Thread: What to use as a straight edge

Try Capral Aluminium Shouldn't be to expensive. http://www.capral.com.au/contact_us/Or maybe Onesteel or any Aluminium Window manufacturer.

Is the straight edge to be used to guide a saw or router?

Clint

I think that I would avoid aluminium section as a straight edge, unless it was a very substantial box section, say 50 x 75. Aluminium is just too soft and potentially flexible in long lengths (such as the 2400 you seek). I would rather go for steel section. This is available from Bunnings quite cheaply. I used a 2400 section (I think 40 x 40 from memory) as a guide fence for a router and circular saw. See below.

Regards from Perth

Derek

This might sound a bit stupid, but why not buy a proper straight edge.

I got one from the 2 Indian gentlemen in the Tent at the Sydney WWWShow last year. Cost somewhere around $20 and is brilliant. It is 1200mm long x 60mm wide with a handle in the middle that houses 2 spirit level bubbles.

It is far more better than some of the many things I have used in the past and a lot more accurate to boot.

Cheers - Neil

This probably won't help you much, but I always rip a piece of MDF on the sliding tablesaw and use that as a straightedge. If it's something that I'm going to have to make a lot of cuts with, I band it with a piece of laminate so that the saw/knife/router bearing doesn't wear a groove into it.

It depends on what you want to use your staright edge for.
I have a variety of lengths of 50 x 25 aluminium & they do many jobs fine.

long ripping or routing (2400) can see some deflection so extra support is needed.
I know several builders who use the same as a general purpose "straight thing"

going wider can be good 25 x75 or 25x 100 would be good but expensive.

steel can be a bit heavy to swong arround & isnt as regular straight out of the mill a aliminium. but that may not bother you.

as neil says inder 1m there are some good manufactured products at the usual suppliers.

stay away from angle though It bends & twists I can do interesting things.

It seems to be assumed that your straight edge is to be a guide.

Check out local manufacturers and fabricators to see if you can get an offcut length of steel or aluminium that has a profile you can use. Otherwise, check out your local sheet metal shop for scrap lengths and have a 12 - 25 mm edge turned up at 90 degrees.

Over 2400 mm you will get distortion if the straight edge is clamped at its ends only. I would be looking for something at least 150 mm wide to minimise that problem.

Nearly a month ago now I purchased a new mitre pull saw, and made a platform using an offcut from a modern mdf door with an hardwood lip, in addition I was fortunate to have a length of 40mm plywood which I have tacked on to the mdf door creating a flat surface plus the 90o .
See picture attached to explain further.
I have since found that laying pieces of timber on the platform against the ply I can ascertain its squareness etc.
This means you can go up to 78" length platform and have 10" plus width or wider, depending on your available space.

Having tried various smaller sections of aluminium and steel angles over the years I discovered that angles can do strange things under pressure. Eventually I bought myself a 3m length of 100x25 aluminium R H S.
I use it as a guide for cutting up large panels MDF etc with a small power saw. Clamp at each end (laid flat of course) leaves plenty of room at each end for guiding the saw into the cut and no flex. I would think twice about anything smaller than 75mil for 2.4m

I think you would find that at 2400mm long Rectangular Aluminium 100mm x 25mm with 2 to 3mm wall thickness would not deflect. It would be lighter than steel and if you have a look at 2400mm spirit levels you would find that they aren't even that heavy.

if deflection is a worry you can always lay a strip of around 300mm wide mdf with a square edge clamped perpendicular to the aluminium section. Set this up prior to pressure and this will stop sideways movement away from a straight line on the non tool side. Make sure its long enough to reach an edge where it becomes clampable. I say keep it lighter/smaller section so you can use it when installing/fitting in a house with one hand holding the straight edge and the level. If you are getting it cut consider the max height of a roof in house or frame you are sqaring if it is for this purpose.

I use a 3m length of 200mm x 50mm 4mm thick aluminium for ripping full sheets and some 75mm x 25mm x 4mm shorter lengths that was given to me by a retired cabinetmaker friend that he used for marking out full sized complicated angles kitchen designs. The lager size has no deflection at all and i have added a length of it to my Triton mk 3 rip fence with spacers to get the fence square to the bench top.

I use a level to do 48 inches on less. Mikie

Here is a link to an article that shows how to make your own straight edge. I haven't tried it so I can't vouch for it, but the information seems to make sense.

http://www.tdl.com/~swensen/machines...ight_edge.html