Page 1 of 2 12 LastLast
Results 1 to 15 of 20
  1. #1
    Join Date
    Sep 2018
    Location
    Boonah Qld
    Age
    82
    Posts
    24

    Default Turning High Tensile Steel.

    Is it possible to buy high tensile steel rod say 25mm by 250mm and turn most of it down in a lathe to say, 12mm and then thread each end without it loosing tensile strength? What tool is required in the lathe and die to cut thread? Or can I heat mild steel and make it strong enough after the work? These bolts will hold the cylinder block to cranckcase as well as hold the main bearing caps on an old old tractor engine. The compression is really low and the RPM also low. Thanks in advance.

  2. #2
    Join Date
    Oct 2011
    Location
    Norwood-ish, Adelaide
    Age
    59
    Posts
    6,541

    Default

    High tensile does not really mean much in a metal working context as it is not specific enough.

    If you were to get some 4140 for example, that could be turned down to the sizes you are after and then threaded, using a single point technique and/ or a thread die. The properties of the material you would buy are uniform and then if you needed to, it could be heat treated to raise the hardness.

    However, I would question whether heat treatment was appropriate. Usually when something is heat treated it becomes stronger but also more brittle. For a cylinder head bolt I would have thought that material in the natural condition was better able to resist the forces in the engine. I have no experience in engine restoration but I think that would be one of the things that I would be checking with others who do similarrestorations.

    Michael

  3. #3
    Join Date
    Jul 2016
    Location
    Melbourne
    Age
    35
    Posts
    1,522

    Default

    I have made the head studs for a few early cars, I just used 4140pre hard but I nearly always make them as studs not as a headed fastener. Means all that has to happen is single point a thread on each end not turning off heaps of stock.

  4. #4
    Join Date
    Apr 2012
    Location
    Healesville
    Posts
    2,129

    Default

    I agree that studs are usually the best way to go. 4140 would be my choice, also allow a bit of extra length to accomodate a grunty hardened flat washer and either make or buy longer nuts to pick up more threads.
    shed

  5. #5
    Join Date
    Oct 2007
    Location
    Sydney
    Posts
    3,112

    Default

    Yes I've done something similar with 4140, both as studs threaded on each end and as bolts. Both began as standard round stock. I single pointed these, but 4140 should be able to be threaded with a conventional good quality die.

    4140 stud.jpg

    Heating mild steel will not increase its strength. It can be case hardened to increase its surface hardness, but it will not increase the tensile strength.

    Is there any reason you wish to make your own instead of simply buying and (if necessary modifying) existing hardware?

  6. #6
    Join Date
    Jun 2007
    Location
    sydney ( st marys )
    Age
    64
    Posts
    4,887

    Default

    Before you purchase material in the size you asked about , have you considered buying something closer to your finished thread size.

    I understand that you require a nut/shoulder in the centre for securing bearing caps or similar.

    If you can machine 3 threaded sections on a smaller diameter piece of material and undercut one end of the thread to the centre you should be able to use a nut in the centre thread for securing, it may even save some expense in larger material size and time.

  7. #7
    Join Date
    Sep 2018
    Location
    Boonah Qld
    Age
    82
    Posts
    24

    Default

    I have now read up on 4140 and it seems it meets the requirements. Perhaps I could make the studs in sections as Pipeclay says with a nut in the middle to secure the bearing cap and hold the next piece of rod that holds the crankcase to the cylinder block. This is a 100 year old engine that was submerged in a creek long enough to fill the sump with silt and badly rust the nuts that hold the bearing caps down. The nuts at the top are also well rusted as the tractor has been in the open ever since. Thanks for the replys. From them I can now cut the nuts off with an angle grinder knowing that a replacement solution is possible. Not sure the bolts will still come out as they are inside the casting for about half their length but once the nuts are off I'll see what transpires. Thanks guys great forum for metal working answers. There are knowledgeable blokes out there. I'll let you know what happens.

  8. #8
    Join Date
    Feb 2003
    Location
    formerly from Sydney (north of The Harbour), NSW, Oz
    Age
    68
    Posts
    306

    Default

    at the risk of being the perennial ...

    what is the preference for "high tensile" steel?
    Mild steel should be easily strong enough -- perhaps over strong -- for the an engine that old.

    for a bolt, high tensile means that the bolt holds the parts together by stretching as it is tightened so that the mating surfaces are under considerable compression and hold by friction.
    In an engine that compression would result in the gasket being crushed.
    regards from Canmore

    ian

  9. #9
    Join Date
    Sep 2018
    Location
    Boonah Qld
    Age
    82
    Posts
    24

    Default

    Quote Originally Posted by ian View Post
    at the risk of being the perennial ...

    what is the preference for "high tensile" steel?
    Mild steel should be easily strong enough -- perhaps over strong -- for the an engine that old.

