Thread: Meet Bertha! U.S. Machine Tool Co. Model VT vertical mill restoration

Meet “Bertha”, my U.S. Machine Tool Co. Model VT milling machine. This machine and a South Bend Heavy 10 lathe of similar vintage fell into my lap in 2010. The lathe was functional, but the mill was in need of attention. Most of the work was done late at night and in the wee hours, as I was spending most of my available daylight time on a protracted house-building project. I found the machine restoration therapeutic, despite having to endure much good-natured ridicule and jokes about “the other woman” from my family.

The mill is a World War II era machine that was purchased by the Physics Instrument Shop at Duke University. It was eventually replaced by more modern equipment and relegated to the “Staff Shop”, where Physics faculty and students can use the machines to work on their projects. After years of abuse there it was finally deemed surplus and ended up on a trailer parked in the new owner’s yard.

This is Bertha as I first encountered her, having never been unloaded by the previous owner, who passed away shortly after obtaining the mill. Attempts to keep her covered with tarps were futile, and most unpainted surfaces were pretty well rusted. The spindle turned, but not smoothly, suggesting that water had made its way to the bearings.









So, clearly she was in rough shape, but I enjoy a challenge and the price was right ($100). I was able to hitch the trailer to my pickup and anticipated an uneventful drive home of about 5 miles. I had the lathe in the bed of the truck, and the mill weighs about ¾ of a ton, so I was pushing the envelope. As soon as I pulled out on the highway my power brake booster died, rendering the brakes ineffective. I forged ahead, downshifting to slow down for traffic lights, and made it home without killing myself or anyone else. I wanted the machines in the basement of my woodworking shop, which has a grade level pedestrian door in the back but no easy access. I got neighbor guy to drive his little rubber-tracked backhoe over, and with the help of some more neighbors we manhandled the lathe through the door without too much trouble. The mill was much more challenging, as the backhoe wanted to tip over on its nose if the mill was lifted high enough to avoid dragging it. We ended up kind of dragging it down the slope to the door, and set it on some heavy-duty dollies that I had made. I had previously removed the table to allow it to fit through the door, and we horsed it in.

At my leisure, I completely disassembled Bertha with the exception of removing the knee. There were a number of revelations during this process, one of which was that the knee was completely packed full of brass, aluminum, and plastic chips, fused by hardened coolant and oil into an industrial fruitcake-like substance. There had been a pin projecting from the underside of the saddle that had both acted as a travel stop for the saddle and engaged the sliding steel plates that are supposed to keep debris out of the knee. One of the inmates at the reform school must have rammed the pin hard enough to snap it off, which made the sliding plates only semi-functional and periodically allowed a large gap for junk to fall through.

Another revelation was that someone used grease to lubricate all of the zerk fittings on the saddle, table, and knee, rather than way oil, so all of the oil galleys were clogged and there was a nice abrasive paste on all of the ways and a bit of scoring. Some of the pieces after disassembly:

Pulleys, saddle feed screw and handwheel next to Lima drive gear motor (motor already repainted):



Saddle, sliding saddle cover plates, table feed screw:



As feared, water had reached the spindle bearings and corroded them enough to make them unusable. The old bearings were class “0” precision Timkens and no longer manufactured. After much searching I was able to locate a class “3” cone and a standard precision cup from W.C. DuComb Bearing in Detroit to replace the upper bearing. The lower bearing is unobtainable in class “0”, and it appears that the only modern use for that bearing size is in aircraft landing gear. I was able to purchase a Timken cone and cup from Sky Geek in LaGrangeville, NY. They are FAA approved! For those interested, these bearings have a 20629 suffix, indicating that they are specially selected as “prime lot”, honed, and roughly correspond to precision class “2”. I also replaced the two “pulley sleeve” bearings with readily obtainable Nachi components. Total expended on all bearings was about $200.

Spindle receiving new bearings:



The feed screws for the saddle and table were found to be in inexplicably pristine condition after I cleaned the crud off of them. The bronze nuts are adjustable, and I was able to get the backlash down to just a few thousandths on each. I adjusted all of the table, saddle, and knee gibs by trial and error and am very satisfied with the result. The saddle gets a little tighter at the extremes of travel due to wear in the middle of the ways, but it is pretty much irrelevant to me. The bronze bushings for the knee elevation crank were worn into ovals, but they were easily replaced.

