Tom Senior

Hi all the main support bar has started to move when milling both the locking bolts are tight anyone had this happen? is there a way to stop it? and am i right in asuming that the locking bolts will need to be replaced if so where can i get some

Many thanks Bob

You could try shims of drinks can metal between bar and housing to take up some clearance and hopefully restore clamping - no risk of machine damage with this try, and virtually no cost.

Thats a great idea i have some steel shim stock will give it a go many thanks.

Bob

First step is to pull it all out and give the bar and clamp a really good clean. Not just wiping but appropriate solvents too.

Counterintuitively roughing up the surface to "key" things doesn't help. Smooth with maximum mating surface area does the trick. Might be worth applying a very thin layer of blue or, probably better, a solvent based felt tip pen mark or two to verify that you have good contact everywhere.

Best to investigate and sort things properly rather than resorting to quick'n dirty shims to fill the gap. Once shimmed you can never go back.

When used in an environment with oils floating around occasionally moved cast iron components seem to get a bit slippy so clamps loose the holding power. Doesn't matter how careful you are to clean the mating components. If the Gremlins so decree it does happen. Takes a fair few years but if you are on the list they will get you.

For me the major disadvantage of synthetic coolants is that this sort of thing happens much faster and much more frequently!

Clive

Sorry, I am not sure what you mean by "main support bar", is it the part that supports the vertical head?

Which model of TS is it?

Edited By old mart on 25/10/2020 15:57:10

Equally confused. picture would help.

Steve.

I suspect it's the round horizontal arbour support

I've done some sleuthing.

This is a Tom Senior "Light Vertical" where the head is mounted on the end of a round bar.

Bob,

I would be checking either of the two clamps aren't cracked if it was lifted by the support when you bought it.

Don't shim anything, that type of clamp relies on everything being the 'right' size, levering the slot open to get a shim in might crack it.

If the clamps are undamaged hopefully it's just oil in the wrong place.

If Dave's sleuthing instincts are true to form, and it is the TS Light Vertical, failure to clamp that top bar only has a couple of explanations.

- Studs or casting are damaged, so the clamp nuts are not closing the split clamp.

- Summat in the split gap stopping it closing

Adding shim etc isn't tackling the problem, its creating another.

So remove the two studs (1/2 whit) and pass a feeler gauge through the split to check for clearance. While checking make sure the clamps haven't cracked through the heel, they're only cast iron. Check the nuts on their respective studs that they run freely.

Clean the bar off so it is free of surface rust and grubbage.

The clamps on mine are a very close fit on the bar, the clamp nuts only need nipping up lightly to stop any movement of the head.

Do let us know how it resolves

Rgds Simon

I would be wary of just removing the studs on a light vertical, the motor makes it top heavy and it could rotate unexpectedly with bad results. I would put a bar in the spindle and raise the knee until blocks could be secured to the bed each side of the bar to restrict any rotation.

The clamps on the LV at the museum only require tightening about 12 ftlbs to fully secure the top end.

There should be a gap of about 1/16" in the clamps where the bolts go through, it should be obvious if the casting is fractured at either, or both clamping points. Also, the two SHCS which secure the head to the bar should be checked for tightness, if loose the head can move about slightly.

Edited By old mart on 26/10/2020 14:24:16

Head removal can be a bit tricky, especially if working on your own.

I made a substantial foot with a vertically mounted R8 arbor to assist removal and reinstallation of the head on my Bridgeport.

Well worth making something similar for the Senior using the appropriate taper to match the spindle.

Although intial fitting needs a touch of care to get the foot securely mounted flat to the table the positive, repatable support makes life so much easier. Especially as table feeds can be used to align the head and studs on refitting.

Extra support for the motor is probably desirable. Some sort of simple bridge should do.

Clive

Old Mart and Clive - thank you for pointing out my over-simplification. You are indeed right to point out that the top is top (edit - I meant too heavy, but the typo is appropriate!) heavy for a one man lift at that height and reach. . My defense is that I thought it self-evident not to undo both clamps together. Even that's not as simple to do as say - if the clamps aren't holding!

I like the idea of sticking something suitable in the taper and restraining the other end laterally!

My contribution is to caution against trying to withdraw the top bar out of the two clamps without having the clamp bolts in position, and just snugged up to stop the split clamp opening. It would be all too easy to allow the overhanging weight etc to crowbar the nearer clamp open as you bring the bar etc. forward out of the rear clamp. Ping!

I'm looking forward to hearing how this pans out.

Rgds to all our Senior citizens.

Simon

edit for typo

Edited By Simon Williams 3 on 26/10/2020 16:35:15

I have the same Mill. I t took me quite a while to get the tram right. The problem with the light is it only has the bolts at one side. When i nipped the bolts down it rotated the head. Eventually by taking the head one particular way round by a few thou too far & then nipping up i got it spot on. It has never moved since. Hope you sort out the problem Bob.

Steve.

hi all thank you for the replies i am using it in the horizontal not vertical the bar goes right through the casting so i would be suprised to find any cracks and there is nowhere to measure what it clamps on.

Hello Bob,

Thank you for the photo, it makes all the difference to understanding what the problem is.

The overarm, to give it it's proper name, is clamped by two pinch bolts, the other is behind the motor at the rear of the body that close shaped blocks onto the bar when tightened.

I suspect the gap between the two clamps is non existent and they close on each other. To put that right, slacken the two bolts, pull out the whole bar and then lift the clamps from the bores they live in. Machine off a little, only a little, of the face where the scallops face each other to increase the gap again, refit and insert the bar again. They should now clamp with no further difficulty.

Lathe tailstocks often use the same method to grip the barrel rather than squeeze a slot.

I hope that helps you

Regards Brian

Thank you for this Brian i will take a look at that.

Bob

An excellent method of locking a shaft from movement, instant release of shaft when nut/screw loosened. First time I used the method was on a Dore Westbury.

Emgee

Ah, a picture which explains everything. The pairs of clamps touching are the prime suspects, strange that both sets should fail to clamp at the same time. This type of clamp is featured on the Light Vertical quill, the drill mill quill, the drill press and the lathe tailstock, all four of the machines at the museum lock perfectly.

Just a quick update i found time today to sort the Tom out i relised i could pull he shaf out without undoing the 2 lock nut so i did as sugested and removed the locking bolts and i took 0.3mm off each end of the brass shoes where they meet refitted everything and it is now rock solid and does not move when cutting so thank you for all the comments i now have a fully working Tom Senior

Bob

Steve.