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[jaymac]

Toying with the idea of having a go at thread cutting .Absolutely clueless and  so far gleaned  I think I need split dies
   for  bare rod  but what thread are propshaft and props usually Fine or coarse please, before I buy the  wrong set
Jay

[imsinking]

The modern props / couplings are usually METRIC standard not fine , M3 / M4 / M5 etc .
Any early props could be BA or UNF depending where they come from.
I set a split die from a bolt or stud before using , as you can overtighten the pinching screws and get a loose thread,  if your going to use stainless bar file a little off the OD of the bar BEFORE screwing as the thread grows as you cut it & when you wind back can rip the thread off (even with a new sharp die    )use plenty of lubricant dont do it dry.
Liberal use of PROFANITIES while do this can help too . . . .
Bill

[sparkey]

  Usually3mm, 4mm,5mm, and maybe 6mm, a good set of taps and dies in these sizes will cover all you need....Ray.

[Brian60]

Contrary to previous advice metric thread does come in fine and coarse variants.

Up to 6mm is fine, after 6mm is coarse, unless of course you have a japanese motorcycle or car, than it is fine thread all the way through to 12mm.

So 3/4/5/6mm is usually a standard pitch so any die you purchase will be fine. Go below 3mm and the thread is superfine obviously as the thread pitch could be wider than the actual material so there would be no strength left.

[jaymac]

Thanks  Guys as the  set was for M4 / M5 as is my shafts and props and  it still said Fine looks like Brian is the winner   Thanks again

[Geoff]

If you have not done this before I would suggest you only do about two turns of the die then back it off. This frees the swarf and stops it jamming and distorting the thread. Then go forwards for another two turns and back of again and so on. A little bit at a time and as above lots of lubrication and taper the end of the rod slightly to encourage the die to catch.
 
If you are looking to do a propshaft you really need a lathe to do this correctly as the chuck can hold the rod and the tail stock a special die holder. This keeps the whole thing concentric as otherwise the thread may be cut crooked and any prop will then be out of balance.

[imsinking]

Afraid not Brian , I S O METRIC FINE can be anything between 8mm & 64mm in dia and I S O METRIC COARSE can be can be anything between 1.6mm & 68mm in dia , a good set of thread gauges is needed in industry to identify miscreant threads , I should know as I was 50 years before the lathe (I never got early release)
Their just continental Equivalents of our very own BSF and WITWORTH groups .
And just to make my post mind numbingly boring you also had American groups UNF / UNC / API / NPT , along with our very own BUTRESS THREADS / ACME THREADS / SQUARE THREADS  / Multi-Start threads / Manufacturers 'Specials' etc . . . anything to make for a stressful day in the machine shop . . . .      
Bill

[bfgstew]

A good old Zuess book is indispensable, always have one in my overall pocket, and have done for #%*!!@* years.

[jaymac]

Now I am confussed all I ever did with threadmaking was  in metalwork class  some 60+ years ago .Anyroad  all I know is some of the sets offer fine or coarse or both  all I need to know is what are  model props and shafts usually . No intention of doing shafts and only looking at perhaps modifying some props I have dont want to buy a set and find its the wrong one
Jay

[bfgstew]

If you buy a prop it will normally state thread size, normally metric or occasionally B.A. All you will need is a standard metric die set. But to achieve correct concentricity that this done on a lathe otherwise you will end up with a prop that will be out of kilter.

[john44]

Hi jay, if you are going to thread stainless/hard steel etc. Get good HSS or tungsten dies
Carbon don't last and are hard to start. In my experience anyway.


John

[RAAArtyGunner]

It would seem that making your own threaded shafts is not practical without using a lathe.

Have threaded steel rod for use as nut and bolt and it is difficult to get the die on straight and square.

[boneash]

A pillar drill a good drill vice and a hole through the bench works just as well as and a lot cheaper than buying a lathe,,, LOL

[ballastanksian]

Trefelux cutting compound is your friend. A tin which will be a few pounds will last you forever. It lubricates the thread and tool as you cut but not like oil does.

[imsinking]

Trefelux cutting compound is your friend. A tin which will be a few pounds will last you forever. It lubricates the thread and tool as you cut but not like oil does.

TREFOLEX . . . .now there's a name from way back for me , their green stuff has a pleasant smell to it, used to be made locally (Liverpool anyway) but I think the Yank's or Bestobell have it now .
Bill

[irishcarguy]

It is very difficult to start the die concentric especially on small rods of 3 or 4 MM. Here we go again having a lathe I made a couple of die holders to stop my threads always running of sideways. It took me about 20 minutes to make them. For whatever reason dies for the same thread are not always the same diameter. You may know someone with a lathe that will know how to make them for you, as a last resort I would do it for you, no cost. The holders also have to have grub screws to stop the die turning in its holder, usually 3MM grub screws which involves drilling & tapping three threaded holes for the grub screws,  Mick B.     

[jaymac]

thanks for the offer Mick but  I am really only thinkin of dabbling in it out of curiousity nothing serious.How's Calgary  these days still got segregated Bars or do they allow men in the mixed bar without a Lady escort now
Jay