Atlas Mill HELP!!!

ThunderDog

ThunderDog

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My issue has to deal with the spindle pulley cone moving along the spindle under power.

I made a temporary unlisted video seen below. Any help would be appreciated.

 
Just a quick question. Is your driving pulley running true and aligned? If the driving pulley is wobbling it can show up this way.
 
The spindle is captivated on each side by the tapered bearings. That collar does not serve that purpose.

The collar on the left should be pushed to the right to hold the pulley/gear assembly to the right, close to but not touching the bull gear. There is a small set screw in the collar for that purpose (maybe two setscrews), which should be tightened, preferably against a flat on the spindle. Similarly, the bull gear should be fixed to the spindle using a set screw. By the way, there is also a set screw in the pulley. This set screw is an oil hole. Do not tighten it.

There are dogs, or large teeth, on the mating surfaces of the gear and pulley. They should always be fully engaged. If they slip apart under power the teeth will likely be torn up. Replacements are not easy to find. I went through that on my mill and ended up having to buy a whole headstock on eBay for $250.

I don't like that little collar with the little set screw. I think it could easily slip to the left and result in damage to the gear and pulley. And, the set screw tends to damage the spindle, making the spindle hard to remove. I'd like to replace it with a compression type shaft collar.

I'm probably not explaining this very well. If you want, I'll PM you with my phone number.
 
JPMAC, that makes sense. Let me see if I follow exactly what you're saying. It sounds like I have two things that I need to address. The first being the collar moved toward the pulley cone. The second is setting the bull gear. It needs to be tightened to the spindle via the set screw to prevent it from front-to-back movement. And for clarity, the pulley cone has two set screws and they are NOT to be tightened as they are simply oil feed holes.
 
I had a similar problem with my mill. You are correct with what JPMAC posted. One other issue I had when I removed my spindle was that the set screw would not tighten down all the way. I ran a tap in and was then able to tighten the set screw and hold the bull gear in place. The bull gear has 2 screws in it. The one that is by the pin is used to hold a ball and spring for a detent for the pin. The other is the set screw from the shaft.

Also there is a shoulder on the shaft that the cone pulley rides against and you set this position first and then set the bull gear. There are 2 bushings on the cone pulley and in my case one of them was pushed deeper into the pulley. I ended up replacing it with a flanged one that I turned the flange off but left in a little proud so it was tight at the end that had a little bell to it from sliding back and forth.
 
Thanks everybody. Everything is good now. I was messing with this late last night and can't believe I couldn't figure it out during that time. Must have been the daylight savings time screwing with my head. If you think about it the collar and the bull gear act as a trap for the pulley.
Oh well, I appreciate the help.
I'm going to leave the video up but will keep it unlisted for the hobby-machinist forum. It's like an exclusive pass...sort of.:D
 
TDog,

If you haven't already done it, go to DOWNLOADS (instructions for navigating DOWNLOADS are in the Sticky area at the top of this Forum) and download Atlas Mill Bulletin MMB-5 M1--MHC Rev6.pdf.

To add to what was written earlier, in the right side of the large spindle gear (AKA Bull Gear) is the Direct Drive Pin. When the machine is in Direct Drive, the pin is pushed in so that the hidden end of it enters a hole in the right or front face of the pulley, locking the two together. Locate that pin and make a mark on the pulley with a Magic Marker in line with the pin for future reference.

After you have re-positioned the spindle components, pull the pin out so that the pulley is free to rotate independently of the Bull Gear. There is a special tool for that purpose. The factory drawing for the tool is in DOWNLOADS.

Remove the oil plug (there is only one in the pulley, not two, and it looks like a set screw) from the pulley and squirt some SAE 20 (ISO 68) Non Detergent oil into the hole(it probably hasn't been done in years). Reinstall the plug and briefly run the motor to distribute the oil. Repeat at least once this time only. In the future, if the back gears are used routinely, oil the pulley bushings before each use. Otherwise, oil them about semi-annually. The rest of the instructions above are correct except that the running clearance between the pulley and the bull gear should be about 0.002" to 0.004".
 
Wa5cab, thanks. I like the marker trick idea. I completely rebuilt the thing so it is well oiled. I use Mobil Velocite #10 on all spindle parts, it's what I buy from bluechipmachineshop.com

Not questioning you, but my pulley cone has two set screws. One is in fact labeled "oil", the other is not. This thing was modded by a previous owner who welded a vertical head to the overarm support. So, it may have been done as apart of their lazy engineering hack, too. I say this because upon disassembly I noticed that the bull gear was missing the woodruff key. Perhaps they hacked the spindle pulley to be permanently driven by adding the second set screw. Who knows, all I can say is that it's working like a charm now and I'm quite impressed with the little machine.
 
OK. The unnecessary modifications to these machines continue to amaze me. It is quite possible that they didn't know haw the back gears work. T existing oil plug is supposed to be a headless Allen socket cup point set screw. If the added set screw hole is tapped through to the ID of the pulley, and the other one still isn't, I would suggest using a slotted set screw in it, with a little red Locktite. Run it in just to flush with the bottom of the pulley groove and let it cure overnight.
 
I'd suggest using a proper-sized belt instead of the link belt stuff, or one of those new urethane belts that you cut and melt together. The link belts seem to chew up the ZAMAK pot metal and aluminum pulleys.
 
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