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StanF Rockwell 21-122 Hor/Ver Mill


Jul 1, 2016
I recently bought a Rockwell 21-122 Hor/Ver mill, and will document it here. I'll share pictures and progress, ask questions and share other info. I bought a 1945 South Bend 9A and cleaned it up and repaired it in the first half of 2024. It's well-documented in a thread here, and my intention is to do a similar thread for the Rockwell. You can find my SB 9A thread here, if you're interested: StanF South Bend 9A

For some background, I've owned several home mills over the years...Millrite, Bridgeport, Jet 8x30 and now the Rockwell. It's just a great size for a home shop. I lucked into this one a couple of hours away and moved it into my garage.

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Everything feels pretty tight - not a lot of slop.
(I still have the Jet 8x30 at the moment, and you will see it in the background. I like the Jet except for the very limited Z height)
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The table is free of any marks. Fine quill feed works well.
The head tilt gear is also fine (I just have it unbolted from when I was moving it)
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It's missing a few minor pieces here and there, but they should all be pretty easy to make: IMG_9361 (Small).jpg
The horizontal motor wiring is a little overkill for my taste.
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I have the rear belt cover - I had just removed it before I took the picture. Backgear will engage, but not easily. No major issues found yet.
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Single phase motor:
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Missing when purchased:
Horizontal Overarm Ram
Horizontal Overarm Support
the two little anti-rotation blocks on the 30 taper
horizontal arbors (have bought a 7/8 and 1" already)
horizontal cutters
horizontal drawbar
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Vertical motor is also single phase:
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I could not find a PN/SN nameplate anywhere, so no idea of the exact age.

Get it running:
1) Clean only - it's not ready for a repaint
2) Make all the missing handles, replace belts, etc. (basically get it ready for another 60 years of service!)
3) Remove and clean the table, saddle and knee. Re-lube everything properly.
4) Add a simple rubber sheet way cover

1) add DRO, cheap imported
2) add a taller base - it sits a little low for my height
3) add a couple of LED spot lights
4) add X Power Feed, cheap imported
5) possibly add a one-shot oiler
6) possibly add way wipers

Make Missing Horizontal Parts (or buy them, if someone has them to sell! :))
1) Ram- will likely machine from 3.25" OD solid rod down to the 3.125" OD.
2) Overarm Support - may machine from a solid block or make a pattern and do a sand casting
3) The two little anti-rotation blocks on the 30 taper
4) Drawbar - pretty easy project

More to come!
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Your best bet for a ram is to buy a piece of 1045 T.G. & P material already to size. It would be a challenge to turn down a piece of material and hold the size on your 9" SBL.
If you're up to the challenge, I believe I have a piece of 4140/45 material here I can rough turn the OD near to size I can offer to sell you if interested. I don't think my lathe will cut straight enough to guarantee size for you. Ken
Your best bet for a ram is to buy a piece of 1045 T.G. & P material already to size. It would be a challenge to turn down a piece of material and hold the size on your 9" SBL.
If you're up to the challenge, I believe I have a piece of 4140/45 material here I can rough turn the OD near to size I can offer to sell you if interested. I don't think my lathe will cut straight enough to guarantee size for you. Ken

I think you're on the right path with just buying a piece of 1045 TG&P. There are a few suppliers that have 3-1/8" OD, but it doesn't seem to be a very common size.

I might take you up on your 4140 offer, and I agree that my little 9A isn't the right tool. My bed is really too short to turn something 24" long. And turning something that heavy on my 9A would likely be scary! I'll keep investigating and get back to you on the 4140 rod.

For general ease of use, handling and storage of the ram, I wouldn't mind going with a thick wall tubing. You would give up some in rigidity, of course. Start with something like a 3.25 OD, 1/2" wall tube. Turn it down to 3.125 OD, and still have a 7/16 wall. Solid weighs about 48 lbs, but a tube would only be 17 23 lbs.
(Edit: My math was off. 3.125 OD and 2.5" ID would be ~17 lbs. 3.125 OD and 2.25 ID (1/2 wall) would be 23 lbs.)

The rigidity of the tube would only be about 2/3 of the solid, but it would also weigh ~1/2 less 2/3 less(Edited)! It might be a good tradeoff, if I can find a tube. More rigidity is always better, but I don't expect to be driving this mill very hard.
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A piece of 3.25 x 2 41xx tubing used to be a common size we used for down hole oil tools. Steel suppliers are getting to the point on tubulars if it isn't one of the common sizes they sell in large volume, they won't stock it.
Just thought of something, you sure the ram on the vertical head isn't the same one used for a over arm support?

