Planing lathe bed

[Mcgyver]

I think you have to have more than 20 thou with Moglice, 60 thou minimum recommended. Most would do the same or more for Turcite as well so there is enough depth to put in oil grooves. Gotta have oil grooves.

You could pour moglice to get the right height, however you'd have to mill away material from the bottom of all mating parts. Needs to be a rough surface as well. With Turcite you still have to scrape it, moglice can be poured with things position perfectly but needs flaking afterward.

SOP is after you grind (or scrape) a bed, you scrape the parts into it for bearing and alignment. That is really what these materials are for; creating proper mating surfaces and avoid scraping the mating part. They could be used to get the right height, but its a lot of work. I'd be more thinking about getting things mating and aligned, thats the hard part....height can usually be changed mechanically; .

On the topic, Turcite and Moglice have some disadvantages. Crap gets embedded in it and it ends up accelerating wear. Its a great commercial solution to get more life out of a machine and minimize the bill of the reconditioning guy. However, in my opinion, its not the solution for that best of breed lathe you want to have in a near perfect state for the rest of your days. I wouldn't say I'd never use them, but doing so requires a lot of finicky prep work (say, milling out the bottom of the headstock) to it and embedding is a real issue. You'd have to put in some fancy wipers to minimize that.

It's your lathe (and back and shoulders lol), but its such a beauty and you're already having biggest part of the job done (bed grinding), you might want to eliminate the rest of the wear. Tailstock quill and bore, HS & TS alignment, cross feed and so on. You'd end up with a best of breed toolroom lathe giving factory new performance

 

[PeterT]

Good info. So on this basis, I wonder if the typical Asian machine with HS mounted onto the bed might actually be a slight blessing in disguise? For example say the regrind removes an aggressive amount from bed like 0.080".
- On an integrated lathe (HS cast integrally with bed) that would mean the saddle & TS are now 0.080" too low because the spindle axis remains the same. They need to be fill gapped 'up'.
- But if HS is mounted to the bed, after the regrind the HS/spindle axis now resides lower, the same 0.080". Therefore the saddle & tailstock are once again aligned? (notwithstanding their own wear).

But what I cant get my head around is how can they regrind the bed sliding surfaces (red line) without it adversely affecting the typical raised pyramid profile of the ways? Removing material on the horizontal flats is just one surface, but ancillaries are also sliding on the pyramid (saddle on red, TS on orange). Regrinding the pyramid would adversely affect the cross section profile, height, center..... What am I missing?

 

[Mcgyver]

Peter, I don't think you are missing anything. After bed grinding (or scraping) the angles of the V's (likely) won't be perfectly matched to what they were before (enough for bearing) and the relative heights will be different (apex of the V to flat). That's why you scrape the parts into the ground bed. It's how they are done new as well, or was on the better ones. Proper mating of bearing surfaces will cut to size and not keep cutting with subsequent passes, as it creates a rigid pancake stack instead of a stack of belville washers lol

I don't get why you've coloured the two V's red though, nothing rides on both V's with that particular arrangement. So long as the two horizontals are parallel (not necessary coplaner) and each V is parallel to its corresponding flat is all that matters. As I think about it, not even sure that parallelism of the flats matters, parallelism of the apex of V ought to suffice.

 

[PeterT]

I don't get why you've coloured the two V's red though, nothing rides on both V's with that particular arrangement.

Brain fart. Saddle rides on red, TS rides on orange.

But back to wear, I would think the Vee area would be become worn to similar degree as flats, so wouldn't they have to recondition both Vee & flat at same session (probably how the bed was originally ground)? Otherwise if they just recondition the flat by X amount then the topside components would just be gliding on the original Vee & would not see the benefit of improved flat?

 

[Mcgyver]

Wouldn't work. Each part is support on three surfaces. Alter one or two, the unaltered will no longer mate

I can't see anyone attempted it, what would it accomplish? You have to scrape the mating parts into the new ground geometry regardless which is where the work is (not grinding two surfaces instead of three). Its a major undertaking with the goal being factory new condition and there is going to wear on both way's not just one, so I'm not seeing the motivation for it or use of doing so.

 

[Rauce]

On the topic, Turcite and Moglice have some disadvantages. Crap gets embedded in it and it ends up accelerating wear. Its a great commercial solution to get more life out of a machine and minimize the bill of the reconditioning guy. However, in my opinion, its not the solution for that best of breed lathe you want to have in a near perfect state for the rest of your days. I wouldn't say I'd never use them, but doing so requires a lot of finicky prep work (say, milling out the bottom of the headstock) to it and embedding is a real issue. You'd have to put in some fancy wipers to minimize that.

