# T-nuts .... the hard way



## Norppu (Jul 9, 2018)

I decided to mount the miniature vice on the milling attachment properly. This puny vice came with the milling attachment and had a flimsy set of M6 fasteners with hilariously tiny t-nuts which were not a match with the 10mm slots on the milling attachment.

I have some mystery tool steel which is quite hard and becomes really hard if heat treated. It is machinable but just barely with my import lathe. The origin of this tool steel is somewhere in the Soviet or DDR.  The setup in the picture is far from rigid. The previous setup was a disaster. Spoiled a perfectly good carbide end-mill and dented the drill chuck. Learned the hard way that carbide end-mills want to come out from the chuck.




The setup with the indexable mill worked and I got the T-nut profile done. Bored the holes and threaded to M8. I have spiral flute taps. When tapping hard material with those one should NOT turn the tap in reverse direction in order to break the chips. The chip does not break but the tap does. Logically - one cannot use these to tap blind holes on hard material. Finally had 5 t-nuts with quite precise dimensions. It appeared that the t-slots in the milling attachment are not at all precise. Lowest slot was actually 10.3 mm and the highest was exactly 10mm. The middle slot is somewhere in between. Little bit of filing and the 10mm t-nuts can now be used in all slots.



The vice was designed to use 6mm bolts for attaching. The 8mm bolts need a bigget hole and recess. Used a boring bar to make the holes larger. The original milling quality in those holes was quite some. Now the holes are smooth and can accommodate a 8mm allen screw. Now the vice is easy to put in place and it also stays put. Much better.


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## markba633csi (Jul 9, 2018)

I have been in your position before- when you discover that you should have turned the tap backwards sooner it is usually too late; you are trapped. Sometimes you can brute-force the tap another 1/3 turn and then reverse, it really depends on the material and the sharpness of the tap and how tired you are LOL  
Live and learn
mark


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