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Scraping in all bearing surfaces on my Wards/Logan 10"

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I've been working on my lathe off and on over the past several weeks or months, but I've been hesitant to start a thread documenting my progress (or lack thereof!) for fear of embarrassing myself.

I'm increasingly confident that I'm going to end up with a very precise lathe rather than a very large pile of cast iron dust and tears, so I'm finally willing to share my progress.

After creating a new cross-slide for my lathe some time ago, I'd already spent a lot of time scraping in the compound and cross slide. But I decided to tackle a far larger project.

I've taken Richard King's class twice now (and I'm about to help out with a third) but I know full well there is no way to really learn something without actually doing it (and even better, trying to explain what you're doing to others). So, despite my old Wards/Logan being in perfectly (well ... "acceptably") useable shape to begin with, I decided to scrape in the bed ways, headstock, saddle, and tailstock. I rationalized that this was "my first lathe" and even if I ended up with an expensive and shameful pile of worthless cast iron, I'd learn something in the process.

As expected, it's been a terrific learning experience.

I decided to attempt the inner ways and tailstock first before tackling the outer ways and carriage. I thought this wise because in case I totally screwed up, the tailstock is less critical than the carriage. It took an embarrassingly long time for me to realize that the headstock also rides on the inner ways, though, so if I screwed them up I was still pretty much SOL.

Anyway, I'm happy to report that after a LOT of work, I've got the inner ways and tailstock base scraped in to about 0.0006" with decent bearing over the entire 42" length of the bed:


If I'm reading Connelly correctly, I think the standard for this test is under less than 0.0008". The width of the tailstock base is only about 4" and the level is calibrated to 0.0005"/10" so, if my math is right, each division on my level shows about 0.0002" of deviation. Three divisions max deviation is under the standard. Whoopee. :cool:

Actually, I've still got just a bit more fine tuning left. I'd like to get a little bit more bearing points on the far side of the rear fee way, as well as a few more on the bottom of the tailstock base (it's bearing across the entirety of all three surfaces, but I'd like to get a few more PPI). I'm pretty sure I can improve 0.0006" slightly but I'm pretty satisfied already (considering the stack of tolerances).

Interestingly, the far side of the inner inverted-fee way needed the most scraping. Not sure why this would be unless it was out a bit when it left the factory.

I'm leaving out an awful lot of things that I didn't document, but here's the rough outline of getting to this point. I'll try to update this thread with more thorough details as I tackle the outer ways, headstock, tailstock top, and carriage.

Step zero was to scrape in a 36" straightedge. It's slightly shorter than my bed, but there's no way I'd have been able to manhandle a larger straightedge. As it was, I really wish I'd acquired a plain casting without the angled edge for large dovetails. The additional weight of the dovetail feature put it right at the edge of what I can manage by myself (my straightedge weighs about 70 pounds if I recall correctly).

Another (critically important!) preliminary step was to determine what to use as the "datum plane." I'd heard from Scott Logan himself that the flattened tops of the inverted vee ways on Logan lathes were ground at the factory at the same time and with the same setup as the ways themselves. Since the tops of the vees receive no wear, this eliminated a lot of what Richard calls "detective work." After a good stoning to remove the raised burrs from 70+ years of nicks and dings, I had an excellent (and convenient!) reference plane waiting for me.

Connelly calls this a secondary reference/datum. For other manufacturers, you'll have to look for unworn edges on the flat ways, or use the bottom of the rear way to determine the original datum plane. After just one lathe job I'm convinced that if I ever work on a lathe that doesn't have the tops of the vees pre-ground to be coplanar with the real datum (the ways themselves) the very first thing I'd do on a refurbish job would be to make the tops of the vees a secondary datum. It's incredibly convenient to be able to just lay something flat across the ways to indicate from instead of having to balance/clamp 1-2-3 blocks and parallels.

The datum plane is everything when it comes to precise alignment and an accurate lathe. Literally everything on the lathe is adjusted relative to this plane. It's worth spending an awful lot of effort ensuring that all points on this plane are as coplanar as possible. Many years ago, I tried to level my lathe using shims. Trust me, screws/nuts (or paired wedges) are the only way to go for the level of precision required. You'll drive yourself insane trying to get things level (planar) with shims.

