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Van Norman 12 Overarm Support - Horizontal Milling

cash register

Aluminum
Joined
Jun 30, 2010
Location
Menomonie WI
Today I stopped at the foundry and dropped off the overarm support for a quote.

They will be $120 each. May be a little less if we get enough of an order. They will fill the large support arm with a 2 inch tube so there will be plenty to re-bore to correct size. The deadcenter hole will be filled, as well as the slits on both ends for re-milling. They will be solid grey iron and will not be hollow like my original. So shipping may be pricy.

If there is any interest let me know before Monday May 9th, as they plan on pouring next week early.
 
These will be rough castings requiring milling to spec, with the foundry filling the holes and slots. I cannot give you the specs off of mine because it is at the foundry, sorry.
 
Cash Register:

I'm taking a deep breath and saying "I'll buy one solid casting of a VN12 overarm support for $120 plus cheapest-way shipping, hopefully USPS flat rate box well strapped."

To BigEarl67, I heard that a VN12 overarm support is line-reamed for the center ON THE MACHINE, thus insuring a perfect center-to-center distance. This appears impossible at first, but it is somehow done by moving the big round overarm lengthwise or by moving the casting lengthwise on the round arm.

Certainly, replacement overarm supports from VN came un-drilled for the center. Only the big hole was finished.

Anybody want to comment on this? Perhaps describe the exact technique? - JRR
 
JRR

There was a thread a few pages back that describes just what you are asking.

The concensus was that nobody knew exactly how it was done in the factory, but there were some pretty clear descriptions of setups that could be performed to do the work on your own machine.
 
VN 12 Overarm Casting Recieved

The VN12 overarm casting which I ordered from PM user Cash Register was retrieved from the Post Office today. (The USPS was holding it for pick-up as it was sent in a Flat Rate box with insurance. Very securely packed, by the way. He even wired on an internal address tag just in case.)

The casting is very nicely done. My compliments to the foundry people, as they carefully plugged the holes and slots in such a way that the location of these features is not in doubt. There is enough "meat" to bore out the main hole.

It's a solid, not cored as the originals were. (This was understood before ordering.)

I think I can safely recommend Cash Register's overarm castings to those seeking an unfinished casting for their VN12's, Considering that the overarm is often missing from VN12's, this is a great service for the old iron community.

Now, to figure out how I'm going to attach it to a faceplate!

John Ruth
 
Cal,

No......boring heads with VN taper are about as scarce as hen's teeth, the pricey one currently on eBay not withstanding.

JRR

The boring head in the link is not a factory accessory. Likely as not, most of us were unaware of the existence of such an animal. It may be possible to contact Criterion, Wohlhaupter, etc. and ask if they could provide a custom ground 5V shank for their boring heads. But that isn't necessary.

Do what most others are probably doing, stick a straight shank boring head into the appropriate sized collet. Most all the machining of the casting can be done right on the mill the overarm is intended to fit.
 
This thread is nice, all this talk about VN overarm supports being cast, machine work being done....


AND NOT ONE SINGLE FREAKING PICTURE!

:D

Come on guys, you know the rule, no pics? It didn't happen!
 
VAn Norman Overarm Support Casting

Here are a couple of shots of the casting for the overarm support.

VN12Casting1.jpg

VN12Castin2.jpg
 
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Castings look pretty good !

What's that extra unfinished boss in the center used for? Casting vent hole? Extra pouring hole?
If you finished it flat in the same plane as the other small hole's face I suppose it could be used as an extra clamping point while the big hole was being bored thru.
 
...
What's that extra unfinished boss in the center used for? Casting vent hole? Extra pouring hole?
...
The older overarm castings don't have the boss. Top 1943; bottom 1952:
attachment.php


It doesn't appear to be a sprue or vent hole that was ground off. It's a cast feature. It may be there to give a little larger surface to act as a stop when the support is installed with this surface towards the ram. The ram bulges out at about this point, so it would have been less likely to damage the paint on the ram when it was pushed against the ram.

The machined face of the overarm hole on the other side of the '52 support has the machine's serial number stamped on it.

Cal
 

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Cal & all, my various machines have machined flat bosses in various locations. The double swivel head for the B&S #2 has around five of them. My Nikken CNC 4th axis (a powered rotary table) has two on every plane. I've always thought these would be used for indicating in the machine, fixtures, or the part - at least that's what I use them for.
That said, the picture that Cal posted with the old vs. new supports doesn't seem to show a particularly fine surface on the raised boss. Perhaps Van Norman didn't intend for these to be used as setup points.
--
Aaron
 








 
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