Lathe Bed Theory

[brendan stemp]

I'm working on a theory about the misalignment of the head and tail stocks and would like some more evidence to support this theory (or perhaps not support it).

This is what I am thinking: I have noticed two things happen over time with both my Vicmarc lathes;
1/ the tail stock seems to stick (or slide less freely) in the last 20 or so cms. of its travel towards the headstock. This is on a surface of the lathe bed the tail stock rarely travels because it so close to the head stock.
2/ over time the head and tail stock alignment seems to get less accurate and the tail stock is in fact lower by .5mm.

So this has got me thinking. Does the movement of the tail stock up and down the lathe bead wear the bed over a long period of time? I probably use my lathe more than most turners so I am guessing this wearing (if it is a factor) would be more evident on older lathes or lathes used regularly every day.

Any thoughts on this from others out there??

[rsser]

Could 2. alternatively be caused by wear in the tailstock quill?

[wheelinround]

Brendon good topic:2tsup:

Lathe bed wear is a fact of life, unless they and the tailstock are hardened like metal lathes..but even over time they also wear. Brendon not just the beds but the slide sides also wear.

Having them re ground is the best way finding someone to do it at reasonable cost :no:

I'll be interested to see where this heads.

[pommyphil]

I'd have thought that the bearing surface on the bottom of the tail stock

would cop more wear then the bed ? Phil

[Tony Morton]

Hi Brendon

Have you thought that the banjo may be wearing the bed in that 200 mill closest the headstock.

Cheers Tony

[brendan stemp]

Could 2. alternatively be caused by wear in the tailstock quill?

I don't think so, no slop in quill.


Hi Brendon

Have you thought that the banjo may be wearing the bed in that 200 mill closest the headstock.

Cheers Tony

Yes, I did think of this but the question of why the tail stock sticks at that point still remains. I really am doing the electronic version of thinking out loud and was hoping someone might be able to shed some light on the whole issue. The fact it has happened to two of my lathes has me wondering.

[powderpost]

I have experienced this on my lathes also. I honed the ways with some fine (600#) wet and dry paper on a block of wood, and the problem disappeared. Clean also the inside edged and and the underneath surfaces of the ways. I put it down to an accumulation of grain fillers, and residue from some timbers. Both these lathes are Woodfast lathes, one is 30 years old and the other is about20 years old. Does the "cleaning" cause excessive wear? Not that i can detect. After "honing" I rub Ubeaut Traditional wax onto the ways.
Jim

[dai sensei]

I have a rotating head lathe, but even after locking it down hard, the headstock does move over time. Not sure why, perhaps vibration or the hard work it does :rolleyes:. I simply unlock it, rotate it back, then re-tighten and it is as good as new. It always rotates in the same direction, away from the cutting edge, so I assume it is from the work it does. I've never had any trouble with the tailstock not running true, except when I bent my live centre :-

[Rifleman1776]

Interesting question. My first blush is that if there is wear it would be so negligible as to be of no consequence. However, you use yours a lot and have experienced the problems described. :hmm:
Other thoughts are: what kind of surface is the lathe setting on? A wood floor might yield affecting the level.
I'll opin that this would never happen with my lathe. :rolleyes: I regularly clean and wax the bed so my tailstock would be sliding on wax not the cast iron. (actually, with my lathe cast steel)
I'll follow this thread. Interesting.

[rsser]

Well, in the mode of thinking out loud ...

The question is what is causing the relative binding in prob no. 1. I'd assumed you'd done the cleaning up that Jim suggested, and also that the clamp plate hadn't cinched up slightly over the years. Not a prob where it's been used mostly if that's where there's wear.

Another possibility is that the bed castings may have moved and narrowed slightly at the headstock end. So is there still good clearance between the clamp plate shoulder and the bed slot?

The banjo, bed and tailstock are all cast iron (which comes with some graphite in it acc to GJ which will help perhaps with sliding) but the clamp plate is steel, prob medium tensile, and maybe this causes greater wear against the iron where it's mostly been used. This, or a stretched clamp plate bolt may have led you to take up the slack on the clamp plate at some stage to accommodate the wear but which now makes for binding where there's little wear.

Anyway, that's my brain dribble for the day.

[Sawdust Maker]

I wonder whether the too and fro (back and forth?) movement of the tailstock along the bed slowly polishes the bed
If that's the case it would seem to bind at the point where it doesn't travel as much :shrug:

My 2c worth

[Skew ChiDAMN!!]

Hmmm... :think: Surely if the bed is wearing it'd be becoming thinner and I'd expect the tailstock to slide more freely rather than stick? Unless it's so worn that it's twisting between the ways as it moves... and I suspect that much wear would be eyeballable.

Have you closely examined the underside of your ways, Brendan? The condition of the top of the bed is fairly obvious at a glance, but how many of us peer underneath our lathes on a regular basis?

A drop or two of finish may've set under there? Or perhaps there's a burr that's catching the lower mech of the tailstock? After all, most of us set the tailstock mech so that it's only barely releasing when we move the tailstock... so it wouldn't take much of a burr or "debris buildup" to snag things.

(Also just thinking aloud. :;)

[joe greiner]

Interesting puzzle. Wear or polishing on the top of the bed should be immediately apparent.

Have you examined the underside of the tailstock after removal? A possible culprit for vertical mis-alignment could be the manner in which you move the tailstock. Pressure near the top would tend to wear the opposing underside, so that it's no longer flat. The same can occur when sanding a block of wood by moving it against sandpaper on a flat surface - if the pressure isn't uniform, the piece can wind up tapered, which of course might be the objective in such a case. BTDT. Corrective action would be to move the hardware by longitudinal pressure nearer to the bed.

