Thread: Headstock flex

Hi Tiger. I'll buy in at this point.

Keep the file/s out - the headstock should be touching all around on the bed of the lathe, and until it does rest flat all round without tightening up the bolts, it will keep tilting. You probably need some bearing blue to find out where it is touching - you can use a marking pen but it will stuff the pen in short order, or spray on a thin coat of paint, then rotate the head a few times, take it off & file the bits where the bare metal is exposed - repeat a few times until the gap/s disappear when not tightened down.

Then you 'only' have to worry about what will happen when you tighten the wood up using the tail stock - this will likely involve more grease under the fingernails, cuts & scrathes as you re-adjust the position of the claws on the drawbolts.

If/when all that does not entirely cure the problem, then you may have to file a very slight taper on the base of the headstock so it is prepositioned down by the amount that it rises when pressure is applied. You may also want to look at how tight you are doing up the tailstock against the wood, and possibly get a 'Steb-centre' or something similar to hold the wood in place & just don't screw things up so hard.

If you remove the "bolt & claws," how much lateral movement is there between the headstock and the bed? ie. Can you move it backwards and forwards or side to side by more than a few mm?

It's really not a good swivel/mount system, is it? IMHO they would've done better to have the clamping bolt run parallel with the drive spur instead of perpendicular to it. But I guess there's probably some reason they went the way they did. [shrug]

bsrlee said "...file the bits where the bare metal is exposed... "

Other way around. In "blueprinting" (has nothing to do with construction plans, BTW), you coat the master surface (in this case the lathe bed) with a thin coat of bearing blue, paint, crayon, marking pen, etc. (Doesn't have to be blue actually). Sacrificial marking pen works well because it makes a very thin coat. Rub/rotate the headstock on the bed as described by bsrlee. File away the marks "printed" onto the workpiece (i.e. the headstock) by the master surface (the lathe bed). Repeat as needed until you get a uniform printed pattern.

This may not correct the immediate problem, however, if the base of the headstock was originally milled non-parallel with the spindle axis. In that case, need to introduce a slight taper by over-filing at the offending location, and repeat the blueprinting process.

In any event, do not consider lapping the two surfaces to each other, because that also affects the master surface.

JG

Originally Posted by joe greiner

bsrlee said "...file the bits where the bare metal is exposed... "

Other way around. In "blueprinting" (has nothing to do with construction plans, BTW), you coat the master surface (in this case the lathe bed) with a thin coat of bearing blue, paint, crayon, marking pen, etc. (Doesn't have to be blue actually). Sacrificial marking pen works well because it makes a very thin coat. Rub/rotate the headstock on the bed as described by bsrlee. File away the marks "printed" onto the workpiece (i.e. the headstock) by the master surface (the lathe bed). Repeat as needed until you get a uniform printed pattern.

This may not correct the immediate problem, however, if the base of the headstock was originally milled non-parallel with the spindle axis. In that case, need to introduce a slight taper by over-filing at the offending location, and repeat the blueprinting process.

In any event, do not consider lapping the two surfaces to each other, because that also affects the master surface.

JG

This is assuming that the "master surface" is flat, true and paralell to the ways of the bed.

This surface should be checked with a good straight edge first: along, across, diagonally and a few points in between.

Originally Posted by Tiger

Dear all but particularly TTIT and Skew,

I tried your suggestions regarding filing the cast claws on the headstock bolt and after several attempts and a few hours it's no better than before. The headstock still lifts up. I'm obviously doing something wrong, could you give me more details please so that I can fix this frustrating problem once and for all. I have noticed that when you test the bolt and claws without the headstock that the grip seems ok (don't know if that helps the situation though).

Would really appreciate any help on this one if you've been able to get this to work.

Did a bit of a sketch to explain what I found was stopping my MC900 headstock from clamping up properly. Don't know if yours is the same deal but filing the toggle so that it seated squarely before the rod started bending sorted mine out nicely. Basically, both ends of the toggle need to seat at the same time, before any pressure is applied.

Thanks so far for the replies. I have tried the bearing blue and filed down areas but still not much improvement:mad: . Am I missing something from the TTIT post as it sounded like a simple fix? I'm wondering whether anyone (besides TTIT) has been able to fix this problem without resorting to tapping a bolt through the headstock.

Skew, agreed the bolt should run in line with the drive centre. On my lathe, it only lifts up where the drive centre is.

Was down at Hare and Forbes on Saturday and experimented with their display lathe, could not budge it the headstock and there was no flex, it was easy to swivel and locked with a minimum of turns of the handle. Why can't they make all lathes that way:confused: ?

Thanks for the sketch, TTIT, I did have it right but I'm still getting that damn flex. Maybe a little more filing but at this rate there'll be no more claw left .

Originally Posted by Tornatus

G'day Hickory
so I'm trying to stamp out any mention of things Morris!

As long as you have no aversion to Morris Garages.

Curiouser and curiouser.

Just as a check, I think I'd try getting myself a small pane of float-glass (so you know it's dead-flat) run a very small bead of oil around the top of the mounting ring, in the centre of the face, and lay the glass on top.

By looking at how the oil spreads out, you should see exactly where any dips, bows or mis-machining in the ring is, if any. I doubt it'd be anything this basic, but...

Looking at TITT's sketch - OMG!!!!:eek: :eek: :eek:

What a poxy way of holding the headstock down! I'm glad I bought a slightly different lathe from Timbecon - it has an eccentric cam that pulls up on a bolt mounted between the ways and a large shaped piece that rides under the bed - much easier to fit up and less potential for flex/stretch.

Multiple inclined planes and a bolt - you'd have to be King Kong to get that tight enough ever time IMNSHO.

Originally Posted by bsrlee

Looking at TITT's sketch - OMG!!!!:eek: :eek: :eek:

What a poxy way of holding the headstock down!

You've got that right but a lot of the MC900 and equivalents have the same action, now the challenge is to work with what we've go and somehow improve it.

By the way it's not TITT but TTIT, but what's a tit between friends

What a poxy way of holding the headstock down! I'm glad I bought a slightly different lathe from Timbecon - it has an eccentric cam that pulls up on a bolt mounted between the ways and a large shaped piece that rides under the bed - much easier to fit up and less potential for flex/stretch.

I agree, my 1100 has a more conventional method of pulling up the plate from underneath against the bed. Much the same as brslees set up. The incline locking set up is a hard way to get it tight, dunno if you will ever succeed....:mad: its just a poor method from the beginning to end..
I wonder what Einstein came up with this idea. :confused: All you can do is improve the fit of the two angled areas so they match each other. Maybe add a backing plate to the clamps to prevent any bending across the clamping rod holes. I suppose its cast iron, so in time it will fail due the excesssive pressure required to hold it from moving. Not good!

Another thought... again a very basic one... is the swivel ring the old style, ie. a part of the bed-casting, or is it of the newer bolt-on type?

If the latter, it is bolted/screwed to the headstock tightly, yes?

(I know, I know... just eliminating the obvious. They're the ones I often miss. )

Skew it it bolted on, from memory there are 3 allen bolts that hold the base down, I'll be doing more analysis and swearing this weekend when I have another look at it:mad: .