Model Boat Mayhem
Technical, Techniques, Hints, and Tips => Engineering Techniques and Materials. => Topic started by: coch y bonddu on February 26, 2020, 10:15:20 pm
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HELP.....i need to thread a new propshaft M4 in size ....Ive got a M4 but it has a thread pitch of .7? tried on a scrap shaft but it is the wrong pitch for the props....the props fit a std M4 shop bought shaft so i know they are correct...anyone out there in Mayhem land know what the correct pitch is ...Thanks
Dave
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I'm not sure if I understand your question but I have a 4mm die here and it is 0.7 which I believe to be the norm for M4
If the shaft you have doesn't work with the prop try running an M4 die over it?
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4 BA was a common shaft size before metric
4BA thread has pitch 0.65mm and diameter 3.62mm.
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Did you measure 0.77 or is it just what the spec said? If it's the latter then you may have got a 4 BA shaft by mistake as, visually, the two are very similar.
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Hi, does the die screw onto the shop bought shafts? Is it a die you can tighten or slacken in the
holder or is it the nut type where there is no adjustment.
If it is a cheap die as you get in some sets and you are trying to thread stainless steel they will
Not cut a good thread because they expand so the thread is shallow and the props won,t fit.
They may be ok on soft metals but useless on good quality stainless steel.
For stainless you will be better with HSS colbalt taps and dies, they are what engineers use and
Used properly will last a long time. They are expensive but in my opinion well worth it.
John
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its not an M4x .5 metric fine is it?, I know my set of taps and dies has several different pitches for some of the smaller sizes