How to cut High Tensile (UK) steel bar (7" long and 1.5" diameter)in half.

Discussion in 'Metals' started by Metal Mickey, Oct 9, 2010.

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  1. Oct 9, 2010 #1

    Metal Mickey

    Metal Mickey

    Metal Mickey

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    I am stuck!!!

    I have a 7" long by 1.5" diameter HT steel bar that I need to saw in half for two crankshaft blanks for the Seal project I am building.

    I tapped one end to fit two 'ears' of steel so I could hold it and have tried carbide tipped saw, band saw and now a 4" diameter slitting saw. All will make some impact on cutting it but is seems very brutal and a long long job to make any headway. I will post some photo's later to show what I mean but has anyone any ideas?

    I have thought about using stainless steel instead and wonder what thoughts you have on the durability that will give? Westbury states in his article that HT would be best (if available) but since this was written in 1947 and there were steel shortages after the second world war, he does say ".....medium alloy steel, about 35 to 50 tons tensile strength, but in view of the present supply difficulties, constructors.........may have to use mild steel, which will be satisfactory as to mechanical strength, but somewhat inferior in respect of wearing properties".

    Since stainless in bar form is available I just wonder whether the effort to get the HT steel cut is blocking my progress when Stainless may do? Any help on either cutting or changing to stainless would be appreciated.

    I checked the Craftsman Museum page but they don't state the material used. I therefore have asked Craig or Tom for there cranks material as well.

    MM
     
  2. Oct 9, 2010 #2

    Jasonb

    Jasonb

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    If you are thinking of going out to buy stainless why not just go out and buy 1"? HT steel to the correct EN Number.

    Thought you had that bit of steel cut by now, was a while ago you were asking about it ;)

    Jason
     
  3. Oct 9, 2010 #3

    cidrontmg

    cidrontmg

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    Already tried an angle grinder?
     
  4. Oct 9, 2010 #4

    Blogwitch

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    MM,

    If you are having trouble cutting it in half, what is it going to be like when you are trying to machine it to fine tolerances and complex shapes?


    Bogs
     
  5. Oct 9, 2010 #5

    Metal Mickey

    Metal Mickey

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    I tried this first Jason so do you have a supplier? I searched hard and long and could only every get it as round bar!

    There isn't enough tolerance for my angle grinder skills I am afraid....


    Bogs, you may be right! I am going to try a machining the bar next time in the workshop. The supplier insisted it would machine...I don't suppose I pressed him on how well!!
     
  6. Oct 9, 2010 #6

    Metal Mickey

    Metal Mickey

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    I set everything up last night ready to make a start on cutting the 1.5" diameter round bar of high tensile steel, in half. I was full of hope that with the carbide tipped saw blade that cuts wood and metal, this would be a successful. However two issues quickly arose, firstly the width of cut was increasing beyond the width of the blade, and secondly, it was very brutal and I suppose to a degree I chickened out!

    So I decided to see whether a 4" slitting saw with side cutting teeth would do the job. I hadn't tried this previously due to how to hold the work and secondly, all the handle work on the mill. These issues were resolved because the power feed was working well and I now had a method to hold the work (the use of tapped holes in one end to secure plates too). Well it worked to a degree, after adding additional table clamps to stop some lateral movement. However it was again very slow going and I was not convinced that this would be successful in a reasonable amount of time (and blades!!).

    So I have decided to approach the problem in a different way. 1, search out a local engineering firm to see if they can help cut the bar. 2, research whether the need for High Tensile steel is still valid bearing on mind how much materials have changed over the last 63 years since Westbury designed the Seal. and finally 3, look to take on another element of the build such as con rods or pistons while I sort out 1 and 2 above.

    100_4681.JPG

    100_4684.JPG

    100_4685.JPG

    100_4687.JPG
     
  7. Oct 9, 2010 #7

    Jasonb

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    I was thinking of using round bar, looking at the general arrangement on Hemmingways site it does not look much larger than 1" which would be a simple matter of milling one side flat, turning it over and milling the other side and less risk of the work warping due to removing more metal from one side.

    Having said that I would probably do all the turning while its in the round and then just mill the webs to shape.

    I don't think there would be any more material to remove than trying to square up a larger semicircular section.

    Jason
     
  8. Oct 9, 2010 #8

    90LX_Notch

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    MM,

    One way to do it is to drill a series of holes through the bar so that the diameters are almost touching. Then saw through them.


    It would look something like this: OOOOOOOO


    Bob


     
  9. Oct 9, 2010 #9

    Jasonb

    Jasonb

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    Another option is to use the bar you have but stick it in your vice and reduce it to a rectangular section first then try splitting it down the middle, this will mean less to cut through and you will be able to hold the rectangular section far more rigidly.

    And if you have not got enough waste to use the stitch drilling method then just take a hacksaw to it, do say 1/2" at a time with some other machining between sawing sessions. Just the thing to warm you up in the workshop now the temps are dropping.

    Jason
     
  10. Oct 9, 2010 #10

    gmac

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    MM

    I'm watching with interest - I have a 12" long 1.75" dia chunk of 4140 for Ron Colonna's Offy crankshaft that needs the same operation. I'm thinking - find someone with an industrial size chop saw or cold cutting saw (bring beer).

    On the issue of material type Ron Colonna has specified 1144 StressProof steel for the crank. After talking to him he's indicated that he now uses a lot of 1144 - camshafts, gears, crankshafts. I've found it's price to be reasonable although not everyone stocks it. Typically found as rounds, haven't found it in bar or flats. Unfortunately I bought the 4140 before I found a supplier for 1144SP.

    As to Stainless Steel - I'd say its the wrong application (crankshaft) for this material - galling is problematic. Secondly it's an expensive way to go. Some reference material;

    http://machinedesign.com/BDE/materials/bdemat6/bdemat6_5.html

    Why not buy a box of hacksaw blades and put out a challenge to the local teenage boys....?

    You'll get there.

    Cheers
    Garry

     
  11. Oct 9, 2010 #11

    tombstone

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    Mickey, one way of cutting your lump of HS steel in half exactly is to source a local engineering company with a wire cut EDM machine typically Agie or Charmilles these are an amazing bit of kit I don’t know what your c.shaft is like but if you gave them your drawing they could possibly make most of it in one hit.The down side is it would be probably a large amount of $US or £ sterling or whatever you local currency is but it is always worth asking.The material would not be a problem I have used it to rough out parts in the centre of jet engines in nimonic & inco.
     
  12. Oct 9, 2010 #12

    peatoluser

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    if mild steel is satisfactory for strength but not for wearing properties, would it not be possible to make it (i don't know what you are buiding so what i'm suggesting may well be rubbish) from mild steel but case harden the bearing surfaces? obviously don't use free cutting MS.
     
  13. Oct 9, 2010 #13

    krv3000

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    HI have you got a dremal ? i have cut 1.1/2" silver steel with it
     

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