Monarch 612-2516 lathe

[rabler]

Hopefully Ok that I'm posting a bunch of different threads on different machines that I'm rebuilding. I hope to make each thread sort of a running commentary, starting with when I acquired the machine, on each machine but it'll take a while to get caught up to current status on each machine.

The Monarch CK taught me that I really enjoyed working on the older machines. Now admittedly I have no clue what I'm doing but figuring it out is a big part of the fun. After the CK and 10EE, I had lusted after a longer bed machine. 20" c-to-c on the 10EE, and 30" c-to-c on the CK, but some of the farm projects I envision could go quite a bit longer. A Monarch 61 from the mid 50s was what I was looking for. I'd been watching for one of those for a few years. The good ones go extremely fast.

In that search I came across an ad on FB marketplace for a Monarch 612 for sale in NE Ohio, about 6 hours drive. I made arrangements to go look at it with my trailer in tow. I was given to believe it was a 16" swing machine with a 10HP motor, 50" center to center. The typical Monarch serial number placard was a 'government sale' version so didn't have the usual swing and c-to-c length info in the ad's picture.

I drove up to NE Ohio and spent the night in a hotel with arrangements for the next morning. Turned out to be this large machine old manual machine shop, bunch of hue lathes and a few mills, along with a huge heat-treat furnace. They had found a problem with the lathe testing it out the day before and were working pretty intensively on fixing it. The feed mechanism was not working in the apron, they had the apron off and were looking at swapping aprons with another lathe.

Three guys, including the shop owner, spent most of the morning working on the machine with no commitment from me other than to see how it worked out. I did get to see the lathe running and everything working except for the feed. They got the parts replaced and were working on reassembling, but it was nearing noon, and with a 6 hour drive plus an hour time change, I was getting concerned as driving pulling a 30' gooseneck after dark is not something I care to do. I talked to the owner and we agreed on a *substantial* price reduction for me to take it without the apron re-installed, but all parts and a three-jaw chuck. They also had all of the documentation for the lathe since it was originally sold by Monarch to a government contractor for $33,000 in 1967. With hotel and diesel fuel costs I got it for less than a 1/10th of that. The shop owner obviously felt bad that they'd spent my time working on it, and wanted to be sure I went away happy. Obviously someone who understands that his customers matter.


So upon getting home and really looking at the documentation, etc, it was clear this was a Monarch 612-2516. 25" swing over bed, 16" swing over carriage, 48" center to center. 20HP motor, everything wired 440v. Actually a total of four three-phase motors, main drive motor, rapid traverse motor, hydraulic pump motor, and coolant pump.



Estimated weight is about 9000 lbs, documented weight is nearly 12000 but that included a no-longer present tracer bed along the back. I built myself a large gantry to unload this. Even though the crane was engineered, hoisting anything that heavy is nerve wracking to say the least. Note that the carriage apron and tailstock, at least 1000lbs worth, where removed prior to hoisting to reduce the weight. (Overhead lifting equiment should be engineered with a 5x safety factor.)

 

[erikmannie]

That looks a lot like what Abom79 has. Monarchs are sweet! You got a screamin’ deal on it, too.

I have a lot of respect for you for taking on a project like this. I am sure that you will be successful.

 

[rabler]

I believe Abom79's is a 1940's CY, which is fairly similar to the 44 CK I have posted on in another thread, although his is definitely a bigger swing lathe.

 

[rabler]

So after getting the 612 lowered to the floor, put on skates, moved across the garage to one side, I needed to start working with it. It came with a 20HP main motor. As far as I'm concerned, 20HP is a RIDICULOUS amount of horsepower for a lathe. A little bit of pondering I decided to use the 20HP motor to build an rotary phase converter, and I bought a new-old-stock 10HP motor to put in the lathe. That required spacers to account for the smaller frame size on the 10HP. The 20HP is a 1 5/8" shaft, the 10HP is 1 3/8" shaft, so the original pulley would not fit on the 10HP. I purchased a 1 3/8" taper bushing from McMaster. On the CK used a test indicator to get the taper attachment to exactly match that bushing, when bored out the pulley so the taper bushing fit in appropriately. Then I needed to drill and tap three holes in the pulley on the mill. Unfortunately the VFD on the mill died so I had to wait for a new VFD. Grizzly had one in stock, but wanted over $950. I could get a new VFD for about $400 but a couple weeks for drop ship from the factory. Anyway, I eventually got it fixed and the bushing matched to the pulley.

While waiting for all of that to work out, I started cleaning and painting the lathe, and putting together an RPC. I bought a 20HP phase converter control panel from WNY, and welded together a frame to hold all that.




I needed to rewire everything from 440V to 220V. Fairly large electrical control box on the back of this lathe: on/off switch on the top right, along with separate forward and reverse contactors on the top. Below those contactors, in the center of the panel is a loop transformer for the load meter on the front panel. To the right of that is the 120V step down transformer for the controls and contactor coils. Below that are contactors for the other motors. The other motors include a rapid traverse motor for the carriage, and a hydraulic/lubricant pump motor.

