Making A V Block , Dimension Question

Subwayrocket

Subwayrocket

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I posted this in POTD , but now I have a question before i go further and cut the angles .
What do you guys think about this ? Looking at the layout it did in red sharpie you can see I don't run the angles all the way to the end. I stop them at flats that are just under 3/4" wide ...my thought is that if I run the angles out too far, the thing would get weak if I held something large enough to contact only at the ends . Do you guys think that's reasonable or could I extend the angles out a little farther ? If I go out just a little farther i'd have 1/2" flats at the ends, and the width it could hold would be greater . This is 6061 , not steel . Anyone have any thoughts on this

1-what-im-shooting4.jpg
 
OK, 6061 aluminum. What is the angle that is laid out? I recommend highly that you stick with a 90 degree included angle. Do you plan to cut off the two "ears" at the red lines? That would work, and I do not think you need that much extra support for the obtuse angle. Perhaps half that amount. The obtuse corners are not meant to support oversize work accurately, and they won't. The cylinder should be located on the V face surfaces. Regardless, you will need to clamp the work lightly enough to not deform the block, and usually the work as well. That is why hardened tool steel is usually used for V blocks...
http://what-when-how.com/metrology/v-block-metrology/
 
Last edited:
Bob Korves said:
OK, 6061 aluminum. What is the angle that is laid out? I recommend highly that you stick with a 90 degree included angle. Do you plan to cut off the two "ears" at the red lines? That would work, and I do not think you need that much extra support for the obtuse angle. Perhaps half that amount. The obtuse corners are not meant to support oversize work accurately, and they won't. The cylinder should be located on the V face surfaces. Regardless, you will need to clamp the work lightly enough to not deform the block, and usually the work as well. That is why hardened tool steel is usually used for V blocks...
Click to expand...
Yes , the tops will be cut down to the red line , leaving 5/8" flats on the face. I just laid it out again, below in blue. The block is 4.35" wide and 1.650" thick. The angle is 29.5 ...it's around the angle I want and I have the angle block to set under it to cut the angles. If I make the angles sharper, the block will be too big for my vise.
My thinking is that if I have something like a 6" round part clamped in there, it will hit at the highest points of the V block ...but there would still be 5/8" flats for strength. If I ran the angles right out to the end, it would contact out at the very end of the block, and be more likely to deform . What do you think ? Please give your thoughts on my line of thinking. For the part I just did, I used the 1-1/2" V steel blocks I have. Although it held fine, I was very uncomfortable with it.
I appreciate it !
I have some hardened steel V blocks , but not this size . For how often i'll need this i'm gona use what I have .
V-Block-LaidOut.jpg
 
As long as you handle everything carefully and your part will fit in the V you should be ok for light work. Just try not to indent the surfaces. You could lay a couple pieces of 1/8 stock in the V to help keep from indenting the surface.
 
I think your on the right track. I like Bills idea of the steel flat stock. Maybe just screw them on like vise jaws. Mike
 
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