Tapping a Thread

[silversurfer1947]

I am trying to tap a thread onto thin brass rod - in particular 0.8mm. I am doing something wrong as I keep shearing the rod so I only get short lengths. Fortunately, I only want fairly short pieces, but it would be nice to know how to do it properly.

[jarndice]

Richard if you start the thread with a tap that is only just touching the inner wall of the tube and make the thread and then using lots of thin oil wind in then out frequently over very few turns using a bigger tap,
The more taps of ever increasing size you can use the better,
You should avoid starting with the Tap that is going to make the final thread, Do make sure you are following the original thread each time.
Exactly the same method should be employed with using "Dies" to make threads on the outside of a tube or rod.
Shaun.

[silversurfer1947]

Shows how much I know - using the wrong terminology. I'm trying to get a thread on the outside of a 0.8mm brass rod. First time I've tried this. Initially, the rod would not fit in what I now believe to be the die so I tried the next size up (0.9mm). This worked fine. I then tried to cut the 0.8mm thread over the previous thread. I tried clamping the rod in a mini vice which has rubber facings, but the rod just kept turning, so i finished up holding it in a pair of pliers. That was when it kept shearing into bits.

[jarndice]

The best way to "Get" a thread on a soft metal rod is to PRESS it on under pressure instead of using Thread cutting tools.
Shaun.

[silversurfer1947]

The best way to "Get" a thread on a soft metal rod is to PRESS it on under pressure instead of using Thread cutting tools.
Shaun.

Is it possible to do this oneself at home? If so, how do you do it?

[silversurfer1947]

I think it might be easier if I just cut the heads of M0.8 bolts. I just wanted to try to do it all myelf.

[silversurfer1947]

Thanks for all the advice. I will give it another go. After all, it's just my time and a small length of brass rod.

[rochesb]

When I was taught metalwork at school 54 years ago, I remember we used to use split (adjustable) dies, first we would chamfer the end of the rod, then open the die up wide in the holder with a grub screw & if I remember correctly we were told to go half a turn forward, half a turn forward, then half a turn backward to clear the swarf, & repeat the sequence until the desired length was reached after which we would unwind the die off the workpiece , back off the grub screw holding the die open a bit & repeat the thread cutting action until the thread was right.

Apologies if I am trying to teach my granny to suck eggs.......

[silversurfer1947]

No need for apologies. Never did metalwork, so this is a new black art to me.