Good thought, but the ram and the vertical head are a one-piece casting on the Rockwell.
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The vertical ram isn't solid, BTW, it is cored out. I don't have a dimension on the ID, but I'd guess 3/4" wall. This reinforces the idea that the horizontal ram could also be a tube.
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I did some stuff tonight...It was totally out of my planned order, but it was fun...

Ram Length:
All the discussion about the ram made me want to confirm the length measurement. The factory ram is right at 24" long according to posts that I've read.

Another Rockwell owner recommended a couple of inches longer than stock. Then, the overarm support could slide onto the ram before the arbor pilot was engaged. You could also just rotate the overarm support out of the way for changing cutters, etc, without having to completely remove it. Let's get a measurement:

The 30 taper/spindle cleaned up nicely.
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I purchased a new 10" arbor a few weeks ago, and did a test fit.
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This gave me a good reference point for the ram length measurement.
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Conclusion: The factory 24" long ram is okay, but it looks like 26" will be a little nicer. If I have a choice in material, I'll go with 26" long.

Horizontal Drawbar:

I started with a piece of 41L40 5/8 Rod:
IMG_9504 (Small).jpg
And then confirmed some measurements that I had found in another post.
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Here's a screenshot that I made of the post - thanks JohnP!
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I like having a drawing to work off of, so I made one a couple of weeks ago.
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1/2-13 threads:
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Good test fit onto a CAT 30 endmill holder:
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5/8-11 done on the other end. I just need to do a test fit, and then pin the end nut to the shaft with the roll pin. After I confirm all the dimensions, I'll post a final copy of the drawing for anyone who needs it. IMG_9527 (Small).jpg

Overarm Support Dimension:
I should add that one reason that I wanted to get the drawbar completed is to get a dimension for the overarm support.

I need the centerline to centerline distance of the arbor to the ram for machining an overarm support. The drawbar will lock the arbor in the spindle, so I can take a good measurement. From what I've read, it should be right at 6.000", but I'd like to confirm that on my machine.

For those that have made the measurement, is this 6.000 dimension correct?
The drawbar was test fit with a tool holder and is finished:
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End nut is pinned:
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I was also missing the two alignment/anti-rotation blocks on the horizontal spindle, so I rectified that today too. The 30 taper dimensions are in the Machinery Handbook under "Standard Tapers for Milling Machine Spindles", which was helpful:
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Squaring up:
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I used some hot rolled off cuts that were close to the correct size from this Wilton vise project:
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Drill and counterbored for 1/4-20:
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Cap Screw test fit:
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Finished except for final length:
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Test fit on machine:
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I'll remove them and shorten them to length:
Blocks test fit and finished...
The CAT 30 endmill holders are a little different than NMTB 30 arbor in the clearance around the keys. And the CAT 30 holders aren't symmetrical on the keys.
In this picture, you can see that the CAT 30 face is right up against the alignment key:
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Here, the CAT 30 holder is rotated 180 deg, and there is a large gap to the alignment key.
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The NMTB arbor is symmetric around the keys:
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And some gun bluing for cosmetics:
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When I was rotating the spindle to engage the backgear, etc, I noticed the TEFC fan scraping on the cover. So I investigated it today. Of course, I had placed the mill too close to the wall to remove the cover :rolleyes5:.
BTW, I also couldn't get the drawbar installed for the same reason! Oops!
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I got the cover removed, and the drawbar installed:
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But the cooling fan has seen better days. This is aluminum, and the bent blades are already cracked - simply bending them back is not an option, unfortunately.
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The cover was not all dinged up, so it appears that the fan cover was replaced at some point? Or maybe the missing blade came off and did the damage to the other blades?
I might look for a new replacement, if that's even feasible. If not, I'll have to do something ugly. Or buy a TIG welder.

