The Shop > Tools
My Squaring Gauge/Indicator Stand
Arbalist:
Good point! :thumbup:
Pete.:
Scribing blocks are cheap as anything to buy - less than £15 brand new from Warco. If you look at many of them you'll see that the main rod has a ball on the end. Someone can correct me if I'm wrong but I thought that this ball was for doing exactly what is shown in the video.
NeoTech:
There is som clever and usefull witchcraft going into that piece of measuring equipment.. i see i have a weekend project ahead of me. =)
leg17:
Something very important missing from the video.
FIRST, the two sides being inspected MUST be parallel with each other.
The preferred way to use this method is to first generate perfectly parallel top and bottom.
Then select a right angle side.
Then zero the indicator on that side and FLIP OVER (top to bottom, the original parallel surfaces) and measure that same side.
That will give you out-of-square in TIR (total indicator reading) on that measured side.
Adjust that measured side by setting up to correct it by half the TIR.
Check again.
Repeat till perfect.
Now you have three sides of a cube square and making the fourth side parallel with the side just adjusted gives four sides perfect.
Remembering which sides are finished, repeat the procedure on the other two remaining sides.
That will give a perfect cube.
Three pairs of parallel surfaces with the same indicator reading no matter which side is inspected.
You can now inspect that fancy machinist square and find out just how accurate Starrett is.
A flat surface plate is the only prerequisite.
The tool and die guy in the video missed this vitally important first step and the better way of utilizing this gage, but he is correct in encouraging you to grasp this concept.
(An interesting related topic is the generation of a flat surface from scratch, but that is for another day. Look up the three plate method.)
sparky961:
--- Quote from: leg17 on January 08, 2016, 08:59:04 PM ---Something very important missing from the video.
FIRST, the two sides being inspected MUST be parallel with each other.
The preferred way to use this method is to first generate perfectly parallel top and bottom.
Then select a right angle side.
<... snip ...>
--- End quote ---
When I originally linked to the video, the purpose was more so show the basic concept or using the gauge to check the squareness of one angle (two adjacent surfaces) relative to a "precision" reference. In the home shop this is probably a machinist's solid square (ok, I guess) or an angle plate (much better, if you have a good one). Side note: absolutely do NOT use a 1-2-3 block unless you have already verified the squareness!!.
The video did mention 6 sides but failed to do much more than that. Discussion of how to create or validate a perfect cube was quite a bit beyond the intended scope of this post but I was nonetheless following your description with great interest. I was a bit confused though... I gather when you're talking about the first step you're envisioning a grinding operation to generate the surfaces, correct? So what you're describing is then a combination of measuring and the process for grinding ('cause you wouldn't likely be milling to this precision) a perfect cube (or rectangular prism, as the case may be)?
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