What's new
What's new

Torches and pitchforks in the village !

stoneaxe

Stainless
Joined
Mar 2, 2010
Location
pacific northwest
The peasants are rioting! Dr. Van Normanstein has brought the monster to life!:D :cheers:

The VN 12 has stirred from it's long sleep, spindle , feed and coolant motors all work, gearboxes have no weird noises, table feed works, so it it getting very close to operation.

The spindle has a very, very light low frequency vibration, either transmitted through the gearbox, or the bevel gear, or more likely the spindle bearings- I think this because the vibration is not uniformly cyclical, it is a bit erratic, not tied to rpm on a one for one basis. this is only evident when a hand is placed on the cutter head, the spindle runout on the OD of Chinese endmill holder is a half thou - so I will watch and see.

The stop- start contactor has some mechanical problem, the solenoid gets energized but the mechanism is too sticky and rough to allow it to throw the lever arm in and out. , I will need to take this apart and look at it. The machine runs ok using the FWD STOP REV switch to control it.

The feed chain needs to be tightened, as the chain jumps teeth when it is set for a high feed rate, I should probably install the new (er) sprocket- but I need to bore and broach it-it has a 1/2" ID with no keyway, just a set screw. The feed motor and original sprocket on the machine has a 5/8" shaft with a keyway. This is evidently a later model than my replacement sprocket. Hard to imagine a non keyed sprocket standing up to that sort of service.

I will post pics of the two different sprockets later, as I am busy right now with an angry mob outside the castle doors. "Igor! Bring the oil!".
 
When I had a #12, it had a 1/4 HP motor on the feed box, so 1/2" shaft sounds right to me. I wonder if someone put a bigger motor on yours, don't think you need it with the gear reduction. Good to hear it's running.
Jim.
 
Fixed the stop-start solenoid using the old" wiggle 'n jiggle it" trick, seemed to free it up enough to work, expect there are some dry or rusty linkages back behind the contactors- probably need to pull it and clean and lube.
 
...
The spindle has a very, very light low frequency vibration, either transmitted through the gearbox, or the bevel gear, or more likely the spindle bearings- I think this because the vibration is not uniformly cyclical, it is a bit erratic, not tied to rpm on a one for one basis. this is only evident when a hand is placed on the cutter head ...
How did you adjust the mesh of the cutter-head bevel gears?

Cal
 
Cal , ya got me all nervous now, with the gear engagement question. I did no adjustment to the cutterhead bevel gears at all- figured " iiabdfi" (if it ain't broke don't fix it) how would one check this fit?
Have not really run the machine yet, been swamped with my real job. :crazy:
 
Setting Spiral Bevel Clearance

Cal , ya got me all nervous now, with the gear engagement question. I did no adjustment to the cutterhead bevel gears at all- figured " iiabdfi" (if it ain't broke don't fix it) how would one check this fit?
Sorry I missed this the first time around.

The spindle gear is keyed to the spindle and able to move back and forth to adjust the mesh with the gearbox pinion. Over the lifetime of the No. 12, Van Norman tried several methods of adjusting the mesh of the bevel gears; all involve a threaded ring that controls the position of the spindle gear. The first generation of cutter-head, used prior to 1947, had a threaded ring, running on threads on the spindle, that was clamped to the back of the spindle gear by a large washer and 4 bolts. The clamping bolts could be loosened and the threaded ring rotated to move the spindle gear in and out of mesh with the gearbox pinion.

I’ve never done it, but as I understand it, adjusting the mesh of bevel gears is done by “bluing” one of gears with something like Dykem Hi-Spot Blue, putting the gears together and rotating them through a revolution or two. The transfer of the marking compound from one gear to the other gear is used to guide adjustment of the mesh.

In the case of a Van Norman cutter-head, spindle pre-load needs to be adjusted before the spindle gear can be adjusted. If the bearing preload is set with the cutter-head on the ram, and the spindle gear collar isn’t backed off while the preload of the spindle bearings is adjusted, it’s possible that the rear bearing is being pre-loaded against the pinion and the front bearing is loose. It’s best to check the spindle bearing pre-load with the cutter-head off of the machine.

While you have the cutter-head off you should run the machine at all speeds and make sure that the vibration that you are noticing isn’t coming from the gearbox.

