About a year or so ago--maybe a little longer--I spun a collet in the quill of my Grizzly G3616 mill. This created a burr way up in the quill which prevented a collet from being inserted easily. However, other tooling inserted without problem. (Upon measurement, I determined that my collets are about 0.0005" more in diameter than the R8 arbor on my drill chuck.) The mill was fully operational other than this issue, which was a pain. I also THINK I can detect a rattle in the quill bearings at 2950 RPM, my mill's top speed. I may be imagining it, though. I am going to send the spindle to Grizzly for them to remove the burr and replace the quill bearings if they determine them to have an issue.
Removing the spindle was straightforward, with some help from Grizzly. The support was good, but my mill was discontinued some time ago. The tech missed two set screws, one of which he finally discovered upon my difficulty in removing the down feed spring housing and the other which I discovered after "taping" (driving) the splined down feed shaft out of the head. The hard steel of the shaft and the spline were not marked by the softer set screw. With a tiny bit of work with a file or on the grinder, the set screw will be serviceable, also.
This topic may be of very limited use to most folks on this forum. However, the 2HP, 1450 lb G3616 was a pretty popular mill. It is very rigid and will hold a very good tram forever. (At least several years, in my case.) If someone searches the internet for instructions concerning the removal of the spindle from this mill, perhaps they will find these instructions.
1. Remove the drawbar.
2. Lock the quill in place.
3. Support the spindle with a block of wood on the mill table. (I used a 2x4.)
4. Remove the screw holding the cover of the down feed spring housing in place and remove the cover.
5. Under the head you will find a set screw that holds the down feed spring housing in place. Loosen that screw. Note that my set screw has a straight head. Yours may or may not.
6. Remove the spring housing. It should be easy at this point. Simply pull it out, maybe with a twist. The spring will expand in its housing when you pull the housing off the down feed shaft. This is a gentle action, not a big SPRONNGG! action.
7. Completely loosen the fine down feed lever and remove it and its integral bolt with spring from the down feed shaft.
8. Remove the three SHCS holding the fine down feed lever and remove the cover which they hold in place. (This may not be necessary, but I did it.)
9. Remove the three SHCS holding the down feed housing in place.
10. Remove the down feed housing. Note that there are three pins that locate this housing on the head. They are not fixed. Don't lose them.
11. Remove the key from the down feed shaft. Mine just lifted out using my fingers.
12. Remove the worm gear from the down feed shaft. It should just slip off. (The "worm gear" is just a regular-looking gear on the down feed shaft. The worm is still in the housing you removed in step 10.)
13. Looking at the down feed shaft, you will see it has a bushing locating it in the head. There is a set screw underneath the head that holds this bushing and thence the entire down feed shaft in place. Totally remove that set screw. Note that my set screw has a Phillips head. Yours may or may not.
14. The down feed shaft should now slip out of the head by pushing or tapping with a rubber mallet from the spring housing side. If you have to tap it out, do so very easily so you don't send it shooting out the right side of the head and off into space.
15. The spindle is now resting on the block of wood you placed under it in step 3. Lower the table until you can remove the spindle from the head. Remember that the drawbar housing extends several inches above the spindle. But, it is narrow in diameter and you can simply tilt the spindle out of the head once the top of the spindle is free of the head.
Here is a picture of the spindle . . .
