Is your straight edge straight??

[Glen Butler]

Are you familiar with the Wixey digital angle guage? It is very accurate. It is what I use to set up my table saw blades, etc. If you think your staight edge is not straight, put it in a vise, put the Wixey on one end, zero it, and put it on the other end. If it still isn't zero, you have a problem.

Agreed, those wixey's are pretty good. I have tested them time and again. Mathematically they are within .003. Certainly not machinist tolerances, but when I check a used machine for purchasing I put the wixey on it first to see if it stays zero the whole time. If it changes I don't bother to go much further. Just recently I was looking a a delta dj-20. The wixey measured .2 out from one end of the fence to the other. My precision square confirmed that there was .004" of twist in the fence.

[Nissim Avrahami]

This is my Aluminum straight edge - 98.5" long so it can "cover" also the 8' length...

It's an 1/2" thick and 4" wide Aluminum profile that is used by the concrete guys to straighten concrete floors or the "wall-to-wall carpet" guys to cut straight edge.

I checked it in the shop by attaching another straight edge, turning one of them to any possible direction and checking against the day light...I was surprised how straight they are and they cost only $20 (in Poland - should be less in the States)...

I use it to cut long sheets or to make a glue line with the router.










I have another one that is 1/2" thick, 2" wide and 67" long solid Aluminum that cost (if memory serves) something like $30 (in Japan - should be less in the US)...also very, very straight (it's my master straight edge).

Dsc00024.jpg

Regards
niki

[Brian Penning]

Matter that much if it's an aluminum or steel straight edge?

[James White]

The only difference is that the steel is more durable.

James

[Paul Simmel]

I prefer aluminum cheap ones because they can be easily jointed on your jointer if screwed to a piece of relatively straight piece of ply.

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And BTW, the Egyptians got their PERFECT level bases for their structures by digging trenches around the foundations and filling them with water and using the water level as an indisputable gage.

Stretching a guitar string seems like a very good idea, but for me that is good conversation in interesting conversation, but not practical in the least. A jointed straight edge is going to be about the straightest… and most very practical straight gage one is going to get (within the woodworking world short of $300)

That’s not to take away from stretching/pulling string to get a straight line (ages old and very workable) in use all the time in many trades.

JUST JOINT the bloody cheap (soft) aluminum and be done with it. If you think it is off after time… joint it again… just like sharpening a planer iron or chisel. It’s easy, accurate, and will NOT mess with your knives if you shave a few thousandths.

Take a SHARPY and mark the straight side. REALLY no big deal. I’ve done this several times. Glad I did. This was MY idea, and it works great.

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I realize there a lots of newbies here. Just do it. Nothing will blow up in your face. You’ll have the straightest section of aluminum you’ll ever have. With HSS knives you’ll not notice a thing, and with carbide… you can do it all day long. Just screw the thing to a piece of ply and run it across. Go to the back side of your jointer if you want.

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I posted on this last year along with pictures.

[Brian Penning]

FWIW I notice the LV aluminum edges are flat to .003 and the steel ones are .001 and .0015 depending on length.

[lowell holmes]

My LV steel straight edge lives in the house as well.

[Greg Portland]

Having a table saw blade that isn't parallel to the fence within ~0.003" will give you burning.

A cheap way to test this is with a screw sticking out the side of a board. Run the board along the fence and use the screw tip as a feeler gauge for the front and back of the blade. Make sure you're measuring from the same tooth in the pattern. This method is extremely accurate...