oldbilbo
...
Just look at what the OP started! They'll be hidden inside/under the 40 y.o. boom, with reefing lines secured to them.
metal file for stainless steel
- Thread starter sarabande
- Start date
Heckler
Well-Known Member
Actually I think he is sending out a hidden message about his skills in making a fiddly thing like that in SS! And I dont blame him, I would be quite proud of the skills needed to make it!
Stu
Stu
sarabande
Well-Known Member
no Stu, I am ashamed of the finish, but it's really the first ones I've had a go at. No commercial value in them at all, and I wanted to make them nice and smooth and shiny. Beauty in the eye of the beholder and all that.
Our local fabrication shop did the cutting out of the 5mm SS sheet in a huge guillotine; the loop is two plug welds into the flat base as I might suspend a block and tackle from it for MOB use.
Our local fabrication shop did the cutting out of the 5mm SS sheet in a huge guillotine; the loop is two plug welds into the flat base as I might suspend a block and tackle from it for MOB use.
coopec
N/A
Just a bit of information which may come in handy.
I was trying to drill holes through the deck and into the S/S chain-plates but was getting nowhere. I got expert advice and was advised as I was drilling near the edge where it had been cut it was undoubtedly work hardened and I was going to have difficulty. Also he said if a drill doesn't "bite" immediately into S/S it will become work hardened.
My BIL happened to pass by came to my aid. He was a Caterpillar Diesel Fitter and he said when they had to drill out broken engine studs they used sharpened masonry drills and a lot of force. There were plenty of holes in the deck so we made up a "stirrup" of threaded rod and a loop of steel. I went below and put a nut on the threaded rod and then came up on deck and put a 9ft piece of timber through the metal loop and across the back of a big tradesman's drill and put all my weight on it while he operated the drill. We averaged a hole about every 2/3 minutes
I was trying to drill holes through the deck and into the S/S chain-plates but was getting nowhere. I got expert advice and was advised as I was drilling near the edge where it had been cut it was undoubtedly work hardened and I was going to have difficulty. Also he said if a drill doesn't "bite" immediately into S/S it will become work hardened.
My BIL happened to pass by came to my aid. He was a Caterpillar Diesel Fitter and he said when they had to drill out broken engine studs they used sharpened masonry drills and a lot of force. There were plenty of holes in the deck so we made up a "stirrup" of threaded rod and a loop of steel. I went below and put a nut on the threaded rod and then came up on deck and put a 9ft piece of timber through the metal loop and across the back of a big tradesman's drill and put all my weight on it while he operated the drill. We averaged a hole about every 2/3 minutes
vyv_cox
Well-Known Member
I see that I am incorrect. I still don't understand why it should happen, as the weld is by definition in the annealed condition. I can only assume that the thickness of the plate is sufficient to cause the weld to be in a normalised condition, rather than slow-cooled annealed, although my understanding was previously that for austenitic steels this should make no difference.
Lyndsey Doyle
N/A
prof pat pending
Well-Known Member
Something else I found last night suggested quite a large increase in delta ferrite in the weld material, That was also on quite thick material samples.
I've certainly machined thinner welded parts and could feel/hear the difference through the machine, even on a quite robust CNC
prof pat pending
Well-Known Member
That may well have contributed to your problem, see the comments on work hardening.
I don't know the application :redface-new: but I might have been tempted to make the hoop from a round bar, constructing it like a padlock hasp, through the plate and welding it from the back. A good weld prep on the back face would allow you to flatten that face if required.
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coopec
N/A
Well, a lot of this has gone right over my head but I think I'd be right in saying:
Cold working (bending, sawing, machining) will work harden 316 and 304.
Welding will work harden 316 and 304
Cold working 316 will magnetize it.
Cold working (bending, sawing, machining) will work harden 316 and 304.
Welding will work harden 316 and 304
Cold working 316 will magnetize it.
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PCUK
Well-Known Member
What you need are special stainless steel sanding discs for the mini grinder. They look a bit like a flap disc covered in scotchbrite. They come in different grades from coarse to very fine. That's what I use before polishing.
rogerthebodger
Well-Known Member
I've hurriedly put together a couple of stainless luff groove slides. Very rough stuff, I know, even after I have had a go with a linishing pad and angle grinder.....
My normal metal files don't make much impression on smoothing out the welds and sharp edges.
Can some kind techy recommend a good make of files for stainless please ?
Just a point. I always polish the components first and weld them together and just trim up the welds after.
As has been said and easy to weld a loop onto a plate is to drill the plate, fit the loop through the holes and weld on the underside that only needs trimming to make the mounting surface flat and no fine polishing needed.
Bend, polish components the weld together the acid wash the welds and finish polish.
vyv_cox
Well-Known Member
Nearly! Working causes work hardening. Sawing is a cutting action that should not cause work hardening. Equally, machining should not. Drilling with blunt bits can cause some plastic deformation (= localised bending) that will work harden the hole.