Or possibly 3d print a new one...but the spring retainer might make that difficult..the fan is held on with a large spring clip:
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Clip installed:
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Suggestions? Is this fan a standard part that I can still purchase? My searching so far hasn't been effective.
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The Rockwell started getting a bath yesterday. It's got a few marks and rust spots in the paint, but I'm not going to repaint it. I like the character and patina. I just did one side - more cleaning is needed!
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I removed the AC disconnect and AC outlet that was on the backside of the machine - neither are needed in my home shop.
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And I found the nameplate underneath the AC disconnect - mine is a 21-120:
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It looks like mine is from 1970. (Here's a link to the SN table at vintagemachinery.org)
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I ran the horizontal motor briefly, in both directions, a few days ago, and everything worked fine. I'm in the process of moving the power input cord and inspecting everything, so this isn't a great picture:
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The lower box is a thermal overload switch, and it may be a factory device. The Rockwell manual shows diagrams for the thermal switch.
It is disassembled because I had to pull it out of the box to access the terminal screws.
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The upper box is not factory, and holds a magnetic contactor. Unfortunately, no ground wire was carried to/from this box, so now I'm wondering how the motor and rotary switch are grounded, if at all. More investigation is needed.
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Cross referencing lubrication specs for a 55 year-old machine is tough! Luckily, some intense Google searches will usually give you a few good nuggets! (and a lot of BAD nuggets!).

I created a table below for my use that others may also find helpful. Keep in mind that this is for a home shop, not a 24x7 production shop! I am not buying 55 gallon drums of any lubricant!

Feel free to add any comments - hopefully, there are no glaring mistakes :cheers:

Rockwell Spec
South Bend
Horizontal Spindle
Horizontal Arbor Pilot
Spindle Oil, 28-812,
58-60 SAYBOLT​
"Spindle Oil Med"
Hand Wheel Bearings
Vertical Fine Feed Shaft
Vertical Quill (this is a guess)
SAE 10​
TRIAX Kompressor MV ISO 46 (SAE 20), Full Synthetic Air Comp Oil
Valvoline Daily Protection Non-Detergent SAE 30 Conv. Motor Oil 1 QT
Marfak #0 Grease:​
Mobil VACTRA # 2 Way Oil
Horizontal Backgears
EP-140 Gear Oil Grease
7 oz​
LubriMatic 11505 SAE 85W-140 EP High Performance Gear Oil - 1 Quart
Y & Z Leadscrew/Bevel Gears
Vertical Head Splines
Vertical Head Tilt Gear
Marfak Grease #0​
Any modern Lithium Grease
Horizontal Clutch Dog
Starfak #2 Grease​
Any modern Lithium Grease

1) Since I have a South Bend Lathe, I wanted to also cross reference to the lubricants that I already have, so you'll see the South Bend designation in the table.
2) Be aware that some greases are incompatible. I am cleaning out all the old grease before applying any new grease.
3) Missing is the lube for the vertical quill, but I am guessing that will be South Bend B. South Bend A spindle oil would also work, but would run out faster.
4) Mobil Velocite 10 does not currently seem to be readily available in gallon jugs. 5 Gallons is available, but that is A LOT of spindle oil. eBay has some quarts of it, which might be your best option.
5) Finding non-detergent ~SAE 10 or SAE 20/ISO 46 oil is somewhat difficult. Amazon had this one from Triax. It isn't cheap.
6) Rockwell specified using grease on the ways, but I recommend way oil...Mobil VACTRA #2 Way Oil is available from Amazon.

Here are the pertinent pages from the instruction manual:

Vertical Lube Manual Page.jpg

Horizontal Lube Manual Page.jpg

Missing from the Vertical Instruction Manual is this quill oiler - I'll probably use the South Bend B.
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I did a custom, 3d printed bracket to organize all the lubricants on my South Bend Lathe, and I'll be using these same dispensers on the Rockwell. I like the needle tips - especially for the spring-loaded ball oilers like on the quill oiler.
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I like your approach to lubrication. Went through the same process with our shops equipment finding modern equivalents to the ancient original recommendations, cross-referencing between machines, and creating a schedule to keep track of all the tasks, and it makes life much simpler.

With the way grease, you can get proper way grease (like here) but I think you are on the right track going to wail oil. Oil is more forgiving if you accidently use the "wrong stuff" once or twice, but pumping the wrong grease into way's can lead to a lot of frustration. We have a CNC mill with greased ways that had generic white lithium grease pumped into it for awhile (it LOOKED like way grease) and it hardened and plugged up the whole system. Fortunately it didn't do lasting damage but we had to tear down the whole system to clean it out. I think way oil is cleaner too in a manual environment as it helps to flush stuff out and away from the ways, whereas with grease, even if you keep the system pumped full and nothing gets between moving parts, the residual grease on the exposed ways lets everything stick to it.
I think way oil is cleaner too in a manual environment as it helps to flush stuff out and away from the ways, whereas with grease, even if you keep the system pumped full and nothing gets between moving parts, the residual grease on the exposed ways lets everything stick to it.

When I take the knee/saddle off to clean everything, there's a good chance that I'll install a one-shot oiler on it. But I don't have any firm plans yet.

