here's a thought. I bought an Ellis DH that the PO had pranged. Minor damage, one position. Same symptom as you have. Binding as it engaged that damaged tooth.

But here's the fix. Worms slide, they do not just engage the one tooth the way a spur gear does. They can sort of self-correct and not add positional error.

The engagement of the worm's components is adjustable.

Flush and replenish the lube. Put a power tool or motor to turning the handle's shaft. Tighten the engagement periodically.

As it "wears in" it can self-correct until the binding is no longer significant. Flush and replenish the lube again.

It will then divide about as well and as accurately as it ever did... for not a lot of time invested, and no real money but a few ounces of kerosene and lube wasted, either.

Which is righteous enough. Because most of us just do not USE a DH all that often, anyway.

2CW
 
Ken,
In a way, it's reassuring to hear that I "definitely have an oddball one." You've also helped me understand the correct sequence for disassembly - if I do try to disassemble it.
Thanks!
Irv
 
Each thread that I've measured has been an exact match to an inch-based thread pitch gauge, so this is probably a home-grown American oddball, not an import (though maybe it could have come from the UK?)
Actually the cap does already have a pair of face-spanner holes, but they're rather badly beaten up. It hadn't occurred to me that of course I could a new pair, thanks! (Of course the condition of the present spanner holes suggests that even then, that cap probably isn't going to turn easily. I've been soaking the joint with PB penetrating oil, will see what happens.)
I have a better photo, but will post it separately just in case it gets stuck in the Moderation Queue.
Thanks,
Irv
 
One more photo: back end of worm shaft

Additional reply to jhruska:
This photo shows the cap on the non-crank end of the worm shaft more clearly. As you can see, some previous owner has managed to chew up its face-spanner holes rather badly.
I like your suggestion of drilling (a new pair of) spanner holes, and will try that unless I decide to heed the advice from "thermite" and cease further disassembly efforts. <g>
Thanks!
Irv
 

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"thermite",
Your comments sound like wisdom to me. In fact, assuming that the two screws on the upper circumference of the gearbox are intended to be lubrication ports, as of now there doesn't seem any lube in there. What would be an appropriate lubricant? (Light oil, heavy oil, grease?)
Unlike the two screws on the top, the setscrew on the face of the gearbox doesn't seem to have a cavity behind it; when screwed all the way in it simply seems to hit bottom. Nevertheless, it that likely to be the adjustment for worm engagement, or would it be the cap on the non-crank end of the worm shaft?
Thanks very much,
Irv
 
Additional reply to jhruska:
This photo shows the cap on the non-crank end of the worm shaft more clearly. As you can see, some previous owner has managed to chew up its face-spanner holes rather badly.
I like your suggestion of drilling (a new pair of) spanner holes, and will try that unless I decide to heed the advice from "thermite" and cease further disassembly efforts. <g>
Thanks!
Irv

That is the results of Bubba using the wrong tool to back out the bushing. At this point, I would suggest to continue the practice that Bubba did using a drive punch or drift and try to get it loosen. Once you get it out, You can dress it up a bit, I know you won't get all of the burgger marks off. Take and drill two new holes that will accept a adjustable pin spanner. That way you have a proper way to reinstall the bushing back into the housing. You're probably going to find that bushing driven in VERY tightly from Bubba. it doesn't need to be that tight. Once tighten with the spanner, give it a couple hits with a small hammer and that should make it good for a long, long time.

Ken
 
"thermite",
Your comments sound like wisdom to me. In fact, assuming that the two screws on the upper circumference of the gearbox are intended to be lubrication ports, as of now there doesn't seem any lube in there. What would be an appropriate lubricant? (Light oil, heavy oil, grease?)
Unlike the two screws on the top, the setscrew on the face of the gearbox doesn't seem to have a cavity behind it; when screwed all the way in it simply seems to hit bottom. Nevertheless, it that likely to be the adjustment for worm engagement, or would it be the cap on the non-crank end of the worm shaft?
Thanks very much,
Irv

Lube one can "copy' from published specs, most any other DH.

It will be one "known non-hostile" to Bronze. Read "NOT automotive differential lube AT ALL". It's about the chemistry.

End cap MAY have a fine-pitch end-PLAY adjuster UNDER it.

Might need to take that other cover off after all, though and see if there is a missing or damaged part w/r that "bottoming" symptom.

With other advice already factored in? The rest has to come from your own detective work, your specific unit and its condition.

DH do much the same job. They do it "mostly" the same way. Just not 100% so.
 
Along with what Thermite has said, I would use a moly base grease in a NGL-1 grade, OR General Lubriplate light grease for assembly. Definitely stay away from axle grease. What I call axle grease. I carry around 10 to 15 different types of grease for my equipment and my general "go to" grease is the moly disulfide grease. The one i have used to sell under the Texaco brand, I don't the cross over name is or if it is offered today. Heck, google it, and find a seller on Amazon to buy it from. mine came from a 25 Gal. drum from the work place I used to work at. A quart can has lasted 20 years now and still have plenty of it left. I even have these nifty hand held grease guns that squirt out a dab at a time. Getting way off topic here. Ken
 








 
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