Thread: How straight does a straight edge need to be?

Good Morning Sir Stinkalot

Possibly the best value for money Strait Edge is a good quality spirit level with milled faces (not extruded el cheapo). Stabilo is excellent and the 1500mm is not much dearer than the heavy duty strait edge that you quoted. And you get an excellent level, as well! Mine are 200, 600 and 1500 mm, which gives lots of versatility.

For longer lengths a section of heavy duty aluminium can work well. It must have thick walls, at least 3mm, to resist denting. It must also have fairly large dimensions of width and depth - mine is 85 x 35 mm with square corners, not rounded. This is stiff in the 2.5 metre length I use.

For light jobs, steel rulers are the old stand-bye. Mine are 150, 300, 600 and 1000 mm. Again, lots of versatility.

I have been trying to stop buying crap tools for years, and the move from el cheapo to Stabila levels was a good one. I do not feel any need to change my other strait edges.





Fair Winds

Graeme

Thanks for all of the feedback. That is one of the great things about this forum ..... you post what on the surface seems like a simple question and it open up so many other avenues.

I think the problem I have is that I am trying to kill two birds with one straight edge. For machinery set up I think I need something that has been machined to be flat. For the second task that I was hoping to also be able to achieve (as a guide for tools) being machined flat is perhaps not so important.

It sounds as if purchasing Al extrusions or even some of the more generic straight edges may be a bit hit and miss in terms of how accurate it will actually be. It sounds as if some have been lucky, others less so. Having a reliable straight edge to check the quality of the other straight edge seems to be the way to go .

So after considering the replies I think I might settle on the 38" Veritas Aluminium version from Carbatec. At $60 its not particularly cheap but it falls within the range of the more generic 2400mm long straight edges which would be good for breaking down large sheets but would be unwieldy for machinery set up. I have quite a few other Veritas products and I am sure it would be a good quality unit.

After I get a reliable straight edge I can then use it to get a reliable Al extrusion to use to break down sheet goods.

Cheers

Stinky

Originally Posted by Sir Stinkalot

So after considering the replies I think I might settle on the 38" Veritas Aluminium version from Carbatec. At $60 its not particularly cheap but it falls within the range of the more generic 2400mm long straight edges which would be good for breaking down large sheets but would be unwieldy for machinery set up. I have quite a few other Veritas products and I am sure it would be a good quality unit.

After I get a reliable straight edge I can then use it to get a reliable Al extrusion to use to break down sheet goods.

Cheers

Stinky

Good choice, it's easy to handle and versatile.

To cut sheets with a circular saw I use the factory cut edge of one of the sheets as a guide.

For a long level I use 50 by 25 steel tube and a magnetic spirit level.

Following Derek's revelation of the Magic Square this week in the Handtools section, I can't help thinking that what you really need is a magic straight edge!
Magic Square - YouTube

Originally Posted by Sir Stinkalot

..... the more generic 2400mm long straight edges which would be good for breaking down large sheets but would be unwieldy ........

True enough, Stinky.

For years I followed Glenn's technique for breaking down sheet material but it does require a large flat cutting surface. Lots of improvisation! Then in a stroke of genius I bought a length of 50 x 25 x 3 mm Al extrusion and cut it to exactly 2400 mm length. I had a real strait edge ! On my first cut I discovered that most sheet material that is labelled 2400 x 1200 is actually 8 x 4 feet. The length is not actually 2400 but a slightly longer 2440 mm. A strait edge that is 40 mm shorter than the material that you are cutting is a right PIA, and introduces lots of subtle errors. Also the 50 x 25 extrusion flexed a little over the 2400 length. I almost cheered when one of my klutzy mate's Landcruiser ran over that strait edge.

The replacement was a half length (3 metres) of 85 x 35 x 3 mm Al extrusion and it worked very well but was a pain to store - my then shed only had 2550 mm height. Then I cut that strait edge to 2500 mm - about 60mm longer than most sheet material - and achieved the best compromise. 25 years later I am still using it.



Fair Winds

Graeme