Welds in 300 series SS are a little harder than the rest of the work but this is not work hardening, it seems to be a metallurgical transformation that I currently cannot explain.
Cold working will not make 316 magnetic. It has been reported that turnings and drillings in this alloy can be magnetic because they have been transformed by heating to over about 800C in the process. The bulk of the metal is not magnetic. Don't forget that many components of your boat, e.g. shroud wires, bottle screws, bolts, shackles, etc are made by cold stamping with the express purpose of work hardening them to increase their strength.
prof pat pending
Well-Known Member
Machining can very locally harden stainless if the cut rate isn't high enough. This doesn't really alter the properties of the part, but can make it difficult to continue machining.
A lot of machinists that are new to stainless break cutters/drills by not pushing them hard enough. Instinct is to back off a bit, but you actually need to push harder (as the comment above about drilling into chain plates)
A lot of machinists that are new to stainless break cutters/drills by not pushing them hard enough. Instinct is to back off a bit, but you actually need to push harder (as the comment above about drilling into chain plates)
Ruffles
Well-Known Member
Don't forget good old wet and dry.
I'm always amazed how fast I can tidy up a piece of rough metal using various grades of paper. Particularly with a carefully chosen backing pad.
I'm always amazed how fast I can tidy up a piece of rough metal using various grades of paper. Particularly with a carefully chosen backing pad.
coopec
N/A
Thank you VYX and the Professor: I think I've got it.
One last question. Often when you buy hose clamps the band is S/S but the screw is slightly magnetic. I challenged a supplier saying the clamp was not all S/S as stated on the package because the screw was (weakly) magnetic: he insisted they were all S/S. Could the explanation be:
"Don't forget that many components of your boat, e.g. shroud wires, bottle screws, bolts, shackles, etc are made by cold stamping with the express purpose of work hardening them to increase their strength.
One last question. Often when you buy hose clamps the band is S/S but the screw is slightly magnetic. I challenged a supplier saying the clamp was not all S/S as stated on the package because the screw was (weakly) magnetic: he insisted they were all S/S. Could the explanation be:
"Don't forget that many components of your boat, e.g. shroud wires, bottle screws, bolts, shackles, etc are made by cold stamping with the express purpose of work hardening them to increase their strength.
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prof pat pending
Well-Known Member
There are two major groups of stainless, Austenitic and Martensitic. On the whole, the afore mentioned is non magnetic, the later is magnetic and usually doesn't have as good a corrosion resistance.
Austenitic stainless can however become magnetic under certain circumstances, cold working for example will increase the magnetism of an Austenitic stainless, it doesn't usually become fully magnetic, but will attract a magnet to a degree. As far as I know this won't affect its corrosion resistance, so in the application you mention, I wouldn't worry too much about it
This was a big worry in my previous life. A superconducting magnet will tear itself apart if there is a magnetic material present.
Going back to boats, Incorrect heat treatment can be a bigger worry however. It is possible to make stainless non resistant to corrosion if you heat treat it incorrectly. Research or ask, but don't guess
Austenitic stainless can however become magnetic under certain circumstances, cold working for example will increase the magnetism of an Austenitic stainless, it doesn't usually become fully magnetic, but will attract a magnet to a degree. As far as I know this won't affect its corrosion resistance, so in the application you mention, I wouldn't worry too much about it
This was a big worry in my previous life. A superconducting magnet will tear itself apart if there is a magnetic material present.Going back to boats, Incorrect heat treatment can be a bigger worry however. It is possible to make stainless non resistant to corrosion if you heat treat it incorrectly. Research or ask, but don't guess
macd
Well-Known Member
The supplier was probably right, but there are inferior 'all stainless' hose clamps with (magnetic) 400-series screws on 300-series bands. Over time the screw is prone to rusting, which may seize the clamp solid -- or, worse, cause it to fail. Thus it's worth sticking to reputable brands, although that seems harder to do in out-of-the-way places.
vyv_cox
Well-Known Member
I suspect that the thinking is that using a martensitic screw gives higher strength and wear resistance. The yield strength of the austenitics is low, only about 50% of the UTS, so vigorous turning of the screw might well deform one in these grades. It might also help to avoid galling, although I am not certain about that.
coopec
N/A
Thanks Vyx
I'm going to use 2X "T" Bolt clamps on all underwater fittings. anyway. But I really don"t want to hacksaw clamps off because the screws have rusted.
I'm going to use 2X "T" Bolt clamps on all underwater fittings. anyway. But I really don"t want to hacksaw clamps off because the screws have rusted.
rogerthebodger
Well-Known Member
I have used norma worm clamps grade W5 available in all 316 ss not cheap but very good and whats more reusable where most I have found aren't due to rusting screws of screws coming out when trying to undo them
http://www.clamps.co.za/Downloads/NORMACLAMP_TORRO_en.pdf
http://www.norma.net.au/products/hose-clamps/norma/norma-torro-worm-drive-hose-clamps
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