Clean & Repaint of a Rockwell 21-122 Horizontal/Vertical

Hey all! First post, first mill. I'm brand new to machining and recently picked up a mill from my local craigslist: a Rockwell 21-122 Horizontal/Vertical mill.

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I purchased it from an estate sale, and it appears the previous owners took great care of it. The ways are all in great shape, the various moving components actuate smoothly, looks like ~10 thou backlash on x-axis, the table has seen better days but doesn't have any major gouges, etc. There's a layer of dust, grime and rust in places but nothing terrible.

The only major flaw on arrival was the quill, which didn't fully retract into the head. It felt like there is some kind of blockage in the rack/pinion gearing near the 1" mark which simply prevented it from retracting fully. The spindle bearings also felt a bit rough.

The mill also came with a ton of tooling, including an extra power feed, three vices, a rotary table, and assortment of end mills, taps, drills, punches, files, and a boring head. It also came with the important horizontal accessories, namely the overarm support, a tool arbor and spacers..

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Because I'm new to machining, and the mill is in relatively good condition, I really don't want to mess it up View attachment 250179 I originally planned to do a full rebuild and scrape ways, re-align, etc. But I've re-considered my skill and the amount of work... and honestly the mill looks to be in good shape and will be fine for me as a beginner.

So instead I'm just doing a clean/repaint/re-assemble. My main objective was to get at the spindle bearings to see if they needed replacing. Also to address the quill travel problem. The paint overall was in pretty good condition... but there were a few areas where it had flaked badly and was rusting. So I'm just going to repaint the whole mill so everything matches.

I decided this would be a fun project to try my hand filming, so I've been shooting a lot of footage of the clean/repaint. Here are the first two episodes:

This video has an overview/walkaround of the mill, some fooling around with cutting aluminum scrap, then disassembling and cleaning the vertical head.

This video is mostly cleaning/stripping the fiddly bits of the vertical head; the fine feed control, the head rotation mechanism and the pulley/brake assembly.

I think there will probably be one or two more videos. I have a bunch of footage of removing the table, stoning it, etc. Also stripping the body + masking + spraying, then re-assembly. I'll post those up once I get the footage edited together. :)
I’m jealous! Would love to get a machine like this. Great videos, too.
 
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Very nice machine. I think you will enjoy running it. I will do spindle and motor bearings on mine in the near futureView attachment 252482 Your videos are definitely helpful!
I would recommend DRO's early on your upgrade list.

Love the paint on your machine! Looks great :)

Part 3 is up:


Took the power feed, table and leadscrew off for cleaning. Derusted the table, although I messed up and left some wrinkles/bubbles in my evapo-rust paper towels, leading to a "marbled" cast iron surface in places. It stoned out easily enough, but memo to self in the future: always remove bubbles :)

Otherwise just doing lots of gruntwork prepping the body for painting. Lots of citristrip and scraping, and masking all the little fiddly bits.
 
Hey all, finally got around to editing the last of the footage and putting up the last video. Sorry for the delay, been super busy with work :)


Overall I'm pretty happy with how it cleaned up. Certainly looks nicer, and all the axis move a lot more smoothly now. Since this video was taken, I've been using the mill for some small projects (including adding a DRO to it) and things have gone very nicely. Just broke out the overarm support last weekend for some horizontal milling and it worked like a treat.

Here's how it looks today. A bit dirtier than the video but I guess it's better to use a machine than keep it spotless :)

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Probably the final update for a while on the mill project: I put up a video about adding a DRO (seen in the last photos). I opted to use cheap aluminum scales from Shars, a Kindle Fire tablet and TouchDRO kit. Fabricating mounting hardware for the scales was a bit touch-n-go, mainly because I forgot I now own a nice mill to cut/drill metal :)

But everything is working and holds reasonable tolerances after calibration. Pretty happy with the TouchDRO setup, it works very well

 
Thank you for taking the time to document all you have done as well as sharing the information you have learned about the machine!

I recently picked up the same model as well. I have little experience with mills in general. Mine came with an assortment of tooling but I am missing a manual as well as hold downs that fit the table. Were you able to locate a manual on line?

What kind of hold down kit do you have since it seems as the table is different from a standard mill table?

I would also like to add at least one power feed and DRO.

Have you found any other required/very useful Tooling or additions for this mill?
 
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Happy to help, thanks for following a long! Goodluck with your mill :)

I believe the Rockwell yahoo user group has a copy of the manual (for both horizontal and vertical, and combo) in their files section somewhere: https://groups.yahoo.com/neo/groups/rockwellmillingmachine/info

It's a pretty good resource in general too. Lots of knowledgeable folks that have spent a long time playing with the Rockwells. I'm not super fond of yahoo groups in general, but this is a good group despite the bad yahoo UI :)

I'm unfortunately working with a hodge-podge of hold downs at the moment. The mill came with a semi-complete set, and I also bought a kit but didn't realize the slots were non-standard. So I have a lot of hold-down clamps and step blocks... but only a handful of t-nuts which actually work (the ones from the kit that came with the mill).

It's on my short list to fabricate some more, or maybe find some similar dimension'ed ones on McMaster or something.

