How to tighten the two big nuts on a Sherline 2000

[j ferguson]

I bought the MB vise-clamps referred to in another post here and am much impressed by them - just the thing for grabbing work pieces like those I use.

But there was a problem, with the two clamps secured to the table, a 5/8 inch thick workpiece held by the clamps wouldn't clear the bottom of the Z axis way which meant I couldn't do what I'd had in mind. But wait!!

With the Sherline, I could add a 2 inch spacer to the support column. I did this and by also using a Beall spindle I was able to cut the metal I intended. It's possible that I took too enthusiastic a cut into the 6061 - .250 2/flute bit .040 depth and 5 ipm feed at 2500 rpm, but it did seem to work ok.

After a while it got noiser and I realized that the setup had come unstuck.

I concluded that I should have better tightened the two 11/16 nuts which secure the head radially and in pitch. I'd tightened them by hand using a box wrench with an 11 inch handle. I can vaguely remember my boss 60 years ago tightening similar bolts on the old Brown and Sharpe first strong arm and then by whacking the wrench with a bronze hammer a few times until the wrench wouldn't turn any more.

What I'd done on the Sherline was to tighten as far as I could and then hit the hand holding the wrench with the other hand to give a bit more torque.

So how do you get these nuts tight, and do I really need to worry about over-tightening them??

 

[EricB]

Make sure all the mating surfaces on the column and ram are clean, dry, and free of any oils. Tighten the nuts by hand with a wrench. Take much much lighter cuts!

 

[j ferguson]

I bought a Blanchard-ground 8x8x1 plate on Ebay. There was no spec for what to expect but then it didn't cost much either. It was 1.0025 +/- but was very flat and the thickess was even on the sides and corners to about .0005, which for trammeling a Sherline ought to be plenty good. I have to assume the middle is the same although when I'm setting up the Sherline, the indicator mostly traces a 6 inch circle.

I clamped it to the bed and found that now that it is so easy to swing the indicator around, getting the Sherline dialed in is much easier. I don't know why I didn't think of this a long time ago.

in any case, I dissassmbled the ram and cleaned it up - it wasn't really oily and no chips. Doubting that it is possible by hand to overitghten this nut, I did lean on it, and then whacked the wrench with the heel of my fist a couple of times. My thought is that if it loosens, it probably should.

The pitch adjustment has the wonderful screw which makes it pretty easy to get the X Axis dialed in. I did not disassemble this but tightened the nut in two stages, checking to see that nothing moved. And again, tight by hand and then a couple whacks on the 12 inch wrench with heal of hand.

And yes, I'll take lighter cuts.

thanks much.

John