Cutting 316 stainless steel...

Discussion in 'Boat Design' started by epoxyman, Jan 3, 2007.

  1. epoxyman
    Joined: Dec 2006
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    epoxyman Junior Member

    For a SINGLE CUT through a several inch diameter stainless steel pipe with a wall thickness approaching a quarter inch, what is a reasonable, low budget, portable approach? I have several right angle grinders from 4 inch dia to 7 inch diameter with abrasive cut off wheels (not grinding wheels), should this do or do I need to look at other options? Has anyone tried the "Alpha-Green" stainless steel cut off wheels made by Rex Cut? (Trying to plan ahead.)
     
  2. SailDesign
    Joined: Jan 2003
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    SailDesign Old Phart! Stay upwind..

    Rent a Milwaukee Porta-Band with a metal-cutting blade. You will thank yourself (and probably buy one afterwards). :)
    Steve
     
  3. lewisboats
    Joined: Oct 2002
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    lewisboats Obsessed Member

    Take it to a shop, pay em 5 bucks to cut it.

    Steve
     
  4. epoxyman
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    epoxyman Junior Member

    Ok, I've looked them up and I have to say they look pretty good! And, I can think of 100 other times when I could have used such a tool. So they can really cut through a substantial piece of 316 stainless and still have a usable blade left over afterwards? I see similar ones by Porter Cable and Makita, any reason why the Milwaukee? Also how many TPI blade do you suggest and how many FPS to cut with?

    Thanks!
     
  5. SAQuestor
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    SAQuestor Senior Member

    The short answer is YES! In a prior life I spent 21+ years in a papermill as a machinist. A porta-band was a mainstay tool for the entire maintenance department. The mill had dozens of 'em. Cutting stainless - 316, 304 or 308 is problematic for 'normal' tools. The best I can offer is to do things at low speeds. So if you're going to rent or buy a porta-band get the one with the variable speed - not the single or two speed model. The reasoning here is that the single or two speed model is strictly on/off regardless - just like a light switch. With the variable speed model you can bring the speed up slowly so there is no sudden on/off jerks - and believe me that's what tears the teeth off the the bandsaw more than anything.

    Other brands - don't know - haven't used 'em. Compare throat size and spec'd capacity and choose on that basis as long as they are variable speed.

    TPI on the blades. 12 TPI is a good standard. Finer TPI if you're going to be cutting thin wall stuff. You want to keep several teeth in contact with the material if at all possible. Somewhere there is a "recommended" TPI for material thickness for hack-saw blades - don't remember exactly - might want to search on the net for that info - same principle applies.

    FPM - With all stainless slower is better. With a new sharp blade you'll be able to 'feel' when it's right. Too slow and it'll seem that you aren't making any progress. Too fast and the thing will most likely jump and chatter and be more difficult to control. Just like Goldilocks there will be one bowl of porridge that is 'just right'. When it's 'just right' the saw will go through stainless almost as fast as a hot knife through butter.

    BUT... Buy extra blades. Several. 'Stuff' will happen and the blade will lose some teeth or get caught or kinked or something... Don't try and fight a bad blade - it'll just frustrate you and cause a crooked cut in the material. Change the blade as soon as it stops being effective - dull or missing too many teeth - and you'll be happier and less stressed.

    No cutting fluid is needed or recommended here as it will just cause the swarf to collect in the saw and cause other problems.

    There you have it - 21+ years of experience cutting stainless with a porta-band distilled into a few paragraphs.

    Bottom line? Buy the saw and a bunch of extra blades of different TPI and you'll be able to cut anything that will fit into the throat of the saw from wood and plastic to stainless and titanium.

    Enjoy!

    Leo
     
  6. ted655
    Joined: May 2003
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    ted655 Senior Member

    Buy a can of "Rapid Tap" cutting fluid. If it's stainless and you are trying to cut or drill it, then you need Rapid Tap. It truly is a miricle fluid
    Blades ,drills, files, etc last 5 times longer and cuts stay cooler.
    Also, use a Lennox bi-metal blade.
     
  7. epoxyman
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    epoxyman Junior Member


    Sound good; it will be a welcome addition to my workshop. Thanks for the input that is / was relevant to my specific concern.:)
     
  8. ted655
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    ted655 Senior Member

    I don't agree with the advice of not using a fluid in conjuntion with cutting. Teeth prt inch, feet per minute, sharp, undamaged teeth are ALL great advice. This is why I draw exception to the use of cutting fluids.
    Stainless gets hot almost instanly. That is what sets it apart when working it from other metals (other hybred alloys such as monel also have this issue).
    Heat IS the enemy of the blade or drill. Transfer it away and life is easier. While cutting fluid (oil) can clog up around pulleys & wheels and make tools just generaly "yucky", IT'S WORTH IT. It moves aside rather easily & I've never had ot bind or disrupt my work.
    In a shop, the price of extra blades are passed on to the customers. When buying them yourself, you want as much life as possible from them. You get what you pay for when it comes to machine shop tools, good ones cost more. Make em last. They dull soon enough .
     
  9. SAQuestor
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    SAQuestor Senior Member

    Perhaps my experience is from 8 different guys using the same porta-band and then my having to come behind a couple of the "slobs" that didn't give a crap what condition they left to tool for the next guy to use.

    Drilling stainless is a whole 'nuther ball game. Slow rotational speeds with a sharp bit and RapidTap IS a great way to do a good job. Avoid the heat build-up that Ted mentions by plenty of cutting fluid and slower FPM speeds.

    But as with most things, there is no one right way. What works for me based on my experience may not work for you. YMMV as always.

     

  10. waikikin
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    waikikin Senior Member

    For 1 cut

    For 1 cut only I'd go for current resource theory, you've got the grinder, stick in a staino cutting disc & after careful scribing of your cut, cut the pipe being careful not to trap the disc in a closing cut- 'cos that is the dangerous thing about cutting discs, besides that use ear muffs, goggles & full face visor & particle mask etc & keep both hands on the handles until rotation stops. Regards from Jeff. PS: I'm gunnu check out those porta bands, they sound cool.
     
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