While it's only necessary to ensure the datum plane is truly flat, and not to align it with any particular plane, trust me that it's worth the effort of making the datum plane truly level. It's awfully convenient to be able to just throw your level onto things to see if they are parallel to the datum plane.

It's also worth calibrating your level instead of always ensuring you have it oriented in the same direction (something I try to do anyway, but am bound to screw up occasionally). The process is easy and satisfying (and likely documented elsewhere on this site).

I carefully re-leveled the bed at the start of each day's work (and often once or twice during a session, especially after jostling the bed or causing heavy vibration from rough scraping things nearby. Just the tiniest movement of the nuts on the leveling feet is enough to move things out of level by a couple tenths. I have the whole thing supported by a massive maple workbench, but temperature and humidity variations are definitely enough to move the bed out of alignment slightly from day to day.

Here's what level looks like:


I started by scraping the inner flat way. The first blue ups showed more wear in the middle than on the ends, unsurprisingly. Because the area under the headstock is fixed and has no wear, I first tried to leave that area alone as much as possible. I thought I was being smart by "tipping in" the scraping and doing most of the scraping at the tailstock end. Naturally, this ended up with the way angled downward toward the tailstock relative to the datum plane. No bueno. So I ended up needing to remove a bit of metal at the headstock end anyway.

Note that the flat way needs to be coplanar with the datum plane in both dimensions (left to right, as well as fore and aft). It's very easy to confuse yourself when indicating in one direction if you're also out in the other.

In case it isn't obvious, here's how I indicated to ensure things are parallel to the datum plane:

IMG_0361.jpg

In this image, I've got a piece of precision granite across my datum plane. Just rest the the base of your surface gauge or indicator stand on this, and use a small parallel or side of a gage block to average out the points on a scraped surface.

I discovered a pretty significant nick in one corner of my mag base, by the way, that was causing me no end of grief trying to get repeatable results. A quick stoning fixed the problem, but for a while I thought I was losing my mind.

As I mentioned it's important to realize you may have tipped the flat way in one of two dimensions. At one point I was trying to determine how far the flat way was tilted toward the tailstock after my initial scrape, but I just couldn't seem to get repeatable results. After several attempts, lots of head scratching, walks, and countless cups of coffee, I finally realized the way was also tipped over a thou toward the back of the lathe as well as left to right. Because I wasn't always measuring in the precise middle of the way, my results would vary.

So I rigged up this ghetto King-Way to at least perform this one measurement reliably:

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I just super glued a couple washers on a flat bar to create a two point reference, and clamped it to the granite square or level I placed across the vees. This photo is a bit of a lie. I only used this setup to measure the flat way (and ensure I was indicating at the same offset from the edge of the way). I didn't actually use it for the vee ways. The front edge of my lathe is not precision ground (you can still see the rough abrasive grinder/saw marks). It's not flat enough for anything super critical, but it was enough for me to figure out how much I needed to correct left to right.

Hope this all makes sense. I've learned quite a bit in the process, and doubt I've covered half of it, but I hope this is at least somewhat interesting and useful.

Doubtless I'm still making other boneheaded mistakes, but I'll continue to share. Please don't hesitate to correct me if I'm doing something wrong or if there's some easier way.
 

Comments

A bit more progress.

I've scraped in:

• All three inner way surfaces (flat and both sides of the inverted vee), of the bed ways:

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• The bottom of the tailstock base to match the bed ways (the flat bed way is narrower than the flat way on the tailstock base - hence the stripe without bluing in the photograph).

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• The top of the tailstock base (scraped to be parallel to the datum plane). This was tricky to scrape and indicate parallel because of the guiding portion that sticks up in the middle. I was using it to mark up the top half when I took the photo (hence the bluing on the scraped surfaces — blacking?).

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• And I've just started to scrape the top half of the tailstock base to match the lower.

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I'm performing various checks along the way with straightedges, the surface plate, and indicators to ensure things are as flat/parallel/coplanar as I can get them.

