[How do I?] Problem Lowering Milling Head, Round Column (3 In 1)

Dataporter

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Hello, I have a 3 in 1 machine that has sort of a round column to raise and lower the milling head. It's about exactly in the center of the picture below. The column is threaded so that you can use its collar to raise the head up. The problem is I can't get the head to go down once I've raised it up. The only way I've been able to lower the head is by carefully hammering on it. Is there a better way?

RoundColumnProblem.JPG

You can see the pinch bolt at the lower left of the Smithy belt speed chart. True confession, I have tightened that pinch bolt pretty tight a few times. It is very aggravating when the head moves during a milling operation.... Thanks in advance for your suggestions! Best Regards, Dave
 
It may be binding in the hole. try lifting the quill end to even out the pressure on the column. I also suspect there may be more pinch bolts.

The head moving while cutting may be caused by "Climb" milling, which is where you are feeding in the wrong direction and the cutter is pulling the work into itself and taking to large of a bite.


John
 
I hope this won't be laughed at - But on my 3:1 - I put a small hydraulic bottle jack on mine to add rigidity, and keep the head from sagging. Could you put some 1/4" plate in there and pop in a bottle jack? I have a tube extension I put on mine. I realize it's a temp fix, but takes 15secs to just snug up when I run.... Just a thought over coffee!
 
I have that same problem with my drill press. It is because the weight is off center of the column so it tends to cock and bind. I find I have to use the quill to help lower. With just a slight amount of upward press and then slowly releasing the upward pressure the head moves down the column. It''s safer than hammering on anything.
 
Do you have a spanner wrench for the threaded collar? If not make one with a long enough handle to make it easier to turn.
 
Thanks for the replies. I'll try lifting on the quill end. There is only one pinch bolt. The threaded collar has a handle and it only lifts the head up. Gravity is supposed to (and used to) bring it down. I can hang all my weight on it, spin it around, etc etc It won't budge coming down. Some day I'll pull the head off and see what I can see, I'm afraid it may be difficult to get it back on. I don't like hammering on anything. I guess I should be looking for a real milling machine that is not too small and not too big. Thanks again
 
Well, good news. Tonight I had to raise the head to accommodate the set up I was doing. I had a heck off a time getting it to go up! I decided I'm going to take it all the way off to see what I can see. It really didn't want to move either direction, but I stuck with it. I got it up as high as I could and decided to climb up and look down into the keyed shaft that runs up the column to drive the mill. That sucker was rustyyyyyyyyyyy. I sprayed some penetrating oil down in there and worked it up and down a little. Viola! That was the problem! The round column and the pinch bolt were not the problem. It was the rusty center shaft. Now it goes up easy and gravity pulls it down. Whew! I'm happy!
 
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