Hello Michael,

It sounds very much as though this is a clamp bolt that grips the column. With the bolt undone by as little as half a turn and the weight of the head supported as you said, give the bolt head a sharp tap with a hammer to separate the clamp halves within the boring that contains them.

Now you should be able to raise and lower the head, before locking it  by tightening the bolt again in the new position. It does not need clamping hard as you have found

Regards Brian

Edited By Brian Wood on 24/10/2022 18:13:39

Edited By Brian Wood on 24/10/2022 18:14:38

Hi Michael – sounds like you’re having a great time 😊

Again, in my 2G the head is clamped by that one screw.

Assuming you’ve not got the clamps free yet. It’s a cylindrical wedge type of clamp – so the bolt pulls together two floating cylindrical parts, one either side of the column. Both of these are chamfered where they touch and tighten against the column.

BUT, I’m sure does really need saying, the head is very heavy – when I’ve removed it in the past, I have used the small table that is meant to hold chuck keys etc, pushed and clamped up below the head so it can’t fall any further. If yours doesn’t have that, be careful !!

So there is one wedge tapped and another with a clearance hole – perhaps loosen the screw a few millimetres and the hit the screw to push the tapped wedge out of position. If the clearance one is also stuck, belt it with a drift with the tapped wedge out.

If it won’t move then, or you already got that far, I fully agree with Nigel.

Cheers – Will

It happens, don't bother about it. Nice to have it confirmed though!

On my ancient No 1. I took the precaution of fitting a Jubilee hose clip round the column just below the head and marked the bolt clamping the head with an exclamation mark to draw attention to the potential hazard in a moment of extreme stupidity or especially senior behaviour

Regards Brian