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Any one have any experience on what the spindle temps should normally run for the taig mill?
Even at the lowest pulley setting ~1100rpm my spindle is getting over 160f ( darn $10 thermometer read any high higher ) in just 5-6 minutes! The bridgeports I used to work on would get warm to the touch, but not burning hot!
I am thinking of putting heat-sinks on the blank faces of the headstock on the right and left sides. But I am concerned about the cooling effect distorting the headstock.
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Yeah, that's way hot in such a short time. I run mine (both lathe and mill) for hours at a stretch and it never gets more than pleasantly warm.
Nick has your best first option. Let us know if it helps.
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Well, the pulley is to close to the top of the headstock to fit a wrench in there. I loosened the set screw, and tried heat ( a hair dryer ) and cannot get the pulley off of the shaft in order to loosen the preload on the bearings.
Trying to come up with a shims or something that I can clamp around the nut under the pulley.
Do not dray to pry the pulley off. A heat gun or a propane torch (held sufficiently back from the pulley) is what you need. With a hair dryer you'll have to heat it for an awfully long time, all around the pulley to get it hot enough.
I got a chance yesterday to move the pulley and adjust the spindle nut.
I checked tir on the inside taper first and got .0005". I then loosened the nut about 1/16th of a turn, and ran it for 5 minutes to see how hot the headstock would get. I did this 2 more times to get the headstock to where it was warm but not burning hot, the spindle itself still gets burning hot to where you can't touch the spindle. The tir is now .0008".
I find that I have a real issue now though. There was a slight "click" when I went to put the collet closer nut on the spindle to run a test piece. I got the indicator back out and checked the tir which still read .0008. Using 1 finger I pushed back in the y direction against the spindle and felt the "click" again and the indicator moved .002", I used 1 finger again to move it toward me and the indicator moved .003". I then checked in the x direction and found .0015 of movement.
I decided to run the test piece anyway in order to get a better picture of how this would affect my work. I cut a .25" hole in 1/8 aluminum. This resulted in a parallelogram with one set of corners .251" apart and the other set of corner .224" apart. The mill was just re-trammed and backlash adjusted before replacing the spindle.
(I forgot to put in my original post that this is a new spindle, my original spindle threw a bearing.)
After the test piece I tightened the spindle nut 3/16th of a turn, and the tir returned to .0005 but the play was still there as evidence by another test piece.
The spindle turns smooth with no noise, so the bearings seem good ( they should be considering it is new ). So I am thinking that the bearings are shifting in the headstock. I am not sure I want to try and shim the bearings in the headstock because that would introduce new problems.
So should I try to exchange the spindle again with taig?
The bearings/cartridge is heat-shrunk into the spindle housing. There should be no play at all. How did a bearing go bad on your other spindle?
I don't know "how" the original spindle went bad. It has always made a lot of noise, it just kept getting louder and vibrating more until I decided to check the tir and turn the spindle by hand. I could hear a rattle in the bearing and it felt rough when turning by hand.
I talked to Cliff at taig and he took a look and determined that a bearing went bad.
I have my cam and post processor set to limit feeds and doc to meet the spindle speeds and materials. I usually see a max feed of about 16-18 ipm and doc around .01" to .005" and a spindle of 9800rpm for aluminum on 1/8" to 3/16" endmill. I compared this to my machinery handbook ( 1992 print iirc ) and it seems fine.
But I have only run the 2 test pieces on this new spindle. I spent the rest of the day working on true-ing the spindle to the axis and getting the pulley removed and re-installed.
If it is a new spindle (or new bearings/cartridge) then you'll need to run it a while to get it broken in. I would guess that after 10 hours or so of use you should have a good idea of what temp it should will.
My friend purposely destroyed many Taig spindle bearings by running then with no lubrication and milling 6061 Al with a 3/8" bit. It takes about 15 hours in this condition to destroy the bearings. I'm not sure what temp he was seeing though. I'll find out.
I am a little confused by the "run-in" idea. When I got this spindle I asked cliff how long the run-in should be and at what speed. He said not to worry about run-in and to just go ahead and use it. After your last post I checked for lube, and the bearings are lubed, so I put the belt on the lowest ratio, turned on the motor and walked away. It ran about 4 hours and there was no change in the TIR or play.
I have tried investigating a little farther, I took the headstock off the column and mounted it to the bed, and then mounted my indicator directly in the vise. I get a reading of about .0005 range of movement for a full turn of the spindle.
I have run out of time for today. So I will have to look for the play in the column tomorrow.
Basically they set the preload nut tight and the grease is fresh. As it wears in the bearings it loosens up and the grease migrates, etc. If it continues to be hot after many hours then it's a problem but for a new headstock then it's pretty normal. When they used to ship the 1/8 HP motor on the mills it often wouldn't run at the highest speed unless you warmed it up at a loew speed for a few minutes.
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