12mm T-slot Nuts

March 01/03/2016

These seem to be impossible to find cheaply and I needed just one for my rotary table, so instead I decided to make a dozen from a piece of EN8 1inch carbon steel bar, the rest will likely be sold. For anyone who wants the dimensions of one then here they are;

Small 12mm T-slot Design

The bar was about 300mm long so I figured this was probably going to take quite a while to machine down. I first used an indexable end mill to do the roughing work.

12mm T-slots - Starting 1", 12" long EN8 Steel bar 12mm T-slots - Milling 1" EN8 steel 12mm T-slots - milling contour

Due to the roughing mill having quite large radius corners I had to use a sharp corner end mill to do the finish profile, it also resulted in a better finish. The whole lot was flipped to have the rest milled away.

12mm T-slots - endmill swap to achieve sharp corners 12mm T-slots - milling bottom of bar 12mm T-slots - endmill swap for better finish

Overall the milling took a few hours but it was certainly worth doing. The next step was to use the chop saw to cut them into equal sections, I managed to get 11 and then a long one due to the limits of the saw, this one will be chopped in half with the angle grinder.

12mm T-slots - Profile milled and complete 12mm T-slots - Chop saw to cut profile sections 12mm T-slots - roughly cut to size with chop saw

After all of the chopping I needed to clean up the edges as grinding left quite large burrs, I chose to first straighten the edges in the miller to minimise the size of the burrs and to make them all a uniform size. I used the grinder to deburr most of the corners but had to resort to using the file to do the rest of the work.

12mm T-slots - face clean-up and final dimensions achieved 12mm T-slots - milled to final dimensions 12mm T-slots - file clean edges after final mill

Each of the nuts then had to be drilled and tapped.

12mm T-slots - drill centre to 8.4mm 12mm T-slots - drilled to 8.4mm 12mm T-slots - drill tapping with M10 spiral flute tap

I finally countersunk the threads to remove any more burrs, all complete. The cast nuts retail for £2 each and are not the best quality either, I would expect to pay at least £5 each for a machined item of this size.

12mm T-slots - counter sinking to remove burrs 12mm T-slots - machined on left, cast on right 12mm T-slots - 12 machined for less than price of cast

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