The most difficult thing to get coplanar is the two parts of the top of the tailstock base, separated by the protrusions to guide the top portion. I neglected to get a photo, but the best way to ensure they were coplanar was to scrape the larger portion flat and parallel to the datum plane (indicating with the rig in the previous post) then clamp that surface down to a matched pair 1-2-3 block on the surface plate and indicate from underneath. I'll try to get a photo of this setup tomorrow.

Once both portions of the base are coplanar and parallel with the datum plane, I need to fit the top half to match the bottom. These were not precision surfaces from the manufacturer. They weren't even terribly well machined, so this will (eventually) be better than factory. This is definitely overkill, but its a learning project so there's no reason not to go overboard.

The "rubber meets the road" test is with a test-bar stuck in the MT2 taper of the tailstock (testing both for vertical deviation as well as side to side as I slide the tailstock along the ways):

IMG_0370.jpg


Because the top and bottom aren't yet a perfect fit, I've still got a thou or two of rock between the two halves. Once I've got a matching flat surface on the top half, I'll use the indicator tests above to step scrape the top half into alignment.

Between the four sets of mating surfaces (bed ways, bottom of base, top of base, bottom of tailstock top-half) the tolerance stack is a lot to control, but I'm extremely confident I'll be able to get less than a half thou or so of deviation along the entire length of the test bar.

All this scraping is lowering the tailstock significantly (possibly 0.010" or more). Once I scrape in the headstock, I'll see how much lower the tailstock quill is than the headstock. If it's less than a couple thou, I'll definitely just live with it. If its lower by only a 2-3 thou, I'll likely lower the headstock with a few extra passes. If it's more than ten thou, though, I'll probably epoxy some turcite or equivalent to the top half of the tailstock. That will require milling the bottom half even lower though, so I'd like to avoid it if possible.

Onward!
 
Great fun!
Rex, how much time are you investing in this?
Perfect timing with the class next week. You will be the star pupil!
 
Between the four sets of mating surfaces (bed ways, bottom of base, top of base, bottom of tailstock top-half) the tolerance stack is a lot to control, but I'm extremely confident I'll be able to get less than a half thou or so of deviation along the entire length of the test bar.

All this scraping is lowering the tailstock significantly (possibly 0.010" or more). Once I scrape in the headstock, I'll see how much lower the tailstock quill is than the headstock. If it's less than a couple thou, I'll definitely just live with it. If its lower by only a 2-3 thou, I'll likely lower the headstock with a few extra passes. If it's more than ten thou, though, I'll probably epoxy some turcite or equivalent to the top half of the tailstock. That will require milling the bottom half even lower though, so I'd like to avoid it if possible.
Shimming between the upper and bottom halves of the tail stock is an acceptable way to get the spindle center lines to match. The scraping is to get the geometry correct. The interface between the two halves is not a sliding surface. Just get the geometry correct. Also, tail stock spindle dead level and dead equal height to the spindle center is not what is called out in Machine Tool Reconditioning (MTR) or in manufacturers' tolerance sheets. In MTR, the tail stock spindle for a 12-18" swing engine lathe shows it should be 0 to .0008" toward the cutting tool at the fully extended and locked down position while measuring the side of the spindle, and 0 to .0005" high when indicating the top of the end of the spindle in the same setup. This is to accommodate side pressure in use, heavy parts mounted, and wear over time (MTR 26.49 to 26.57)
 
Shimming between the upper and bottom halves of the tail stock is an acceptable way to get the spindle center lines to match. The scraping is to get the geometry correct.
Yes, using loose shim stock is common, but I'd prefer to have the shimming material permanently attached and scraped to ensure the alignment stays true. Putting loose shim stock on scraped surfaces just seems wrong to me. It's a little weird using turcite for a fixed bearing surface, but not unheard of from what I've read.

... shows it should be 0 to .0008" toward the cutting tool at the fully extended and locked down position while measuring the side of the spindle, and 0 to .0005" high when indicating the top of the end of the spindle in the same setup.
I read a "zero to 0.0008" spec as "just don't angle it away from the operator and if anything favor toward you slightly." No?

