Monarch 612-2516 lathe

[rabler]

When you say "roll pin", is that a "C" cross section (McMaster calls them "Slotted Spring Pins") or the wound spiral sheet metal type
(McMaster calls them "Coiled Spring Pins")?

What McMaster calls a slotted spring pin.

 

[rabler]

It is always fun to break down a piece of equipment that 1) you are not familiar with, 2) have no manual, 3) and have limited information available.

You seem to have the right mind set. When doing this kind of work it is so easy to overlook a connection, obstacle, etc and because of the weight of the pieces, cause serious damage to a component(s). Taking your time and reviewing the situation multiple times is the way to go. Getting in a hurry will only serve to complicate the project. I am sure over that week, even though you were not face to face with the lathe, you were thinking through different scenarios and options.

Nice work in getting that apart.

I recently put together a new gas barbecue grill. It had over 40 steps, each step a page with detailed illustrations. I found that annoying, I think it just insulted my intelligence.

Taking time is absolutely critical. I certainly couldn’t have done this before retiring. Lots of cellphone pictures also help with reassembly.

 

[rabler]

A question, how did you support that beast when lifting it. In the one picture, it's doesn't look like it was supported at the time.

Your project reminds me of the local antique tractor association. Part of the deal is that you join and "adopt" one of the sad old lumps, restoring into like-new condition. Your situation is like what I heard someone there saying about adopting a bulldozer, "It was fun restoring it, but it's a real pain because every single part coming off it required a hoist of some sort."

The red and black strap is a light-duty ratchet strap, wrapped around 3 times. It was small enough to get into odd holes in the casting, necessary to lift it from a balance point. Just above the top of the picture it goes around a large hoist hook.

What isn’t intuitive is how much we count on the feel of moving things by hand. As soon as a hoist is involved that is lost. You can make up for it partially by paying very close attention to how things move, manually wiggling things, etc.

 

[rabler]

Cleaned up the shelf where the QCGB sat, and slapped a coat of light blue on it. The light blue is a reject color, something I use on interior and other not often seen areas that I want clean and painted but not visible. Note the box of ziploc bags on top of the headstock. Those, along with a sharpie, and cellphone camera, are critical tools in keeping track of what parts went where.


The broken tumbler of course has a shaft through it, with three bearings on that shaft. I prefer not to drive things out with a hammer if at all avoidable, so you can see the solution I came up with. The first picture is the apron face of the QCGB, with the circular bearing plate held by 4 capscrews, covering the end of the shaft in the lower middle. The second pictures is a quick tool I drilled up that has a hole in the center tapped for a 1/2" bolt that I used to press the shaft out. Turns out a 8" carriage bolt was what I happened to have lying around that worked.


I got the shaft pressed over about two inches, enough that the bearings on either end are free, but the bearing in the middle is pressing the outer race out too. It feels like it is binding now that the shaft is free of the ends and only held by this last bearing. These are tapered roller bearings, so the two ends come out easily, the center is facing the other direction and so that whole bearing needs to be pressed out with the shaft. I'm leaving it for another day. It was lunch time anyway Probably get in there with a brass hammer and brass punch to tap around the outer race and try to free it up. That race is behind the crossweb in the casting on the left of center.

 

[rabler]

Well, it's not the center race binding, there is a gear on another shaft that is interfering with that bearing being pushed out by a tenth of an inch or so. So this job just got a lot more complicated, as it means more disassembly. I've pulled the gearbox apart on my CK, and while a different scale the design has some commonality.

Interesting side note - in the last picture above, the small gear prominent just right of center that is brownish, is not rusted. It appears to be phenolic. I think it's purpose is to pick up oil from the bottom of the gearbox and lubricate the gear above it.

 

[rabler]

Success! I got the tumbler out. I'm feeling a bit better as this, plus the 10EE motor issues , were getting a bit frustrating.

Started to pull out the other shafts, then had an inspiration after I'd already shifted one of the other shafts a tenth of an inch or so. One the shaft with the tumbler, the left side of the shaft is a larger diameter than through the tumbler. So the tumbler has to come off the right side of the shaft. Which lead me to try to initially drive the shaft left. When doing so the center roller bearing hung up. But if I drove the shaft initially right, it would unseat that bearing race. And then I could remove the circlip next to the bearing, and then drive the shaft left. That worked, and the tumbler is out.

With the two tumblers side by side, the only difference appears to be that the back of the tumbler has a roughly machined radius whereas the replacement tumbler is an unfinished casting. Given how this seats on the mechanism that shifts the tumbler left/right, I may have to mill this smooth. The replacement tumbler also has bushing set in the casting, where the original was just bored to diameter, but same inner diameter.

 

[rabler]

To smooth out the tumbler, I wanted to set it up on my rotary table, but is isn't flat on the side (rough casting). So I made up a bushing with an MT2 taper on one end, and a 1.25" stub on the other, to hold the tumbler on the table.

Turning the bushing was a good workout for the CK lathe. I started with a 3" diameter chunk of hot rolled round, chucked up in the three jaw and turned all in one operation to keep concentricity. I used the taper attachment to turn the MT2 taper. Then when to work on making the 1.250" shaft stub. Got a chance to see how much the CK could hog off in one pass, as turning 3" down to 1.250 for a 2.75" length was a bit of steel to remove. Had it working enough the the inverter duty motor was not happy at 1200RPM (45Hz) and cranked it up to 1800 (60Hz) with the spindle shift to a lower gear to get more torque at the same spindle speed. Using a WNMG insert for much of it.


This really isn't a precision part on the tumbler, it just sits in a cradle at the shaft end that it had to clear. I only needed to mill .025 off the casting, which is just enough to not get below the hard face of the casting. You can see the milling really is rough. Table has too much play in it. I did have a clamp on it when milling, this picture was a photographic re-creation.

I just need to finish the K&T vertical and use the 16" rotary on that, will be much nicer setup.


The gearbox has been assembled with the new tumbler in place. Now I just need to mount it back on the lathe, although it needs a bit of cleaning before that.

 

[rabler]

Useful trick for flushing out things without full disassembly. $15 1 gallon lawn sprayer from any hardware/box store, and a 1/2 gallon of diesel fuel. Pretty good pressure, and while diesel fuel isn't the best smelling thing in the world, not as harsh as a lot of cleaners such as brake cleaner.

 

[rabler]

Well several things have come up so progress on this project took a two month vacation. Had to take a month for medical issues, four years after radiation treatment some odd side effects showed up, late radiation cystitis. Series of tests and procedures to rule out more severe issues. And the normal summer backlog of chores, horses hooves grow faster so more hoof trimming. Grass grows so more mowing. I’m trying to mow enough to discourage johnson grass from the fields. Fences to fix and yardwork. Maintenance on pickups, and farm equipment. And somei intensive remodeling.

Not all chores, as I did some work on building a diamond lapping machine too.

I’m starting to spend an hour or so here and there bck working on this lathe. Got the QCGB bolted back up, and the end gears re-installed. Next I’ll attach the rod to the back of the headstock for the clutch and the rapids drive motor.

 

[Papa Charlie]

Life too often gets in the way of our projects, but that is just life. Happens way too many times.