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Author Topic: Thread pitch  (Read 147 times)

Brian60

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Thread pitch
« on: December 15, 2017, 03:51:06 PM »

I'm having a bit of bovver! This particular problem has been ongoing for 7 months, I kept putting it off and putting it off, but now it has to be conquered because I cannot progress any further.

I have to thread my own tunnel thrusters no problem I've threaded stuff loads of times before. This time though something is not right.....

4.2mm rod, 4mm threading die. Requisite amount of thread added to rod. However the propellor, in fact a nut, any nut of 4mm will not run down the thread.

I've searched the internet and found that 4mm comes with a pitch of .7mm, in fact it is marked on the face of my 4mm / 0.7, so why can't I get a damn nut or a propellor down the thread? The nuts are of several types, steel, brass and bought from different places, as are the propellors.

One last thing, its a right handed die, not a left, so the thread is going the right way :-)) :}


Anyone with any advice what to try next?

Brian60

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Re: Thread pitch
« Reply #1 on: December 15, 2017, 04:52:44 PM »

Now sorted.

Turns out the cutting die is conical shaped so that you introduce the rod and the further into the tool the deeper it cut the thread. As I was only wanting 8mm or so of thread it really wasn't going deep enough to cut cleanly, in essence I had a piece of rod with a cone shaped thread.

I turned the die over and cut from the opposite side, job now done. seven months of procrastination now over, amazing what you achieve is you sit and study a problem rather than sweeping it to one side.

manofkent

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Re: Thread pitch
« Reply #2 on: December 15, 2017, 07:53:20 PM »

Glad that is sorted.  Don't forget, thought, that there is a fine pitch metric range i.e. 4 x 0.5
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