engineer needed in essex

[ron hawesParticipant @ronhawes49865]

[ron hawesParticipant @ronhawes49865]

I need some help,

 

 i need m4 thread screwed on my driveshafts the engineer i normally use has disapeard and i cant get it right to do it myself,

 

is there anyone near me in southend on sea essex who could possible screw the threads for me please.

 

obviously i will come to you and pay whatever it costs this is really holding me up on my latest build.

[ashley needhamParticipant @ashleyneedham69188]

Ron. As an alternative, how about simply buying some commercial m4 shafts oversize from Hobbies or whoever and cutting to size (assuming you only want one end threaded..???

 

I have used brass rod before now for propshafts, and this is very much easier to thread.I know it can be a bit tricky, but brass rod is relatively cheap and after a few goes i am sure you could get a result?

 

Ashley

[Bob Abell 2Participant @bobabell2]

My advice is on this thread…….

 

http://www.modelboats.co.uk/forums/postings.asp?th=36925&p=1

 

Bob

[ron hawesParticipant @ronhawes49865]

thanks ashley for your response, my trouble is my shafts are 800mm long, i looked everywhere to try and buy some but couldnt get any that lenghth so i made my own,

 

ive made the outer tube with bearings but i cant grip the inner drive shaft hard enough without marking it, i put the original piano aside and bought some BDMS to use this time but im getting nowhere i have screwd a thread on one shaft but as soon as i get to any length it spins in the vice,

 

thats why i wonderd if there was an engineer local to me who could help,a three jaw chuck grips much better without damaging the shaft.

 

 

 

[Bob Abell 2Participant @bobabell2]

Ron

 

Drill a block of metal, the same size as the prop shaft…….Saw the block in half, along the centreline of the drilled hole……………and use it as a clamp in the vice to grip the prop shaft.

 

Clamp the shaft well clear of the bearing area…..to avoid any scuffing

 

Don`t use your damaged die nut!

 

Bob

[ashley needhamParticipant @ashleyneedham69188]

Oo er…800 mm is very very long at only a 4mm shaft size, I think you will need a centre bearing at least or else the shaft will flex and bash against the tube wall in the middle.Assuming you dont have one, that is. Or may be even 2 midpoint bearings…..or are we talking of a lesser length of tube, with a skeg/a-frame arrangement?

 

My HMS Manchester had 300mm shafts, and this vibrated horribly at full revs (only 9000rpm) .   <only !!>  .I started the boat 25 years ago and is has sat in the shed as a hull and superstructure only and  i actually finished it year before last ..anyway, I had originally fitted  a single long tube.  (each side, twin props and some natty 5 blade 40m,m props)….so I had to convert it to the correct short tube/exposed shaft arrangement thats normal for a warship. 2Ba of course at that time, so a bit of fiddling had to take place as regards A-frame bearings etc. 

 

Ashley ,

[TelstarParticipant @telstar]

Ron When cutting any thread it is essential to turn the Tap/Die back to clear the swarf from the cut.    As an apprentice (many years ago) we were taught after you had the die properly started to turn one turn forward the half a turn back, this stops the swarf (cuttings) building up in the die and causing it to jam.    Also some light oil, preferably cutting oil, (but at a push 3 in 1) helps the action.

Cheers Tom

[neil hpParticipant @neilhp]

i’m a little puzzled here, by all the worry about scratching the surface of the shaft by gripping it in the vice without vice guards on the jaws.

the only two places that the shaft will be harmed by such would be in the two  exact possitions where they run through the bearings, and as long as any damage [ as slight as it may be] is not in these two places, i have never ever had any problem with gripping a shaft tightly in a vice  to tap a thread and away from these specific positions without using vice guards….just a gentle file afterwards with a needle file will also allow the “damaged” area to pass through the bearing with ease….i think we are being a little over cautious here.

neil.

[ron hawesParticipant @ronhawes49865]

i intend to fill the shafts with mastic like i did with a submarine i built years ago which will stop the shaft slap and also water proof them as they are horizontal and will be perminantly below the water line,

 

im using MFA geard motors 11/1 so i should get a max prop rpm of around 700 which should make it quieter with less strain on the shafts,

 

i dont want to risk marking the shafts in a vice however small it might be so if i can get an enginer around essex who has the correct equipment i will be much happier,

 

 

but thanks for your comments and that prop arrangment on your HMS MANCHESTER certainly look complicated ashley.

 

[ron hawesParticipant @ronhawes49865]

got the shafts done thanks for your advice guys

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