Finding the center on a pc. of round stock-milling machine tilted 45*

Discussion in 'General Engine Discussion' started by namonllor, Aug 26, 2011.

  1. Aug 26, 2011 #1

    namonllor

    namonllor

    namonllor

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    Hello guys,
    Wow, how this group has grown. Looking through the posts, I see we have some great chippers out there.
    With that in mind, I've come up with a problem I can't figure out.
    I'm in the process of making a spring winder from plans I got from Model Engine Builder and one of the pieces had to have a V cut notch put into it. Here's the setup I used.
    I inserted the round stock, end up, in the vise, then I had to find the center of the rod (I eye-balled it). I then tilted the head 45* and cut the V groove into the face of the end of the rod.
    It came out pretty darn good and thruth be told, it's only going to support the mandrel the wire will be wound on, so it wasn't critical.
    My question is, how does someone go about finding the center of a rod when the milling head is tilted 45*? Can't use an edge finder...so how is it done??
    Good to be back and posting,
    Ren
     
  2. Sep 3, 2011 #2

    joeby

    joeby

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    There are several ways I can think of, depending on how accurate you want to be. For getting the corner of an endmill on the center, which seems to be the question, I would use the center head for your combination square and scribe a couple of lines across the center of the round stock. Bring the endmill down just until it cuts a line on the part and adjust the table so the cut line crosses the intersection of your layout lines.

    Quick and dirty, I know; but will get you within a few thousandths if you're careful.

    Kevin
     
  3. Sep 3, 2011 #3

    tel

    tel

    tel

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    The trouble with that is that as soon as you cut any depth at all with the cutter, the centre position will have moved, relative to the tool. The couple of times I've done things like that is to use a vee block and height gauge, strike the centre line and then strike a line above and below, each representing the outer edge of the proposed Vee.

    Now, depending on how you like to work, with the piece tilted 45°, take a cut across the face, then sneak down with the Z feed until you are splitting the lower line, then start moving sideways until you are doing likewise with the upper line - sounds finicky, I know, but that's just my poor explanation - in practice it works quite well!
     
  4. Sep 3, 2011 #4

    Jasonb

    Jasonb

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    When a rod is at 45deg the vertical measurement from the highest point of the end to the lowest is 0.707D (Basic Pythagorus)

    So if you touch down on the higest point and then lower your tool 0.707 xD x0.5 this will put the bottom of the cutter on ctr height. You can then do the same comming in from the side, touch lower edge of the bar and move the x axis 0.707 x D x 0.5.

    This will have your tool just skimming the ctr line. You can now feed down AND accross by the SAME AMOUNTS

    Jason
     
  5. Sep 3, 2011 #5

    Ken I

    Ken I

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    wrt to Tel's comments - if you are cutting a "V", finding the centre for the start of the cutting is not the same as the finished depth position - although you can go in equal x & z increments for 45° from there on in. (for other that 45° do the Trig.)

    If you want to be accurate follow the prior steps until you are somewhere close and then put a suitable drill rod / wire in the "V" - measure and make your final x & z adjustments for the last cut.

    Ken
     
  6. Sep 3, 2011 #6

    mocaquita

    mocaquita

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    I would cut the V by "eyeballing" the corner of the cutting tool to a scribed mark on the stock. Take a cut and without changing your settings, flip it around 180 degrees and take another cut. You may want to make a slight adjustment to your settings at that point and then cut down to the depth you need, always flipping it around. This technique is self centering but may leave you with a slight defect in the very bottom in the V. Chances are the very bottom is not used anyway!

    Dave
     
  7. Sep 4, 2011 #7

    Lew Hartswick

    Lew Hartswick

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    I'd use a V cutter and keep the head vertical.
    ...lew...
     

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