How to Make Circular Clamps - the Good and the Bad.

Making clamps is a common task for those who make stuff. This Instructable is about making circular clamps in general and clamps for the quill of milling and drilling machines and objects like high speed spindles and routers in particular. Clamps are simple devices but there are some traps and there are many cases of bad design and manufacture which I outline in the video. The video is the best resource but I will duplicate some operationss below illustrating some steps in making a clamp for my mill.

Here is the finished clamp that I made to clamp to the quill of my Bridgeport milling machine. To the left is a beam to connect to a ball screw to drive the Z axis, to the right is another but integrated clamp to hold a high speed spindle.

The first step was to bandsaw out the rough shape prior to finishing by milling. This was sawn out of some scrap aluminium tooling which I had been keeping for reuse in projects. This plate was 40 mm thick and I will machine it down to 35 mm. The plate had numerous holes from its previous life and it took some trail and error before I found an area where I could get the object without unwanted holes.

After cutting out the basic shape the next task was using hole saws to rough out the clamping bores. They will be finished on the milling machine. The first picture shows the plugs cut out with the hole saws.

The nearly finished clamp, with the outside milled to the final shape and the bores machined to size.

The left hand end of the clamp needs a slot for the tang on the ball screw to fit. Being aluminium there is a chance that the ball screw would brinell into the clamp over time and use. To avoid such a problem I inserted a stainless steel slotted bush. The sequence of photos show how the clamp was bored and the insert slot milled.

In conclusion I suggest that you view the video for the full story and hints to design a good clamp and avoid problems.

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