Making precision machinists squares from scrap of metal

[kwm24@o2.pl]

Hi.
Below you have a link to instructional movie how to make precision machinists squares from scrap of metal.

[Crusty]

I like this sort of project which requires precision and care to complete, even if it's ignored by the majority here.

[DIYer]

Thanks kwm24@o2.pl! We've added your Machinist's Squares to our Angle Guides and Try Squares category,
as well as to your builder page: kwm24@o2.pl's Homemade Tools. Your receipt:

Machinist's Squares by kwm24@o2.pl

tags: square, measurement

[N00b Machinist]

I don’t understand the mechanics of a surface grinder. How do you avoid a rising surface owing to the gradual wear of the grinding disc?

[Crusty]

You take light cuts to avoid changing the wheel diameter, and maybe even retrue the wheel periodically. A wheel wears by fracturing of the surface particles and if you can mostly avoid that the wheel wears little since it's much harder than the steel it's grinding. A surface grinder can be a tool that works in the ten thousandths of an inch realm.

[Karl_H]

I don’t understand the mechanics of a surface grinder. How do you avoid a rising surface owing to the gradual wear of the grinding disc?

In addition to the light cuts, you are really only cutting with the very first part of the wheel to contact the piece. As that part wears down, the cutting surface of the wheel moves over to "fresh" wheel. So now, the leading edge of the wheel is cutting the first 1/2 tenth and the "fresh" part of the wheel only has the cut the second 1/2 tenth.

In the video, from 9:05 to 9:20 you can see that the portion of the wheel closest to the machine is doing the cutting, and that there are no sparks forming on the surface closest to the viewer.

[mwmkravchenko]

Yep. Many people do not think through the mechanics of how a surface grinder works.

Nice project and very constructive comments.

I'm going to watch the video.

I like this kind of project to.

Mark

[old_toolmaker]

kwm24@o2.pl,

Nice looking work, although I prefer to see much thinner legs of precision squares. The thinner legs are able to show squareness better. The thicker legs tend to not show light gaps as easily and tend to not be as sensitive. Just my thoughts. Thank you for posting!

[mwmkravchenko]

kwm24@o2.pl,

Nice looking work, although I prefer to see much thinner legs of precision squares. The thinner legs are able to show squareness better. The thicker legs tend to not show light gaps as easily and tend to not be as sensitive. Just my thoughts. Thank you for posting!

I have a few thicker precision squares that have chamfers on the edges for just this reason.

[Karl_H]

I made one out of 1/4 inch aluminum, but my surface "grind" was simply an edge cut with the mill.

I align my horizontal band saw blade by attaching a 6 inch steel gauge to the blade with a small rare earth magnet, being sure the magnet is not displaced by any of the teeth. When I tried to use my commercial machinist's square, the magnetic fields carried through the steel gauge would pull the gauge to the square, so no matter how far out of alignment the blade was, the gauge would line up perfectly with the square.

Since there is no "fine adjust" on my band saw - I twist the roller assembly with a big adjustable wrench and hold it in place while I tighten the screw - the precision of an end mill cut is good enough.