Measuring pre-B type Drummond bedways. How?

[stew 1Participant @stew]

Hi all.

Bit of a head scratcher.

I’d like to measure across the dovetails of my Drummond pre-B type lathe bedways.

Obviously on something like a cross slide you can put an (accurate) piece of round bar each side and measure across these with a micrometer.

But on the Drummond lathe bed, this is not as easy. Any suggestions? I’d like to take measurements at intervals along the bed length, using the tailstock end as a relatively unworn reference, and then see how much wear there is closer to the headstock end.

My idea was to make a tool such as a piece of flat bar that would lay across the top of the bed, with a ball fixed onto the underneath of the bar at each side, up against the dovetails. This would be adjusted to be snug at the tailstock end and then it could be moved toward the headstock and if the bed has wear, the resulting gap at one side could be measured with feeler gauges.

Your thoughts please?

Stew.

[BazyleParticipant @bazyle]

Your method sounds reasonable. If you have any fine screws or a 40tpi tap and die you could rig something on the bar to check the change at each point. It is relative change you want rather than the absolute I assume.
The saddle is effectively the bar etc. can you loosen it up and measure the gib strip gap at the font end ?
One thing is that this doesn’t tell whether the front or back is worn, or evenly on both.

[StewartParticipant @gaunless]

Thanks Bazyle.

Upon reading the ‘Machine Tool Reconditioning book’ (Connelly) he suggests a very similar method.

He states that the 1st objective is to get the top of the bed ways flat, then move onto the male dovetails.

I have run a DTI down both ways, and the needle barely moves on a 0.01mm instrument, so its just a matter of a little frosting to pretty things up there. (quite unnecessary, but hey, I like that look!).

There is wear on the dovetails towards the headstock, as the saddle gets tight after about moving around 1/3 of the way back towards the tailstock, so that needs dealing with. I could of course live with the wear and compensate for it, but I bought the machine to restore properly and use properly, rather than a ‘Wire wheel and green Hammerite’ restoration…

To be honest, it’s only going to sit and do one specific task when it’s completed, which doesn’t need really great levels of accuracy (cutting small worm gears) but if a job’s worth doing etc.

 

Stew.

[peak4Participant @peak4]

Is it a flat top with dovetail sides, similar to the column on my Herbert grinder?
If so, something like this maybe??

Several photos either side show other views of similar, along with earlier ones showing a clamped angled straight edge to check the first side.

Bill

[StewartParticipant @gaunless]

Hi Bill. Yes, flat top and dovetail sides. That setup looks very similar to the one I was thinking of. Thank you for the pics.

Now I have the lathe stripped down to basically a bare casting, it’s time to think about dealing with the wear that has occurred over the past 117 years!

I may have found a company here in the North East that does machine tool reconditioning and sales, and they have said they can grind the ways on small lathes, so I’m going to send them pictures and measurements of my little Drummond. The price is the only thing that would stop me going that route. I can imagine it will be more than the lathe is worth, but who knows, I may be pleasantly surprised… (Because life’s just like that….hmmm).

If it’s a no-go financially, then out with the scraper and the elbow grease!

Stew.

[StewartParticipant @gaunless]

Sorry all, I must start using only one account. please see ‘Gaunless’ and ‘Stew’ as the same person!

[peak4Participant @peak4]

I’ve never used them personally, but James Garside seems to have decent reviews for bed grinding.

https://www.jamesgarsideandsonltd.co.uk/engineering-services/

He had a load of photos on Facebook, but I can’t immediately spot them; as I recall, not on their main page.

Edit, they are on the Myford Lathes Facebook Group, but you might need to join it to see them

See Also
https://www.facebook.com/groups/917590484920210/user/1024131739/

Bill

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