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Dividing head for Tom Senior Mill advice

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Rannsachair10/03/2022 19:16:30
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37 forum posts
61 photos

I have just bought a Tom Senior Mill and was after some dividing head advice for a Light Vertical with S type head: I quite fancy getting a dividing head and a few questions come to mind:

  1. What size? from mounting face to centreline.

  2. Better looking out for a good old English made one or are the Chinese one's ok, if so what make to look at?

Thanks

s-l1600.jpg

s-l1600 (2).jpg

Emgee10/03/2022 19:47:23
2445 forum posts
291 photos

As it seems you have a good height from spindle to table I believe a BS0 Dividing head will suit your machine and provide a good range of divisions and working angles.

Emgee

Rannsachair10/03/2022 20:14:58
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Posted by Emgee on 10/03/2022 19:47:23:

As it seems you have a good height from spindle to table I believe a BS0 Dividing head will suit your machine and provide a good range of divisions and working angles.

Emgee

Thanks, appreciated, that is 4" centre

old mart10/03/2022 20:23:49
3892 forum posts
268 photos

_igp2672.jpgOur light vertical at the museum has lost about 1" of Z height since I converted it to R8 from MT2, but the 6" vertical/horizontal rotary table fits on it no bother. With a 5" chuck on it the height is hardly any more than your vise with swivel base. I say rotary table rather than a dividing head as it will do everything that a DH will do and all the angles in between. Dividing heads are primarily for production work for fast indexing over a limited number of positions, and you may regret not going for a RT. Some time back,I bought a long cranked handle for moving the knee when there was something heavy on it, and the one I got on ebay had 7 castellations in it, easy with a RT at approximately 51 degrees and 26 minutes each.

Edited By old mart on 10/03/2022 20:29:54

Simon Williams 310/03/2022 20:28:23
662 forum posts
82 photos

As a Senior citizen (Light Vertical division) myself, and the owner of a BS0 head I can vouch for their compatibility.

Having said that I have done a number of jobs where I thought a dividing head which could be mounted horizontally or vertically would be a good thing. Then I bought a 6 inch (being the diameter of the rotating platen) rotary table and all was well in the world.

I also have a 10inch diameter rotary table; this is too big for this little mill as it's too easy to not be able to reach the centre of the table with the limited y axis travel.

Rannsachair10/03/2022 20:30:57
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37 forum posts
61 photos
Posted by old mart on 10/03/2022 20:23:49:

_igp2672.jpgOur light vertical at the museum has lost about 1" of Z height since I converted it to R8 from MT2, but the 6" vertical/horizontal rotary table fits on it no bother. With a 5" chuck on it the height is hardly any more than your vise with swivel base. I say rotary table rather than a dividing head as it will do everything that a DH will do and all the angles in between. Dividing heads are primarily for production work for fast indexing over a limited number of positions, and you may regret not going for a RT. Some time back,I bought a long cranked handle for moving the knee when there was something heavy on it, and the one I got on ebay had 7 castellations in it, easy with a RT at approximately 51 degrees and 26 minutes each.

Edited By old mart on 10/03/2022 20:29:54

Thanks, food for thought

old mart10/03/2022 20:44:30
3892 forum posts
268 photos

I checked out my picture album and there were some photos of the 6" Soba RT on it, unfortunately the wrong way round, but better than nothing.

_igp2653.jpg

Bazyle10/03/2022 21:12:12
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6381 forum posts
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The Elliott one shown on a recent thread was intended for that size machine (Elliott equivalent) but does not tilt.

Emgee10/03/2022 22:14:28
2445 forum posts
291 photos

Why recommend a rotary table that can only be used vertically or horizintally when a BSO Dividing Head will do both and any angle from -1 to +90 degrees.

Yes you can fit the rotary table to a sine table but that reduces rigidity and increases the overall height.

Emgee

Edited By Emgee on 10/03/2022 22:17:52

Steviegtr10/03/2022 22:28:18
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2459 forum posts
341 photos

I have the same mill. I bought a 8" indexing rotary table , with the 8" 3 jaw chuck. It was way too big for the mill table. I have since sold that & bought a 6" Vertex style & it's just the right size for the Senior. No indexing plates though. Not something i think i may ever need. Oh what have i said. Never say never.

P.S. Nice looking machine you have got there rannsachair. If you are thinking of doing any mods to it, I have a few youtube vids of the many mods done. Tom Senior light vertical

Steve.

Saxalby10/03/2022 22:57:42
182 forum posts
26 photos

Likewise, have a Senior "Major" mill and can recommend the BSO. Use it quite a lot for cutting spur gears and with the tilt facility on the BS0 have done lots of bevel gears.

Barry

JasonB11/03/2022 07:11:44
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Although a rotary table can only easily be mounted flat or at 90 deg they do tend to be a lot lower when used flat than a dividing head when it is set vertically. Add onto that something to screw onto the nose so you can hold work like a chuck and that is the height to be considering not so much when it is set a zero.

