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Technical Machining Putting a hole in the right place

Discussion in 'The Hokey Ass Message Board' started by ekimneirbo, Mar 28, 2020.

  1. ekimneirbo
    Joined: Apr 29, 2017
    Posts: 1,709

    from Brooks Ky

    A week or so ago a fellow Hamber showed some interest in gaining a little knowledge about using math and machines. It occured to me that probably most Hambers have never gotten the opportunity to use real industrial machinery or struggle with how to make accurate cuts with small home machines. So in that vein I decided to try and create a thread that shows the basic Trigonometry (keep reading) and how simple it can be. Hope I didn't make any obvious mistakes here, but I tried to put this together so that its easy to understand. If anyone has any questions about how to do basic machining, I'd be glad to try and help them. Anyway, here are some pictures that I hope will help anyone wanting to give machining a try.:D

    Trig 1.jpg
    Trig 2.jpg
    Trig 3.jpg
    Trig 3a.jpg
    Trig 3b.jpg
    Trig 4 001.jpg
    Trig 5.jpg
    Trig 7.jpg
    Trig 6.jpg
  2. Thanks for the refresher. Been a long time since I saw a lot of the terms you used but I do still use some of the techniques.
    ekimneirbo, mgtstumpy and blowby like this.
  3. s55mercury66
    Joined: Jul 6, 2009
    Posts: 3,980

    from SW Wyoming

    Thanks for posting that up, it has been a while since I used any trig. I used to have a small book that had all of the info for angles in it like you posted, it was handy as hell. Our machine tool instructor was always telling us that if you know two things about any triangle, whether it be the sines, cosines or angles, you can calculate the rest. Now we need some instruction on using a dividing head vs the rotary table :)
    ekimneirbo likes this.
  4. 6sally6
    Joined: Feb 16, 2014
    Posts: 1,331


    ekimneirbo, partsdawg and chop job like this.

  5. southcross2631
    Joined: Jan 20, 2013
    Posts: 4,177


    Reminds me of all those log books we had when I was an artillery surveyor in the army.
    Before computers you had 3 guys figuring out math problems and comparing answers to see if the guncockers hit the target.
    Then it went to a computer we carried in the back of a 5 ton truck powered by 2- 5 kw generators.
    Now you can get on your phone.
  6. Fortunateson
    Joined: Apr 30, 2012
    Posts: 3,614


    Great post! I admire your teaching style. I used to do the same thing with my students, get the general idea into their heads and then go back to fill in the details. Terminology can be very intimidating which scares/turns people off impeding learning...
    ekimneirbo likes this.
  7. Dave G in Gansevoort
    Joined: Mar 28, 2019
    Posts: 281

    Dave G in Gansevoort
    from Upstate NY

    Remember slide rules? Good job with the math. Mechanical engineer by training. I still like mathematics. Of course today its all done with computers and analytic programs.
    ekimneirbo likes this.
  8. X-cpe
    Joined: Mar 9, 2018
    Posts: 1,059


    I google "side angle side" (because that is about all I remember) and up jump a bunch of sites that have formulas where you can plug in your knowns and they spit out the rest.
    ekimneirbo likes this.
  9. It comes easy for me since I have been doing it for 40 years. One thing I do is work from a convenient X, Y datum. Working from a 0,0 centerline is very powerful. Or a mirror line. Always sketch up what you want to do on paper first. Graph paper is best, but I have scribbled numbers on napkins and post its.
    ekimneirbo likes this.
  10. 53 ford
    Joined: Apr 8, 2012
    Posts: 143

    53 ford

    The first thing an old machinist taught me was, you cannot drill a hole in the center.
  11. Ekimneirbo,
    I was the guy asking about the trigonometry. Thanks for the lesson, it was very interesting. It had never occurred to me how machinists make the parts they make before this. Where did you (and the other machinists) learn to do this kind of work? This is really fascinating stuff to me. Thanks again for taking the time to teach this to us.

    Sent from my iPhone using The H.A.M.B. mobile app
  12. ekimneirbo
    Joined: Apr 29, 2017
    Posts: 1,709

    from Brooks Ky

    One thing I have learned in life is I can always learn something from just about anyone if I just take the time to listen. Just about everyone has some knowledge or experience that they can pass along. The problem is that what is interesting to some of them may be of no interest to me. Things I'm interested in may not be interesting to them. Your interest was the reason I decided to make an attempt at passing along the general info that might get others started in the right direction. I was lucky enough to get into a really good apprenticeship program when I was younger. 3 months of schooling and 9 months in the shop.......for 4 years. I have forgotten a lot,but the basic machining is pretty easy if people get a decent old machine and some tooling to make it work. I hope I explained things well enough , but if you have any additional questions I'll be glad to try and help.

    One additional thing, most of the time the machining done in home shops is simple cuts to a dimension you want something to a diameter or a length. Most holes are placed by manually moving in one or two directions to a location that you want the hole to be. The problem is when you progress to trying to match a hole pattern to something redrilling a Ford axle for a Chevy pattern. That's when you have to do some calculating.
    Truckdoctor Andy likes this.
  13. Boneyard51
    Joined: Dec 10, 2017
    Posts: 4,741


    Ekimnierbo, that brought back memories! I took all the math our little local school gave!Made good grades, too, because I tried! Well more than a few years after I graduated , my Dad wanted to built a headache rack for the new truck he bought. I said no problem, Dad, I can figure the angles we need to cut just by knowing the lengths and width of our need!
    Well, I couldn’t do it with all the math I had taken in school! I was really disappointed! I was so upset, I called my old math teacher and asked her what I was doing wrong! She laughed and told me I needed trigonometry to do that and at the time I attended our school, it was not offered! So I acquired a trig book and taught my self basic trigonometry! There was no internet back then! I have used it many times since then. Thanks for reminding me about those times!

  14. Beanscoot
    Joined: May 14, 2008
    Posts: 1,761


    I only had five weeks per year in machining school during my apprenticeship, but I did like that we learnt only basic trigonometry and other math, enough to make required tapers on a lathe for instance.
    When you are taught some math in the class room and then use it in the afternoon to make some parts, it tends to stick more and you appreciate that it does in fact have some use.

    As for solving polynomial equations like we were taught in high school, I am not sure about the usefulness.
    ekimneirbo likes this.
  15. sliceddeuce
    Joined: Aug 15, 2017
    Posts: 2,982


    A hamb member that owns tools, has actual skills and can speak without saying dude, bro and ya know...When did this happen ?
    ekimneirbo likes this.
  16. Beanscoot
    Joined: May 14, 2008
    Posts: 1,761


    dude, ya no i was thinkin the same way it happen one time, bro.
    ekimneirbo likes this.
  17. clem
    Joined: Dec 20, 2006
    Posts: 3,138


    This is a lesson for most today. Well said !

    We learnt a lot of the stuff you mentioned when we were 14 at school. Had a retired sailor who was our maths teacher and we didn’t learn it with a calculator. Used it daily in my life, so thought everyone knew and understood it. Over the years I realised that very few actually did.
    ekimneirbo likes this.
  18. 57JoeFoMoPar
    Joined: Sep 14, 2004
    Posts: 4,822


    This is a great lesson because the trig involved also can be utilized to figure out another common automotive issue that arises; figuring out how much rotation per amount of linear motion.

    Think about it in terms of a throttle blade, and how far away from the throttle shaft centerline you need to attach your throttle rod to realize full throttle range of motion.
    ekimneirbo likes this.

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