Mill "transmission" For The Rockwell Mill

[platypus20]

I have decided at this point, to run the new Rockwell mill, with a single phase motor. Whether its going to be 120 vac or 240 vac, I'm uncertain, the 3/4 hp motor I have can go either way. With the 1725 rpm of the motor, I'll end up with 6 speeds, 370 rpm in low and 6300 rpm in high.

I've decided to build a "transmission", like I did for the Jet mill, adding a 4 step layshaft between the mill head and the motor. I'm building it to be a cartridge, to allow the mill to be returned to original configuration, within about 15 minutes, drilling no holes, using the manufacturer's original holes. Also reusing the original motor drive sheave.

So today I went to Graingers, for (2) sheaves (pulleys) and (2) 5/8" plate bearings. Then to the local machine shop supplier, for 5 feet of 5/8" ground and polished shafting. Then to the metal suppler for some tubing, then to the industrial supplier for some nuts and bolts.

I cut out (2) 10-1/2" discs, one of of 1/4" plate, and one out of 3/8" plate, then trued them up on the lathe. I laid out the bolt placement and drilled the holes on the 1/4" plate. Transferred the hole to the 3/8" plate, then threading the required holes in the 3/8" plate. Took a piece of the 5/8" shafting and set up the Jet mill, to cut a 3/16" keyway.

The cut up some 1/4" pipe nipples, to 3" long, the bored them out to 25/64", so some 3/8"-16 B-7 allthread would pass though to make the spacers.

Then assembled the "transmission" set, placed it on the mill and set the correct sheave height, so the belt was aligned properly. Set the new drive sheave height and tightened the bearing collars and shaft collars.

So today, I used the lathe, the Jet mill, the Jet drill press with the tapping head, the Franken-Drill, the belt grinder and finally the new saw. The shop was quite a mess.

Here are a few pictures of the work so far, next up is the motor mounting brackets and the wiring.

[spro]

Your work to achieve the extension of speeds while maintaining originality, is astounding ! I will say something which you obviously knew.. Stepped pulley drives usually have the widest dia closest to the bearing support. more..

[spro]

My thought would be that the motor be not too high up, as it would appear. However I do have the head "ram" from a Rockwell. There is no way it could bend from any motor.

[platypus20]

Working the rpm numbers this morning, the original spindle rpms with a 1725 rpm motor, were a low of 370 rpm to a high of 6300 rpms, I have some options, each give 24 different speeds.


Option #1

low of 185 rpms, to a high of 12,600 rpms, with average steps of 230 rpms between speeds

0ption #2

low of 111 rpms, to a high of 10,080 rpms, with average steps of 150 rpms between speeds

Option #3

low of 111 rpms, to a high of 8190 rpms, with average steps of 78 rpms between speeds

[spro]

How about Option #4 . Leave it go at original for awhile. See how that works for you. These really high speeds are beyond the bearings limitations. The really low are useful for heavy drilling or swinging a large fly cutter but that is not what that mill was designed for. I regret saying this, yet it must occur to others here. I am total anal about things and go into dead musicians as it fits my mind at the time. It may trigger a few to explore or remember but hardly rational when it comes to spindle bearings.
FWIW I have the empty quill housing of a Rockwell here. It is very well built. The outer diameter is 3" and inner sections vary from .. well it took some engineering to drive R-8 collets reliably. It comes to that.

[Harold_V]

I'm impressed with your design, and would most likely emulate what you're doing, were the mill mine.
Spro has a good point. Bearings in the spindle may not be capable of handling high speeds. It would be prudent to determine the bearing type and ensure that they can handle over-speed. If they can, the next decision would be to determine the type of work you intend to pursue. If you specialize in small work, the high spindle speed is almost a must. By contrast, if you don't expect to use tiny end mills (1/16" and smaller), given the choice was mine, I'd select option three, as the close steps in speed change would be quite nice.
Very well done, by the way.