Saddle feed screw and knee elevation shaft and bevel gear after clean-up:



The mill has its original motor, which is mated to 4-speed gearbox known as a “Lima drive.” The gearbox had been weeping oil around the shift lever, so I replaced that seal and the motor shaft seals and filled the tranny with Mobil1 gear lube.

The motor is 1 horsepower, 220v 3-phase, and my shop only has 220v single phase power. I am a novice with motors, but I did my research and learned about variable frequency drives (VFDs). It was a 100% no brainer to go with one of these rather than a rotary phase converter. I used a TECO JNEV-201-H1 to power the motor (Dealer’s Industrial Equipment, $131). This is actually a “sensorless vector drive”, which is supposed to maintain full torque regardless of speed. The motor is now variable speed, rendering the Lima drive transmission and step pulleys unnecessary. The tranny can be left in 4th gear and the belt can be left in one position for eternity. This little VFD replaced about 25 pounds of electrical apparatus that had been bolted to the back of the mill.



Bertha also has a power table feed, which has a 1/4 hp 3-phase motor and a bizarre and obsolete variable speed mechanism known as a “ring roller”. There is only one source for the special oil that this mechanism requires, known as “traction lube”, and it is $100 a quart! I did some research, learned that similar technology is used in certain automotive continuously variable transmissions, and the lube for them is only 8 bucks a quart. I bought some, and it seems to work perfectly. To supply 3-phase power to the motor I obtained a ‘last year’s model’ General Electric Model D7206 VFD from Dealer’s Industrial for $31. It is the blue one on the right in the pic above.

Ring roller power table feed:



The mill’s main casting, knee, and head were riddled with chips, and the paint and underlying filler in the coolant pond under the knee were blistered from water pooling there. I bought a cheap needle scaler at Harbor Freight that made quick work of the blisters, and I used Bondo and red oxide putty to fill the defects. The repair sites were primed and the entire casting was then wet-sanded. I sprayed the knee, body, saddle, and misc. other parts with Valspar industrial enamel from Lowes using a $10 spray gun from Harbor Freight. The head and motor were painted using a brush. The access door and the belt guard were too rusty to be worth fooling with, so I made replacements out of aluminum diamond plate.





Most of the rest of the restoration involved de-rusting parts with the help of Evapo-Rust, wire wheels, sandpaper, and glass bead blasting. Anything chuckable, including the solid steel cylindrical ram, was mounted in a lathe and sanded and polished to remove rust and pitting. The 42”-long table was so rusty that I took it outside and lightly sandblasted the top surface, then polished it up with mesh abrasive pads on a hand held grinder. The table, saddle, and knee ways cleaned up pretty well with light polishing with mesh pads.

If you look closely at the “before” pics, you will see that there was a power downfeed gizmo that ran off of a timing belt from the spindle. Unfortunately, like so many other aspects of the machine, the timing belt is obsolete and unobtainable. I have found 2 other people in the U.S. who have the same mill, and one was nice enough to take a pic of his timing belt for me. Even with the Uniroyal (now Gates) part number, the engineers at Gates can find no evidence that a belt with that pitch ever existed. I doubt if I will be needing a power downfeed, but I have all of the parts and I suppose I can make new pulleys that will accept a contemporary belt if I need to. The mill has two manual downfeeds--a drill-press-like lever on the left side of the head and a fine downfeed handwheel on the front. These are selected by engaging or disengaging a clutch via a knob on the right side of the head. The fine downfeed is sweet--I can turn the handwheel with one finger.

Part way into the project, I got a call saying a vise was found in the previous owner’s effects that might belong to the mill. Lo and behold, it is apparently the original vise that came with the machine. That made my week! I cleaned it up and painted it but still need to make some new jaw faces.



