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Materials

Discussion in 'A BEGINNER'S FORUM (Learn How To Machine Here!)' started by gregc, Apr 21, 2017.

  1. gregc

    gregc United States Active Member Active Member

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    I am not sure where to place this

    I was wondering how most here select the materials for a project
    Do you have a handbook of different material properties ?
    Just experience. What you have handy. What is cheapest that you think will work ?

    Where do you get your materials? If you have some mystery metal do you try to determine what it is?

    Maybe I'm just making this too complicated. Did some research and thought that vespel might make a good material for a steam engine piston. I discovered it was pretty expensive. Invar may also be an interesting material but not sure where I can get a small quantity. Also wondered how hard invar is to machine.
     
  2. Bob Korves

    Bob Korves H-M Supporter - Premium Content H-M Supporter-Premium

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    Small steps, Greg. Learn well about the basics before you venture farther afield. Steam engines have done just fine on cast iron, plain carbon steel, and brass for centuries. No need to reinvent the wheel. If it is a model steam engine, then aluminum and other metals will also do the job. Exotic metals are for exotic needs. Welcome to Hobby Machinist!
     
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  3. Tony Wells

    Tony Wells United States Vice President Staff Member Administrator

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    Try to get your hands on an old blue EMJ book or a similar (although imo there are none) reference book. It's a stock list, plus tons of tech and application data. You can request a CD, but the books are getting a little harder to come by. Of course, they have it all online, but to me that's just not the same.

    I agree with Bob overall.....stick with the tried and true materials for stuff like model steam engines. Not that they couldn't be improved, so when you get the desire and learn what material properties you want to experiment with, by all means, this is a hobby for most here so go for it!
     
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  4. ghostdncr

    ghostdncr United States Active Member Active Member

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    Here's a pretty good write up on material properties that discusses how to determine the physical properties of various engineering materials. It's fairly dry though, so you should be wearing your math hat and be fully caffeinated before reading: http://www2.isikun.edu.tr/personel/ahmet.aran/mfgprop.pdf

    An old friend of mine, long since dead, worked for the ordnance department during and after WWII. One of the many projects he worked on during his career was extending the barrel life of the .50 cal Browning Machine Gun. Tommy said that under great conditions the steel barrels were only good for something like 3-5000 rounds before reaching the end of their service life. Someone developed the theory that a barrel fitted with a Stellite liner would extend the useful life of these barrels to some degree. I machined some Stellite many years ago and to this day can't imagine how the bore, rifle, and chamber a tube of that stuff to the level of precision needed for a .50 BMG, but nowadays it must be the standard. I don't recall ever seeing a BMG barrel that was just made from steel. Anyway, Tommy would laugh about his role in the testing. He set up a pair of M2's (fitted with the new barrels) in their range shack and started shooting, switching between guns after every belt of ammo. He fired those two guns for weeks, with pallets of fresh ammo being delivered throughout the day. When he tested throat erosion after 5000 rounds, he said both barrels still gauged as new. I think he said they quit after both barrels had clocked 50,000 rounds and the 1-5 TEG (Throat Erosion Gage) was still a snug fit at #2 or #3! I only relate this story because I always thought it was a great real-world example of how a simple material change dramatically enhanced the performance of a finished product. Of course, I was also kinda awestruck by being around someone who had fired over 100,000 rounds through a Ma Duece. I do miss him.
     
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  5. Dave Paine

    Dave Paine United States Active Member Active Member

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    I try to use whatever I have available. I purchased some steel from an online vendor, but shipping is very expensive. I now look on EBay or try my luck at a local metal recycling company where the prices are not expensive, but it is the pot luck. The aluminium typically has the spec printed on the surface, but the steel will be mystery steel.

    I expect most hobby machinists have their share of mystery steel pieces. Some machine well, some do not but easy to test machining. A bigger unknown is whether the steel can be hardened if required. A spark test may give some clues.

    The steel I do purchase is O1 drill rod. Available in many diameters. Consistent diameter, easily machined and easy to harden. I used to purchase from ENCO. Now I have to get from the parent MSC and wait for a free shipping offer.

    Last weekend I accompanied a machinist friend to pick up some items at the shop of one of his friends. This person does precision gunsmithing. We looked at his scrap bin and saw some nice shiny short pieces of steel. We asked if we could have these. He was happy to give them to us. He then said "Do you want some scrap rifle barrels of the same material?" We both got a couple of scrap barrels in 416R stainless. We did not ask why these were scrapped, just happy to have some nice metal available for some future need.
     
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  6. dulltool17

    dulltool17 United States Active User Active Member

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    "I try to use whatever I have available"

    A good philosophy until you need an alloy for specific properties, such as high Tensile strength, etc.

    One of my lingering projects is a tailstock indicator holder. The goal is to use what I have on hand, so it will have Aluminum, Stainless and Brass parts, as well as hardware that's sitting around in bins.

    As already been said, stick to the tried and true while learning. The exotic stuff might be 'better," but will likely not provide a cost-effective solution.

    Whatever you use, have fun and be safe.
     
  7. gregc

    gregc United States Active Member Active Member

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  8. gregc

    gregc United States Active Member Active Member

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    Thanks for all of the great replies.
    Found a place near me that ca supply small quantities of most common metals. They claim 75 locations so it may help some here. The local people are friendly and helpful.
    https://www.metalsupermarkets.com/

    The EMJ and the other post is a bit dry but as an engineer I read a lot of stuff like that.

    Thanks to all
     
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  9. Silverbullet

    Silverbullet Active Member Active Member

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    Hi Gregg welcome to the site, help is offered , no question is wrong . If you dont ask ya dont learn. Just be safe doing any machining. Eyes and ears , no rings or long hair. Yupp the lathe will grab and cutters will cut. Have fun and learn a very rewarding job.
     
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