Back to home page
I needed some serious milling capability and, having a small, narrow workshop, I was looking for a machine that wouldn't crowd me out. A Tom Senior Major came up on eBay and, being one of the later models with vee slide overarm, looked like a suitably meaty base on which to fit a decent vertical head. It was also reasonably local, which was a big plus as I could examine it prior to purchase and later be able to dismantle it to get it home over a number of trips.
It turned out to be in very reasonable condition. It was clear it had never even had its original factory protective wax/grease coating removed, except where it had worn away on slides etc. It was fitted with an Abwood vise that had been modified for some special repetitive machining operation. The down side of this was that the long travel table had suffered plateau wear in the middle section but with the factory wax still present on the extreme 6" of slide at either end. I doubt it had ever been fully travered since new.
I took readings across rollers in the table shears at 1" intervals all the way along. This produced a very telling graph showing that full table travel would not really be useable without a regrind or very heavy scraping. All of which happened to fit in nicely with what I had in mind in the way of surgery to make the machine more compact for my workshop. (Tom Senior fans with weak stomachs should look away now ;-)
I had always intended to cut a table down in length to give me the best combination of table length and unobstructed travel. I had planned to cut one end off a table, figuring that losing an unworn end section would leave the rest more evenly worn. I hadn't expected to have to rescue a central section and lose both ends. This was a much trickier operation than I had bargained for, as the machine would still have to perform all this butchery on itself given that I had no other milling capability.
I'd managed to find a loose Bridgeport J-head for a reasonable price, so the first task was to work out how it could be mounted to enable machining of the table.
This shot shows the temporary assembly of a belt-change j-head fitted to the vee-slide overarm of a Tom Senior Major horizontal mill - in order to machine some of its own components prior to full build. The complete unit has now been stripped and is being rebuild (slowly) indoors in its final position.
Below are two close-ups of the small dumbell pivoting lever that 'knocks off' the BP head's quill power downfeed. (I thought the close-up might be interesting for those who've never seen one dismantled.)
The hole at one end of the dumbell is threaded, presumably for an extractor screw as it's very awkward to winkle it out without one. A retaining screw goes outboard of the dumbell to stop it being displaced and falling out. This screw is missing on my setup but the dumbell seems to stay in place and operates normally without it.
Each end of the dumbell should be a close sliding fit in the two circular housings. As the quill stop collar reaches the top of its travel it pushes the protruding base of the cylindrical pin upwards. This causes the captive dumbell to lever the upper end of the micrometer screw downwards and release the powerfeed. If the cylindrical stub is 'sticky' in its housing the micrometer screw will remain in the stuck down position and power downfeed will refuse to engage. Stripping and cleaning these few components will often fix a 'busted' power downfeed. Ditto the corresponding lever components at the lower end of the micrometer screw. Components 'stuck' in this way can actually be a good sign, as it's an indication that the power downfeed hasn't seen much action.
© Neil Fazakerley, 2003.
Back to home page