After painting:



Bertha’s spindle has a NMTB 30 taper, and fortunately she came with some tooling. There was a decent set of end mill holders and a couple shell end mills, which all cleaned up well. I subsequently bought an extra ½” end mill holder to dedicate to my edge finder, and a drill chuck arbor and ¾” drill chuck. I also picked up a cheap set of fly cutters and a selection of cheap end mills. I recycled a cleaning cart into a tool caddy to hold the tooling:



I have had fun with the finishing touches…I got some ¼” felt from McMaster Carr to make new way wipers, and used vinyl shower pan liner to make way protectors. I bolted a 1x1 aluminum bar through the hole where the coolant line used to be to mount lamps and the VFD controls on. The adapter between it and the mill body was made out of maple. I don’t think I’ll be needing coolant for my little projects, but I have the coolant pump if I do need it. 3-phase again, of course. I re-used the original drum switch to control the VFD, and mounted the speed control rheostat next to it. I splurged and bought new knobs for all of the levers (the only plastic on the machine!).

I decided the mill was a little on the low side, so I lagged the base onto some 4x6 sleepers.

After I got the mill up and running I measured the spindle runout and it seemed excessive. I used a mirror to look up inside the taper and I could see a tiny crescent-shaped ding halfway up where another reform school denizen must have neglected to tighten the drawbar and a tool holder came loose. I glued 1000-grit sandpaper on the taper of one of the holders gave it a spin. The runout is now absolutely minuscule, and I’ve been pleased with the finish on everything that I’ve milled so far. The mill runs super quiet and smooth. I have about $800 in the machine, and she should be good for at least another 60 or 70 years.

Finished:











That’s about it. I hope you enjoyed my little narrative! The project was very fun and a great learning experience.

Beautiful machine. Has a strange powerfeed system, but looks very useable. That looks like it should last a long time! Nice work and thanks for sharing.

-Josh

What a cool machine!

Thanks for posting the build process.

Originally Posted by Glitch

Meet “Bertha”, my U.S. Machine Tool Co. Model VT milling machine.

Serendipitous! I have a Quartet that seemed to have no visible common lineage with other Burke/US/US Burke/Houdaille models. Yours has a vertical head that reveals what must be the ancestry of the lighter of the two vertical heads made for the Quartet. The handwheels and their dials are also similar. Note Adam's photos:

U.S. Quartet mill

Another revelation was that someone used grease to lubricate all of the zerk fittings on the saddle, table, and knee, rather than way oil, so all of the oil galleys were clogged and there was a nice abrasive paste on all of the ways and a bit of scoring.

Similar situation here. Damage not yet assessed, but seems minimal, as the Quartet had infrequent use.

Bertha also has a power table feed, which has a 1/4 hp 3-phase motor and a bizarre and obsolete variable speed mechanism known as a “ring roller”.

AFAIK, these - or one of their variants - are still available new. I shall have to dig out WHERE found, as it was an accident.

There is only one source for the special oil that this mechanism requires, known as “traction lube”, and it is $100 a quart! I did some research, learned that similar technology is used in certain automotive continuously variable transmissions, and the lube for them is only 8 bucks a quart. I bought some, and it seems to work perfectly.

Same basic lube, but the 'class' of it isn't actually that rare. Again 'Seniour Moment' I shall have to dig into the packrat bundle for the characteristics I ratholed somewhere, but ball, cone, and roller 'friction' speed-change drives come first to mind.

If you look closely at the “before” pics, you will see that there was a power downfeed gizmo that ran off of a timing belt from the spindle. Unfortunately, like so many other aspects of the machine, the timing belt is obsolete and unobtainable. I have found 2 other people in the U.S. who have the same mill, and one was nice enough to take a pic of his timing belt for me. Even with the Uniroyal (now Gates) part number, the engineers at Gates can find no evidence that a belt with that pitch ever existed.

It could well have been an equivalent to a Pirelli or Continental Gummiwerke item. The Quartet has four - horizontal spindle final-drive, (razored to ease turret removal) two on the vertical spindle intermediate (intact) and one on final drive (missing). I recognized their pitch, so didn't hesitate to razor the one. At their age, I'll use all new. Consider exchanging 'casts' of several teeth of our respective sheaves, and I should be able to get you into the right product line, as I designed-in numerous Gilmer belts 40-odd years ago and MAY still have the source material ... somewhere.... that should have covered all older items still current as-at 1970's.

