I have a number of Jigs that I have made for use on my Taig CNC Mill. Now that I have my TM20VL mill operational (Not finished with the conversion yet), I wanted to use one of the jigs on it. The jigs have been designed to mount to the Taig with 10-24 bolts and Taig T-nuts. I need to make some T-Nuts for the TM20VL but with a 10-24 thread, rather than the usual M8 thread.
The slots in the mill need a T-Nut that is about 12mm high, 16mm wide at the bottom and 10mm wide at the top. The local bolt store that by now, I deserve to go to their Christmas party has some key steel with the dimensions 12" x 1/2" (12.5mm) by 5/8"(15.875mm). This is near enough for the nuts.
Using the key Steel stock, the machining required to create the T-Nuts is ;
- Mill 3mm from either side of the stock to a depth of 6mm.
- Score the lengths of the nuts where they will need to be cut with a hacksaw.
- Drill with a 4mm bit.
- Counter Sink the holes (forgot to do this step).
- Tap the holes to 10-24.
- Cut to length.
- Mill the T-Nut lengths to size.
The first job was to draw the T-Nuts in Draftsight to create a dxf file for Sheetcam. The stock was divided into 28mm segments, with the last 2 segments being 24mm in length. The width of the T-Nut drawn below is 10mm as this is the required width needed for the table slots. The holes are 4mm diameter.
The drawing is designed purely for sheetcam to allow for the necessary making operations. As such, the bottom part of the T-Nut is not shown as there was no machining required on that part.
The dxf file was then loaded into Sheetcam and the machining operations were applied;
- The recess on either side using a 10mm Slot mill
- 4mm drilling
- Scoring of the cut lines with a centre drill
The machining was quite straight forward with the stock held in a vise. There was a little deflection when drilling the end holes but none of the dimensions were critical.
As my hack-sawing skills are mediocre at best, I needed a way to machine the nuts to all be the same length. What I came up with was to thread them onto a 10-24 threaded rod, with the 2 end nuts put on either end of the threaded rod. I did this as the 2 end nuts has a square and uncut end on them so I could use the height of them as a reference. You can see this in the images below. Once one side was machines I flipped the lot over and machined the other side.
In the end they came out looking OK, but are a little long as there is only about a 1-2mm gap beteen the X-axis end plate and the nut when inserting it into the slot. If I can find the energy I might get around to shortening the nuts by 5mm so as to make it easier to insert into the slots.