Originally Posted by ogesII  I picked up an old M-head this weekend. Using the course quill feed requires about 15lbs of breakaway and 12lbs continuous pull at the end of the 8" factory lever. This seems stiff to me. I am thinking I should pull the head apart and see if there is a surface I can hone out to make round again. Thoughts? The pull does seem to be the same throughout the travel so it isn't just one sticky spot. |
That sounds like trouble to me. There may be chips stuck in the quill bore or some other mayhem. There is a "quill skirt" screwed to the top of the quill, and sometimes these get severely mangled.
Anyway, this is easy to disassemble. First, remove motor with two big screws. Then, there is a sideways clamping bolt that holds the belt housing to the main spindle housing. Loosen the bolt and you can rotate the belt housing. Now, you have to dismantle the collet pusher ring at the top
of the spindle (I'll talk more about this below). Then the belt housing can be lifted straight up.
The pulley is splined, so you have to lift carefully to slide it up the spindle spling and not bend the spindle.
Now, you can look down into the main casting and see what is going on, check the ID of the bore, etc. Or remove the quill skirt. Then, you can remove the clock spring that counterbalances the quill, the worm gear and pull the quill pinion out the right side. You need to block the quill up or it will drop at this point. By rotating the head, you can drop the whole quill out the bottom. Now you can examine the entire quill OD and the ID bore in the head for burrs and embedded chips.
Oh, you mention the fine feed doesn't work. There is a clutch knob on the left side of the clock spring mechanism that grips the worm gear to the pinion. If that knob is tight, there is a lot of friction to the pinion and handle. But, with it tight, the worm will drive the pinion. With the knob loose, the quill handle should be loose.
To make the fine feed work, there is a coaxial rod in the center of the fine feed shaft that engages a gearbox to the worm drive. (I never understood this, as there was no power feed to the feed handle, so why they needed a reversing gear here escapes me.)
There is also a collet stuck in the spindle. I have been running penetrating fluid down the drawbar hole a couple times a day for the last two days. Then with the drawbar loosened a turn or two I tap on the top of the draw bar. If I am doing everything correctly, I am only using nut 'A' in the image below. Is there anything I can do with nuts 'B' and 'C' to help with removing the collet? Or what are they for? |
That ring you call "B" is the collet ejector. I never had one on my M head, but it was pretty obvious what it was for. It presses down on the top of the drawbar, forcing the collet out of the taper. For a normally-tight collet, it is enough to press down and push out the collet. But, if the collet is REALLY stuck, the drawbar may bend, the ejector will break (like mine probably did when they got an endmill holder stuck in it) or the threaded insert in the collet will punch inward.
It should unscrew relatively easily from the top of the spindle, allowing the whole drawbar to be removed.
Nut "C" is the top of the driven pulley, the one with the splines that drive the spindle.
Jon
11-16-2009, 10:17 AM
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