SteveG's Van Norman #12 mill

[SteveG]

About a month ago I bought my first milling machine - a 1940's Van Norman #12.
My plan was to give it a quick cleanup and just use it, but I've found it needs a bit more work before the "just use it" happens.

Thought I'd start a thread to document the work in case its of any interest/use to others.

Here's the coming home photo. The white page taped on says "heavy on right side" (to save you straining your eyes....)
   

First thing that got fixed was the missing oil level window made one from polycarbonate sheet and fitted it with an o-ring behind to seal it.
Before:
   

After:
   

Gearbox oils are easy - just plain old SAE30.

Steve

[SteveG]

Cutter head lubrication is a bit less straightforward. The bearings are greased, but the 90deg gearbox runs oil.

The original manual specifies 600W oil, which is Mobil Cylinder Oil (ISO 460 grade). Still made today but not easy to get hold of in small quantities. ISO460 is the same viscosity as SAE140 gear oils which ARE easy to get hold of.
Whenever there's an oil/gearbox discussion it always brings up the subject of not using EP oils as they will eat bronze bits in the machine. I was doubtful that there would be any bronze in the cutter head, but given the age of the machine and parts (un)availability didn't want to risk it if there was.

So to make myself feel better about what I could use, I opened up the cutter head to have a look:

Here's the pinion gear on the ram:
   

And the mating gear in the cutter head:
   

Good thing is the gears look to be in pretty good condition.
Not so good is there's no sign of oil in the gearbox - just the remains of the grease from the bearings that has made its way through the seals.
Bad news is that when I rotated the spindle, it felt like it had quite high preload, and was notchy. Bugger :(
The ram gearbox is nice and smooth though..

So its onto the bench for a proper stripdown of the head to check the bearings.
Upper bearing was worn, but not stuffed.
On the other hand, the lower one is definitely past its prime:
   

Both bearings are up against shoulders with no easy way of getting behind them to pull them out. You can see in that photo the small recess behind the inner edge of the bearing - only about 1mm to try and get anything onto.
Not having a suitable puller to do that, I had to resort to running a bead around the inside of the cups and then welding a small bar across them so I could tap them out.
The photos may be offensive to some so I'll omit them !!

After removing it, I found the lower bearing cup had a 1943 date engraved on it. So it still had the original bearings in it after all these years.
The seal above the lower bearing must have been original too, as the rubber lip just crumbled with light pressure. 
Hopefully the bearings and seal aren't too hard to source, but I'm a little anxious they could be. Will find out tomorrow.

Oh - and I've confirmed 100% there aren't any bronze bits in the head so no need to worry about having to use a bronze friendly oil .

Steve

[SteveG]

All back together again with new bearings.
Thankfully I thought to measure the backlash in the gears before stripping it down, as the backlash is set by a threaded collar above the gear, which needed to be removed to get the spindle out.
Here's a quick video of where I measured it beforehand: https://www.youtube.com/watch?v=S_t-djSp5cY

Not knowing what its actually meant to be set at, I opted to set it a touch smaller at around 0.3mm as the wear in the bottom bearing would have opened up the clearance slightly, and since the bearings were original I doubt anyone has ever messed with the backlash adjustment.
I set it dry as there wasn't really any oil in it when I originally checked the backlash. Once I was done - by feel there was distinct clearance dry, but felt smooth and no obvious backlash once the head was filled with oil.
I ended up putting some decent 85W140 mineral gear oil in it.

Next challenge is to modify some R8 arbor tooling I bought so it fits the Van Norman taper. Both the parallel and tapered sections of the R8 need to be reduced.
First up will be the ER32 collet chuck...

Steve

[SteveG]

I need to make the R8 arbor on the left, look like the VN one on the right 
I'll make a new drawbar to suit the 7/16 thread in the R8 rather than messing around trying to cut threads to suit the VN one.

   

I don't have a taper turning attachment for the lathe, so its going to have to be the compound slide. I specifically bought a cheap arbor in the hope that it would be reasonably soft and able to be turned, as I also don't have a toolpost grinder...
This one is hard-ish when checked with a file, but a quick test looks like HSS tooling will work OK (alas no carbide lathe tools yet).