Bertha’s spindle has a NMTB 30 taper, and fortunately she came with some tooling.

Quartet has the uprated 5 HP horizontal option but NMTB 40, not NMTB 50 option. Has the lesser 1 1/2 HP vertical option with B&S #9 (uprated option was 3 HP and NMTB 40). B&S #9 is common with my Burke #4, so I have tooling.

PM me, and we'll see what can be done about your missing cog-belt.

Thanks for the 'familial' lineage link! The 'Quartet' is a mite less of an orphan now!

Bill

Ring roller units are pretty neat, still made & used- speed reducers, variable speed drives, right angle drives, variable speed reducers - Ring Roller. Yours looks like one of theirs, but a bit older. If you give them a call w/ the model #, they may well have some info on file. The manual I got for mine isn't extensive but it does go into details wrt construction, servicing etc.

I bought the $$$ magic juice from them for a more recent model that I'm driving a little hacksaw with. Nice to know theres an automotive related alternative. A table power-feed seems a great use for one- hadn't considered it before.

Nice job on the mill!

Greg

Originally Posted by Glitch

If you look closely at the “before” pics, you will see that there was a power downfeed gizmo that ran off of a timing belt from the spindle.

Tilt.

if you refer to the cylindrical object to the left side of the quill, its equivalent on the (more recent) Quartet is driven by Vee belts, not Gilmer.

The way to restoral may be to simply convert it to the same step-pulleys and vee-belts as the Quartet used.

I don't kid myself that original parts could be found, but mine can be measured, and the sizes are probably generic. If not, vee-belt sheaves are far easier to fab than Gilmer, and the belts may be oddly short, but still stock items.

This may matter to you, as these heads ass u me predominant use of power feed or handwheel.

Adam (right handed) mentioned that it was awkward to have the lever handle on the off-side. I (fully ambidextrous) did not at first twig to why that might matter....

Bill

Hi Glitch.

I said it on another thread and I'll say it again: WOW!

You seem to have really enjoyed the rebuild; please let me know if you would like to repeat the process and we'll work something out with my Model V!

I have a question about the appearance of the spindle and accompanying bits. Did you have those anodized or is that the way they came with your machine?

Your machine is simply a work of art. Beautiful.

gkbikers

PS

I would welcome any information on the motor and gear assembly to drive the table. My Model V has the optional mount for the motor, but alas, no motor!

gkbikers--

All of the spindle components are steel. I glass beaded and wire-wheeled the splined portion of the spindle that the stepped pulley slides on. That was after fixing the end, which was slightly mushroomed by some dimwit pounding on it (not me!). The piece adjacent to the spindle nose was glass beaded. The actual spindle nose had a chrome plated finish that was rusting and flaking off. I learned somewhere that hydrochloric acid will remove chrome, so I gave it a dunk and no more chrome. It was quite pitted, so I chucked it in the lathe and sanded and polished it.

See my response to Greg below for info on the the table power feed.

*************

thermite--

Here are better pics of the power downfeed. It uses a couple of very short v-belts for what I believe would be called a Reeves drive (the outer half of one of the pulleys is AWOL), but the drive belt from the spindle is a small (about 3/8" wide) timing belt. There is no room for a v-belt there. The first pic is the timing belt on an identical machine. It also says Uniroyal Powergrip on it. As far as I have been able to determine, it is the only one of its kind in captivity. Thanks to Steven in Louisiana for the pic!









--------------

Greg--

Here is the response I got from the the company that the original manufacturer (Graham) morphed into when I inquired about the ring roller power feed:

"The unit you have is a Series 29 unit that has been replaced by our N29 series. I am attaching our literature for the N29 unit. We do have the traction lubricant for this unit. It is our Alpha "Gold" oil. We sell it by the quart at $98.08. The Alpha Gold is the only oil we know that provides the traction required. This is something we inherited so we haven't experimented too much. Sorry but it is expensive stuff. We typically sell the N29 units for about $5,000 list price. You got a deal."

Regards,
Brian Duchac
Motor Specialty, Inc.

