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Combination squares

Posted: Sat May 03, 2014 4:25 pm
by Mr Ron
Are the square, center and protractor heads interchangeable between brands; SPI, Starrett, Mitutoyo, etc?

Re: Combination squares

Posted: Sat May 03, 2014 6:25 pm
by ken572
Mr Ron. :D

I think your best bet will be, getting all your

measuring instruments out on the workbench

and start to measure and document all your

Machinist Combination Squares that you have,

by BRAND and Component. When you are done

you can put your report in our Resource Library :idea: :D

Ken. :)

Re: Combination squares

Posted: Sat May 03, 2014 7:49 pm
by Bruce_Mowbray
I am constantly swapping rules with heads of different brands. Especially when I need a bunch of tools set up all for simultaneous use. As long as there isn't too much slop in the blade fit, it should work Also, make sure the tang on the blade lock fits without forcing or falling out of the slot. Some of the blade slots are shallower and narrower than others.

All of the tools mentioned use the same method of locking the blade. A screw device pulls the blade against the edge with a tang that engages in the slot of the blade.

Re: Combination squares

Posted: Sun May 04, 2014 7:30 am
by Lew Hartswick
In some cases YES and in some NO . One of those "It depends" I have several of those in some cases only the square and a couple of the entire set. Offhand I can't remember which will "swap"
blades and which won't. I know the CHEEP ones that look like the blade was stamped won't fit the
B&S heads. :-)
...lew...

Re: Combination squares

Posted: Sun May 04, 2014 10:58 am
by Mr Ron
The reason why I ask, is I have a Starrett combination square , but no center or protractor heads, since I don't have much need for them; but when I do, I have to find other means of doing what these heads do. I don't want to spend big bucks for the heads from Starrett and wanted to know if I could substitute heads from other brands such as Fowler or SPI. I read somewhere that the rules were standard as to width, groove size, thickness. If that is the case, my assumption would be the heads are interchangeable.

Re: Combination squares

Posted: Mon May 05, 2014 6:10 am
by ken572
Mr Ron wrote: I could substitute heads from other brands such as Fowler or SPI. I read somewhere that the rules were standard as to width, groove size, thickness. If that is the case, my assumption would be the heads are interchangeable.
Good Morning :!: Mr Ron, :D
That's why I suggested that you measure them and compare them, etc. :idea: :lol:

ken. :)

Re: Combination squares

Posted: Mon May 05, 2014 3:55 pm
by SteveM
You can probably find Starrett heads on ebay. Complete units go for quite a bit, but you can luck out and get the heads for cheap.

Just be sure to compare what width and thickness ruler they are for vs what you have.

Steve

Re: Combination squares

Posted: Mon May 05, 2014 4:37 pm
by Lew Hartswick
Darn it. I forgot to bring the paper home, I measured about a Dozen at school today. There were
two of my own, a 60 year+ Craftsman and a "Union Tool" and about 10 of the Schools or maybe more.
Most of the good ones were Starrett and a few off brands (cheep junk). The surprising thing to me
was the variation in the width and thickness of the good Starrett ones. I haven't gotten around to
my B & S one and another in the garage. There was a range of (as I remember it) from 1.002 to
0.98? in widths and thickness from .08? to .098 (I'll try to remember the paper on Wed and post the
actual numbers)
So It looks like the variation is fairly great even within a single manufacturer. As long as the blade
will go in the head it should work. :-)
...lew...

Re: Combination squares

Posted: Mon May 05, 2014 5:25 pm
by BadDog
I've got a hodge podge of rules up to 24" in B&S, Starrett, Stanley (old stuff from my Grandfather), and General. I've also got various heads in the same range, plus a (assumed) Chinese no name. As far as I know, all my stuff interchanges. Or if it doesn't, then it's a combination I've not tried. Beyond that, I can't say.

Re: Combination squares

Posted: Sat May 10, 2014 8:51 am
by Lew Hartswick
Machinist.doc
(19 KiB) Downloaded 85 times
Second try: First an attach using a .txt file didn't work. Trying a .doc file;

...lew...

Kind of cumberson but I guess it does. I'll have to try and figgure a way to make a .txt into a .jpg
file. :-)
...lew...

Re: Combination squares

Posted: Sun May 11, 2014 11:15 am
by Mr Ron
Lew Hartswick wrote:
Machinist.doc
Second try: First an attach using a .txt file didn't work. Trying a .doc file;

...lew...

Kind of cumberson but I guess it does. I'll have to try and figgure a way to make a .txt into a .jpg
file. :-)
...lew...
The txt file opened using MS word. It appears there is no standard for blade width or thickness. I'm surprised at the Starrett dimensions. The parts may be interchangeable, but no guarantee square will be square. Thanks Lew for your work.

I looked at my Starrett catalog and it was stated, (under individual parts) "all heads fit any blade having the corresponding size on all combination squares, combination sets and bevel protractors....", so based on your measurements and the catalog statement, they are interchangeable (at least Starrett). I could therefore assume the heads from others will fit a Starrett blade so long as the blade width fits.

Re: Combination squares

Posted: Mon May 12, 2014 3:11 pm
by Mr Ron
Lew Hartswick wrote:
Machinist.doc
Second try: First an attach using a .txt file didn't work. Trying a .doc file;

...lew...

Kind of cumberson but I guess it does. I'll have to try and figgure a way to make a .txt into a .jpg
file. :-)
...lew...
Lew, I measured my two combination squares. The Starrett blade measured .995 wd x .092 thk and a Stanley blade measured .986 wd x .081 thk. There doesn't seem to be any standard. I use the Starrett for machine shop use and the Stanley for my woodworking tasks. Thanks again.