Its giving me a bit of a head-scratch as to how to do it though.
Thinking to modify the taper first, with the parallel portion of the arbor in the 4-jaw, and a center in the collet taper.
Then turn it around, chuck some round stock and true it up then put a collet in the arbor and clamp it on. Use a center in the other end and turn the parallel diameter to size.

Any better suggestions for those of you with more experience?

Steve

[Vinny]

This video might be helpful. It was done by a member here, don't recall seeing anything from him lately tho. It's about setting up the compound for that angle.

https://www.youtube.com/watch?v=YCllVu4K738

[SteveG]

Thanks Vinny. That's a great video.
I'm fortunate in this case that I've got an existing taper to copy, so can just chuck it and set the compound up to match using a dial indicator rather than having to cut a known angle.
I made a start last night, but having some issues with runout. Not sure if its the crappy cheap R32 arbor or if my 4 jaw has issues. First time I've mounted the 4 jaw since I got the lathe, so really need to check it.
Anyway, got the taper dialed in off the old arbor and roughed out the new taper. Still thinking about the best way to finish it off true (which I know should have been worked out first!!).
Not really the ideal first project with my level of skills on a lathe I'm not familiar with, but its a chicken and egg situation. Need an arbor for the mill so I can cut the change gears needed for the lathe so I can cut the threads I need to make my own arbors for the mill from scratch (which I think would be much easier than modifying this one)!!

Steve

[Pete O]

If you're having trouble getting the thing to run true Steve perhaps you would be better turning it between centres, if you chuck a lump of bar stock in your 4-jaw and turn a point on it it will be centred, then you need a dog to drive it- can be makeshift if you don't have any proper lathe dogs.

[SteveG]

Thanks Pete. I did think about turning it between centres, but couldn't get my head around how I was going to get a center in the collet end of the arbor.
In hindsight, that would actually be really easy - just turn a short spigot to of diameter to suit a collet, center drill then part off and chuck it..

But there's always another way, and here's how I did it - similar, but not exactly "between centres":

Chucked a piece of stock and turned so it would fit one of the collets.
Left it in the chuck, fitted the collet to the arbor and clamped it up on the spigot. Managed to find a 7/16 UNF bolt in the depths of my scrap bucket, and fitted that in the drawbar end of the arbor with a few washers. Spun it up and center drilled the end to take a fixed center.

Here it is set up and turned to diameter:
   

Next issue was that I'd set the compound up to cut the taper on the tailstock end of the work, but it was now at the headstock end.
No problem, l'll just cut it on the rear of the job running in reverse. Wrong - not enough travel on the cross slide to get to it with a standard toolholder  

Finally managed to get to it with a long boring bar. Definitely not ideal and the tool grind was crap so I battled a bit with chatter but got there in the end:

   

Next step was to make up a drawbar to suit the 7/16 thread in the new arbor. I've got a long high grade shoulder bolt from a previous life that is almost perfect - just needs cutting to length and threading.
Most of my threading gear is metric apart from a couple of small sizes - no 7/16-20 :(
No problem, I'll just cut the thread on the lathe  
Except I haven't yet made the 126T change gear I need for 20tpi....
So the temporary solution was to machine down a length of 1" all-thread I've had lying around for 20 years just for this purpose, drill a hole in the end to take the shank of a 7/16 bolt and I'll glue it together with the MIG.
Here it is in all its nearly finished glory - will cut to length and throw some spatter at it tomorrow.

   

All going well the mill might even get to make its first chips tomorrow!!

Steve

[Dr Stan]

Had a Van Norman in my machining lab at UNK. Wish I'd been there when they sold off the equipment as it was in excellent condition.

[SteveG]

Got a bit busy with chores and visitors yesterday, but managed to get the drawbar finished.

Tonight was a milestone - first chips on the mill - for both myself (ever) and this mill during my ownership 

   
   

On the not so good side is my modified arbor has about 0.1mm (4 thou) runout measured just below the collet :(
Spindle itself had just over 0.01 when I checked after reassembling it, so the problem must be with the arbor. Not surprising really given my limited skills the amount of messing around and head scratching involved in modifying it.

Still - good enough to get me going for now and I've learned lots doing it. I'm sure the next one will turn out better.

Steve