I can't imagine that they can give the things away now with the advent of $100 vector drives to obtain variable speed. My cheap traction lube substitute:

Well, I keep learning more about my machine as I read your thread Glitch. I had thought my downfeed was powered, but I see now that it is not, at least according to my recollection of how the cutterhead looks. I also don't think I'll be buying a new powerfeed for the table.

I have to say I'm beginning to think I might be better off selling it and finding another machine.

Thanks everyone for the information on this rare machine.

gkbikers

Glitch, how much do you want to bet the $100/qt green "Alpha" fluid that I bought is pretty well indistinguishable from the green Eneos CVT fluid available for < $20/qt? And, that the magic "Gold" fluid is correspondingly nearly indistinguishable from the red Eneos? Once my qt of magic juice is used, I'm going w/ the CVT fluid.

I have one of the N29 units w/ single stage reducer. Did not pay full-price- it came from the pig-in-a-poke pile in trade for a nice 2hp 3ph motor. Have not driven it at the specified 3k rpm to see if it slips but rotating by hand it seems to be doing the right sort of thing. I should think an efficient, small, quiet, self-contained variable speed trans unit that doesn't need magic belts or power or electronics is of considerable use in many applications.

Greg

Originally Posted by Glitch

Here are better pics of the power downfeed. It uses a couple of very short v-belts for what I believe would be called a Reeves drive (the outer half of one of the pulleys is AWOL), but the drive belt from the spindle is a small (about 3/8" wide) timing belt. There is no room for a v-belt there. The first pic is the timing belt on an identical machine. It also says Uniroyal Powergrip on it. As far as I have been able to determine, it is the only one of its kind in captivity.

As a drinkin' buddy of mine once said to the guy who introduced himself as 'The Town Drunk' .... "not no more you ain't".

I had thought that belt on Quarter Q6041 was a small vee like its bed-partners. All fully intact, BTW - just a bit aged.

Just took a flashlight and fingertip to it and confirmed it is indeed like the one Steve photographed. The pitch is uncommonly coarse for the application - early-adopters of apparently-resilient (NOT!) Gilmer system belts often being unaware that as with comparably-coarse straight-cut spur gears, they can 'cog' like a dog crapping chicken bone.



I'll get more info once I've measured the pitch. Worst-case, one or more of us can split the cost of a wider belt (as a pitch this coarse usually IS) made up to proper pitch and length, then precisely sliced to width we need at the factory.

Downside to these for feed use is that whilst preserving a consistent advance per-spindle rev, the 'cogging' can couple with cutter tool diameter and tooth or flute count to reinforce vibration at select speeds. Moving target, as it were, but one that we'll just have to deal with if/as/when it raises its hand. Adapting an independent electronic power-feed drive would be much less work than re-engineering this one.

Bill

Bertha’s spindle has a NMTB 30 taper

Interesting. I'm guessing that there were not many of these machines made. Mine evidently has an R8 spindle taper,
so maybe the company had a number of options available?

Question about the motor and gearbox: Is the actual motor separate from the gearbox or are they combined?
If I remember, the outside case holds both the motor and the gearbox? I may have to replace the motor, or at least some parts,
if the motor shaft is bent.

Question about the downfeed: How well does the downfeed work, since you are evidently not using the power function
at the present time? Since I see that mine is manual and not powered, I'm just curious about the functionality.

Thanks!

gkbikers

gk--

I edited my original post to add that there are 2 manual downfeeds: A drill-press-like lever on the left side of the head for coarse feed and a fine downfeed handwheel on the front. These are selected by engaging or disengaging a clutch via a knob on the right side of the head. The fine downfeed is silky-smooth--I can turn the handwheel with one finger.

I know you mentioned that you intended to use a rotary phase converter. If you scrap that idea and get a VFD you can hang ANY 3-phase motor on the back of the machine and have complete control over its speed. They only used the gearbox and step pulleys because there was no alternative 60 years ago. I think that the Lima motor and gearbox are matched units and you can't readily substitute a different motor. If the pulley wobbles it probably means that the gearbox shaft is bent.

A terrific job!! No mention,though,of how worn the sliding surfaces under the table,on the knee,and on the saddle were,and if you scraped them back to accuracy.