My thought for the ideal model large Monarch is a series 61, the predecessor to the 612. The 612 uses a hydraulic transmission, so speeds are all set by one dial, and feeds/threading by another dial. I'm a bit nervous about the 612 transmission, as long as it works all is good, but my understanding is they are fairly complex to troubleshoot. The pump for the hydraulic/lubricant system runs on it's own 1/3 HP 3 phase motor. That needed to be rewired to 220V. Same for the rapid traverse motor. Both of those motors live in the lathe base below the headstock. The way the lathe is wired, if the heater/starter/overload for either of those motors or the main motor kicks out, then the lathe shuts down completely. (I do have a complete set of schematics).

 

[rabler]

Rewiring the three motors was just a matter of opening up all three motors and following the wiring diagrams. Interesting bit of trivia, is that one of the three motors was a Y-connected 3 phase while the other two were delta. Fortunately all the wiring labels were legible. It was just tedious getting in there, the traverse motor is behind the main motor in the headstock (fortunately I did this while the main motor was out). The coolant pump motor is in the front of the headstock base.

The control panel took a bit more consideration. All of the contactors use 120V coils. Fortunately the step-down transformer for that was strappable between 440V and 220V. The motor overloads (starters) are based on current. Re-wiring from 440V to 220V (halfing the voltage) means the current needs to double to get the same horsepower. Since I replaced the main motor with a motor of 1/2 the horsepower rating (20HP to 10HP), the main motor starter is about the right current. The original starters have +/- 15% adjustment range on them, so I can do some tweaking if I get compulsive. The current for the other two motors, traverse and lube pump, doubles. So those will need new overload relays.

I ordered out a couple of new overload relays, of course I hit a month long backorder. I ordered WEG overloads from MarshallWolfAutomation, total of about $60, for which I figured it wasn't worth trying to find original equipment.

In the mean time, I got the RPC built:


It is wired in to the main breaker panel using 2/0 aluminum wire into a 100A breaker. For now this lathe is in my garage (not my workshop). The garage is actually a 1/4mile down the road from the house by the horse barns. Those all run on a separate 200A service from the house and workshop.

Once wired in, I tested the RPC. It draws 205 amps peak at startup (obviously for a very short duration as it doesn't trip the 100A breaker). Once running with no load it draws about 9a. My garage runs a little high on voltage, around 245V. 9a * 245v / 746 = 2.96HP, so the idler motor is using about 3 horsepower equivalent of electricity with no load. I was actually surprised that it wasn't more, electric motors often run around 40% current for no load. I wasn't measuring phase angle (power factor) for those that really want to geek-out.

I went ahead and wired the lathe into the RPC even though the replacement starters for the two motors haven't yet arrived. I left the belts disconnected from the main motor and hit the Forward button. Sure enough it all fired up and ran for about 30 seconds and the the traverse motor heater/overload popped. Still nice to see all the motors at least spin up. I don't yet know whether they are wired in the correct direction, who wants to bet how many of them need a lead swap? Fortunately that's pretty easy to do up in the electrical panel.

I've also got the lathe mostly repainted (the blue color you see on the chip pan above). Still need to re-install the apron. I'm hoping to have an operating lathe at that point without any major rebuild work, although experience says I should soon at least clean the oil lines in the apron/carriage.

 

[rabler]

Here's a picture of the current state of the 612 as of 3/1/2021. Painting in progress. Still waiting on the overload relays (heaters). The open door under the headstock is the hydraulic/lube reservoir, filter and pump. Apron is still not installed.
The current chuck is a 12" 3 jaw. I'm keeping my eyes out for a used 16 or 20" D1-6 4-jaw, ideally one that has T-slots. Probably have to by a plain chuck and turn a D1-6 plate.

 

[Papa Charlie]

Looking good.

 

[rabler]

Progress on the big beast continues. I received the new overload relays (heaters) for the 220V conversion of the rapid traverse motor and the hydraulic pump. These have been wired in.


The hydraulic pump doesn’t seem to be pumping, probably turning the wrong way. This turned out to be fortunate, as the return hose had come off. If it had actually worked I’d probably be mopping up quite a bit of oil. The pump, motor and reservoir is mounted to the inside of the door below the headstock on the front of the lathe. Apparently some one had trimmed the return hose short enough that opening the door was enough to pull the hose off the elbow on top of the tank.


So I’m waiting for a new hose from McMaster.

I did get the RPC wired up, through a three phase panel nd a couple of twist-lock L15-30 outlets. Sorry this is rotated 90. Dang iPhone. The yellow and black thing on the front of the rotary panel is a magnetic light, illuminates the Monarch’s electric panel on the back of the lathe.



Still need to clean up the apron, paint it, and hang it on the carriage. Not planning on disassembling it for now, so this is a cosmetic not functional issue.

 

[rabler]

Haven’t mounted the apron yet, but the spindle turned under power yesterday, both forward and reverse. Hydraulic gear shifting worked well. Given that getting this far involved swapping out the main motor, rewiring three motors for 220V from 440V, and building a rotary phase converter, as well as cleaning and painting, that felt like a significant milestone.

 

[rabler]

Looks like I'll be pulling the QCGB unfortunately. While the end gears are turning, nothing I can do on the settings gets the feed rod or leadscrew turning. It worked a couple times erratically. So goes the challenges of resurrecting old equipment. The QCGB on this thing is a beast, I wouldn't be surprised if it is 400 lbs. I've pulled the cover off to look inside and will probably trying pulling the faceplate too. But I suspect I'm going to need to be removing it completely to chase down the problem.