Van Norman #12 makes chips!

Mine was missing the chain; I found one for sale for an amazing price, but turned it down. I ended up putting timing gears with a toothed belt in place of the original setup.

Steve Smith

Jeff Taylor wrote:

As far as the 1" spacers go, you might consider buying a 1" arbor fully populated with spacers. These are hardened and ground and have the correct 1/4" keyway (although a lot of guys just turn the spacers on the lathe and don't bother with a key according to Dave Sobel). Keep the spacers, turn around and resell the arbor bare-naked.

Grant Erw> I bought a #12 Van Norman mill back in November 2002. It appeared to be

The spacers work fine without the keyway. It is there so that you can use a key that is wider than the cutter and not have a problem assembling the spacers.

There's absolutely nothing wrong with the idea of making them so long as good machining practice is employed so they are properly made. One might consider the use of 1045 steel, or stressproof, both readily available. For non-production use, they can be used in the soft (annealed) condition with good success.

The spacers should be made to be a light slip fit on the arbor and be dead square and parallel. They should be bored and faced on one end in one operation to guarantee the desired condition, with the other end either faced in soft jaws or ground on a surface grinder, insuring parallelism A reasonable corner radius, inside and out, is desirable to minimize the chance of burrs being raised on the edges, causing the spacer to tilt the cutter.

Harold

Steve Smith replied:

Mine had a streched chain. Like Steve, I replaced it with a timing belt. The small (motor end) pulley I bought (Stock Drive Products, IIRC). The large one would have been expensive (or unavailable, I don't remember which). So I turned the silent chain teeth off the old chain sprocket and machined timing belt grooves on it instead. There was enough meat in the pulley rim to do it, and the cast iron machined quite nicely.

John Kasunich

This brings up a topic that has had me a bit confused. I have a Hardinge miller with a 1" arbor which has no keyway in it. All of the cutters that I have (*lots*) for that arbor size have keyways in them. It always seemed strange that the arbor had no keyway in it.

Is it standard practice for milling arbors to not have keyways? If so, why do so many cutters have keyways? Are there special keys with a proper radius on one side that I should be using with these cutters? It would seem that the arbor should have a keyway in it to keep the cutter from slipping and marring the arbor.

What's the best practice for installing keyed cutters on a "keyless" arbor?

Hey Jeff,

For starters, try here:

from a Google for "silent chain".

And sadly, lots of these old machines are going to the scrap yard. You may be able to find freebie parts on the internet somewhere.

I can't speak about silent chain, but be aware that in many cases where there is such extreme wear of the chain as to cause "slipping", the drive and driven sprockets are very likely to require replacement as well. In fact, maybe even sooner than the slipping occurs

Take care.

Brian Lawson, Bothwell, Ontario XXXXXXXXXXXXXXXXXXXX

The mechanical advantage side cutters have is tremendous, especially when a cutter is used to its capacity. Running one without a key is not only not a good idea, it's down right stupid. There's little doubt in my mind that you could tighten a nut tight enough to drive a cutter that'd be doing serious work without overstressing the thread. Not only should the cutter be keyed, the outrigger bushing should be as well. You don't want it to spin on the arbor, galling in the process.

The arbor you have may be home made by someone that knew that the keyway would cause the shaft to distort, so they left it out. Such an arbor would be, at best, suited for the use of small, narrow slitting saws only. One could also conclude that the arbor was intended for inspection or cutter grinding use only, where there would be no load applied that might spin the cutter. I would strongly suggest you do not use it for milling, especially if there's a heavy cut involved, for often, when they slip, they ruin the arbor by galling. The resultant slipping then loads the cutter heavier because it's not taking the cut and can lead to bending the arbor or doing other damage because the feed mechanism is then overloaded.

Harold

I made some for my arbor (homemade) out of 1 1/4IPS S40 pipe, had to take a small cut out of the inside to get it to 1" ID (wasen't a full clean-up, but close) and made sure the ends were parallel. They work well enough for me, but then I am not too fussy. Steve

Hardinge mill arbors do not have keyways in them. What you have is probably just as it left the factory in Elmira lo many years ago.

Harold has forgotten more about machining than I'll ever hope to know, but in this instance I'll have to be contrarian to his comments. In my own experience I've never had any problems with cutters slipping on either the 7/8" or 1" arbor that I use on my Hardinge UM mill. I just used it the other day with a 2 1/2" slabbing mill and didn't see any problems, but probably wasn't pushing the mill to its limits either.

There is no bushing on the overarm of a Hardinge mill either. The end of the arbor has a taper that fits in the socket of ball bearing in the overam support.

Quite possibly the smaller work envelope and ensuing smaller cutters typically used on a Hardinge mill made the designers feel the keyway to be unecessary. And who am I to argue with them? Hardinge was never known for taking cheap short cuts.

Dick

What he said. Although I also don't push my UM to heavy cuts, I've never seen a plain milling cutter spin on my keyless arbor - which is stock from the factory.