I don't think a few tenths of height difference will be detectable due to cosine effects, but I guess it makes some sort of sense to angle it ever so slightly toward the operator when fully extended. Since tailstocks are adjustable, though, what's the point? If I'm doing precise work and turning between centers you can be darn sure I'll adjust the tailstock to eliminate any taper anyway. I'll ask Rich his opinion next week.

I get adjusting the cross slide to cut ever so slightly angled, but intentionally scraping the tailstock off axis seems odd.
 
I read a "zero to 0.0008" spec as "just don't angle it away from the operator and if anything favor toward you slightly." No?
Yes!

I think the purpose of those specs are for allowing a longer time of usage before being out of limits again, i.e., the job lasts longer, and is more practically accurate in the real world where there is more than a DTI point pushing against things. Doing 'perfect' work when reconditioning a lathe will give you a nice, warm, fuzzy feeling, but with first usage accuracy will be deteriorating. Think of the specified tolerances allowing "final lapping to perfection while in service..." ;)
 
Think of the specified tolerances allowing "final lapping to perfection while in service..." ;)
Well, another way to think of intentionally misaligning in this way might be “Only at some unpredictable point in the future will the machine be in alignment — it will be out of alignment both before and after that point.” :)

Still, I get the point that (unpredictable) part weight and tool pressure will cause wear and deflection.

I’ll target the middle of Connelly’s spec range for final alignment (normal engineering practice).

Per Connelly for tool room lathes (ch. 26.56 to 26.63):

Tailstock taper hole alignment in horizontal plane: 0 +/- 0.0005” at end of 12” test bar (target is dead nuts zero)

Tailstock taper hole alignment in vertical plane 0 to 0.0005” at end of 12” test bar (target is 0.00025” high)

Spindle center runout: 0.0004” TIR (target zero)

Spindle nose runout: 0.0003” TIR (target zero)

Spindle taper runout at end of 12” test bar: 0.0006” TIR (target zero, but this spec is at odds with the next spec).

Spindle taper alignment in vertical plane 0 to 0.0005” high at end of 12” test bar (target 0.00025”).

Spindle taper alignment in horizontal plane: 0 to +/- 0.0003” at end of 12” test bar (target zero)

I’ll follow your (and Connelly’s) advice to slope the tailstock and spindle tapers ever so slightly upwards (a few tenths at the end of a 12” test bar). Frankly, this is so close to dead level that I suspect it’s outside my ability to measure, much less scrape reliably.
 
The whole idea of introducing a machine tool into a production environment knowing that it will wear into spec., then work it's way back out through use, is bizarre. IMHO
It's like a break-in period. Maybe that was the idea?
 
Here's the picture of the setup for indicating both sides of the "step" on the top of the tailstock base:

292880

You should also check your matched pair of 1-2-3 blocks if you do this kind of thing:

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Mine are cheap blocks and I was a little annoyed to find that one side of one of them was about 0.0002" thicker than the other. Still good enough for what I was doing, but I eventually just used the single better block to clamp the piece off of the surface plate.

The top of the tailstock base was WAY out of flat (it was never precision ground). It's taken quite a bit of scraping to get it anywhere close to flat, and I've still got a "hole" in the middle of the back end (bottom of the photo) but here's where I left off:

292882

I've made one pretty bad boo-boo. The step between the tailstock base and top half needs to be a very tight fit as it keeps the top from twisting in the horizontal plane. In order to leave some room for the "overstroke" while scraping the top of the base part (its quite hard to scrape to a square corner) I needed to file (and eventually mill) some clearance (see the photo in comment #2). I used a file with a safe edge and carefully indicated before milling, but I must not have been careful enough because I can now twist the top half left and right about +/- 0.0025" —much more than I'm willing to allow.

When I'm finished matching the bottom of the top half to the base piece, I'll likely take a careful milling pass on both pieces, then glue in some sort of permanent gib-like piece onto one side of the channel in the top half, and mill or scrape to a tight sliding fit. I'll allow several tenths of slop, but not +/- 2.5 thou!
 
