Archives for posts tagged ‘brass’

DIY tube-bending tool

My plans for the milling machine oiling system call for some small-diameter bent brass tubing. I looked into the various tools designed for this, but the high end is too expensive and the low end looks pretty cheesy. I also wanted a small bend radius, which is hard to come by in off the shelf tools. It seemed easy enough to design a simple bending tool, and besides there’s nothing I like better than making stuff that makes other stuff.

My tubing has a 3/16″ OD and I was aiming for a 3/8″ bend radius (to the centerline of the tubing). I only anticipate needing 90 degree bends, but it didn’t seem any harder to allow for 180 degree bends. With these parameters I modeled up a simple design in CAD and ordered a few pieces of brass and steel from onlinemetals.

The first step was to grind a lathe tool blank to a 3/16″ diameter half-round shape. With this I turned some 3/4″ brass round rod into a set of rollers that closely fit the 3/16″ tubing.

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I then milled the end of a 4″ length of 9/16″ square brass bar to accept the smaller roller, and drilled it for a tight fit to a 1/4″ dowel pin (1″ long).

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I then drilled two 12″ lengths of 1/8″ x 3/4″ mild steel to accept the two rollers and welded two more shorter lengths of steel to create a rectangular tube handle. Done and done!

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The square brass bar is clamped into the vise, and the tube to be bent is gently clamped to the brass bar with a rubber-jawed clamp. The first test worked perfectly!

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The bends aren’t perfect– there’s a small amount of collapsing, probably from the small bend radius and the imperfect roller profiles. But I sawed through one of the bends at the thinnest part to see how much collapsing there was, and I think it’s acceptable for my needs.

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Here is the collapsed section (top) next to the normal tube section for comparison. Not bad!

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Next step: experiments in brass soldering.

CNC mill oiling system – plumbing

This is it… Grizzly Miller is in several large pieces on my bench, and the major upgrades have begun. First up, oiling system.

I made some refinements to the original concept and even built a tube-bending tool for the small brass tube I’ll be using.

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First step was machining the X and Y axis ways on the mill’s cross slide. I used a simple ‘S’ curve, programmed point-by-point into an old ProtoTRAK-converted Bridgeport. On the same machine I pocketed out some clearance for the X-axis ball nut.

Beyond these sketches, most of the design work happened on-the-fly. This is unusual for me, but I don’t have CAD data of the original milling machine parts, and tube fabrication turns out to be more sculpture than engineering anyway. I also bought a silver solder kit specifically meant for joining copper alloys, and tried a small test piece from some scrap material.

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I then fabricated the main brass manifold and mounted it to the cross slide. From there it was a matter of drilling end points in the cross slide and connecting the dots with brass tubing. Each of the four ways are connected with my modified banjo fitting, which allows for flow control adjustments. The two ball nut mounts were modified to accept an oiling tube, which will simply splash each ball screw with oil. The manifold will be fed by a flexible tube, which will attach to the little stub coming off the manifold.

The soldering process is messy and dangerous, but once the parts are cleaned up they’re really quite beautiful.

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The finished cross-slide assembly:

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The Z-axis got a similar treatment:

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More to come, stay tuned!