Announcement

Collapse
No announcement yet.

Round foundation help

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • #31
    Re: Round foundation help

    Tony

    Try this:

    http://www.cleavebooks.co.uk/scol/callipse.htm

    So for your 21x18 (axis 42x36), the foci = 21.6.

    Measure over to the middle, 21 inches, then put a nail in at 21.6/2= 10 3/4 inches each side on the base line. These are the ellipse foci.

    Put a nail in at one end of the 42 inch line. To get the loop length, tie a cord loop tight around this this nail and the farthest of the two foci nails. Now, take the cord loop and loop it around the two foci nails. Now put a pencil inside the loop and draw the ellipse.

    Note that the height you have chosen, 18 inches, is 85% of the radius. This is at the most aggressive end of the 85-90% "rule of thumb" ratio. At 90%, the height would be 21x.9= 18 7/8. I would go for about 18 1/2 inches. Take a look once you have drawn it.

    Note also that because your soldiers are 4 1/2 inch vertical, you have to "catch up" to the ellipse over the first 2-3 courses, see below (this sketch is for a smaller ellipse - on a larger one it is easier to "catch up").
    Last edited by Neil2; 08-28-2009, 05:35 PM.

    Comment


    • #32
      Re: Round foundation help

      Neil,

      How does this look? I put the top nail 18.5" from the base line. Place the two base nails (foci) 27" from each other. If I place the full soldier on the perlite without an angle cut, the pen goes right to the top of the soldier. But this will also this will give me a mortar joint of 1.75" between the soldier and the first course. What's your opinion? Do you think the mortar joints will be too thick?
      Cheers!
      Tony

      See My Photos:http://picasaweb.google.com/tonyboca5/IlForno#

      My thread:
      http://www.fornobravo.com/forum/f8/t...orno-6995.html

      Comment


      • #33
        Re: Round foundation help

        I changed the foci to 23" apart. This gives me a 16 degree angle to cut for the soldiers. This also decreases the mortar joint significantly. The next course should have a 1/2" mortar joint. I'm going to play with these measurements in a dry run and see what happens.
        Cheers!
        Tony

        See My Photos:http://picasaweb.google.com/tonyboca5/IlForno#

        My thread:
        http://www.fornobravo.com/forum/f8/t...orno-6995.html

        Comment


        • #34
          Re: Round foundation help

          That 23 inch foci ellipse looks good Tony.

          It helps to mock it up and figure out what "looks right"

          Comment


          • #35
            Re: Round foundation help

            Hi,

            I'm also interested in achieving a lower ceiling height, but at the same time use the "indispensible too" brick jig/guide posted over at tools and techniques. The tool seems fool proof by people who have used them.
            Anyway, I posted sketches of a variation of this tool (post #51) which I think might work to achieve a low ceiling.

            One question I have is, must ellipse domes follow certain profiles or would most any low arc profile work?
            George

            My 34" WFO build

            Weber 22-OTG / Ugly Drum Smoker / 34" WFO

            Comment


            • #36
              Re: Round foundation help

              fxpose,

              I would start by using the elipse that gives you the height you want and the tallest soldier possible. I kept going back an forth with the foci to find what worked. My problem now is that i pitched the oven 1/2" higher in the back to keep the rain out. Now my soldiers sit below the floor even more now. Back to the drawing board.
              Cheers!
              Tony

              See My Photos:http://picasaweb.google.com/tonyboca5/IlForno#

              My thread:
              http://www.fornobravo.com/forum/f8/t...orno-6995.html

              Comment


              • #37
                Re: Round foundation help

                "One question I have is, must ellipse domes follow certain profiles or would most any low arc profile work?"

                I think any low arc profile will work but an ellipse is the "theoretically" best shape.
                Last edited by Neil2; 08-30-2009, 10:05 AM.

                Comment

                Working...
                X