Elliot 3 1/2 dividing head.

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Elliot 3 1/2 dividing head.

This topic has 60 replies, 15 voices, and was last updated 28 August 2021 at 22:46 by Ady1.

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6 December 2016 at 20:44 #270353
mark smith 20
Participant
@marksmith20
Hi Just bought this on ebay after wanting something of suitable size ad deciding whetehr or not to make one .

Anyway it was advertised with 2 broken gears ,although has a nice burnard 6" four jaw which from inspection looks like it will clean up like new with no jaw wear.

On taking it apart (or trying to) i discovered another broken gear under the cover! I knew it may have other problems when i bought it so not too annoyed about that . But on trying to be clever and dismantle it without any manual or instructions i buggered up the part on the end of the worm(on the opposite side of the main body).

I dont know what i was thinking at the time but thought it was just a cover so gave it a little tap with a very thin metal knife edge after removing the 2 socket screws and a hammer and the whole bit shattered leaving what looks like half of it in the side of the dividing head. I wasnt expecting the boss on the other side of the diamond shaped bit.

Anyone have an info on these heads ,such as how to get that broken bit out .

Also the gear info . all the broken spur gears appear to be 26 teeth and possibly 16DP.

Anyone have a parts diagram they could post??

Rather annoyed with myself.

Edited By mark smith 20 on 06/12/2016 20:47:04

Edited By mark smith 20 on 06/12/2016 20:48:44

Edited By mark smith 20 on 06/12/2016 20:51:48
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6 December 2016 at 20:44 #18304
mark smith 20
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@marksmith20
6 December 2016 at 20:55 #270355
John Stevenson 1
Participant
@johnstevenson1
Measure those gears up.

I have done loads of conversions to stepper drive and my have something but not certain, most of mine have been 5" heads or similar but the gears could be the same.
6 December 2016 at 20:56 #270356
Anonymous
Well at least it's not the helical gears that are broken; you should still be able to make spur gears on the dividing head as is.

I have a manual, with exploded diagram and parts list, including the 7" swing version, which is presumably this one? PM me for details.

Andrew
6 December 2016 at 21:02 #270357
Phil P
Participant
@philp
Damn some people are quick.

I have just been and rooted out my copy of the manual, only to find I have been beaten to it.

Most of the differential gears including the banjo and spindle attachment parts were missing on mine, and I had to design and make them myself.

If you need any of those parts you are welcome to my drawings.

Phil
6 December 2016 at 23:59 #270376
mark smith 20
Participant
@marksmith20
Posted by John Stevenson on 06/12/2016 20:55:05:

Measure those gears up.

I have done loads of conversions to stepper drive and my have something but not certain, most of mine have been 5" heads or similar but the gears could be the same.

Hi John, I`ll measure them tomorrow ,Thanks
7 December 2016 at 00:00 #270377
mark smith 20
Participant
@marksmith20
Posted by Andrew Johnston on 06/12/2016 20:56:43:

Well at least it's not the helical gears that are broken; you should still be able to make spur gears on the dividing head as is.

I have a manual, with exploded diagram and parts list, including the 7" swing version, which is presumably this one? PM me for details.

Andrew

Andrew , sent you a PM.
7 December 2016 at 00:03 #270378
mark smith 20
Participant
@marksmith20
Posted by Phil P on 06/12/2016 21:02:18:

Damn some people are quick.

I have just been and rooted out my copy of the manual, only to find I have been beaten to it.

Most of the differential gears including the banjo and spindle attachment parts were missing on mine, and I had to design and make them myself.

If you need any of those parts you are welcome to my drawings.

Phil

Phil, yes i would be interested in any drawings you have,are they in digital format?

Thanks
7 December 2016 at 00:40 #270381
Ady1
Participant
@ady1
Looks like a seriously worthwhile project

GL
7 December 2016 at 12:34 #270428
mark smith 20
Participant
@marksmith20
John S, ive took some measurements ,sorry about the crappy freehand paint drawings.The measurement may be slightly off due to wear .

The first is gear in the middle

the second is the one on the same shaft as the worm which the dividing plate attaches.

the last is the one attached by two grub screws in the end to a shaft with the undamaged helical gear on.

Edited By mark smith 20 on 07/12/2016 12:35:42

Edited By mark smith 20 on 07/12/2016 12:37:18

Edited By mark smith 20 on 07/12/2016 12:40:43

Edited By mark smith 20 on 07/12/2016 12:43:41
7 December 2016 at 13:04 #270433
John Stevenson 1
Participant
@johnstevenson1
Not in work again until Friday so I'll have a look and photograph what i have then.

Looks worse than it is as it can still be used as a straight dividing head without these gears and if worse comes to worse you can fit 3 new off the shelf gears from someone like HPC by pinning as ones is already done,
7 December 2016 at 20:43 #270525
mark smith 20
Participant
@marksmith20
Anyone any ideas how to get this out ,its the remains of the broken bushing ,it extends about and inch or more into the main body with the worm shaft going through it . It is whats left after the end of it shattered .

I tried filing a couple of flats on eith side but there is hardly any material on one side of it(so hard to avoid damage to the worm shaft.). I managed to turn it on th eflats with a spanner but no change of getting a good grip and wiggling it out.

Thanks

Edited By mark smith 20 on 07/12/2016 20:48:35
7 December 2016 at 22:50 #270558
Bazyle
Participant
@bazyle
Drill and tap a hole in it, insert a threaded rod and arrange a slide hammer type system to pull it out.
7 December 2016 at 23:50 #270565
Swarf Maker
Participant
@swarfmaker85383
As this bushing retains the worm shaft, isn't it a simple case of withdrawing the worm shaft such that it brings the remains of the bushing out with it?