Here's the picture of the setup for indicating both sides of the "step" on the top of the tailstock base:
The parallax in the photo makes it look like the clamp is between the two clamps (not the case — I was squeezing directly onto the right one). It's important, of course, not to clamp someplace that doesn't have support (you'll definitely distort the part).
 
Confidence level is through the roof now. I've got the tailstock finished. Woo hoo!

Less than 0.0002" along a 9 or 10" test bar in both the vertical and horizontal planes. Since my individual scrapes themselves are about 0.00025" deep this really amazes the engineering nerd in me. Behold the glory:


The horizontal plane is also well under one indicator division over the full length of the test bar.

The stack of potential errors is astonishing:

1. Flat inner bed way
2. Side one of the inner inverted vee way
3. Side two of the inner inverted vee way
4. Flat bearing surface on the bottom of the tailstock base
5. Side one of the vee on the bottom of the tailstock base
6. Side two of the vee on the bottom of the tailstock base
7. Front half of the top of the tailstock base (in front of the bump)
8. Back half of the top of the tailstock base (behind the bump)
9. Bottom of the top half of the tailstock.
10. Bored hole for the quill (I've not touched this)
11. Morse taper hole in the quill (freshly reamed to remove any burrs)
12. Morse taper of the test bar (not touched nor tested)
13. Ground cylinder of the test bar (I've not touched nor indicated this, though I should)

Before anyone asks, NO I AM NOT GOING TO EVEN LOOK AT IT WITH MY TENTHS INDICATOR. (Laugh) Seriously, two tenths at the end of a foot long bar is so crazy precise that even breathing on the thing (literally, I think!) will affect the results.

Anyway, I'm confident enough to start work on the headstock tomorrow. It will be a little more nerve wracking because I have to make any alignment adjustments on relatively small way surfaces instead of big flat areas like the top of the tailstock base. It will also be a little more nerve wracking because it's the freaking spindle, the heart of the lathe!

A few interesting things from today's work:

When I first indicated in the vertical plane after flattening the bottom of the upper half, I almost freaked out. The end of the bar at the headstock end was 0.0065" lower than the other end. I thought I was going to be scraping for days (at roughly four passes per thou, I thought at first I'd need 24 passes).

Then I realized it's over a foot from the back end of the tailstock. Tiny little changes back there have a big effect at the end of the bar. Whew.

In the end it only took me a couple hours at most to get it to the point you see in the video.

Since the upper half of the tailstock has a channel rather than a bump, I could just mark it up on the surface plate. After getting it roughly flat (maybe 5-10 PPI) I inked up the bottom half and checked the fit. I was extremely gratified to see almost identical markup using to the bottom half as I did with the plate (proving I did a decent job scraping in the bottom half despite the bump). Cool.

So I spent the next several passes fitting it to the bottom half. Once I had it bearing pretty well everywhere (maybe 15-20 PPI) I blued it up once more on the plate.

And almost had a heart attack. It was bearing on only a few points! What on earth had I done?

Eventually (walks, cursing, coffee, etc.) I realized that the clearance grooves I'd filed into the bottom half had come back to haunt me. Since there was no bearing where I'd filed the grooves, and I'd gone through a dozen or so scraping passes, those areas on the top half hadn't been scraped at all and were now proud by a few thou. I forgot to take a picture of the original mark up, but here it is in the middle of one of the corrective passes:

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Anyway, today was a good day.

Next up is the headstock. Hopefully the results will be equally good.
 
Nice work, just a quick quesiton, why have you not duplicated the King Way Alignment Tool? I really like the one I built. Tim
 
why have you not duplicated the King Way Alignment Tool?
Good question. At least in part because I don’t have a working lathe at the moment! (Laugh)

I also need to acquire some leveling tubes and figure out a way to manufacture the C-shaped foot part.

How did you make the latter? I’ve been thinking of modeling it and sending it out for 3D printing in sintered metal.
 
