Rockwell Vertical Mill 21-100

Discussion on all milling machines vertical & horizontal, including but not limited to Bridgeports, Hardinge, South Bend, Clausing, Van Norman, including imports.

Moderators: Harold_V, GlennW

Post Reply
germaneighter
Posts: 32
Joined: Fri Oct 30, 2015 2:28 pm
Location: Owasso, OK

Rockwell Vertical Mill 21-100

Post by germaneighter » Wed Apr 03, 2019 4:26 pm

hello! I've acquired a Rockwell mill serial number D06372. I'm trying to determine the date of manufacture but have not had much success. I would also like to know which came first, the Delta/Rockwell mill or the Rockwell mill? Serial numbers for the Delta/Rockwell seam to be longer and include only numbers while the Rockwells are Alpha Numeric. One web sight I found showed a Delta/Rockwell serial number 1319486 as being manufactured in 1964.

Thanks

choprboy
Posts: 222
Joined: Sat Oct 29, 2011 11:23 pm

Re: Rockwell Vertical Mill 21-100

Post by choprboy » Wed Apr 03, 2019 9:44 pm

Are you sure it is not DO-6372 (Dee-Ohh)? Delta/Rockwell serial number format apparently varied by manufacturing plant. a DO prefix would seem to indicate a 1967 Tupelo. Do you have the original motor on the mill? It may give you some additional information. See:
http://wiki.vintagemachinery.org/DeltaS ... mbers.ashx
http://vintagemachinery.org/mfgindex/detail.aspx?id=698
http://vintagemachinery.org/mfgindex/de ... px?id=1141

My own 155xxxx mill seems to have the original motor and "wreath" tags, though it doesnt seem to have a date, which would make it an early 1973 model, just before Rockwell International rebranded.

spro
Posts: 7472
Joined: Mon Feb 20, 2006 11:04 pm
Location: mid atlantic

Re: Rockwell Vertical Mill 21-100

Post by spro » Wed Apr 03, 2019 11:18 pm

Yes. My Rockwell catalog of the 1980's has the same 21-100 mill but it doesn't mention Delta. There is some sub script notes: Rockwell Manufacturing Company 1972 and Rockwell International Corporation, 1979 .

germaneighter
Posts: 32
Joined: Fri Oct 30, 2015 2:28 pm
Location: Owasso, OK

Re: Rockwell Vertical Mill 21-100

Post by germaneighter » Thu Apr 04, 2019 4:07 pm

choprboy,
you are correct. It is a DO 6372. Thanks for the info.

Another question - are there some 21-100s that are taller? I'm looking at various pics on the internet and it appears one version (possibly shorter) has a straight column where it rests on the base, and another version (taller) where the sides of the column taper out where they rest on the base.

User avatar
platypus20
Posts: 200
Joined: Sun Aug 26, 2007 1:24 pm
Location: camillus, ny (syracuse)

Re: Rockwell Vertical Mill 21-100

Post by platypus20 » Thu Apr 04, 2019 7:40 pm

My 21-100, has no serial number tag, the drive pins are there, but no tag. Mine came out of a vocational high school, where it go almost no use, after 25-30 years it was sold to a ASME boiler repair shop, when it remained wrapped in shrink-wrap for another 10-15 yrs, when I bought it before they planned on sending it to the scrapper.

Mine is in excellent condition, the motor was shot, so I built a lay shaft transmission, increasing the 6 speeds to a now current 24 speeds (85 to 6500 rpms). I mainly use the mill with a ER 32 x R8 collet chuck. As this is the 4 milling machine in the shop, it’s currently only used for small jobs, (key ways, etc)
jack

choprboy
Posts: 222
Joined: Sat Oct 29, 2011 11:23 pm

Re: Rockwell Vertical Mill 21-100

Post by choprboy » Thu Apr 04, 2019 10:54 pm

I don't know if they are taller, but yes apparently there are two versions, one with a flanged column and one with a flared column. I *think* the flanged where the earliest, production ran thru a couple versions of the Delta/Rockwell company from the late 50's to early 80s, but I don't really know more than that. Lathes.co.uk has some more info:
http://www.lathes.co.uk/rockwellmillers/
http://www.lathes.co.uk/centex/

choprboy
Posts: 222
Joined: Sat Oct 29, 2011 11:23 pm

Re: Rockwell Vertical Mill 21-100

Post by choprboy » Thu Apr 04, 2019 11:00 pm

Yes... After a few years of using mine, I find one of the biggest drawbacks to the 21-100 is the lack of a lower speed range. I find I never go more than 2400 rpm, but even the lowest 370 rpm is frightful when trying to do a large fly cut or bore a 4" hole.

