Planing lathe bed

[PeterT]

Look at the first sequence of interrupted cuts. How does a lathe get that way? (Or maybe come 'delivered' that way?)
No amount of test bars or jacking legs up to fiddle lathe twist is going to fix a machine with this geometry.
Sure turned out purdy in the end. Wouldn't it be great to have a shop down the street that did this kind of work?

 

[Johnwa]

Most of the wear on the front way was just in front of the headstock. This is where the carriage spends most of its time. I didn’t pay much attention to the rest of it.
I have heard that the owner of modern tools has a planer and does lathe beds. I also heard it cost a fortune to get it done. Seeing how quickly that lathe was done though suggests it shouldn’t be too bad.


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[YYCHM]

Is that thing actually planing it like in planing wood or surface grinding it?

 

[RobinHood]

Is that thing actually planing it like in planing wood or surface grinding it?

it is planing it. Works only with non-hardened beds.

 

[Alexander]

That type of wear is pretty common. I have worked at production shops that would plan on buying new manual lathes every 5 or 10 years. If the shop has 2 shifts 5 days a week. The lathe might leave the shop with well over 10 thousand hours of run time.

 

[Tom Kitta]

Some US lathes came with replaceable ways for a reason. Also there is a reason why a good machinist will have no issues working with beaten lathe - most are beaten. The main difference here is time needed to complete work - since time == money it makes sense to replace a lathe at some point.

I am a bit surprised they did not do the piece in the gap - that thing is way off - maybe they lost it?

 

[DavidR8]

Would the cross slide need some attention to conform to the new ways?

 

[Tom Kitta]

Yes, lots of work needed to do - your cross slide drops which means the gears may not mesh well in apron. The head stock needs to be obviously placed back on and re-aligned. At least in this case no need to worry about tailstock being too low.

This was more economical thing to do few decades ago were we live - now maybe still makes sense in China. India maybe, through they luck expertise.

 

[PeterT]

In one of the other YouTube links I provided, shows a similar process for re-grinding. They guy had an affinity for Myford lathes & rebuilt them into spectacular condition c/w scraping all the necessary surfaces. I'm not actually sure if Myford ways were hardened or not but that's what he had done. I wouldn't have thought planing could be as accurate as grinding, or maybe that is a precursor to scraping? I guess it depends on the machine itself & maybe such exist.

David, was wondering the same. The ways are now vertically reduced, there has to be compensation somewhere relative to the original vertical spindle line. Whether they take it off the bottom of the headstock assembly or go after the carriage / top assembly I cant say. Probably the lathe configuration itself would factor in.

 

[trlvn]

Would the cross slide need some attention to conform to the new ways?

Yes. Keith Rucker (Vintage Machinery on Youtube) did a video related to this while rebuilding his Monarch (I think). The machining on the ways changes the interface between the lead and feed screws and the related gears in the saddle.

Craig

 

[Tom Kitta]

Of interest is, if the lathe bed has lots of wear, what caused it - we all know its the cross slide moving back and forth on it, right? So what about the wear on cross slide - its not made of some special material and has less surface area then the bed... so wear here should be more.
So total drop can be quite large.

 

[RobinHood]

Excellent observations gents.

The video’s comments address most of your questions - especially when Rees Acheson replies to them.

He goes into detail about tool geometry, accuracy, next steps, etc.

 

[Former Member]

This is interesting.

 

[Rauce]

My hendey bed is out for grinding right now. The wear wasn’t terrible but I decided for what I paid for the machine (a bargain) and since I was stripping it down to clean, paint etc. I might as well have it done.

Regarding compensation for the height change, on my machine there’s only two places where it needs to happen. They’re a gear that’s part of the back gear mechanism that mounts inside the bed under the headstock. This was shimmed at the factory so it’s just a matter of re-shimming to get the desired clearance/backlash.

The other place is the apron. If the apron was re-attached to the saddle after grinding without modification then the leadscrew and feed shaft will be pushed down. One solution is turcite or moglice to restore it to original position. Another option is removing material from the one of the mating faces between the two. Not sure yet which path I will take… trying not to think about it too hard and taking things one step at a time. Hopefully I’ll have the bed back any day now.

