How bad is this SB 10L bed?

[Gard]

I am working on rebuilding this war badge lathe for home hobby shop use and as a learning experience. So far I made a new cross slide lead screw, scraped in the compound slide, cross slide and taper attachment. The bottom of the saddle has wear ridges that are approximately 0.024" on the headstock side and 0.012 on the tail side, measured perpendicular to the V surface.




The bed V way did not look terrible, I cleaned up the burs with a fine file and stone. The tops of the V ways are worn and uneven, the best reference surfaces I could find are the small flat strips between the ways. These are scratched but flat within about 0.002" as checked with a precision level. Parallel blocks were set on the bed (between rack screws) which supports a transverse parallel block which supports the indicator base. Another parallel rests on V blocks that rest on the V ways. The photos show how the parts are stacked up. The indicator is aligned directly above the V way of interest. This basic setup also used to measure the ways for the tailstock, the mounting surface for the rack and the leadscrew.



This was just a little discouraging, 0.025" wear near the headstock. Is it bad enough that I should get it machined? I cannot imagine hand scrapeing off almost 0.025" from all the way surfaces. If so any rough guess or experience on what it would cost and who does this kind of work? I am in Vermont so it would be nice to find someone within driving distance. This swayback can also be easily seen with a SE but I do not have one quite long enough for the entire length.

I think it would be possible to make the lathe useable with this bed. One option is adding approximately 0.045" of Turcite or Rulon to the bottom of the saddle V ways, this will align the apron to the lead screw where it exits the QCGB on the left. The bearing on the right side of the lead screw would need to be raised about 0.045" . It is curious that this bearing is currently 0.022" lower than the QCGB measured from the rack mounting surface. Any idea how that can happen? The gear will have a little backlash on the tail side rack and looser but still usable on the left side. I think it may even be possible to shim down the rack on the left side to follow the bed. The Turcite would need to be about 0.016" thinner on the right side to keep the saddle level. If I were to go this route would it be better to machine the bottom of the saddle first or just install the Turcite and try to scrape the right side down?

It might also be possible to do a little scrapeing on the bottom of the saddle then shim down the rack, QCGB and lead screw bearing. I have not yet removed the headstock and QCGB so not sure what I will find in there, also still need to disassemble and clean the apron.

 

[metalmagpie]

I love this posting! Wish I knew the answers!

 

[jim rozen]

Take the headstock off and exend the data to the left end of the bed, if only to verify the far left and far right numbers align, as they probably will. You have discovered the 'simpler to buy a less worn lathe than to fix the worn one' connundrum.

 

[Gard]

Thanks, good point on checking the rest of the bed, its now on the list. I have been working on one part of the lathe at a time between other projects around the farm. I started with just fixing the 1 or 2 things that obviously needed work and keep finding more. I enjoy renovating old machinery. The projects always are a lot more involved than initially thought.

 

[lucky7]

First thing I’d look at is condition of spindle bearings. If worn, move on to another lathe. If good, then consider whether you enjoy scraping and are willing to pay roughly a thousand $’s to grind bed. I’d still move on to another lathe as life is too short…

 

[Richard King]

Member - Warren - Warren Jones has a friend in New Hampshire who has a planner and could plane the bed and Saddle. Warren has been the class coordinator of 4 of my Springfield VT scraping classes. I will add his email address so you can write him and get his friends email or phone #. The Saddle is easy to measure from. On a surface plate set it upside down on 3 points, Then indicate where the Carriage bolts on as that is original and no wear. After you get it to indicate long and side ways to .0005" Measure the flat and lay a dowel pin in the V and that will give you a better reading then using the narrow flat you indicating now. Use a marker and write the error on the saddle, so when you take it to the Planner guy he can use that to plane the bottom and top. Planning the bed and saddle is the way to go. We are talking about doing another Springfield VT class possibly in November or December. here is Warrens email...[email protected].

 

[Gard]

Lucky7, I will check the condition of the spindle again, I did a quick check a year or so ago and it seemed OK. Pretty sure it is an adjustable plain bearing like my 14/1/2 " SB of the same era. I had no idea grinding would be on the order of $1000, guess I will make some calls.

Richard, thanks for Warren's email. Sounds like a good idea to measure both sides of the 2 V ways on the bottom of the saddle relative to the apron mounting surface. Not sure what you mean by planning the top and bottom, I have scraped in the cross slide to apron dovetail so I hope I am done with the apron top side?