Jim

================================================== please reply to: JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com ==================================================

Harold,

I think you are right, but wrong in this case. If I remember correctly, the Hardinge mill has a 5C drive. And if you can shear the drive key on an R-8 Collet, then you can do it to a 5C drive key, though it might take twice the torque. What ever the torque required to shear the 5C key, it has to be less then the standard key way on a 1" arbor. Personally I would like the cutter to slip before the drive key shears.

I have a Burke with a B&S #9 drive (if I am remembering correctly), and I have slipped the drive belt before slipping the cutter or arbor. Though I have slipped the cutters on the arbor, which is better then the arbor in the spindle.

I believe the clamping force on the arbor nut is much higher then you might think.

Vince

Harold & Susan Vordos wrote:

Dick,

Thanks for your very kind remarks. For you, Jim, and Vince, in this particular instance it's clear my experience with larger mills was not taking into account that to which all of you have alluded, and I stand corrected.

The bulk of the horizontal milling work I had was running K&T mills where we'd take cuts that would leave you wondering what kept the cutter intact. It was clear in those instances that you could not get away without a key, including one in the outrigger bushing. As I result, I apparently have a bit of tunnel vision. I had addressed, at least in part, using narrow slitting saws on arbors without keys, but it's clear one can get away with more than that.

It's been interesting to read the experiences of others and understand the greater capacity than I had envisioned.

Harold

In addition to the normal 5C alignment key, the Hardinge TM also has a heavy drive collar with two square dogs engaging notches in the spindle, with a Woodruff key to the arbor.

Pete Keillor

LOL. What you say there is, you could flop one of our hardinge UM machines up onto your Kearney and Trecker table, and just cut the thing right in half, without even using the power feed.

:^)

To put this in perspective, the UMs have a two speed motor, and I think it's rated at 1 hp on the high speed, and half horse on the low speed. *That's* why they get away without a drive spline on the arbor.

Even so, I'm always amazed at how fast they can remove metal with such low hp. I think if I ever saw a real horizontal machine in action, I'd probably pass out.

Jim

================================================== please reply to: JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com ==================================================

That's an interesting observation. The builders of machines appear all too aware of the hazards of slipping components. It goes without saying that the #50 taper devices used on the larger machines (K&T, Van Norman, Cincinnati, etc.) were equipped equally.

Cutters that fail to turn while cutting create monumental problems almost immediately. Considering the minimal amount of HP that Jim mentioned on the small machines, I think it puts the issue of no keyway perfectly in focus. It's pretty obvious that one would experience motor stalling before cutter slipping, assuming everything is assembled properly. There isn't enough power available at the arbor to do the kind of damage possible on the larger mills, with their gear reduction transmissions and high horsepower motors.

Harold

I second that-- same experience. My #4 burke mill 1" factory arbor is keyless. So is the 7/8" arbor. The cutters rarely slip -- when they do it is usually because I haven't cleaned the cutter or arbor spacers properly. The keyless arbors have one significant advantage -- they slip when overstressed and abused. This is especially important when you take too big a cut and the cutter digs in. Much better to deal with a slipping arbor than with broken cutters or broken mill.

Boris

Not an advantage if the mill has power feed. Load gets too high, cutter slips. Cutter is no longer cutting, but power feed is still pushing. The "push" can bend the arbor or damage the power feed mechanism or other mill parts.

John Kasunich

I have a power feed. I have a 1.5 hp motor running through a 4:1 gear reducer. Depending on the drive belt position (one of three) and the gear selected (one of four) I can further reduce the speed and therefore up the torque -- my lowest speed is about 75 rpm -- which is roughly a 20:1 torque increase. Now that's one hell of a lot of "push"as you put it. Just has never been a problem. Here's what actually happens if I set things wrong and the cutter digs in -- other than ruined work, of course:

Cutter digs in to the work. Power feed drive belt slips and then the power feed lever kicks out. Cutter slips on arbor. Drive belt slips on motor. All that takes about 50 milliseconds, by which time I've already hit the off switch. Sometimes, especially with soft metals such as aluminum or brass, the tool digs in and starts to slip on the arbor -- maybe a revolution or two before I hit the off switch. BTW, I don't walk away from the mill when taking big cuts where cutter spinning on the arbor is possible. As for damage to the mill -- It hasn't happened in over 15 years of my usage. The over-arm is 2" crs, the arbor is 1" -- no damage to them or anything else. I think that the damage to mill is far likelier if the arbor were keyed. Why would Burke arbors for the number 4, all be keyless otherwise.

Boris

What a world of difference between industry and home shop work! Your comments remind me of a friend that is quite pleased that his lathe can be stalled by hand, a safety feature should one get tangled in the machine. You do that on industrial machines and you expect someone is going to be seriously injured. A lathe that would stall would be quite useless.

Any of the conditions you described would have lead to something breaking on larger horizontal mills, or at the least damaged. A stalled cutter, one that was being used without a key, or one that sheared the key, would have lead to serious consequences, a broken cutter, a bent arbor, etc.. If you've ever watched a large mill running a side cutter of a reasonably large diameter (lots of teeth), with appropriate feed rate, the travel is so fast that unless you are standing on the switch anticipating the failure, you'd be in trouble. It is becoming clear that this thread is showing two distinctly different set of circumstances and they don't cross over very well.

Harold