Ive been MIA for a little while now, but I am absolutly stunned at the restoration of this beautiful mill. Its looks great! Its already making me miss the Quartet that Bill now ownes. But unfortunatly I just havnt ever had the extra time to take on the cleanup projects like this. Im glad to see Bill has made some more connections with people with these mills.
Great job Glitch! You did an awsome job.
Bill, I expect to see my old Quartet looking as purty as this one!

gwilson-- The table and saddle ways show wear, not from extensive use I don't think, but from negligent maintenance. However, it's perfectly suitable for my purposes (casual fooling around with cars, guns, motorcycles, etc.). Learning scraping is probably going to have to wait 'til my next life!

Originally Posted by gkbikers

Interesting. I'm guessing that there were not many of these machines made. Mine evidently has an R8 spindle taper,
so maybe the company had a number of options available?

Seems so if one casts and eye over the various Burke, US, US-Burke, US --> Powermatic/Houdaille offerings.

But the R-8 may have been one of the least-common. The stronger, but sometimes problematic as to getting stuff OUT of it, B&S #9 was still a major player in that earlier era, and the NMTB 30, 40, 50 the upper-crust.

Question about the motor and gearbox: Is the actual motor separate from the gearbox or are they combined?
If I remember, the outside case holds both the motor and the gearbox? I may have to replace the motor, or at least some parts,
if the motor shaft is bent.

May just be a need for bearings. The gearbox preserves full power at more speeds than a VFD alone can offer. Gears etc have been reported to be stout, nearly silent running, and not overly demanding w/r lube. There are parts lists online, and ISTR parts are still available from Lima or a successor firm.

Really flexible to have both the ability to shift gears AND the VFD for finer control.

Bill

Originally Posted by Abom79

Ive been MIA for a little while now, but I am absolutly stunned at the restoration of this beautiful mill. Its looks great! Its already making me miss the Quartet that Bill now ownes. But unfortunatly I just havnt ever had the extra time to take on the cleanup projects like this. Im glad to see Bill has made some more connections with people with these mills.

Ah, well ... ahem.

I'm very grateful that the auto-mechanic's shop before you..... plus three generations of the Booth family ... all quite reasonably pumping grease into all the Zerk fittings on the Quartet instead of way oil ....made it so damned stiff to traverse... that the other mills in the shop were easier to use ... and the Quartet got near-zero use the past 40-plus years! .. (ducks and waddles away to a safe distance...)

;-)

Silver lining in every cloud, as they say. Maybe even those that dumped so much rain on Pensacola the two days we were loading it.

Great job Glitch! You did an awsome job.

That he certainly did!

Bill, I expect to see my old Quartet looking as purty as this one!

Given that it has a #4 Burke and a 10EE ahead of it (Sheldon 12" shaper nearly finished), all I have to do is live long enough.

Not to mention cut a clearance well into the overhead and build bespoke lifting gear to get the turret back atop the base under an otherwise sub-nine-foot ceiling inside a sub seven-foot garage door. Seems easier than turning it on its side, then back upright ...but then again ....we shall see.

And yes - clean and good-looking as well as fully functional is certainly in the plan.

Bill

Originally Posted by Glitch

gwilson-- The table and saddle ways show wear, not from extensive use I don't think, but from negligent maintenance. However, it's perfectly suitable for my purposes (casual fooling around with cars, guns, motorcycles, etc.). Learning scraping is probably going to have to wait 'til my next life!

What matters is not the less-than-beautiful long streaks and gouges so created, but the 'trueness' of the material NOT cut-into that is still carrying the load and alignment.

No need to scrape, nor even flake for-pretty if that is still as accurate as I suspect it is.

Bill

WOW ! ! !
This gives me hope. I have 6 WW2 machines. 3 usable lathes (2 work well), 1 "partially usable" lathe, a large vertical Cincinnati mill, and 1 complete disaster LeBlond lathe that I picked up an auction a couple years ago for scrap price. I want to do to the LeBlond what you did to this mill...but know it will be a labor of love and have yet to dedicate the time to the project.
You did a wonderful job, I hope you get years of enjoyment out of it!