Engineers Square - reasonable quality

**ian** · 14th February 2017, 07:28 AM

Originally Posted by pmcgee

An under-measurement of 1mm in 300mm x 400mm x 500mm

-> 300 x 400 x 499 would give you a "right" angle = 89.8 deg

300 x 400 x 501 => 90.2 deg

It's still prone to possible error.

Cheers,
Paul

Hi Paul

the key to making an accurate 3-4-5 triangle is to leave the rule in a drawer.
The tools of choice are a straight edge and a pair of dividers.
You use the straight edge to create a three straight lines, and then you use the dividers to step off 3, 4 and 5 units along the lines.
Using dividers removes any error that might creep in when attempting to measure with a rule.

**dazzler** · 14th February 2017, 01:00 PM

But as you move the divider from one spot to another the climatic temperature variations may result in the caliber arms becoming longer or shorter resulting in an error.

I couldn't sleep at night knowing this.

BTW - Taking the P.

Let's go and cut some wood.

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**pmcgee** · 14th February 2017, 02:04 PM

Originally Posted by ian

Using dividers removes any error that might creep in when attempting to measure with a rule.

I think 80%+ of divider use would contradict that.

I wasn't suggesting any particular source of error, just a feel for the potential effects.

Short of using laser interferometry (RayG) ...

Cheers,
Paul

**dazzler** · 14th February 2017, 03:41 PM

[emoji16]

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