If the spindle gear and adjusting ring are still in the as-found position, it's a good idea to put witness marks on them so that you can get back to the previous adjustment, as necessary.

Once the preload of the spindle and gearbox output shaft bearings is correct, the gearbox pinion gear can be blued up and the cutter-head installed to check and adjust the mesh of the spindle gear. This means that the cutter-head is going to have to come on and off a few times. (I don’t know what the transfer pattern for correctly meshed spiral bevel gears should look like.)

Hopefully someone with some experience setting up spiral bevel gears can provide better guidance. I have two Van Norman cutter-heads apart and I’ll have to go through this in the near future myself.

Cal
 
Hi guys I've had a fair bit of experience setting spiral bevel gears. Years ago I worked on Buss-Ko Kneader gearboxes, they are a Swiss company that made extruders for the food and plastics industries. Most of the final drives were by means of spiral bevel gears, we had to set the backlash on these gears regularly. As you said it involved much blueing, feeler gauging and running lead string through the gears etc. The Swiss kindly sent us a fully annoted drawing which showed the different blueing patterns you could obtain and how to correct them, unfortunately the drawing was handed incorrectly, very confusing !

Yes even the Swiss get things wrong, having said that these gearboxes were beautifully made and a pleasure to work on most of the time. Having said all that these machines ran slowly compared with a milling machine ( 100 rpm ish ) and the gears I mentioned were about 15 " in diameter. We aimed to get a blued impression on the middle 75 % of the tooth looking down it's length and on about 50 % of the height of the tooth in the middle. You obviously don't want to be running on the edges of the gears. Regards Tyrone.
 
Setting Bevel Gears

Tyrone,

Thanks for the suggestions. The spindle for a Van Norman No. 12 has a top speed of 1450 RPM; the No. 16, which uses essentially the same cutter-head and gearbox, has a top speed of 2000 RPM. The spindle gear for the No. 16 is 4.56" in diameter and has 45 teeth; the gearbox pinion has 25 teeth.

I don't know if it would be possible to feed a piece of fine solder in between the gears to check the clearance since the spindle and gear hide the pinion from view from the access cover. It might be possible to tape or hot-glue a piece or two of solder to the pinion and then install the cutter-head. There's certainly no way to get a feeler gage in there. Do you have any idea what sort of clearance we should be looking for?

I guess we could blue up either the spindle gear or the pinion and check the other. Is it better to blue up the smaller gear or the larger one?

Thanks!

Cal
 
Mount something in the spindle that you can put a dial indicator on at approximately the same radius as the center of the gear teeth. You want to measure how much it moves from tooth contact in one direction to tooth contact in the other. You should be able to feel the backlash rotating the spindle gently back and forth. It takes some feel, you want to move the spindle fast enough that you can feel the teeth contact, but not so hard that you move the driven gear. You should check at several points since the backlash may not be consistent. You are looking for the least backlash at any point to be your number.
 
The Dana info is very much like the info Buss sent me. Given the fact the gears I refer to were about 15 " in dia we were looking for a backlash of about 0.018" to 0.024". With smaller gears I would have thought the backlash would be a lot less, 0.003" to 0.004" sounds about right to me. These gears were a matching pair so you other question is not relevant, I'd blue the big gear in your case. Regards Tyrone.
 
Setting Spiral Bevel Gears

Mount something in the spindle that you can put a dial indicator on at approximately the same radius as the center of the gear teeth. You want to measure how much it moves from tooth contact in one direction to tooth contact in the other. You should be able to feel the backlash rotating the spindle gently back and forth. It takes some feel, you want to move the spindle fast enough that you can feel the teeth contact, but not so hard that you move the driven gear. You should check at several points since the backlash may not be consistent. You are looking for the least backlash at any point to be your number.
OK, so it more of an angular backlash that we're trying to control.

Thanks for the link to the Dana doc. That helps a lot! The only gear that can be moved is the ring gear (spindle gear), so we'll start there. If the patterns indicate that we need to adjust the pinion, then we'll worry about that when it comes up.

Tyrone, Thanks for your comments! :cheers:

I'll report back as we get when we try to put this information into action...

Cal
 
Wow- thanks for all the replies!

Do you suppose a piece of plasti-gauge could be run through the gears to measure clearance? Same stuff that is used to check bearing to crankshaft fit?
 








 
Back
Top