I turned a pieces of cast iron bar down in the lathe, put 2 rings on it, then drilled the mount holes so a mag base stand would fit in it. I posed pics on here of the one I uses to measure my rockwell lathe. Here are a few pics of it. Do you want to borrow it? I made 2 different sizes.

 
Rex, looks good. I didn't read it word for word....though.... Be sure to relieve the middle 40% of the slides approx. .001" so they don't rock. Be sure to lock the tailstock down when making the tests, That test bar in the TS quill is a bit long. I would also use some Phenolic between the TS halfs that is glued down. Good scraping :) you must have had a good teacher :);)
 
Rex, looks good. I didn't read it word for word....though.... Be sure to relieve the middle 40% of the slides approx. .001" so they don't rock. Be sure to lock the tailstock down when making the tests, That test bar in the TS quill is a bit long. I would also use some Phenolic between the TS halfs that is glued down. Good scraping :) you must have had a good teacher :);)
Whoops! I relieved the sliding ways in the middle (less than a thou) and I did lock the quill in the tailstock, but I didn’t lock the top half to the bottom or to the bed. I’ll test that today and see how much of I need to correct.

Phenolic sounds like a perfect material. Thanks.

Thank heaven I had a good teacher - I shudder to think of how many more bad mistakes I’d have made with only YouTube and HM to guide me. Following the class(es — in my case — slow learner) with a real project has been extremely educational.
 
Do you want to borrow it? I made 2 different sizes.
Nice work! Mag base parts were a clever idea. Were you able to radius the inside edges of the slot in the C foot part? The only way I could figure out how to do that was with a custom ground cutter and somewhat tricky workholding and alignment in the mill.

If you are anywhere near San Jose, I’ll definitely take you up on your generous offer. It’s a fairly small 10” lathe. John York’s large Kingway is too big for my vees.
 
If you are anywhere near San Jose, I’ll definitely take you up on your generous offer.
I’ll also 3D print a plastic foot for the ball end in exchange. I think it’s important to average out the bearing on a scraped surface instead of using the point contact of a ball. Seems like individual scrape marks would drive you insane otherwise.
 
Be sure to lock the tailstock down when making the tests
Whew!

I just dug out the locking parts and indicated with the tailstock locked down. It did seem to affect the result, but only ever so slightly (about half a division or 0.00025" at the end of the test bar, but in the wrong direction with the test bar tipping down). It's not enough to worry me greatly — I think a heavy stoning will be enough to get it back to perfect, definitely no more than a single scraping pass on the back half.

One other thing I want to run past Rich (and the collective wisdom of the group): since the fit of the step on the base into the channel in the upper half is already a sloppy fit, I used that most precision of tools, a triangular file, to adjust the alignment in the horizontal plane (i.e. the top half spinning around the Y axis). I reasoned the front surface of the steps on the headstock side were the most critical, so I carefully filed away minute bits of metal on the leading edge of one of the bumps until the test bar showed no deviation in the horizontal plane when the top half was pushed firmly agains the headstock edge of the steps.

My plan is to mill off the back edge and then glue in a shim that I'll file or scrape to a tight sliding fit in the upper channel. As long as the headstock edge is already adjusted for alignment, then milling/shimming the trailing edge shouldn't be critical to alignment (just adjust for a tight sliding fit). Does that seem like a reasonable plan?

I was happy to see that McMaster-Carr sells sheets of "Garolite CE" as thin as 1/32" quite cheaply. I just ordered a 1' x 2' x 1/32" sheet (way more than I'll ever need) for ten bucks in case I need to shim up the tailstock as I suspect. Per their website:

"These Garolite CE sheets are often fabricated into parts where high strength is not required. They are made of a phenolic resin with cotton fabric reinforcement, which makes it easy to machine into mechanical parts, such as pulleys, gears, bushings, and washers. Garolite CE is sometimes called canvas-grade industrial laminate, phenolic, and Bakelite."

I saw in an old post of Rich's (elsewhere) that he recommends 3M Scotch-Weld Epoxy EC2216 for phenolic, and 1838 Green for for Turcite/Rulon. The prices for those from McMaster made my eyes water ($54 for a 3.3 oz tube of 2216). Since this is a fairly static way on a hobby machine, I'll likely just use some cheap slow-set epoxy from the hardware store.

