Need a New Blade for that Combination Square?

[dusty]

There is a thread here on the forum regarding combination squares. After reading that, I got to looking at mine and decided I needed a new blade. I went looking and found a site that I thought I would pass on.

I got mine yesterday, three days after I ordered it. I could not be more pleased and it cost me only $10.00. I did not know who the manufacturer would be. The site does not say. All I knew was that I was getting a 12" ruler, graduated as I wanted and that it would have some cosmetic defects. A quality control reject. There are two blemishes neither of which effect my ability to read the markings. The blade I received was manufactured for Products Engineering and was Made in the USA.

If the blades on your combination squares are hard to read, messed up from being dropped on the concrete floor or whatever - you might want to check these folks out.

http://scales-rules.com/collections/com ... blade-only

[dusty]

WORD of CAUTION

Combination square blades are not necessarily interchangeable. The blade that I just purchased will not fit into my Stanley head. The blade is thicker that the Stanley blade.

[Gene Howe]

Well, that's a bummer.

WORD of CAUTION

Combination square blades are not necessarily interchangeable. The blade that I just purchased will not fit into my Stanley head. The blade is thicker that the Stanley blade.

[kablerj]

Thanks for the heads up Dusty.

They also have good deals on rigid and flexible rules from 6" to 48" in a variety of graduations.

Jim

[Gene Howe]

Don't mean to hijack the thread, but HF has a 6" and 12" stainless, etched rulers for $1.99.
I bought the 6" and it's accurate down to 1/64th. Although, that really doesn't matter. To my way of thinking, measurements are all relative, anyway.
I'm not a machinist, if you couldn't tell.

[dusty]

Don't mean to hijack the thread, but HF has a 6" and 12" stainless, etched rulers for $1.99.
I bought the 6" and it's accurate down to 1/64th. Although, that really doesn't matter. To my way of thinking, measurements are all relative, anyway.
I'm not a machinist, if you couldn't tell.

Good News: The blade works in my other combination square. Bad News: It did not correct the inaccuracies that brought this discussion to light.

Now to another point. How accurate does the combination square really need to be? It is a marking tool. Most of the time the cuts (at least mine) are made with the table saw whiling using the miter gauge. My combination square(s) are about equally inaccurate (1/32" over 12"). When I do use a hand saw, that degree of inaccuracy in the mark is the least of my worries.

[Gene Howe]

[/quote]
Good News: The blade works in my other combination square. Bad News: It did not correct the inaccuracies that brought this discussion to light.

Now to another point. How accurate does the combination square really need to be? It is a marking tool. Most of the time the cuts (at least mine) are made with the table saw whiling using the miter gauge. My combination square(s) are about equally inaccurate (1/32" over 12"). When I do use a hand saw, that degree of inaccuracy in the mark is the least of my worries.[/quote]

Exactly so X 2!

[JPG]

Don't mean to hijack the thread, but HF has a 6" and 12" stainless, etched rulers for $1.99.
I bought the 6" and it's accurate down to 1/64th. Although, that really doesn't matter. To my way of thinking, measurements are all relative, anyway.
I'm not a machinist, if you couldn't tell.

Good News: The blade works in my other combination square. Bad News: It did not correct the inaccuracies that brought this discussion to light.

Now to another point. How accurate does the combination square really need to be? It is a marking tool. Most of the time the cuts (at least mine) are made with the table saw whiling using the miter gauge. My combination square(s) are about equally inaccurate (1/32" over 12"). When I do use a hand saw, that degree of inaccuracy in the mark is the least of my worries.

Accuracy and resolution are two different things.

If a combination square isn't accurate(90 and 45)the blade is not the cause unless bent(not straight).

Resolution is the distance separating the closest marks.

Accuracy is the maximum deviation from precise location of those marks.

The head is usually cast and the machining of the reference edges affects angular accuracy.

The blade has an internal reference surface(s) in the head that the blade slides against that also affects the angular accuracy.


Very fine resolution with poor accuracy is still inaccurate.

A cut off 1/32" over 12" off will create about .15 degree error.

Good enough? Depends upon what ye be making.


I think paying attention to the miter gauge(or sled or whatever) is more productive to accurate(square) cuts than the 'layout device'. Trouble is, we use that 'layout device' as a check after the cut.

That is why the 5 cut or opposing corner test of the gauge/sled are better ways to 'check for square'. Then all things being perfectly aligned in the universe assumed, your cuts will always be square(ignoring technique ).

[Gene Howe]

I think paying attention to the miter gauge(or sled or whatever) is more productive to accurate(square) cuts than the 'layout device'. Trouble is, we use that 'layout device' as a check after the cut.

(slaps head) As long in the tooth as I am, I'm still finding that I'm doing things that make little sense. Thanks (I think) for showing me another, JPG.

[JPG]

I think paying attention to the miter gauge(or sled or whatever) is more productive to accurate(square) cuts than the 'layout device'. Trouble is, we use that 'layout device' as a check after the cut.

(slaps head) As long in the tooth as I am, I'm still finding that I'm doing things that make little sense. Thanks (I think) for showing me another, JPG.

Nothing 'wrong' with doing that. It simply is expedient. But it is not 'the best'.

It will make gross 'mishandling' evident.