Tom Senior / Maho Vertical Mill Spindle Mod

Hi All

I have been working on and off building a new vertical spindle for my Tom Senior M1 Milling Machine. She is a old english machine dating from the late 50s. The current knucklehead vertical spindle i have has a set of helical gears that has seen better days. I wish to preserve the old knucklehead but having the gears cut will cost more than what another newer mill will cost. The Tom Senior is for it size class much more rigid than anything on the market and i really would love to keep on using it.


So i have started to build another vertical spindle to replace the knuckle head about a year ago. The spindle was made from EN19T , fairly tough stuff , especially on the old Myford ML7 i used to own.


I completed the spindle, bought the matched pair of angular contact bearings and deepgroove bearings for the floating part.


I started work on the quill and got hold of a cast iron "air operated vibrator"that has seized. i pressed the piston out and found that the bore was still in good condition. That would have been the housing for the whole assembly.

Earlier this week i got wind of a guy selling a Maho mill vertical spindle only for less than what i have paid for the set of AC bearings. It was a 6 hour drive and border crossing from me , but luckily i also had some business to do in the same area that i have been putting off for a while. Needed no convincing to go and look at it even if it was just to get the quill and housing pack to use





I got the spindle and found that the power quill feed wasnt working and has been partially dismantled to probably find the issues. The bearing pack was untouched and incredibly smooth!!! Bargain!!!

The first problem i found was that the drive gearbox lacked a woodruff key on the output shaft. I found the key in the gearbox housing and proceeded to fit it. Works perfectly!! I think someone in the past took it apart and didnt seat the key properly. Upon assembly it probably fell out and the gearbox was perceived as broken...




The next issue i found was that a brass gear selector pin was completely worn out and thus not selecting the ratios properly. I proceded to make a new improved version of the selector pin.


Then i found that the drive dog clutch would not remain engaged unless you keep the engagement lever in place by hand. Upon investigation i found that the assembly was also removed. A similar pin as on the drive gearbox selector was worn out thus engaging the clutch was the first issue

Another issue found was that that even with the selector pin back to original the drive would engage but not remain so , unless the selector lever is held in place by hand... I found a tube in the assembly that had 4 small holes in it and what looked like a spring loaded plunger. I found four small ball bearings in the pack of odds and ends that came with the spindle and fitted them in the 4 holes i found on the tube. Eureka !! the dog clutch was held engaged by the four ball detents and worked as advertised!

My plan is to mount the spindle on a horisontal hollow bar in a similar fashion as this


I want to use hollow bar so i can drive the spindle with a driveshaft running in the hollow bar and thus use the vertical head's original drive


Any advice?

Not sure how the hollow bar would mount to your machine? Would you have a separate drive motor mounted out back?
Watching with interest as i am looking at doing something similar

The hollowbar will be mounted on top of the mill vertical as per the second to last photo. The drive motor i want to mount in the vertical cabinet that the hollowbar mount upon. That would enable me to still run the horizontal spindle when needed by just changing belts. The hollowbar will have a driveshaft running through it, driving the vertical spindle , and be driven via belt and pulley arrangement from the motor.

Got a little time in on a friends Lagun mill so i squared up some old tractor weights to use as a backplate for the maho head. The weights are actually very nice cast iron with no voids or sand pockets!

Will continue tomorrow or saturday. Hope to have the head mounted before my daughter is born!

Got a bit further tonight. Stuck the plates together with four 10mm allencap bolts and 2 dowels to keep everything lined up



Then we started to bore out the central bore



Flipped it over and then did the larger bore.



Drilled four twelve mm clearance holes for the allencap bolts that will hold the backplate to the mill head. Unfortunately through poor planning i drilled these clearance holes right on to of the four bolts holding the plates together so it resulted in very carefull drilling after the offending bolts were removed, only the dowels holding it all together.

Decided to then rather drill twelve 10mm holes around where the flange will attach, using 6 alternating holes to clamp the lot together and the other six holes for the hollowbar/driveshaft unit flange. Centredrilled it, but will continue tomorrow

Got the whole day to play today! So i continued by drilling and tapping the twelve holes


Fitted the assembly and its a slight push fit! Perfect!!



Next up was the flange that connects the head assembly to the horisontal hollowbar.
Chucked up a piece of 20mm truck wearplate, not sure what grade of steel but it was pretty hard


Drilled the flange six 10mm holes to attach to the head assembly and countersunk it for M10 allencap screws

I found this photo, would like to show what the whole assembly was made out of:



Castiron tractor weights that was discarded. Very nice cast iron!!

Lined up the whole cast iron sandwich assembly in the four jaw, gave it a bit of tailstock support and started rounding things off