Steel ruler

If anyone is after a cheap 60cm steel ruler there is some in Poundland for a quid. I know it's not he best but it's better than I had before.

I haven't seen it but from past experience, just place the edge up against a straight surface.

I got a beautiful 1 metre aluminium rule from Woolworths many years ago. Yes it is straight but three others were not when I tried them

To check whether a straight edge is straight, just look down it. The eye is as good as a laser beam for judging that.

Well said, that man. I once worked with a car designer who could look at a clay model and spot if it was out one side to the other, by as little as half a millimetre. "yeah sure", we scoffed and measured the model again on a Stiefelmayer measuring machine (accurate to 1/100th of a mil.) and he was spot on! The eye is astonishingly accurate.

BTW, to be pedantic it's a steel rule. A ruler runs a country.

Martin

It's difficult to tell if it's streight in the shop as its in a plastic sheath with a cable tie round the top so you can't slide it out. So far it's seems ok, a bit on the flexable side though but still better than what I had before. My other was hinged in the middle which made it stand off surfaces over 30cm and it made using cutting blades tricky.

Simplest way to check the straightness of a rule or straightedge is to place it on a flat surface, a piece of white contiboard is ideal and using a sharp pencil draw a line along the edge(s).Then flip the rule/straightedge over and align the same edge with the pencil line at the ends of the rule/straightedge. Now draw a second line. It should coincide exactly with the first line, if not it's not straight.

... and of course lasers aren't very good if you want to slice a straight line with a scalpel.

As John says, an eye along its length soon shows up any errors, as it does when checking the alignment of wing and tailplane on a build.

Geoff

Hi all,

Spent £40 on a 1 metre steel rule 30 years ago, best money I ever spent !!

Regards Ray