The shortlist of tooling that I use frequently:
  • Vice
  • Hold-down clamps
  • Parallels
  • Dial indicator, test indicator, spindle/clamp mounted indicator stand (useful for tramming the head, since the round ram can move under heavy milling)
  • Magnetic indicator stand
  • Set of cheap two-flute and four-flute HSS endmills. The china import stuff works fine since I mostly don't know what I'm doing :)
  • R8 Collets
  • R8 Jacobs chuck for drilling
  • Set of 123 blocks
  • Taps
  • Spring-loaded center punch
  • Layout tools; layout blue, scribes, compass, dividers, etc
  • Digital calipers, good enough for like 95% of measurements
  • Combination square
  • Twist drills, center drill
  • Edge-finders
  • Wobbler/Wiggler
That's the most common stuff, off the top of my head. This stuff is useful but definitely not necessary:
  • Micrometers for precise measurements
  • Telescoping gauges for measuring holes
  • Boring head and boring bars, reamers. Hard to get precise holes otherwise
  • Flycutter. Not needed, but makes cleaning up large surfaces easier/faster. Can do the same with a big 3/4" endmill or something instead, just slower
  • Rotary table. I don't have a lathe, so I've been using the rotary table a lot to do round work. Also helps with nice corners, etc
  • 4-jaw chuck. Weird one, but I needed it for a certain project and find myself using it a lot now. Bolt it down to the table, and it can grab weird shapes on the edges that would be otherwise hard to clamp. Or put it on top of the rotary table
  • Counterbores. Makes nicer holes for bolt heads than a drill bit since they are flat bottomed
  • Roughing end mills
  • Slitting saws and arbor
  • 5C collets and collet block, useful for quickly milling square and hex shafts (can do it with indicators but takes longer)
  • V-blocks, super helpful for holding round stock
  • Small surface plate if you need/want to do precise measurements
Some of the tooling came with the mill, and a lot is stuff I picked up from import dealers (Shars, Grizzly, etc) or eBay.

Goodluck!
 
Because Downloads costs us money for the storage space each month, access to Downloads is limited to donors. The minimum amount is $10, good for a year. But if you have access to Downloads, first read the operating instructions in the Sticky area at the top of the Rockwell forum (the one we are currently in). Then go to Downloads, "drill down" to the Rockwell folder, and download TM 9-3417-211-14&P Rockwell Intl Milling Machines 21-122.pdf. This is an excellent scan of the original TM, unlike most of what you find out on the Internet. I don't personally know anything about Rockwell machines but I think that it is on the machine that you have.

On another subject (undersized T-Slots), if you need to reduce the height of either the narrow or the wide part of your T-Nuts, be advised that most T-Nuts that I have encountered seem to be case hardened. They eat end mills. So first use your bench grinder to take off about 1/32nd of the surface you need to reduce. And then use a solid carbide end mill as the vertical edge that you will still have to cut through is still hard. But the bulk of the surface you will be cutting won't be as bad.
 
My 21-100 mill seems to take 7/16" T-Nuts.
You can get these as part of a 7/16 clamping kits on ebay and LMS but they are kind of skimpy on material.
They are setup to take 3/8"-16 studs.
I plan to make some better ones from scratch at some point.
 
Mini update to this thread. I decided to replace the stock induction motor with a brushless. I wanted variable speed control without pulleys, the step pulley on the motor is not original (feels like a zinc casting) and is only a five-speed instead of six, so it doesn't quite match up with the spindle pulley. And the motor has a bent shaft which causes a lot of vibration.

I could have picked up a VFD to go with the existing motor, or a larger induction motor + VFD... but I had this BLDC on hand and it looked like a fun project. I'm creating an entirely new motor swivel/mounting plate so if I don't like the BLDC I can just put the old motor right back on.

The BLDC (192kv Turnigy Aerodrive) is just a beefy "hobby" brushless, like those used on very large RC planes. The manufacturer is wildly optimistic and rates it 4kW at 48v, yielding around 9000 RPM. But if you run the motor spec numbers it's closer to 2600W/7300RPM, and that's almost certainly peak wattage. Continuous should be about half that without forced external cooling.

Still, that works out to 1.7 to 3.4hp compared to the original 3/4hp. :)

The BLDC's torque is theoretically around 3.5 Nm, while the original induction motor is near 2.3 Nm. So it should be an all-around upgrade; more torque, more power, smaller package, variable speed even after a healthy de-rating of the manufacturer specs

First part in this upgrade is fabrication of the mounting plate, and mostly me struggling against some stainless. I didn't realize how evil stainless was to drill/tap :) Lesson learned for the future


The next video will be milling up the motor mounting bracket and assembling, probably electronics too (tachometer, hall sensors, watt meter, ESC, etc)
 
Another update to the forever-project :) Summer time around here means not much shop time, but I have made a small amount of progress on the motor upgrade. I removed the top of the brushless motor and copied the features into CAD. That let me CNC a replica directly into the new motor mount plate, instead of using the bracket that came with the motor.

Not at all necessary, but it was fun and gave me a chance to play with a little baby Taig CNC mill that I picked up for cheap on craigslist earlier this year. All in all, the process went fairly smoothly. Coolant worked well, tolerances were good, finish was acceptable. Only major complaint is speed... but you can't expect much from a ~200lb 1/8hp milling machine ;)

 
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