See my post part way down this page for illustration

So first best to decide what you are going to be wanting to divide, if it's a lot of gear cutting and radial holes then the dividing head is probably best. If it's a lot of axial holes such as bolt PCD are machining curved parts then a rotary table may be the better option.

Rannsachair11/03/2022 08:45:25
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37 forum posts
61 photos
Posted by JasonB on 11/03/2022 07:11:44:

Although a rotary table can only easily be mounted flat or at 90 deg they do tend to be a lot lower when used flat than a dividing head when it is set vertically. Add onto that something to screw onto the nose so you can hold work like a chuck and that is the height to be considering not so much when it is set a zero.

See my post part way down this page for illustration

So first best to decide what you are going to be wanting to divide, if it's a lot of gear cutting and radial holes then the dividing head is probably best. If it's a lot of axial holes such as bolt PCD are machining curved parts then a rotary table may be the better option.

Thanks, looks like I will focus on a dividing head.

Phil P11/03/2022 10:56:05
805 forum posts
195 photos

Just for your interest, this is a genuine Tom Senior indexing & dividing head with tailstock.

I made a new spindle for it to use Burnerd multisize collets, and I use it on my Alexander Master Toolmaker milling machine.

simplex engine 041.jpg

Edited By Phil P on 11/03/2022 10:58:14

David-Clark 111/03/2022 11:26:12
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222 forum posts

A BS0 should be fine.

I had one of there Tom Senior Light Verticals,and they are great.

Mill 5head height is not usually a major problem.

Turn the mill head at 45 degrees and the dividing head at the same angle will increase the capacity considerably.

You can clock up the centre of the dividing head spindle and as long as you only use the y movement of the table you should be able to do very large workpieces. A bit of trigonometry should enable you to mill in the x directin.

i can’t remember the cross slide travel but by positioning the dividing head on the table and the mill head in relation to it, you could probably divide about a 12 inch diameter workpiece.

I fitted a digital readout to my Tom Senior. I can’t remember If,I wrote it up but if not, I probably have the photos.

David-Clark 111/03/2022 11:39:58
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222 forum posts

Further advice after looking at the main photo.

you might like to remove the vice bottom plate. Increases rigidity when milling.

Also if you have two similar vices side by side, you can hold longer workpieces between them or use one as a stop, hold any odd scrap of metal in one vice as a stop for the second vice.

Also, a ring spanner is very useful as a vice handle but don’t over]tighten it.
For Abwood vices a 19 mm ring is ideal and if you cut the handle of a ring spanner, so it is only 2 inches or so long, you can use it as a spinner to open and close the vice fast.

old mart11/03/2022 13:55:14
3892 forum posts
268 photos

Shame there is no one mentioning the exact height of a BSO with chuck when used in a vertical position. Even though it comes with indexing plates, it is still only a dividing head and cannot rotate at any angle. I have 3 dividing plates and there are many missing positions. When I wanted 118 divisions, there was no way with the plates to get that. I would like one for its strong locking tilt, but only in addition to already having the RT, which holds a 5" three jaw scroll and also a 6" 4 jaw independent.

Andrew Johnston11/03/2022 14:18:18
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6668 forum posts
701 photos
Posted by old mart on 11/03/2022 13:55:14:

...wanted 118 divisions, there was no way with the plates to get that...

Simple enough to make one, index 20 on a 59 hole plate. Here's one I made for 63 and 69 divisions, as I was too idle to set up for differential dividing:

Division Plate

The ideal set up would be a dividing head and a horizontal/vertical rotary table. As discussed by JasonB they have different strengths and weaknesses.

Andrew

DC31k11/03/2022 15:00:23
727 forum posts
2 photos
Posted by Andrew Johnston on 11/03/2022 14:18:18:
Posted by old mart on 11/03/2022 13:55:14:

...wanted 118 divisions, there was no way with the plates to get that...

Simple enough to make one, index 20 on a 59 hole plate.

I am not sure if your reply is tongue in cheek or meant to be serious, but if he had a 59 plate, he could produce the 118 from it directly. 118 = 59 x 2 and 59 is prime.

DiogenesII11/03/2022 15:01:18
589 forum posts
234 photos
Posted by old mart on 11/03/2022 13:55:14:

Shame there is no one mentioning the exact height of a BSO with chuck when used in a vertical position...

Immediately beneath the photo in thelink below, there's some text that says 'BS0 Dividing Head Manual', which is a link to a pdf (although it doesn't look like one)

Chronos - BS0 Precision Dividing Head

The point of a centre up the bore is shown as being 7.59" from the back surface, so given that the base is square-'ish' and the flange will sit level-'ish' with the end of the thread (so below the point a centre, say 1/2"?), it looks like the overall height of the flange will be about 7" off the deck with the thing pointing 'up' - a chuck will be another, what, 3", bringing the lot to about 10"... ..I guess a lot will depend on what chuck / backplate combo is available - a recess mount chuck would be nice, eh? ..is it an American thread?

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