Harold

[platypus20]

The option thread was somewhat tongue-in-cheek, Option 3 is the only real option. I made up a motor mount, mounted the motor and ran the mill at about at 500 rpms for about an hour, the ran the unit at 5000 rpms for about 15 minutes, constantly checking the head temperature, hardly any temperature rise.

As I have 2 other larger mills, I seriously doubt the Rockwell will ever see a end mill bigger than 3/8". Probably a lot of keyway cutting and lots of small jobs.

I picked up a used 4" vise and have ordered a handles to replace the existing ones.

One thing I'm going to have to do is build a riser platform to rise the mill higher, I'm only 5' 8" and even setting on 2 x 4s, I looking directly into the Rockwell logo, bottom of the quill is about mid-chest.

[Harold_V]

In regards to mill height, I'm not personally familiar with the one in question, but it's commonly known that many of the small mills were intended to be operated from a sitting position. The Gorton Unimil, 0-16A and 8-D were amongst them.

Not suggesting that yours was built with that in mind, but it may have been. Standing at a machine for hours on end gets very tiresome.

Harold

[platypus20]

Norm (a friend and fellow Chinese Buffet fan) came over yesterday, and helped out with the preliminary motor bracket, we mounted motor and ran it off an extension coed for a little while.

This morning, I rounded up all of the parts to wire the mill, the Square D on-off switch, forward-reversing switch, the plug and some SO cable. Wired up the mill, to operate on 230 vac, single phase. Wonder will never cease, I had a 50/50 shot on getting the rotation right, on the direction switch and damn, I got it first time. Usually when wiring a motor, you get that 50/50 chance and I'm usually wrong about 80% of the time. I ran the mill under no load for 1-2 hours at various speeds, motor got to about 110 degrees, mill head assembly remained at about 85 Degrees.

The UPS truck arrived at the end of the driveway (strange for a Saturday, at least here) and I got 3 boxes. My order from Grizzly came, new table handwheels and folding safety handles. Grizzly did screw up the order, the packing slip showed a dozen 7/16" t-nuts, but none were in the box. At least they are consistent, they have screwed up my last 5 orders, in someway or another. They have made them right, just takes time.

My HSS end mill order hit, all was correct.

My new Shars 4" vise arrived, I bought from a guy in Rochester area, he bought it brand new, opened the box, said looks good and then 3-4 days later got a hell of a deal on a much bigger mill, then retooled for that, this has set for about 6-8 months in his garage, so I snapped it up for $75, which included shipping. I set the vise on the table, will probably remove the swivel base, but vise look very nice.

So this afternoon, I started to change the handles on the mill, I did the knee and the Y- axis handle, and started to work on the table end handles, ran out of daylight. Placed my nut bolt order for the shop and ordered the 4" x 4" x 3/8" box tubing, to start my riser/base. The tubing and the adjusting feet should get the mill about 6" higher than it is now.

[platypus20]

I finished up the table handles today, after making the 3 handle adapters. I then did some more mill clean up, then started the shop clean up. I had used almost all the machines in the shop and had swarf from one end to the other.

While I was at it, I did some serious rooting and ended up throwing away 3 huge bags of stuff. Somehow the shop looks cleaner, but with the stuff thrown away, I expected to see some more room in the MAchinery Closet, but to no avail.

I getting ready for a week of work in Vermont, installing a burner on a boiler in a dorm at a college in Northern Vermont. A tiny burner, but the job start to finish is 5 days. With two new minions, this could be a struggle.

1 - the mill
2 - new handles
3 - vise
4 - vise and the ER32 x R8 collet chuck

[platypus20]

The temporary motor bracket, the Mark 1, it just slides onto the ram post, held in position by (2) 8mm x 20mm full dogpoint set screws, that set into the keyway groove, for the tramming drive collar. I'm working on other design concepts. Not really sure which way to go. I like the concept of the increased number of speeds, the correct motor drive sheave/pulley, will be here, by Thursday. I wanted to get the mill powered, to check out the head assembly, sounds great.


5 - new handles
6 - all folded up
7 - temporary motor bracket
8 - the controls

[spro]

Your mill/work looks great. I didn't understand at first.