If it's really tight then a tube with an internal bore larger than the bushing diameter and of a length such that the wormshaft nut can be tightened against a washer over the end of the tube, will allow tightening of the wormshaft nut to withdraw the shaft and the bushing.
8 December 2016 at 00:03 #270566
mark smith 20
Participant
@marksmith20
Posted by Bazyle on 07/12/2016 22:50:46:

Drill and tap a hole in it, insert a threaded rod and arrange a slide hammer type system to pull it out.

Im not sure theres enough room for to drill a hole and tap unless it was very small diameter?

Edited By mark smith 20 on 08/12/2016 00:03:44
8 December 2016 at 00:07 #270568
mark smith 20
Participant
@marksmith20
Posted by Swarf Maker on 07/12/2016 23:50:24:

As this bushing retains the worm shaft, isn't it a simple case of withdrawing the worm shaft such that it brings the remains of the bushing out with it?

If it's really tight then a tube with an internal bore larger than the bushing diameter and of a length such that the wormshaft nut can be tightened against a washer over the end of the tube, will allow tightening of the wormshaft nut to withdraw the shaft and the bushing.

I`m not sure that would work as it is, as the worm cant be just easily disengaged from the worm wheel. It has, ive been told a split worm wheel instead which would have to be removed along with the spindle ,before i could pull on the worm shaft.Though not certain if im understanding correctly.
8 December 2016 at 00:24 #270571
Swarf Maker
Participant
@swarfmaker85383
The key to dismantling something can often be found simply by thinking about how it was put together in the first place!

I would have assumed that the worm was no larger in diameter than the bushing, otherwise how would it be assembled? Granted, the worm will need to rotate as it is withdrawn from the worm wheel.

Edited By Swarf Maker on 08/12/2016 00:26:33

Edited By Swarf Maker on 08/12/2016 00:26:57
8 December 2016 at 07:01 #270579
not done it yet
Participant
@notdoneityet
I'm not seeing any problem if the flange was part of the whole casting. It will knock or press out from the other side after dismantling whatever is on the shaft (on the other side) or shaft removal.

Looks like the shaft was secured after some form of adjustment on the worm side?

Or is there no clearance to remove the shaft from the other side and won't push out? If so just start drilling or other machining to remove it in small bits!

Edit to add: slide hammer on the shaft, maybe?

Edited By not done it yet on 08/12/2016 07:15:55
8 December 2016 at 10:32 #270606
mark smith 20
Participant
@marksmith20
Hi Thanks for the further ideas, i am terrified of breaking any other part ,hence the caution. The other side of the worm shaft also has a flanged bush ,see photo. Although i have the parts diagram i can hardly see anything of the worm shaft on the inside and certainly dont want to strip any teeth on the worm wheel.

The worm wheel is a split type which id never heard of and cant even see the split down the middle . I assume its for some sort of backlash adjustment . Other bigger heads have an essentric shaft to disengage the worm this doesnt. Heres a few photos of the inside as well.

I didnt know what a slide hammer was but looks useful if the worm shaft was clear of the worm gear wheel.

Edited By mark smith 20 on 08/12/2016 10:44:46
8 December 2016 at 10:50 #270607
Nick Hughes
Participant
@nickhughes97026
Try turning the shaft, whilst holding the chuck (to prevent it and so the worm wheel revolving), the worm "unscrewing" from the wheel should push the remains of the bush out. Only gentle turning should be used and try turning the shaft in both clockwise and anticlockwise, as you may not know if the worm is LH or RH.

Nick.
8 December 2016 at 12:19 #270620
mark smith 20
Participant
@marksmith20
Nick , tried that first it didnt work

Anyway finally made progress ,i decided only way was to remove the spindle by slackening the locking nut and tap with a hammer on wood on the back end of the spindle. Because the worm wheel is keyed to the spindle the slackening of the locking nut and tapping released the spindle without damaging the worm shaft or wheel. Once out i just put my hand in and lifted the worm wheel out.

Then i tapped on the front end of the worm shaft which drove the broken bush out. The thrust washers on the worm shaft next to the broken bush were all rusted up and one is still rusted on and wont move.

I still cant see the split in the worm wheel ,which must be there as its indicated in the parts diagram and the adjusting screws on the worm wheel itself.
9 December 2016 at 21:41 #270907
John Stevenson 1
Participant
@johnstevenson1
Sorry Mark,

These all came off bigger heads and are far bigger on the gears.

The gear in this pic is well over 2" in diameter.

If you want new gears then for just 3 off HPC is probably the best bet but you do realise you only need these gears for spiral milling or compound dividing.

Normal straight dividing just using the plates doesn't use these gears.

Edited By John Stevenson on 09/12/2016 21:41:34
9 December 2016 at 23:06 #270919
Phil P
Participant
@philp
You might need them if you do any "Spiral Slotting"

This is part of the clutch on my Pollitt & Wigzell barring engine.

Phil
9 December 2016 at 23:16 #270922
John Stevenson 1
Participant
@johnstevenson1
10 minutes with a 4th axis and cnc
9 December 2016 at 23:17 #270923
Bazyle
Participant
@bazyle
This thread is showing some interesting 'innards' of a common variety of dividing head which I have not seen elsewhere on the 'net. Anyone know more about the split worm-wheel? It seems odd that one screw is slotted (forcing screw perhaps?) and the square headed ones are not done up to their shoulder, nor are they evenly spaced.
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