Just to provide some more detail, what I have done so far was install the saddle on the right (unworn) side of the bed and put shims between the bed and saddle. The right to left shims were adjusted so that an indicator on the apron mount surface does not change as the saddle slides. Also adjusted for proper alignment of head stock to cross slide (-0.001" in photo). Next I installed the apron and adjusted all shims by the same amount to align the apron to the lead screw near the QCGB. Made sure the gear would not bind on the rack at right side. Finally measured the new position of the lead screw support on the right. The shims I come up with this way are in reasonable agreement to what I would end up with by looking at the wear ridges on the saddle V ways and the bed wear so its kind of a sanity check.

 

[stephen thomas]

The tops of a V-way are not a reference surface. They don't change much, even as the flats on each side sink, variably.

When i planed (& scraped) my 10K bed, the first thing made was a set of 3 reference V's out of a dowel. I ground them all the same/same set up. One side is a flat, as would be expected. The other has a radius (dressed into the grinding wheel with an R & A dresser), so that the Vee does not have to match a specific angle. It is often the case that unless scraped to a master, or due to wear, an inverted V in use is not a known actual degree shape. My reference gages will adapt to the Vee shape (within limits.) The radius of one leg, means that it will settle and follow the actual condition of the ways. The top of the gage is also a round, so it is compensating, for how the gage settles on the inverted Vee.

A Kingway aligner is another method.
A Kingway inverted Vee reference, in section, is a "C" with radiused edges, so it, too can "settle" to the given shape of the ways, and be non-influencing.

My gages don't specifically rely on leveling, though they can certainly be used with a level.
(I did use a couple levels, when at the scraping stage)

 

[jim rozen]

Well. Clearly all he needs to do is go and purchase planer! Holy cow, I'm trying to parse what's going on in the first photo, with the 123 blocks.... and the measurement between the gage top and the underside of the bed rear way.

 

[dalmatiangirl61]

My opinion, your lathe bed is just fine for making tractor parts and other stuff in a home shop, put it back together and make chips.

 

[M.B. Naegle]

My opinion, your lathe bed is just fine for making tractor parts and other stuff in a home shop, put it back together and make chips.

^^^ Agree'd. I'm 100% behind putting impractical amounts of time and money into properly rebuilding a lathe, but if it's a question of "is it worth it," I think the answer lies in is it functional, and can you produce the parts you need with it to the tolerance desired? Perfect ways get you there faster, but I wouldn't put down a lathe based on measurements alone.

 

[Richard King]

My opinion, your lathe bed is just fine for making tractor parts and other stuff in a home shop, put it back together and make chips.

I agree. I always ask what are you going to do with a lathe. On a LeBlond lathe Keith Rucker measured, it was off I believe .004" up near the chuck. We figured his labor for disassembly, assembly and grinding bed would be over $10,000.00. He said he would file and emery cloth a long shaft. One thing you did wrong, you don't make the head-stock square to the cross-slide, you make the cross slide square to the bed and then make the headstock square to the bed. Or out of square .0008" / 12". So if you face a large diameter shaft it goes concave This also helps to counter push away when turning a shaft with-out the tailstock. If Stephen still has his planer, take a weekend and drive over, He's in New York. The top of the saddle flats have to be co-planer to the saddle bed ways. The long thin test bar you have in the chuck will sag, For measuring you would be better to have a tapered test bar and put it in the spindle hole. If not you could use a parallel attached to the spindle and it's zeroed to the TIR of the spindle bearings.

As Lucky 7 and girl61 said... Use the machine as is. It's a South Bend. Unless your wealthy and have a lot of time on your hands use it as-is. If you want to spend a lot of time and $$ get the bed plained, Glue on some Turcite under the saddle and scrape it.

Here is Keith Rucker - You Tube show - showing lathe bed alignment and saddle Turcited.

 

[Richard King]

How to align saddle to bed.

 

[M.B. Naegle]

I like the analogy of lathe bed wear being like burning oil in a car engine. There are owners who can't stand it and will rebuild or replace a car that burns oil, but in reality it can still get you around. If you take care of it NOW, keep things clean and oiled, and don't abuse it, it can still have many many years of service left in it. On the other hand, if this lathe/car is your pride and joy, or you need to be able to treat it like a brand new car/lathe, then new or rebuilt is what you need.

A perfect lathe bed means you can make one or two cuts and have perfectly concentric on-size parts. A worn one means you take a couple rough cuts, measure, a couple finish passes, measure, and maybe take the last couple tenths off with emery cloth... and have perfectly concentric on-size parts.

 

[JST]

That's true.

On the other hand, 24 thou is significant wear. And, with the differential wear on front and back ways, you can get into some pretty significant differences in diameter if cutting over the end of the wear. The change moves the cutter in and out.

