60 degree or 90 degree V- block, which is better for determi

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Don Bailey
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Joined: Fri Dec 19, 2014 4:23 pm
Location: Auburn Hills, Mi.

60 degree or 90 degree V- block, which is better for determi

Post by Don Bailey »

Strong opinions that 60 degrees is better. We cannot find any scientific data to support this opinion. So, we go to the lab for a demonstration and show you the results.
We purposely created an out of round condition on a roll from one of our Suburban Tool Sine Plates. We measured it first on one of our TAFT-PEIRCE Bench Centers for a point of reference. We then measured it in a 90 degree V- Block and then a 60 degree V-Block. Take a look at the results. You may be surprised.
https://www.youtube.com/watch?v=YUeFNGslzZo

redneckalbertan
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Joined: Thu Nov 01, 2012 10:39 am
Location: South Central Alberta

Re: 60 degree or 90 degree V- block, which is better for det

Post by redneckalbertan »

Interesting video, while watching it I got to thinking about comments made about grinding with a centerless grinder and how if not done properly you could wind up with a 3 lobed shape instead of round. Which, when measured with a mic., ends up indicating a round condition even though it is not. With an item like I just described if you were to perform the same test, as done in the video, would one v block be better to use for determining a three lobed condition?

In my minds eye when I rotate the shape in each V-block it seems that a 60* V-block does a better job showing this out of round condition. That being said I am not extremely confident in my thoughts on this matter as my brain started hurting when I was rotating in the 90* block!

Does anyone know the answer to my query? Has the ability, and time, to run this test then present their findings? Or hazard an educated guess?
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GlennW
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Location: Florida

Re: 60 degree or 90 degree V- block, which is better for det

Post by GlennW »

A 60 degree V block would be better for tri-lobed parts, as you could quantify the error.

It's a bit more complex to quantify a 60 degree error using a 45 degree V block as it will show more humps and valleys (using an indicator) than you actually have.
Glenn

Operating machines is perfectly safe......until you forget how dangerous it really is!
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