I’m hoping to avoid it if I can. One thing that I hadn’t thought about until just yesterday (a post in this thread prompted the thought) is that there’s a potential issue in the apron/saddle interface where gears mesh for the power crossfeed. This was where I had assumed I could remove material to account for the saddle being lowered.

You can see in these photos there’s a gear on the leadscrew in the saddle and a gear in the apron.

Turcite/moglice would eliminate this issue. Not sure how I would work around it otherwise.

With the headstock and tailstock I think it should be straightforward. The headstock and tailstock mate to the same surfaces and they had no real measurable wear before I sent it out so geometry coming back from grinding should be very close to what it was. I was also able to provide an original factory drawing of the way geometry to the grinder.

This lathe is also a franken-lathe. The headstock came off of another machine. This lathe had an accident in transit that cracked the headstock and it was later bought almost entirely for the taper attachment. Peter, who I bought the lathe from had another very rough parts machine that this headstock came from before the bulk of it got scrapped. I got a number of spare small parts from the scrapped machine as well.

Because of the swap my headstock and tailstock are not perfectly matched in height. I measured the tailstock to be a couple thou high, which is ideal since I can bring it right in without any shimming needed.

 

[Mcgyver]

Have you chatted with Peter about it? He knows his way around reconditioning (you'll remember I posted Peter's lathe here as someone just had to pick up that lathe!)

I don't think there is much of a chance they will mate to the level necessary, but check it out when the bed gets back. Who knows...even a broken clock is right twice a day. Level the bed, apply with a piece of felt the thinnest of layers of blue and touch the mating parts off, HS, TS and saddle. To work as it should, you want an indication of bearing all over the mating surfaces you touched to the bed. If they have good bearing all over their surface, and are aligned, and you used thin blue....run don't walk and buy a fist of full lottery tickets!

Whats the bottom of the headstock, scraped?

 

[Rauce]

Have you chatted with Peter about it? He knows his way around reconditioning (you'll remember I posted Peter's lathe here as someone just had to pick up that lathe!)

I don't think there is much of a chance they will mate to the level necessary, but check it out when the bed gets back. Who knows...even a broken clock is right twice a day. Level the bed, apply with a piece of felt the thinnest of layers of blue and touch the mating parts off, HS, TS and saddle. To work as it should, you want an indication of bearing all over the mating surfaces you touched to the bed. If they have good bearing all over their surface, and are aligned, and you used thin blue....run don't walk and buy a fist of full lottery tickets!

Whats the bottom of the headstock, scraped?

Headstock bottom was scraped and the bearing/alignment were very good when I got it. I will definitely be checking it when I get it back though.

I have chatted to Peter about it, he used moglice on the carriage to retain the height relative to the leadscrew/feed screw and everything else was simply scraped.

 

[Mcgyver]

Headstock bottom was scraped and the bearing/alignment were very good when I got it. I will definitely be checking it when I get it back though.

I have chatted to Peter about it, he used moglice on the carriage to retain the height relative to the leadscrew/feed screw and everything else was simply scraped.

That's the same as about every lathe I've work on, including how I saw it done at Standard Modern. i hadn't been in the Hendey plant so didn't want to assume.

Reason is, the geometry of every lathe bed is or can be slightly different. Dress a wheel on the gang grinder and its a different bed. Different slightly, but enough that a parts won't mate properly without being scraped in.

Maybe nowadays there is some super fancy CNC grinder that could do the six surfaces, three at different angles, then grind the mating part and have the fit accurate enough to create proper bearing, but if does exist I'm rather doubtful such a critter has made its way into manual lathe manufacturing. For sure there wasn't when our lathes made, one expects manual fitting (scraping) to mate the parts into that bed so every ends up a little different. Put simply, they are generally not interchangeable which is what I would expect for that lathe...but confess I don't know. There are exceptions, Schaublin is one I know of, maybe Hendey as well. Good news it shouldn't be that onerous; regardless, you'd expect it to be close.

 

[Rauce]

Good news it should be that onerous, you'd expect it to be close.

Assuming the bed met the tolerances on the drawing I have the width of the angle surfaces are +/-2 thou and +/- 2’ on the angle. From what DiPaulo told me they will take off equal amounts from surfaces that need to retain their relationship. Like you said I’m not expecting to do nothing but I’m thinking it won’t be much!

For the cross slide and compound I’m preparing a straight edge right now to assist in the scraping. Was just roughing it out today on the mill. It’s from a casting I got from my pattern maker friend here in Hamilton. He no longer sells these unfortunately, not enough demand locally and they kept getting written off in transit to the US.