How to build a radius tool

[kbartman]

Re: How to build a radius tool

How did you get it out from under the brick?

LOL....

Calculus says it shouldn't work, but you're really talking about 1-2 mm difference which you can probably smooth over in a build

Seriously speaking I'm no geo or calculus wiz. Just seems with IT rod in the middle of the brick "mechanically speaking" when IT was lifted it disturbed the brick. In my "Geometry for Dummies theory" (build it and try it). I thought the bottom was the way that worked best. I was thinking that it would or could be calculated from the bottom of brick bracket. Just my opinion......I eager to learn if this is true.

[deejayoh]

Re: How to build a radius tool

How did you get it out from under the brick?

Calculus says it shouldn't work, but you're really talking about 1-2 mm difference which you can probably smooth over in a build

[kbartman]

Re: How to build a radius tool

I have difference of opinion on where to attached the bracket to the rod. I feel any part or the brick bracket that is below the rod, will affect the brick placement when the IT is lifted from the brick. I feel the perpendicular portion of the bracket that is below the rod will cause a issue. I chose to attach my rod to the bottom of the bracket after my test simulation. All seemed to work out great......Just my opinion, what's yours?

Attached are pictures of the simulation and my end result.

[oasiscdm]

Re: How to build a radius tool

Hi

Hey DJ good pickup. I read through this and saw what had been done and had same thought. But as always you had already made the comment.

[UtahBeehiver]

Re: How to build a radius tool

Dazag12,

If at all possible make it adjustable. There is no such thing as a perfect dome and you will find being able to adjust will help you during your build, with a tapered arch or it you want a flatter dome. I bequeath my IT to another builder rather than throw it away. Ask the forum and maybe someone has one that needs a new home.

[Cyungle]

Re: How to build a radius tool

With the modified version, there are about 2cm of play in either direction, probably more if you use a larger turnbuckle. You just have to cut the brick end of the rod at approximately the right place in order to give you the 2cm range of play at the turnbuckle.

Take a look through the forum posts at some of the other home-made radius tools that others have used. The wooden ones that don't require welding are probably easier to make and do just as good a job. After all, you're probably going to throw the radius tool in the rubbish bin after the dome is built. Or you can use it to plot mortar fire trajectories for the upcoming zombie apocalypse, which is what mine is slated for.

[dazag12]

Re: How to build a radius tool

hi does your radius tool have to be adjustable in length or once made does it retain the same length???

[Cyungle]

Re: How to build a radius tool

Thanks to deejayoh! You were right about my original design. I tried it at first and the layers didn't line up. I re-welded the rod so that the it pointed directly at the center of the brick and the layers lined up perfectly. I also ground a beveled edge and it didn't catch as much as I was moving it around to take measurements.

[deejayoh]

Re: How to build a radius tool

Here's a better picture of where the bracket needs to attach to the IT rod. Credit to JCG31


His is a good thread to read

http://www.fornobravo.com/forum/28/my-indispensible-tool-variation-fb-theme-2985-4.html

[Les]

Re: How to build a radius tool

Or you could go real simple... This was before the invention of the I.T. but it worked just fine.

[deejayoh]

Re: How to build a radius tool

Cyungle - thanks for posting. If this is going to be a "how to" thread, that design will not work. The rod that is connected to the pivot needs to hit in the center of each brick - otherwise you will not have a constant radius for each course. See this thread for an explanation of what will happen.
http://www.fornobravo.com/forum/8/tr...tml#post132328

I am sure there are better pictures - but I don't have time to search, so here's one of Russell's IT that shows what the design needs to look like. Note how the arm hits the brick right in the center. That ensures each course will line up with the next.

[D.Rod Wood]

Re: How to build a radius tool

Thank you for sharing.

[Cyungle]

Disclaimers: I've seen a few good ones in posts here so this is by no means the best design. I just wanted something quick and inexpensive and that's what I got. Also, this requires a little bit of welding so if you don't have a rig and don't know anyone who does, this approach may not be for you.

Total cost of materials: $10.30 from Home Depot
Total time to fabricate: 15 minutes

Also, I'm an IT nerd by profession and not by any means adept at fabrication. Therefore, I estimate the level of expertise to do this at simple/moderate difficulty.

The first photo shows the parts that I used.
1 ball bearing caster wheel
1 24inch x 1/4 inch coarse threaded rod
5 1/4 inch coarse threaded nuts
1 1/4 inch turnbuckle
1 piece of 2x2 angle iron

1. Remove the wheel from the caster and discard. I used a grinder to remove the axle ends and the wheel pops out.
2. Remove the hook end from the turnbuckle. Thread one 1/4 inch nut all the way to the end. Insert the threaded end into the caster axle hole but before continuing through the other hole, thread another nut onto the screw and fit the loop end of the turnbuckle over the nut. Now insert the hook threads through the other side of the caster axle hole and thread on another nut to tighten.
3. Screw the 24 inch threaded rod into the turnbuckle hole that is now vacant.
4. Spot weld the loop end of the turnbuckle to the nut that is between the caster axle holes. This allows the vertical dimensional rotation for the tool.
5. Thread two 1/4 inch nuts onto the other end of the 24 inch threaded rod. Estimate how much distance you will need based upon the inside radius of your dome. Don't worry about getting it exactly right because you can rotate the arm end after welding to move it to any distance that you need.
6. Spot weld the nuts to the piece of angle iron as shown in the picture.

That's it for the radius tool - now you just need to center and stabilize it in the dome when you are ready to start laying bricks.