It might be too late to institute that new habit, but shim stock at one or more corners of the tailstock could restore alignment. BTDT too.

Cheers,
Joe

[issatree]

Hi to Brendan & Others,
I also do a lot of Turning, & had the same Problem with my 1990 " Tough " a while back.
Like Powderpost, Jim, I completely cleaned my Bed with I think 800G.& the Banjo, as well as the Tail Stock.
I don't think 800 would take any steel off anyway.
I then used my "Silbien Gliet " Silver Glide, on all surfaces,& Bingo, it did the job.
So I thought I also may have had some Rubbish where it shouldn't have been.
So that was my solution. Hope that might help Brendan.
Regards,
issatree.

[brendan stemp]

The sticking ain't the problem. I was more concerned with the possible connection between the sticking and the tail stock/ head stock misalignment. Is it possible that the lathe bed and the underneath surface of the tail stock wear over time to the point that the tail stock no longer aligns with the head stock.

As Wheelinround said, bed wear is a fact of life and I perhaps need to have the whole lot reground. However, I would only trust Vicmarc to do this and it is such a hassle to get the lathe up to them (or down depending on your cosmic view the world).

Thanks to all who have contributed thus far and your suggestions.

[wm460]

Hi to Brendan & Others,
I also do a lot of Turning, & had the same Problem with my 1990 " Tough " a while back.
Like Powderpost, Jim, I completely cleaned my Bed with I think 800G.& the Banjo, as well as the Tail Stock.
I don't think 800 would take any steel off anyway.
I then used my "Silbien Gliet " Silver Glide, on all surfaces,& Bingo, it did the job.
So I thought I also may have had some Rubbish where it shouldn't have been.
So that was my solution. Hope that might help Brendan.
Regards,
issatree.

I have thought about using Silver Glide on the bed, but heard somewhere that it makes it hard to lock the tailstock in position.

[Big Shed]

I use Ubeaut Traditional Wax on most of my machines, including the wood lathe bed, works like a charm.

[rsser]

IIRC warns against Silver Glide on the bed.

[issatree]

Hi to all,
I've been using Silver Glide since I first heard about it. Have never had a problem with it.
The trick is, you only use a very small amount on any Surface. A small amount on the Tip of your Finger, will nearly do the whole Bed.
The 1 thing you don't do is, to put it on the Cam Bar? under the Banjo, as then it will slip.
The Tail Stock only gets S/G on the Bedding Surfaces, but not on the Washer underneath
Hope that sets some minds at rest.
Regards,
issatree.

[Sawdust Maker]

IIRC warns against Silver Glide on the bed.

Yeah
He gave the same warning during the visit when he tuned my lathe here (at the GTG)
In fact he used WD40

[hughie]

Brendan,
Yes there is wear, minimal at best. What will occur is that the tail-stock will 'polish' the high spots of the machining off. In the old days of hand scraped beds. The scraping produced an more even wear surface as well as allow for lubrication to be present on the surface.
The area just under and up near the headstock gets no wear and also will in time have a build up of grime associated with wood turning such as sap etc.If you cleaned of the grime etc it will improve to some extent buy no where near as good as the rest of the bed.

[brendan stemp]

Thanks Hughie; that makes sense. I will have to discard my theory about the wear contributing to mis alignment.

[hughie]

;
that makes sense. I will have to discard my theory about the wear contributing to mis alignment.


Well if you turn a lot and move the tail stock up and down a great deal you will wear it down. Dunno if you could get sufficient wear to make any great difference.

[wheelinround]

Been watching this Brendon some interesting replies.

Just re-read this again.


I'm working on a theory about the misalignment of the head and tail stocks and would like some more evidence to support this theory (or perhaps not support it).

This is what I am thinking: I have noticed two things happen over time with both my Vicmarc lathes;
1/ the tail stock seems to stick (or slide less freely) in the last 20 or so cms. of its travel towards the headstock. This is on a surface of the lathe bed the tail stock rarely travels because it so close to the head stock. Brendon whats the underside of the ways like how often do you clean that area. Over time build up of material would create a gum like surface.

2/ over time the head and tail stock alignment seems to get less accurate and the tail stock is in fact lower by .5mm. This would lead me to consider that the quality of material is to soft. A shim would/could fix it or re-grind and block fitted.

So this has got me thinking. Does the movement of the tail stock up and down the lathe bead wear the bed over a long period of time? I probably use my lathe more than most turners so I am guessing this wearing (if it is a factor) would be more evident on older lathes or lathes used regularly every day.

Any thoughts on this from others out there??

Last one any metal to metal surface will wear rub steel wool on a metal surface and of course it does its job. If your using certain finishes they could be corrosive as could sap over time.

[NeilS]

Another possible culprit is the abrasive grit particles that have been shed during sanding and deposit along with the dust on the bed. Must admit that I don't clean the dust off the bed every time I move the banjo or tailstock. Must look at the wear pattern under my tailstock to see if there are any telltale parallel lines to indicate that this could be happening.
.

[rsser]

Another good point.

FWIW I've taken to putting an MDF board on the bed where most of the dust of some timbers drops. Makes it easier just to lift the board at sanding's end and brush the muck straight into the 'Big gulp'. Also stays there to catch any fling-off of CA/dust fill and later of finish.

[Toymaker Len]

Good thread. It reminds me of an old engineer who told me he would often get the job to mill flat the bed of metal lathes that had a some mm of wear. What most of the owners didn't realise was that there were adjusting screws built into the base of the lathes that he would access through little port holes. He would use the screws to adjust out 90% of the error then mill the bed back to perfect flatness. The old rogue thought it was great that he could charge for milling off 5mm when in fact he had only milled off 1mm.