In addition to the ways, I'd like to also add oilers to the X, Y, Z leadscrews/nuts/bevel gear. It'll should help ensure that the mill lasts another 50 years.
When I take the knee/saddle off to clean everything, there's a good chance that I'll install a one-shot oiler on it. But I don't have any firm plans yet.

In addition to the ways, I'd like to also add oilers to the X, Y, Z leadscrews/nuts/bevel gear. It'll should help ensure that the mill lasts another 50 years.
I did that with a few of our old Bridgeports. Used Bijur pumps on eBay are plenty affordable. Proper built systems will have metered jets to ensure that each point is getting oil with each pump, but I just used standard fittings and made it practice to pump a few times. The fit between the ways was good enough that I could see oil coming out all around. Those same mills had previously been lubed with axle grease on the ways, so it was a big improvement.
When I was cleaning the mill, it was rocking around on my uneven concrete garage floor. That got annoying fast, so I started making a base to level out the mill and also lift the mill up to a more comfortable level. I'm looking for about 3 - 3.50" total lift.

Steel is expensive, so I started off with an old Jeep tire carrier that I had made many years ago:
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After a lot of cutting and grinding... At this point, I wish that I had just used new steel!
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It's all 2"x2"x .120 wall square tubing. Size is 26.50" x 17.50" per the manual.
No picture, but all the tube ends were later welded shut with 1/8" steel.
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Test fit was successful:
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Angles bolted in place and ready to weld:
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3/16" thick angle, since that is what I had available.
And you can see the crappy paint. The darker gray is the factory gray, I believe. Someone painted it a lighter gray at some point. It's bothering me, but I'm going to try to live with it.
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Another set of angles (1/4" thick) will be added to the four corners. Then some leveling feet will be used to level out the mill. I'm expecting 1-1.5" of lift out of the leveling feet.

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I have some sheet steel, so I may add a bottom plate to the base - just to keep spiders, etc, out of the base. And it will all be painted too.
I’m currently in the middle of putting my Rockwell Vertical Milling machine 21-120 back together joined the https://groups.io/g/RockwellMillingMachine/topics as there is some good information there such as covering the two big holes in the knee that face the column in order to keep chips from falling inside the knee.

The Rockwell Milling Machine groups.io also has a current thread (see below) that may be of some value for you.
Horizontal Arbor Support (Overarm) - Machined or New Casting? - RAM details

Horizontal Ram:
I bought a solid hunk of 1045 TGP for the ram, and it arrived yesterday. OD is 3.125"; length is 26"; and weight is about 52 lbs. This OD does not seem to be readily available from all sources, so you might have to do some searching to find it.
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The last piece of the Horizontal Puzzle:
I've also been playing around with a 3d printed pattern for a sand casting for the overarm support.
This is not the final version - I am just trying to figure out the best way to secure the dowel pins, smooth out the finish, etc.
Test version:
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I'm not going any further with this test piece - it served its purpose.
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Vertical Head Removal:
As I get closer to getting the horizontal pieces together, I am also now thinking about how to safety remove the vertical head. It's just difficult to strap/lift it safely, as there are no lift points. I also do not want to damage the vertical head when swapping it out, of course. 1st Priority = protect me! 2nd Priority = protect the mill

I am thinking about drilling and tapping the side of the vertical ram for a 1/2-13 lifting eye. I would first tilt the head over 90 deg, install the lifting eye, unbolt the tilt mechanism, and then use an engine hoist to aid the removal of the ram from the base.

Even with a lifting eye, it might still be a 2 man operation, as it won't be balanced, and will want to swing around when it clears the base. I think it will be tough to keep it balanced and straight.

It may be better to have the lift eye on the bottom of the ram.

(this is not my mill - it just shows the general area where I would install the eye)
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A 1/2-13 eye is good for 2000 lbs in a straight pull, but there will definitely be some side loading. Still the head is probably only 250 lbs, so I think 1/2-13 would be fine.

I could also run a strap through the housing to better support the motor weight, and reduce side loading the lifting eye.
IMG_9261 - Copy.JPG
Example strap through housing (automotive axle strap):
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Other options
1) I've read where people remove the motor and just manhandle it out of the base. I'd rather not remove the pulley and motor.
2) I also thought about just machining a 2 piece clamp with a lifting hole. It would be clamped to the ram in the same general area as the proposed tapped hole. Clamps can slide, break, etc, so I liked the lifting eye better.

Any constructive thoughts?