    for a bolt, high tensile means that the bolt holds the parts together by stretching as it is tightened so that the mating surfaces are under considerable compression and hold by friction.
    In an engine that compression would result in the gasket being crushed.
    May be but this bolt holds the main bearing cap as well as the crankcase to the cylinder block. I am tempted to use mild steel but 4140 can be machined and will do the job. So no risk. The other possibility is two HT bolts joined by two nuts welded together or a long nut for cyclone rods. The head studs will be another problem to face if I can get the head off.
    M

  10. #10
    Join Date
    Feb 2013
    Location
    Laidley, SE Qld
    Posts
    1,038

    Default

    I'm not far away if you want a second opinion on what you propose, I often make bits and pieces for old machinery belonging to Laidley Pioneer Village.

    As has been said mild steel bolts/studs will be adequate considering the age of the engine, but no harm done if you use 4140.

  11. #11
    Join Date
    Feb 2003
    Location
    formerly from Sydney (north of The Harbour), NSW, Oz
    Age
    68
    Posts
    306

    Default

    Quote Originally Posted by Flocar View Post
    May be but this bolt holds the main bearing cap as well as the crankcase to the cylinder block. I am tempted to use mild steel but 4140 can be machined and will do the job. So no risk. The other possibility is two HT bolts joined by two nuts welded together or a long nut for cyclone rods.
    It's a very long time since I did any design work for bolted connections and consequently my memory could easily be faulty. I have a vague recollection that mild steel bolts were stronger in sheer than HT ones, and that the strength of a HT bolt depended on how well the bolt threads engaged with those inside the nut. In a cast engine component I'd be concerned that a HT bolt can not be tightened as well as a mild steel one.
    regards from Canmore

    ian

  12. #12
    Join Date
    Dec 2005
    Location
    South Australia
    Posts
    1,656

    Default

    This is a bit off topic, Ian does that mean that that mounting a jockey wheel bracket to a trailer with high tensile bolts into mild steel is fundamentally wrong

  13. #13
    Join Date
    Sep 2018
    Location
    Boonah Qld
    Age
    82
    Posts
    24

    Default

    Quote Originally Posted by bob ward View Post
    I'm not far away if you want a second opinion on what you propose, I often make bits and pieces for old machinery belonging to Laidley Pioneer Village.

    As has been said mild steel bolts/studs will be adequate considering the age of the engine, but no harm done if you use 4140.
    Hey yes Bob, That would be great. Our Village wheel wright is currently making wheels for one of Laidleys horse drawn vehicles. I would welcome another point of view. If you want to take a look at what is what. I have PM'ed you with my phone number. Rob
    H

  14. #14
    Join Date
    Sep 2018
    Location
    Boonah Qld
    Age
    82
    Posts
    24

    Default

    Quote Originally Posted by China View Post
    This is a bit off topic, Ian does that mean that that mounting a jockey wheel bracket to a trailer with high tensile bolts into mild steel is fundamentally wrong
    Not really off topic. It adds to the knowledge. I must say I have never had to think about this subject matter before. Any discussion that adds to knowledge about HT and mild steel bolts being used for a similar purpose is welcomed from my point of view.
    N

  15. #15
    Join Date
    Oct 2011
    Location
    Norwood-ish, Adelaide
    Age
    59
    Posts
    6,541

    Default

    Quote Originally Posted by China View Post
    ... does that mean that that mounting a jockey wheel bracket to a trailer with high tensile bolts into mild steel is fundamentally wrong?
    Not necessarily. In Design Theory, threaded fasteners (bolts) are only used to increase the friction between the items being joined. If the high tensile bolts are going into high tensile nuts then that is fine. If the high tensile bolts are going into MS nuts or holes tapped in the frame then there could be issues, simply because in order to fasten correctly, a bolt must stretch a small amount (effectively it acts like a spring to maintain force on the joint). If the thread that it goes into is too weak then it will strip before the bolt is tight enough and fail. The other alternative is that without that 'spring',vibration will allow the joint to loosen.

    Michael

Page 1 of 2 12 LastLast

Similar Threads

  1. M12 grade 8.8 "high tensile" bolts
    By bob ward in forum METALWORK GENERAL
    Replies: 8
    Last Post: 23rd Feb 2015, 02:51 AM
  2. Replies: 3
    Last Post: 25th Jun 2014, 12:44 PM
  3. HIGH TENSILE BOLTS Vs MILD BOLTS.
    By chambezio in forum METALWORK GENERAL
    Replies: 13
    Last Post: 3rd Jan 2014, 08:25 PM
  4. Cuting High speed steel??
    By iron bark in forum METALWORK GENERAL
    Replies: 29
    Last Post: 26th Jun 2013, 03:01 AM
  5. welding high tensile chain??
    By Mathuranatha in forum WELDING
    Replies: 14
    Last Post: 17th Jul 2009, 09:59 AM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •