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  1. #11
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    Aug 2013
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    Country: Wales

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    Hi Maik, no it's not my first round steel door- it's the biggest round working door in steel so far, but I've made lots of smaller ones in steel over the years. The ones in the group shot are the only ones I've got now.

    Youre right the One King West door is aluminium, the tiny one is actually steel with brass trim, although I did make one in bronze about 20 years ago as a desk pen stand for my dad.

    Years ago I made quite a few 4 inch (100mm) steel display models styled like the Chatwood door in the old Midland Bank London.
    From that pattern I also made a few more ornate American style variations with brass bolts and trim. I made one of them really elaborate like a Remington Sherman with the square brass frame over the boltwork- only made one like that though, it took double the time. Also made a few big pen stands in Aluminium and stainless, all around 100mm diameter, some of those were about 75 or 80mm thick- really chunky.
    Almost forgot, also made a few small Cleveland Fed doors in solid 316 stainless steel. They were about 45 or 50mm diameter and one much smaller version around 30mm I made into a pendant. There's more from over the years that were rectangular but that's probably it on the round ones. Oh, plus a few batches of small key rings or key chains as some call them. Some were brass and some in aluminium all had stainless bolts.

    For the eccentrics on the ends of the pressure bars on this new door I'll machine the cam blocks from solid in stainless, and add shouldered stainless eccentric pins afterwards. The cams will then be pinned onto the bars like you say.

    Regards the eccentric pins bending under the the force, on a big working model like yours you ideally want the pins being a tight press fit in perfectly reamed or bored holes in the cams. There's too much 'play' in screw threads to have them threaded, no matter how good the threads are cut, its still down to very small interlocking surfaces coming together which will crush under heavy sideways pressure creating play/wobble- rigidity is paramount under extreme sideways forces like these. You could incorporate heavy rollers as the eccentric pins as that's a well proven method of relieving wear in 'camming' applications like this where there's big forces involved. The improvement of a 'rolling' action where the pin can rotate is superior over the harsh 'biting' action of a fixed pin, and is easily achievable using a good set of roller bearings designed to take that sort of axial load.

    For fixed eccentric pins you ideally want really accurate holes in the cam blocks either reamed to size or bored out with a single point tool on the lathe.
    Make the eccentric pins stepped with a shouldered head and a tight press fit, use a smear of cyano or loctite on assembly as you press them together. It would make sense to use a tough grade of stainless or tool steel for the eccentric pins so you've got no worries about surface wear but might be OTT regards the shear strength- more on point later..
    Making the pins shouldered so they are stepped into the cam blocks, adds good stability- doesn't need to be much of a step as you still want the 'root' of the pins as thick as possible into the blocks.

    Pressure bars are quite an unusual mechanism when you think about them, they have a few hidden points to note the more you go looking. Don't forget that no matter how big, heavy, precise and strong the cams, bars and eccentrics etc are, if the cams are sleeved over the drive bars and then pinned in place then the whole system is only as strong as the shear strength of the small cross-pins holding them. So, shear strength is very important, but it's easy to go overboard on say the cams and eccentrics, when the tiny cross-pins are the ones to really think about. Weakest link in the chain so to speak...
    I know you'll get it worked out and sorted Maik, unique projects like your Monster vault always involve a fair amount of experimentation- that's the challenge and enjoyment of doing them!

    Cheers again mate

  2. #12
    Join Date
    Oct 2009
    Location
    Cleveland, Ohio USA
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    1,433
    Country: United States

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    Huw, there should be a special section on the forum, to showcase the work you and Maik have done. Both of you have put an extraordinary amount of effort and passion on these vault doors. Your list of the doors you have made is astounding. When I did bank service, I was always curious on how they were made. Your description on the design of the pressure bars is similar to the unobvious design features in making a combination lock lever/fence. I remember several times seeing cracks on the pressure bar jamb receiving blocks. That told me some serious forces were being generated. Keep up the good work. Doug

  3. #13
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    Aug 2013
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    Country: Wales

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    Hi Doug and thanks very much!

  4. #14

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    Hey guys :)

    Doug, thanks for your kind words and yes, if you like to make a subsection for vault door modeling and stuff, I would join there

    Huw,
    about the eccentric cams: Mine are 74mm in diameter and they have a pin (12mm in diameter) that is screwed in but it has a reamed hole where it is held and at the end you have the thread. So the force does not go into the thread. On this pin there is a roller that takes the friction away. The cam is then pinned onto the shaft and tightened by a M16 hexhead screw. The shaft is 32mm in diameter and stainless. I was not able to test the construction, but I have good faith in it so far.

    In your model I see why you dont put rollers on the pins and I saw some doors of smaller safes which did have pressure bars but their cams didnt have rollers either. I think both versions (with and without rollers) are somehow sophisticated to machine as you pointed out.

    Again, thank you for your kind words regarding my door

    I am really looking forward to new pictures of your great work! Keep it up!

    Cheers

    Maik

  5. #15
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    Aug 2013
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    Country: Wales

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    Finaly replaced the temporary cheese head screws for proper shouldered bolts turned from hexagon brass.
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  6. #16

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    Hey Huw,

    that is much better than the former screws!

    Keep it up

    Maik

  7. #17
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    Aug 2013
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    Country: Wales

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    Quote Originally Posted by RiemannHypothesis View Post
    Hey Huw,

    that is much better than the former screws!

    Keep it up

    Maik
    Thanks Maik, trouble is a few others have now convinced me to go fancy brass and replace all the steel nuts on the back of the door- American style. Started making Replacements, acorns, pointed, pointed with painted centres etc but can't decide which I'm going with yet. Will also make some solid one piece hex bolts in different styles to see what looks best.

    Dug out my old turret for the tailstock- saves a lot of time on boring repetitive stuff like this when there's 16 of everything! (By 'boring' I mean tedious, not lathe boring as in boring holes!!!)
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  8. #18
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    Aug 2013
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    Country: Wales

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    After many hours machining more hexagon brass into swarf, it's now looking a bit more ornate American. Made just about every style of hexagon nut possible, and strangely out of everything this simple pattern still seems to look and work the best.
    Now working on some fancy brass embellishments, some engine turned and some engraved,taken this route now so there's no going back- having got this far might as well go the full monty!
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  9. #19

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    Yeah it looks very good And a turret of this kind you showed there before is a good idea for me to buy :) I have to pause building my door for a few days due to getting a new drill press stand operational and also working on my small Pittler B lathe for small parts. Here is a pic of the new drill press stand for my Eibenstock 32.4 drill (hope you dont mind me posting pics in your thread):
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    Keep it up, Huw!

    Cheers

    Maik
    Last edited by RiemannHypothesis; 04-03-17 at 11:27 AM.

  10. #20
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    Aug 2013
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    Cheers Maik, seeing the Eibenstock drill on your drill press reminds me of the old AEG unit on my BUX magnetic drill rig I used for drilling safes. You've got some really heavy kit there in your workshop, it dwarfs my stuff! I think you should be going quarter scale 1:4 on your next one...

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