Digital Angle Gauge Vs Space Blocks

RJSakowski said:
You don't need a space block set to set an angle. Turn a piece of scrap to the desired diameter and verify with your mike. Part the piece to an appropriate length and place at one end of the vise with the end of the spacer touching the vise jaw and the cylindrical surface flush with the end of the vise jaw. A magnet helps to hold it in place. Lay your parallel with one end on the vise floor and the other on the cylinder. (If your vise jaw overhangs the floor of the vise, you will have to correct for that overhang.)
The relationship between the diameter of the gage pin, the width of the vise and the angle is: (D/2)/(W-D/2) = tan(a/2). If you let A = tan(a/2), then D/2 = A/(1+A) * W.
The drawing shows the geometry of the setup. With suitable care, very accurate angles can be set up.
View attachment 106968
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Thanks RJSakowski, sounds like a lot cheaper method than purchasing as set of space blocks.

Joe
 
Although I appear to be in the minority, my digital angle gauge has worked great for me. I zero it on bed or the vise (depending on how I'm holding the work) and then adjust the work to the angle needed. Super easy.
 
I have a digital angle cube too and use it for setup of non-critical angles. Although the stated accuracy is +/- .1 deg., I have found it to be less than that at times. It is based on a pendulum and friction is involved in settling the pendulum to a true vertical position. Sometimes, there can be a difference of a couple of tenths of a degree. The base of the cube is just over 2" so any variations in the surface become important. I usually make multiple measurements to verify the setting.

The digital angle cube is a handy tool. You just have to appreciate its limitations.
 
Thanks RJ, It is good to know that even if the stated accuracy is .1 degrees, it actually is not.
I was wondering if these digital angle gauges were actually accurate to the specs.

Thanks

Joe
 
T Bredehoft said:
My sine bar is 6" long, my vise is 3.8" wide. They won't work together. Do what ever works for you, that's why its a hobby.
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You need a 6" or longer parallel bar turned on it's side to sit on the bottom of your vice. My shop had a couple of heavy bars so I would use one.
 
I also frequently use a Digital cube (Fowler brand). It works extremely well when you don't need really critical angles. I trust it to .5 degrees. If you want accurate angles then guage blocks and sine bar are the most accurate. If I understand things correctly. I don't know what a "Jo" block is. The accuracy of gauge block is certified depending on the type. A set is very expensive, but vital for complete accuracy. I like the idea posted of using a turned rod with a mic'-ed diameter, though it seems hard to measure the distance of the one leg (can't remember which letter was used for the variable) from the point of contact with the mill or vice surface to the arc point of the rod's circle. Anyway, I have both the gauge blocks and an electronic protractor http://www.use-enco.com/CGI/INPDFF?PMPAGE=396&PARTPG=INLMK3&PMITEM=317-0585 like this one.
 
What I used to do was to do the trig to find the height I needed to set the angle. I would borrowed a few gage blocks from the shop and set the sine bar. It was my experience the bar was wider than the part so I would use a sacrificial spacer to hold the part tightly against the solid jaw of the vise then I would remove the sine bar. No sense trying to catch all the gage blocks due to vibration from machining.
 
Joe Pitz said:
Sweet. much cheaper than LMS, got to go shopping

Joe
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My experience with an angle cube is that they are not really repeatable within a half degree. OK for wood work or "eyeball" work. Maybe OK for one off part. Similar to 3 jaw or 4 jaw chuck variations.
SteveMetsch in Santa Barbara
 
Jo, or Johansen blocks were chosen by Henry Ford when he wanted a standard to use in his factory. Gauge blocks have become called Jo blocks, just through use, not that all are Jo Blocks the are nominally (chuckle) 5/16 by 1" by whatever, .100, etc., and finished to a degree that they will wring together, stick to each other. Mine are Brown and Sharp, .900 square and whatever thickness, with a hole in the middle so they can be held by screws and nuts. (I don't use them that way.)

Edit, correct typo.
 
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