Countershaft very HOT.

ThunderDog

ThunderDog

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Let me put as much info as I can to solve what should be a simple problem.

Atlas MFB
Cutting mild steel
Using 1/2" end mill (because I don't have the original arbor...yet.)
Each pass I raise the knee (Y axis, correct?) to a depth of cut set for .010" - .015" and my Z axis(parallel direction to the spindle) is always set to .125" cut.
Tried all of the various back gear speeds (160? rpm(can't recall the setting at the moment) and 440 rpm)
Tried table feed set at .006" and .003"
I've adjusted the countershaft screws for the pulleys to the point just beyond where the belt will slip as I don't want to burn up the belt. The problem then is that I can't take but the tiniest of cuts without the belt actually slipping. So, I tried tightening the belt so I can actually take a cut. But then the countershaft bearing heats up real hot, like 150º hot measured with a infrared laser thermometer.
I checked the alignment of the countershaft pulley in relationship with the spindle pulley using a straight piece of square stock and it checked out fine. Of course, the heat is being transferred through the pulley to the spindle which measured much cooler but still hot for my liking. 90º on the spindle pulley.
Everything is oiled with Mobil Velocite #6 spindle oil.

My thoughts, just buy a new belt after work to eliminate that variable. I'm probably overthinking all of this, right?:D
This all got me thinking, what's the average depth of cut that one can expect from this machine using an end mill. I know that question has alot of variables like material being cut, type of cutter, etc. Just trying to learn this new to me machine.

Pic of what I'm talking about for clarity. The front pulley/bearing are the hot spot.
Pulleys.jpg
 
I know you said that you checked the alignment with a bar, but is it possible that it is seizing within its journals? When is the last time you cleaned out the oil port holes?
 
What I'm seeing looks like grease on the end of the shaft, not oil? How often do you add oil or need to add oil?
 
I think you answered your own question. I would try a fixed length belt. I have link belts on a couple of woodworking machines, a jointer and drum sander. Both work well. If the belt is slipping I would try a different belt. I liked the cogged V belts even with normal pulleys since they flex easier on the smaller diameter pulleys.

I am not surprised the tight belt is causing heat. A lot of friction with a tight belt on the solid bearing shaft. If these were roller or ball bearing, they could likely take the pressure without heating up.
 
I completely disassembled and cleaned this machine and have only ever used oil. The oil ports were cleaned and cleared. Didn't they originally have some type of filter material in the oil ports to keep dirt out? Mine never had anything inside of them.

Rustrp, I thought the same thing when I started using the machine.
I was thinking, "Wow that's spewing dirty oil already? Here, let me wipe that off with my finger(machine was off, of course). WOAH, that's hot!!":eek: And then the investigation began...

I'll change the belt and post my findings later this evening.
 
ThunderDog said:
I completely disassembled and cleaned this machine and have only ever used oil. The oil ports were cleaned and cleared. Didn't they originally have some type of filter material in the oil ports to keep dirt out? Mine never had anything inside of them.

Rustrp, I thought the same thing when I started using the machine.
I was thinking, "Wow that's spewing dirty oil already? Here, let me wipe that off with my finger(machine was off, of course). WOAH, that's hot!!":eek: And then the investigation began...

I'll change the belt and post my findings later this evening.
Click to expand...
Not filter material, but felt. The felt holds the oil so it gets a steady stream of oil. It wicks it down. That might be your problem, you might be slinging it out w/o a felt. You are relying on only whats there at the moment, there's no constant delivery system.
 
ThunderDog said:
10-4. I'll definitely add that.
Click to expand...
Generally there are 2 ways that felts are installed. One there is a key way cut in the bearing. The felt fits in there and wicks the whole bearing length. The other is that the feed tube will have a felt installed that will hold the oil and contact the journal. That's for smaller journals. Larger use the keyway. At least from the couple of machines that I have rebuilt .
Others may have more info. See if you can get a diagram of your assembly and see how and if felts were used. If you don't have oillite bearings, chances are they need felt.
 
By looking at your pulleys there either worn badly or the belt needs to be wider 5/8" instead of 1/2". The red belt is riding way to low in the pulley . The flat of the belt should be level or a tiny bit above the pulley. Just my observation of the set up.
 
I think we can put a lot of emphasis on the belts but if the belts were at issue it would be the pulley that's hot, not the end of the shaft, although you did say front pulley/shaft. If it were the belt, that's a lot of heat transfer to get the shaft hot to the touch and if so the belt should be close to smoking. Based on your comments it does seem to be a lubrication issue. I'll ask something that you've probably already checked, but with the belts off, does the shaft turn freely?
 
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