4 Bolt Compound Clamp

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The number one mod suggested by people who own a "9x20" lathe is a 4 bolt compound clamp. Here's how I made mine.

I followed the drawing linked on Steve Bedair's Lathe site.

Starting with a chunk of 16mm thick steel, I cut an overly long section off. Marking the centre, it was drilled and a bolt tightened through it. The part was mounted in the 3 Jaw chuck and the outer section (that forms the bolt-down tabs) turned to thickness. An Annular cutter was used to punch a large hole through the centre.

The part was flipped, the centre hole opened up, and then the various counter bores cut to fit the division ring. The corners of the piece were taken off so they didn't interfere with the top slide's handle when rotated.

The bolt holes were drilled, and then counter bored using an end mill. This didn't go very well because all I had was a pillar drill with a sloppy quill. I have since bought drills specifically for counter boring, and had much better luck. The clamp was then finished in my fathers milling machine, by tidying up the saw-cut edges.

My clamp is a fair bit thicker than suggested, and as such, I have had to thin the heads of the bolts clamping it to the cross slide. My cross slide was also altered to fit an off-the-shelf tee nut; of which I bought a meter length and so have full length 'nuts' installed. This prevents the buildup of swarf in the tee slots, and is much nicer than the ground down hex-head bolts that came as standard.

Here is a poorly edited Youtube video of how I made the 4 bolt clamp.