senior mill with R8 spindle

[mike e]

hi all, i have seen drawings of the tom senior m1 milling machine with vertical quill head with an r8 bore rather than the standard 2 morse taper. does this actually exist and if so are they available or is it possible to convert 2 morse to r8?
cheers
mike e

[Andy B]

Hi Mike,

Back in 2008 there was a thread on the Yahoo Tom Senior group, started by someone who had bought a 1984 'S' type with R8 taper, and I got hold of the original TS test record for him. I think there are some photos too.
This is the only one I have seen evidence of. Unfortunately the TS test records are no more, so it is impossible to determine how many others were made.

I seem to recall that the machine mentioned above had a very square head casting - I guessed at the time that it may have been developed for the 'Senior 3C' mills, and built as a 'one-off' S-Type (Seniors seemed quite willing to mix and match parts / features across machines throughtout their existence). There were various other changes to the heads over the years, especially around the Senior / Denford buy-out era, so it could be that only selected heads will actually take an R8 spindle.

So whilst, by making a new spindle, it ought to be possible to convert an MT2 machine to R8 - but first I would check your existing spindle dimensions against the drawing for the R8 one and check that there is actually enough metal there with the bearing sizes you have.

Please keep us updated with any more info you find.

Andy

[DavidB]

I saw this topic earlier and thought it worthwhile adding a reply. My neighbour has a Tom Senior Light Vertical mill, looks like it from https://www.lathes.co.uk/senior/page6.html , and he converted it from the 2MT it came with to R8 maybe 6 to 8 years ago. He thought it worthwhile due to the more plentiful and substantial tooling and I have a R8 Bridgeport mill with lots of tooling to borrow if required. IIRC he used the upper end of the quill with the spline, thread and upper bearing seat and that was pressed into a new larger lower quill section to take the R8 tooling that he made from EN24. He needed a new larger lower bearing so IIRC he fitted a new extension housing to the bottom of the original quill into the lower bearing seat to take the new larger bearing. I think he drew all this up on CAD as he often does to work out the details so could ask him if he has those in a suitable format to post if required. All in all it has worked well and he is happy with it. The run out is higher than that of my Bridgeport when tested and between us we have the equipment to have ground the final upper diameter and lower taper in situ but he felt it wasn't worth the effort for what he did.

[Rgvbaz]

Sorry - had info wrong - please delete.

[Andy B]

Could you post a picture or two of the vertical head on it?
I'm interested to see if it is the original TS head casting, the later 'import' style, or something else.

Thanks,
Andy

[DavidB]

I just taken a few pics of the Tom Senior and my neighbour had the drawings he did of the R8 conversion parts so I've scanned those, see below.

[Andy B]

Thanks for posting the pictures.
I was always of the view that there was not enough 'meat' in the original spindle and casting to take R8.

Looks like a neat conversion, though.
As in many things, there is a trade-off - and here it is losing around 30mm of headroom under the quill by having the spindle extension.

Andy

[DavidB]

My neighbours work is mainly small and I don't think the loss of 30mm or so in the Z direction has ever been an issue for him but if it was he can always come and use my Bridgeport J head mill. He did most of the machining on his Myford Super 7 but the machining of some final details such as the R8 spindle bore was done on my Harrison M300 due to it being able to hold the new spindle addition in the collet chuck. IIRC last year I idly looked for a Tom Senior R8 mill and https://www.homeandworkshop.co.uk had one for sale.

[Rgvbaz]

Could you post a picture or two of the vertical head on it?
I'm interested to see if it is the original TS head casting, the later 'import' style, or something else.

Thanks,
Andy

Sorry after some more looking around it looks like this could be different to a TS head casting. I've attached a couple of pics.

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Cheers

[Andy B]

Thanks for the pictures - they align with pictures I've seen elsewhere (e.g. on the Model Engineer forum), and having looked again at the cross-section drawing in the late issue manual it makes sense as below:

On the original Tom Senior quill head (known as an 'S' type or 'E' type), the vertical fine feed hand-wheel is on the right on the lever feed on the left. This would only take a MT2 spindle.

The later Denford Senior quill head (also confusingly referred to as the 'S' type head) was, as far as we can make out, an import. The vertical fine feed hand-wheel is on the left and the lever feed on the right. It had an appreciably wider quill, so could accommodate the bigger R8 taper.
The bearing arrangement is also quite different, having ball bearings for the pulley shaft instead of the plain bronze bearings used originally.

Andy

[Rgvbaz]

Thanks for the info Andy.

That would explain no oil points on the head for the spindle bearings. Does the quill require lubrication?

What other machines were these heads used on?

Is there a reason for no spindle lock?

Sorry for all the questions... Information is quite sparse and there doesn't seem to be a manual.

Cheers

[Andy B]

I believe the head came from the TiP machine - manual here
It shows and describes a big oil cup on top, which yours clearly doesn't have.

But the later Senior manual - here - mentions Springwell oilers, as were used on the earlier Tom Senior heads, and the cross section (which is for the later head) does not show the oil cup or passage.

Sorry, can't help beyond that as I've never seen one close up.

The TS heads never had a spindle lock; they had 2 flats on the bottom of the spindle.
I can't quite make out from your pictures if there are flats on yours.
As Denford's prime market has, for many years been education, not having a plunger or clamp type spindle lock is understandable........

Andy

[Rgvbaz]

Thanks again for the info Andy.

I had a look at TiP manual. It seems to be the same head. I had a look inside the pulley case and there is metal in the casting that looks like it could be drilled for the oil cup and oil ways?

I found a coupe of springwell oil points on the head but are for the quill lever and the fine feed handle. Maybe these also lube the spindle?

I had a peer into the spindle through the front and the bearings don't appear to be sealed and packed with grease so I gave it a squirt of oil. There is a hole in the side of the quill too - would this be for oil? I took the ally bearing cap of the bottom of the spindle and the bearings in there appear to have some grease in them.

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Cheers