# New To Me Rockwell 21-100 Milling Machine



## Buffalo20 (May 5, 2017)

Tuesday of this week, i bought a Rockwell model 21-100, milling machine. The machine started its life in a vocational school, where it saw almost zero use, then about 10 years ago at an auction the shrink wrapped mill, was sold to a contractor, where it sat in their warehouse, unused. On Tuesday, he offered it up to me, and i instantly grabbed it up.

the mill is a small knee mill, with a 6-1/2" x 24" table, an R8 spindle, with 5 spindle speeds. It weighs about 800#, i will take possession on Wednesday of next week. 

The table and knee are tight, if not a bit stiff, but some TLC, will bring it back to life.


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## Billh51 (May 5, 2017)

Congratulations on your find, sounds like the mill should be in fairly good shape with not much use on it. I don't know too much about your mill but others who do will be here to help you out if you need it. Great people here and a wealth of knowledge.


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## lowpass5 (May 6, 2017)

Congrat's!  I recently picked up a 21-100 myself.  It replaces an RF40 clone that I have owned for a number of years.  

I think you will enjoy the little Rockwell.  It will have 6 speeds ranging from 245 RPM to 4200 or from 370 to 6300 depending on which motor is installed.
Mine was stiff as well at first but a little clean up and lubrication has everything moving nice and smooth.  

They are great little machines for those of us with limited shop space.


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## 4GSR (May 6, 2017)

I would rather have it stiff and tight than I would loose and shaky!  

Nice find guys!

Ken


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## lowpass5 (May 6, 2017)

My hands are already loose and shaky as it is!  Here's a picture of my machine in my small garage shop.  

From the sounds of it, Buffalo's machine has a fewer miles on it than mine.  I hope you will post a picture after you pick it up.

Just a word to the wise: Be careful of the aluminum belt housing when you go to move it.  More than one person has broken the housing during a move.  The 21-100s are very easy to move with an engine host, but you want to tilt the head to about 45 degrees so the lifting straps doesn't bear against that housing.  

Good Luck!


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## Buffalo20 (May 7, 2017)

What size milling vise are you using?? I have 6" vises on the other 2 mills, but I thinking either a 4" or a 5 would better suit the Rockwell.

As the spindle is R8, as are the other mills, the milling vise is really the only tooling, I'm going to need to buy, at least at the present.


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## lowpass5 (May 7, 2017)

I'm using a 3" import.  I had a 4" on my RF40 and when I moved it to the Rockwell, it looked oversized so I let it go with the RF.  I think around 3 1/2 would be ideal if there is such a thing.  Most of what I do fits in the 3 " and anything large I will clamp to the table.

Oh, and you will need a 7/16 clamp down set.   The slots in the Rockwell table are narrow.


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## Buffalo20 (May 7, 2017)

I picked up a ER32 x R8 arbor for the mil and collets from 1/8", up to 3/4", which should work nicely with the new mill, Started the search for the vise and apparently I'll need a 7/16" t-nut/stud set. With the vise, T-nuts/studs and the ER32 x R8 (with collets), I've already spent more than I bought the mill for........


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## bobl (May 7, 2017)

I have this mill also it's a great for its speed range I have made a swivel turret for mine and a DRO on 3 axis and a 4 inch modified vernier caliber for the quill
Only wish I had looked for the horizontal vertical version 


Sent from my iPod touch using Tapatalk


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## john.oliver35 (May 7, 2017)

I agree with Lowpass5 - a 4" is as large as you will want on this mill.  The Y Axis Table and Travel are both pretty small, and a 4" overhangs quite a bit already.

It is a great little mill and I have never regretted buying mine.  It is not a full size Bridgeport though, so I recommend you scale down the tooling recommendations from full-size mill owners


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## Buffalo20 (May 9, 2017)

I spent a good part of the day getting the Rockwell mill to the shop today. I went to the seller's facility and stripped the mill, down to the column and table/knee assembly. After lunch, where I bribed my friends, Trombone Pete and Norm, to pickup the stripped mill, on Norm's small utility trailer. 

I based my purchase of the mill on my seeing the mill 2 years ago, last week, I saw it again, with a flashlight, it was far dirtier than I had remembered. Nothing serious, just grime and some swarf. With a few towels and some red Brakleen, the grime pretty much wiped right off.

The table moves smoothly side to side and back and forth, knee is tight and smooth, that table has some surface rust, but nothing serious. Over all, I very pleased so far.

I was unable to power up the head assembly, no 3 phase power (Not yet), but the spindle is smooth when moved by hand. Powering the head assembly is high on the To-Do List.

here are a few pictures


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## Buffalo20 (May 9, 2017)

a few more pictures


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## lowpass5 (May 9, 2017)

Congrat's Buffalo, it looks great from the pictures! 

Check (remove and clean) the fine feed mechanism - that seems to be one of the weak points on these machines.  Mine is in good shape but many have found the worm wheel stripped.  Don't know if that's from use or abuse.  I find I don't use the fine feed much in favor of the knee for any milling operations anyway.

A lot of people prefer the 3 phase motor with VFD over the single phase motor.  There is a guy on Yahoo groups that posted that he is selling some single phase motors that he replaced with 3 PH if you would rather go that way.  I am happy with my single phase motor except that the motor/spindle has a lot of inertia and takes awhile to spin to a stop.  I think you can program in a motor braking function in the VFD which would be of benefit.  There is a brake/lock in the spindle so you can slow it down that way, but there seems to be a difference of opinion whether this is a good practice.  I find myself using the brake about 30% of the time.


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## john.oliver35 (May 9, 2017)

Buffalo - I would second the vote for a VFD.  This mill has a pretty fast high speed and it is useful to have some additional low speed control.  I only have a single-phase motor, and have been planning to look for a 3PH so I can install a VFD on my 21-100.


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## 38super (Feb 12, 2019)

Try 7/16 carriage bolts, grind the head to fit the T slot.


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