How to make measurements on a non square frame?

[dntknwhowtogokart]

So I have made a frame using some pieces of metal I had laying around. The shape of my go-kart ending up being this: .

It is important to note that the back of the frame is not a straight bar, it is a bar that has some minor curves on it. Additionally, the front of the frame has curved edges.

1) How do I accurately measure the holes I need to make for the rear pillow blocks that I will be installing? The pillow blocks require 2 holes each.

2) Additionally, the same question but its also needed for the spindle bracket I need to weld on.

3) Lastly, when I put my engine mount on the frame, does it need to be level with the frame OR level to the ground because I have a bigger back tire and smaller front tires.

 

[Mrmonk7663]

Run a string line. Assuming your bars are same length on the sides then the front two and rear two corners will be the reference points. Take a string across the two front points and back points and that will give you the reference sides. If you need a full square then extend the string beyond the corners. Kind of like mapping out a deck in the backyard if that makes sense.

 

[dntknwhowtogokart]

I understand the concept of using a string line. However, what I don't understand is how to use it in this concept, "Take a string across the two front points and back points and that will give you the reference sides. If you need a full square then extend the string beyond the corners.", is where you lost me haha. Could you expand on this further

 

[Defiantarms]

Take a string run it along the left frame go two feet past each corner front and back. Take a string on the back run it out till it goes over the string you pulled on the left side try and keep it as straight to the center of the back bar as you can. Now you made a right angle for reference you can then mark on the frame with a hack saw blade or something at a known distance evenly on all sides so you won't have to run string again.

 

[karl]

Its pretty easy, I just measured from the corner of the front bumper to the where the rear bumper meets the frame , diagonally.

In my case it measures 72in on both sides , so its close enough.

When in doubt use your eyeballs

Rear axle is a simular endevor, and you can mount the engine either way, whatever makes more sense after a mock up.

 

[dntknwhowtogokart]

Ohhhhhh, okay, I got it now. Awesome thanks so much for the advice everyone!

 

[Bansil]

Why not just measure up each leg and mark it, then put a straight pc of metal across both tubes and clamp it at marks, now this 3rd bar is parallel to front and back bars? Make 3rd bar a little longer than rear bar and then just use a construction square to make your marks, you can move 3rd bar forward and backwards as needed.

 

[itsid]

two long carpenters edges (T-head preferred)

slide them along the side rails and where they cross (reading the same value)
you'll have the centerline of the kart and you can mark the floor (crayons anyone?)
and as long as you don't move the chassis a perfect reference line.
(both side running front to back flaring out at the exact same angle)

Anything perpendicular to said line will be nice for your axles.


PS frankly line lasers are cheap these days (I paid less than 10 bucks 8 years ago)
use it to read the angle between the side rails, divide by two set as new angle, shine laser.. drink beer to celebrate perfect centerline