How machinable is phenolic? Can it be scraped?
 
How machinable is phenolic? Can it be scraped?
Whew, caught it in time. Found someplace where Richard specifically recommended NOT USING ANY PHENOLIC UNLESS IT IS "linen grade" (which can be scraped). I just changed my order to Garolite LE (vs. CE) which is linen for only a few pennies more. I'd still like to find a cheaper glue than the 3M 2216 Rich recommends (I wonder if even a thick gel-type CA glue would suffice?).
 
You can use any 2 part epoxy with a 8+ hour dry time. I did a lathe in Oklahoma last fall and we used J D Weld that I bought in a Auto Store. ( I brought brand new Tri-Star Epoxy, but TSA said it was hazardous and took it) Be sure to either bead blast or sand paper the shinny side of the Phenolic. Also clean with Acetone or fast dry brake cleaner or electrical contact cleaner. On the 3M products I think both would work on either product, but 3M info line recommended those for the different materials.

I wish you had asked about the between the halves key as I would have never filed a perfectly good surface to correct an issue on the ways. I would have first used some shim stock between the bottom and the way to get the bar alignment and then scraped off the opposite side of both ends. You may have had to set scrape the complete bottom to get the top of the bottom half so it runs parallel to the cross-feed travel.

If I were you I would put it on a mill and indicate in the front 1/2 (the one you filed) and then kiss that side to be sure it is straighter then a filed surface, Then go to the other side and mill out the back end then mount a piece of square key stock and cap screw bolt it down. I wouldn't glue some shim on the one you filed or back side.
 
If you want, bring it with next week and we can figure it out (for those who don't know, Rex is assisting me teach the Vacaville CA class. He has attended 2 of my classes and I have a lot of confidence in him and his skill. Also I sent a vintage used Challenge brand 36" plain (no angle) camel back that will need to be touch up out via UPS, so your club has it for the next lathe bed.
 
If I were you I would put it on a mill and indicate in the front 1/2 (the one you filed) and then kiss that side to be sure it is straighter then a filed surface,
Yup, that was exactly what I just decided - thanks for the confirmation. It was far enough out that I knew I wanted to mill it eventually, the filing was just a quick and dirty way to get it aligned horizontally enough to make reading the tip in the vertical plane easier (so I could just sweep along the test bar instead of continually having to find the top via maximum deflection).

The fit was pretty sloppy regardless. I know at least some of the slop was my fault, but none of the mating surfaces between the two halves had been precision ground even at the factory, just rough milled. I was kind of shocked at just how out of flat the top half was to begin with.

I should have taken the time to do it right, of course, but I reasoned that way is just used to (VERY infrequently) adjust the tailstock way set over for cutting tapers (or not). Like most people, I usually set the tailstock for zero taper when cutting between centers and avoid setting over like the plague.

For the rare occasions I did want to cut a taper longer than my compound travel, I even built a GHT designed tapering jig quite a while ago expressly to avoid adjusting the tailstock off zero once I had it dialed in! Basically just a dead center with an adjustable offset and an MT2 mount.

Found that McMaster also recommended a slow cure JBWeld epoxy for their “Garolite” material. Much more reasonably priced, so I ordered some along with a 1’x2’ sheet of Garolite.

Anyway, I’m definitely bringing the whole lathe with me next week. Looking forward to getting your advice on the more critical components coming up. I’ll hold off on doing the actual glue up and final scraping of the phenolic until the class. I’ll do the preparatory milling etc. tomorrow.

Thanks!
 
I
Nice work! Mag base parts were a clever idea. Were you able to radius the inside edges of the slot in the C foot part? The only way I could figure out how to do that was with a custom ground cutter and somewhat tricky workholding and alignment in the mill.

If you are anywhere near San Jose, I’ll definitely take you up on your generous offer. It’s a fairly small 10” lathe. John York’s large Kingway is too big for my vees.
Built a small one and a large one, and USPS is only $8 away
 
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