germaneighter
Posts: 32
Joined: Fri Oct 30, 2015 2:28 pm
Location: Owasso, OK

Re: Rockwell Vertical Mill 21-100

Post by germaneighter » Mon Apr 08, 2019 11:07 am

Can anyone suggest a good VFD for this mill? I have 220 single phase in my shop.
I believe the motor is the original. It is a Rockwell.
Specs as follows:
Model # 66-530
5A 56T11D29B W
1/2 HP
208-220/440 volts
1140/960 RPM
60/50 Cycle
3 Ph
2 4/1 2 - 2 6/1 3 AMPS
Frame 56-8
Type TS
Class B

thanks

User avatar
Bill Shields
Posts: 5438
Joined: Fri Dec 21, 2007 4:57 am
Location: Somewhere in the World
Contact:

Re: Rockwell Vertical Mill 21-100

Post by Bill Shields » Mon Apr 08, 2019 4:26 pm

the first question you have to ask is:

do I want to spend the money that will allow me to shut off the motor using the existing on / off switch or am I OK with only using the control / switches for the VFD?

Many of the lower cost VFDs (nothing wrong with them), will not allow you to disconnect the load using a switch between the VFD and the motor...so you can forget the existing on / off switch -> unless you like replacing parts (or entire VFD assemblies).

The next question is:

is this the only motor you want to drive with the VFD?

3rd question:

Can you REACH the VFD to adjust speed from the machine, or will you need a remote 'keypad'?

A 1/2 horse VFD is practically a consumable in today's market...but one that will drive 2 HP is a horse of a different color.

Plan carefully....

FUJI and Allen Bradley make solid units...but so do 100's of other companies

a 1 HP Fuji unit is in the neighborhood of $150.00....but you may not be able to disconnect between the unit and the motor while under load.

you will hear good and horror stories about any piece of electronics...just plan carefully for where you are headed...

And note that with any of these things, you will not be able to take a standard 'non-inverter-rated' motor down to very low speeds and expect the same torque output you will get from the belt / step pulley.
Too many things going on to bother listing them.

germaneighter
Posts: 32
Joined: Fri Oct 30, 2015 2:28 pm
Location: Owasso, OK

Re: Rockwell Vertical Mill 21-100

Post by germaneighter » Wed Jun 26, 2019 4:55 pm

I was using a 1/2" end mill to modify a hardened steal tool (making very small cuts but not very successfully) when the spindle bearing retainer came lose and started un-threading from the bottom of the quill. I stopped the machine and tightened the retainer but I don't know the cause and I can't find any specs on how tight this should be. Anyone have any ideas? (BTW -I gave up on milling the tool and used a bench grinder....)

spro
Posts: 7472
Joined: Mon Feb 20, 2006 11:04 pm
Location: mid atlantic

Re: Rockwell Vertical Mill 21-100

Post by spro » Wed Jun 26, 2019 11:57 pm

The Rockwell vertical quill housing: The nose bearings are held tight by a fine threaded, internal ring of ~ 2 3/4" diameter. This ring is tightened by use of a face pin spanner. There Are other ways and adjustable spanners but I don't know how they would determine the preload. It is common to see drift marks at these pin holes and one would think it was from disassembly. Not so, on this one. The drift/ punch marks were to tighten the ring.
The quill is thin around the ring and there was no lock screw. I think you need clean the lower end to the point of using acetone in the threaded surfaces, quill and ring. These threads could use a certain "lock tight" product which does release at +over temperature. The spanner should present the recommended torque for preload .

Post Reply