If the wear is over a good deal of the bed, that's much better than if it is limited to a smaller region, where many typical cuts might get outside the worn area. The actual worn area is often pretty consistent as long as you do not go outside it..

 

[johansen]

24 thousandths drop is about what my 1941 era Southbend 9 had, but the carriage was so worn it was rubbing on the tailstock flat way.

after i was done with everything, the land on top of the front V way is non existent. the land on top of the front V way to the left of the headstock is original and is about 1/8th wide.

I fixed it by scraping .015" off both ends of the front v way, and .003" off both ends of the back v ways. i did this by hand mostly with a dremel and a grinding wheel, using a 40$ 38" long aluminum straight edge (sold for aligning table saws) as a reference.

I then lifted the carriage with 1/32" turcite, setting the carriage down on the bed with all 6 pieces of turcite epoxied to the carriage.. its weight presses down and it squishes out the epoxy, and you don't have to scrape it.. but after i ground tiny oil grooves in the turcite there is a lot less friction.

regarding the cross slide, i had to remove about .003" off the ends of the flat way on the headstock side, and probably .001 on the other side. this i did with a modified lapping procedure.

I scraped the bottom of the cross slide flat ways flat on a surface plate, but instead of flaking it, i ground about 10 divots per square inch (about 1mm by 3mm in a random orientation), then set it on the carriage and tightened the gib until it would bind at both ends. then i scraped the flat way. running the cross slide back and forth, where it binds it will rub the cast iron that was just scraped and make it shiny.. you then scrape the shiny spots only. i used heating oil as lubricant, you want something really thin so the film breaks down and polishes the high spots, but you need to flush away the debris so you don't wear the cross slide convex and have to re-scrape it. i did this until the gib was basically uniform tension the whole way. the reason this works is because only the flat way on the headstock side is worn. the dovetail is likely hardly worn at all.

if i were to do this again, i would have just used the bridgeport at work to cut a beveled edge on a piece of 3/8" thick bar of steel about a foot long and then peen it until it is mostly flat on the surface plate. then lap the dovetail of the cross slide back to what it should be.. keeping the abrasive only on the flat way.

the cross slide and the lathe ways do not need to be flaked.. you want them smooth so your way wipers work. grind divots or flake the carriage and the gib and other 3 surfaces of the cross slide.

if i were to do this again i would have lapped the bed after scraping using 4 pieces of steel about 18 inches long, epoxied into a carrier while resting on the bed in the middle. this would then take out some of the twist and the V to V way center distance variation.

 

[stephen thomas]

Well. Clearly all he needs to do is go and purchase planer! Holy cow, I'm trying to parse what's going on in the first photo, with the 123 blocks.... and the measurement between the gage top and the underside of the bed rear way.

This is why i stopped posting about rebuilding subjects, and will take this as a hint to stop again, going forward.

The gages on the inverted Vee's were the point of illustration, to show where/how you keep track of deviation in an inverted way. It is applicable to the OP's inspection as contrast to leveling over the flats on top of inverted Vee's which are not a reference surface. They don't wear at the same rate or in the same way, as the rest of the inverted Vee, and provide no useful information.

The photo's i had available show the use with the lathe bed on the planer, and give some ideas to how the references can be used.

To answer your first Q, the planer tool is being adjusted, before using to plane the underside flat of the back way. But it does not matter what the purpose is. Concentrate on a method, any method, to keep track of deviation in the inverted Vee's, and then reference that to other cross sectional features in the bed.

smt

 

[lucky7]

smt, this one guy enjoys your rebuilding posts. And learns…

regards,
L7

 

[cyanidekid]

the answer, BAD.
I think I had about 10-12 thou on the '45 10L I wasted a couple of months on, but I knew it was a stupid waste of time going in, but had just fired my primary client, and had some time on my hands.
also, it had the taper attachment on the backside, so the wear was more symmetrical so the drop wasn't pulling the tool away from the work as much as dropping the whole carriage in a level manner, front to back.
if you have 20+ wear on the front ways only, consider your "sunk costs" a learning experience and move on.
don't know your situation, but sometimes its best to cut your losses..

 

[john.k]

Friend gathered all the worn 9" SB and Hercuses from farm and clearing sales around.....he had over 20 of them.....I reground the beds (only) for him using my Landis 16x72 universal grinder,with a grinding head rigged to sit on the same mounts as the universal wheelhead.....he milled out pads in the saddle sliding areas for plastic .....worked quite well..so far he's finished and sold 8 of them.