 

[John Conroy]

I guess they are not worried about running over all the grinding dust with his bearing/wheels and causing mis-alignment?

 

[Mcgyver]

Would the cross slide need some attention to conform to the new ways?

Everything that mates with it needs attention then to conform to the new ways. tailstock and headstock get scraped into proper mating and alignment as well as the carriage. As you don't worn beds without worn cross slides and tailstock bores, they to need reconditioning. Machine tool reconditioning is a BIG job!

I wouldn't have thought planing could be as accurate as grinding, or maybe that is a precursor to scraping? I guess it depends on the machine itself & maybe such exist.

Its not unheard of. I have a Holbrook B8 that had planed ways when I got it (it's since been scraped). Most I think would put Holbrook on the top of the quality ranking. Standard modern had a massive planer they'd rough the ways out on, although they did grind afterward. The grinder was something, gang grinder that could do 20' beds. Very different than a slideway grinder, it had all the wheels necessary to do all the way surfaces on a huge spindle and would grind all surfaces at once.

Once ground, everything was scraped into perfect mating and alignment with the bed

 

[cuslog]

Speculation on my part; but I'd expect to see as much or more wear on the underside of the carriage, where it rides on the ways.

 

[Mcgyver]

I would have guessed the same, but it wasn't at all rough. I don't know if they stoned or what, but it was really smooth. I'd read about planed bed, but its the only one I've actually seen. Here's some photos from the Holbrook. Last photo is as it is now....still haven't scraped in the mating parts so its a work in progress

 

[PeterT]

The other place is the apron. If the apron was re-attached to the saddle after grinding without modification then the leadscrew and feed shaft will be pushed down. One solution is turcite or moglice to restore it to original position. Another option is removing material from the one of the mating faces between the two. Not sure yet which path I will take… trying not to think about it too hard and taking things one step at a time. Hopefully I’ll have the bed back any day no

This will be interesting. I have not direct experience but just interested in the process. I watched a few restoration type videos on turcite installation, bonding it on with their special epoxy & then scraping in. From what I could tell Googling its available in thickness from 0.5 - 5mm (.020 - 0.197"). So I guess if the bed was reduced by more than .020" you could be in the turcite range. But if it re-surfaced less than that, say 0.010", or scraped a surface, say 0.002" then maybe turcite would be more of a pita because you have to take the vast majority off to make up the gap and that precedes scraping it in. Maybe that lower gap domain is where Moglice comes in? Maybe it has some maximum thickness not sure. My mill has turcite & it is silky smooth.

When I examined the underside of my (Taiwan 14x40) saddle it was, uhhhm, underwhelming. Someone had a bad day with a file, I mean my oil frosting pattern looks quite random haha. Made me wonder why it even runs as accurately as it does. In the back of my mind I was wondering about doing a Moglice job on it. Basically roughen it up (even more), get it set up & aligned on some permanent shims, apply the goop & let it cure. But I'm also not 100% clear if Moglice is meant to be a constantly running friction running surface like this vs. more of a fit-up or low movement surface. The other consideration is I would think the mating surface should be as shiny & perfect as possible so it releases properly & runs well. I wonder if scrape marks, even though the are very very shallow, might cause grief trying to pop the two surfaces apart even with the recommended mold release.

 

[Rauce]

From what I could tell Googling its available in thickness from 0.5 - 5mm (.020 - 0.197"). So I guess if the bed was reduced by more than .020" you could be in the turcite range. But if it re-surfaced less than that, say 0.010", or scraped a surface, say 0.002" then maybe turcite would be more of a pita because you have to take the vast majority off to make up the gap and that precedes scraping it in. Maybe that lower gap domain is where Moglice comes in? Maybe it has some maximum thickness not sure. My mill has turcite & it is silky smooth.

Moglice has a min/max thickness and I believe the min is more than .020”. You’d have to mill out the carriage side and use shims or fixtures to hold it in position for application.

There’s more than one formula as well. One is a turcite alternative intended for sliding surfaces and others are for taking up gaps in fixed assemblies.

I’ll have to do some inspection once I get it it back to see how much lower I am. On the bed ways, it shouldn’t be more .010” but if the carriage had worn the same amount the total error could be larger.