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Van Norman "C" horizontal arbor

riodeloso

Aluminum
Joined
Apr 23, 2010
Location
Ventura, CA
Does anyone have a good drawing of a Van Norman C (5V) taper horizontal arbor (or shell mill holder or endmill holder)? I picked up a Model 1/2 (details and pics here:http://www.practicalmachinist.com/vb/antique-machinery-history/my-new-van-norman-model-1-2-pic-heavy-questions-211202/ )
It had some tooling, the horizontal arbor looks a little beat, and it is not clear if it is the original. I can't afford what I've seen on ebay, so I figured I'd probably just make one if it is a reasonably easy job.
Thanks!
 
The VN arbors just have a flange that grabs two drive lugs on the face of the spindle. Make it just like any other 5V tooling, up to the nose of the spindle. Give yourself 1/16
" or so past the spindle nose (can measure with another piece of tooling) and then turn a flange about 2 1/4" in diam and 1/4" thick with two opposed 1/2" slots. Other side of that is your arbor, 1 or 1 1/4" with a keyway the entire lenght, ending close as you can get to the flange. Left hand threads on the outboard end, and leave enough extra stub length (1/4" or so) slightly reduced diameter to pick up the support center. Just look at a pic of one on Ebay and you'll be able to figure it out.

Here's the taper drawing, just add what I explained.

Van Norman Milling Machine Spindle Tooling
 
Van Norman 'C' arbor & tool-holder drawings

Here's a scan of a Shell Development Co. drawing of a Van Norman 'C' taper 1-1/4" stub arbor:
VN 'C' 1-1/4" arbor drawing

Here's a scan of Van Norman Machine Tool Co. drawing C-385-C, '1/4" to 23/64 CHUCK'; it appears to be a collet or tool-holder blank:
VN 'C' tool-holder blank drawing
I haven't been able to figure out what the abbreviations 'F.T.', 'R.G.', and 'G.R.' mean and how they apply to the 'B' dimension. Anyone?

Cal
 
I haven't been able to figure out what the abbreviations 'F.T.', 'R.G.', and 'G.R.' mean and how they apply to the 'B' dimension. Anyone?

RG == Rough Grind
GR == GRind

Not sure about FT, but it must be something that means "machined size" -- maybe "For Treatment" meaning the size going into heat treat?

Regards.

Mike
 
Thanks for posting those arbor and collet drawings, Cal. Any idea what sort of steel would be a good choice to use for an arbor? And the hardening if any? I do not know anything about this, it would seem to be safe to think the arbor should be a bit softer than the spindle?
 
For home shop use, especially on something relatively low powered like the VN12, you don't need it to be hard as diamond. I'd just get some good quality shafting material, 4140 or such and whittle away everything that doesn't look like a horizontal arbor.

If you aren't pushing big cutters really hard (and you won't with a VN12), the spindle nose lugs are also optional. I was running an 11/16" diam x 3" radiused cutter just today on my VN12. 6061 T6511 aluminum bar, .375" deep cut, full depth one pass. The spindle taper key was quite adequate to pull the cutter to the point of chatter, if feed was upped. Still faster and a LOT prettier job than using a ball endmill.
 
Thanks for those drawings....I had just been about to ask about the outer flange. The model 1/2 (at least mine, and I don't have too many others to reference!) doesn't appear to have any keys on the outside of the spindle to drive the horizontal arbor, it seems like it only relied on the inner keyway.

If someone else with a 1/2 can confirm this, that would be great!
 
... The model 1/2 (at least mine, and I don't have too many others to reference!) doesn't appear to have any keys on the outside of the spindle to drive the horizontal arbor, it seems like it only relied on the inner keyway.

If someone else with a 1/2 can confirm this, that would be great!
I used to own a No. 1/2. I checked the photos and it didn't have drive dog keys either, so I guess you're stuck with the half-moon key.

Cal
 
The #6 at the museum didn't have drive keys, that's why I wasn't afraid to run an arbor with just the woodruff key. I think they knew there wasn't enough ass behind the smaller ones to really need drive dogs. Probably, the slots in the arbor are overkill for the 12, but as they were built more as a production, versus a toolroom mill like the 6, it makes more sense. Thought was probably go ahead and key all the arbors, those without lugs can still use them, so there will be total interchangability.

Again, on the hardening thing, I wouldn't recommend it. You are going to have to grind some final dimensions, and you probably can't harden at home. In a home shop duty, it'll never wear enough to be an issue.
 
A friend has a #6 that was built in 1940. It has the same cutter-head as a No. 12 and has the drive dogs.

Mike, What about pre-hardened 4140?

Cal
 
Straightness is critical

I think most materials that the others have mentioned may "move" when you remove away enough material from flange size down to arbor diameter, and perhaps not evenly. The big trick is keeping the final product straight - any wobble of the arbor will cause only a few of the cutter's teeth on one side to do most of the work.

Got a good lathe with centers lined up, a drive dog and a follower rest?
And access to a set of bench centers for testing?
 
Don't get too concerned about having an arbor perfectly straight. I think most every one I have used had some degree of bend in it. In a perfect world, they'd be within .0000001, but most are about .010 or worse in the real world. They still cut just fine.

Museum VN6 was a late model (1953 or 54, one of the last ones made).
 
Any idea what sort of steel would be a good choice to use for an arbor? And the hardening if any? I do not know anything about this, it would seem to be safe to think the arbor should be a bit softer than the spindle?

You will get many years of usage out of an arbor made from 4340HT. This is machinable as-sold, and goes ~35 on the Rockwell C scale. I have many arbors, endmill holders, and other tooling I made from 4140HT and 4340HT, that I use on my 3 HP horizonta mill, on a more-or-less daily basis.

If you go with a post-machining heat treat, you will likely have to grind the arbor back to straight and to size, so unless you have an OD grinder, you're out of the shop-made game.

Regards.

Mike
 
You will get many years of usage out of an arbor made from 4340HT. This is machinable as-sold, and goes ~35 on the Rockwell C scale. I have many arbors, endmill holders, and other tooling I made from 4140HT and 4340HT, that I use on my 3 HP horizonta mill, on a more-or-less daily basis. ...
It seems like a waste to turn down a 2" piece of steel to make a 1" arbor. Could the 2" drive flange be welded on?

Cal
 
It seems like a waste to turn down a 2" piece of steel to make a 1" arbor. Could the 2" drive flange be welded on?

Cal

Certainly possible, but 4140 and 4340 are tricky to weld with strength.

Yes, it's a bit dismaying to turn a 30# blank into a 10# arbor (in my case NMTB40, with 2-1/2" flange), but at least you get to experiment with maximizing your lathe's MRR :reading:. On the plus side, if you get up enough SFPM, DOC, and feed, 4140/4340HT chips break nicely, and insert life is pretty good.

Regards.

Mike
 
Yup, just get a hunk of material and start whacking away at it. Times like this that "slow" old L&S makes quick work of things. That's about four roughing passes to get the flange and arbor done. Flip it around, re-zero and whack out the taper. Probably rough on the L&S and finish the spindle end on the SB10L.
 








 
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