Turning very hard stainless steel

[hunter27]

Hi all

I am changing my boat and the new boat has a larger stainless steel shaft to the propeller. On the old boat I have a rope stripper fitted to the 7/8" shaft, I would like to fit this to the 25mm shaft on the new boat.
A friend with more experience at turning said that he would do it for me but has found that the stripper is too hard to cut (it is a type of stainless steel that retains it's very sharp teeth)

I do have am old clunker of a lathe to give it a try but are there any lathe cutters that would cut this.

Thanks
Pete

 

[hotrodder]

I'll take a punt that 17-4ph stainless is maybe a likely candidate*? Over to the machinists regarding what it's like to turn in it's hardened state. Aalco say difficult but still machinable... http://www.aalco.co.uk/datasheets/Stainless-Steel_1.4542-17~4-PH_100.ashx, some hardness numbers for different aging temps here... http://www.westyorkssteel.com/174ph.html which also mentions machinability

*googling '17-4ph propeller rope cutter' got some hits, they also seem to be available in 316 but that wouldn't (or shouldn't!) be difficult to machine

 

[awemawson]

Internal cylindrical grinder is what you need. Though I'm surpised that a carbide insert in a boring bar doesn't touch it.

I'd offer to do it for you but I'm just embarking on a major refurb, emptying the house and builders move in on Monday!

 

[hunter27]

Thank for your reply's. My friend did said that as he was struggling to cut it he would try to get it ground where he works but unfortunately the guy that used to do this has just left the job and apparently no one else knows how to use the machine.
I will probably think about it for a while before I try it on my lathe and probably mess it up.

Thanks again
Pete

 

[hareng]

If its Grade 316S11 thats machineable, done a fair bit on a toy lathe.
It will wear decent cutters, think i used Kennametal Top Notch stuff meant for cast steel coal board joints.

Some engine valves are really hard, above tool on decent lathe only polishes them.

 

[brightspark]

If its Grade 316S11 thats machineable, done a fair bit on a toy lathe.
It will wear decent cutters, think i used Kennametal Top Notch stuff meant for cast steel coal board joints.

Some engine valves are really hard, above tool on decent lathe only polishes them.

it wasnt on a myford [toy ] lathe by any chance was it

 

[v10mike]

Get yourself some low CBN hard turning tips: http://carbideinserts.blogspot.co.uk/2008/02/hardturning-with-cbn-finish-machining.html

 

[hareng]

it wasnt on a myford [toy ] lathe by any chance was it

Yes it was on a Myford toy heavilly modded.

 

[hunter27]

Thanks v10mike I will look into the CBN. DR 50 inserts

Pete

 

[langy]

I have some 50mm prop here that I was given and although it's very hard normal tips cut it fine, you just need to go a little slower with plenty of coolant.

 

[PhillipM]

Carbide should cut it fine, but they'll need to be sharp insert and you'll need to go slow with lots of feed otherwise you'll just work harden the surface and then never get anywhere.

 

[rocketron]

wouldn't it be easier to get a rope cutter/stripper for a 25mm shaft rather than the aggravation of machining such material? Wouldn't like to try and bore out the clamped part, they are usually held together by 2 stainless allen bolts, which may let go thus wrecking a sellable item.S/h cutters available on flea bay fairly regular. You can also sell your old one!

 

[500e]

Some type of A4 marine grade SS hard & work hardens even faster will require sharp tools, Good lathe & sensible cuts, trying light cuts will work harden
The grinding would be best.
Have turned shafts for boats using tipped tools from Sandvic they recommend the tips\speed & cut, even then on my student it was not easy Also made a 5" universal joint out of bilet A4SS another story, farmed all the stainless turning out after that episode

 

[penfold]

wouldn't it be easier to get a rope cutter/stripper for a 25mm shaft rather than the aggravation of machining such material? Wouldn't like to try and bore out the clamped part, they are usually held together by 2 stainless allen bolts, which may let go thus wrecking a sellable item.S/h cutters available on flea bay fairly regular. You can also sell your old one!

What he said.