tapping a shaft

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8 February 2010 at 16:14 #25481
ron hawes
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@ronhawes49865
i need to cut a thread 4mm on my shafts im using piano wire, but i cant get the die to start correctly ive cut a shamfer on the end but what am i doing wrong ??
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8 February 2010 at 16:14 #3506
ron hawes
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@ronhawes49865
8 February 2010 at 16:27 #25482
Bob Abell 2
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@bobabell2
Ron!…………..You`ve ruined your die!

Piano wire cannot be screwed…..It`s too hard!……..Sorry

Bob
8 February 2010 at 19:10 #25484
ron hawes
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@ronhawes49865
lol ok bob maybee thats my problem!!

could you run through how to do i though i havent tapped a thread in years
8 February 2010 at 19:33 #25486
Bob Abell 2
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@bobabell2
OK, Ron…………I assume your making a prop shaft?

Assuming you haven`t got a lathe either?

Get a suitable length of stainless steel…….From the model shop or Engineers suppliers

You will probably need to buy a new die too!…….Your old one will surely be damaged

File a chamfer on the end of the shaft………Grip the shaft in a vice, protect the shaft from damage using brass or ali vice pads

Place the die , in a die stock, on top of the shaft……Press down…….Rotate the die `till you feel the thread just starting to bite, keeping the die perfectly square and level, slightly reverse the die in order to break the chip being formed……..repeat this process till the thread is formed.

This process takes a lot of practice…….The greatest problem is keeping the dia level and square to the shaft axis.

You will find after a few bum starts that the tread is ok after a short while. You could saw the dodgy bit of thread off……If you do, keep the die on the shaft, during sawing….chamfer the sawed end and unwind the dia…….and that should be ok

Best of luck………………Bob
8 February 2010 at 19:58 #25489
ashley needham
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@ashleyneedham69188
Notoriously tricky this operation i find, tricky to get that die dead square, even on “easy” material, brass or whatever.

Needs practice…sadly lacking in my case .

Ashley
8 February 2010 at 20:17 #25492
Bob Abell 2
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@bobabell2
It can be done in a vertical drill

Grip the material in the chuck and place the die and holder on the base……..Wind the drill head down and get crackin`!……….A bit of dexerity is required though!

It`e eay in the lathe though……………Bob
8 February 2010 at 20:25 #25495
ashley needham
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@ashleyneedham69188
Bob…I LIKE that idea! you are a real engineer.

Ashley
8 February 2010 at 20:34 #25496
Bob Abell 2
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@bobabell2
Thanks Ashley

I sometimes tap holes out in the drill, in the same way….You can get them dead square dead easy!

Btw, Ron…….The correct terminology is….We screw a shaft and tap a hole

Bob
8 February 2010 at 20:46 #25497
ron hawes
Participant
@ronhawes49865
thanks ashley i think the last time i SCREWED a shaft was at school some 30 yrs ago !

ill get some new 4mm and try again

thanks for the replys
12 March 2010 at 20:16 #25890
Phil Winks 1
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@philwinks1
If like me you have some off those fairly cheap non adjustable dies the taper on the shaft needs to be quite long I usually form it on a bench grinder but then I’ve lots of experience with grinders also if the steel is a tad hard I heat to cherry red and cool to make it easier to get the thread started also start with the shaft a good bit longer than needed so there’s plenty to trim off.

Phil
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