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Thread: Squareness comparator
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18th Feb 2021, 10:31 PM #1Novice
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Squareness comparator
The decision to fab a squareness comparator came about whilst trying to check if the jaws on my milling vice were square (they were not).
I rigged up a mag base with a dial indicator attached and a bit of linear rod stuck to the magnetic base as a work around, but knew I needed something a little better and a little more accurate.
So after hours of scrolling the interwebs I found a design that was perfect for what I wanted to use it for and I set out to make it.
This is what I came up with...
-Base is cast iron
-Knobs are brass that have been blued
-Pivoting arm, dial clamp and front bumper insert are 4140 hardened and tempered
-The rest is hardened stainless steel
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18th Feb 2021, 10:34 PM #2Novice
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The fabrication process.
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19th Feb 2021, 10:54 AM #3Most Valued Member
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Nice work John.
Can I ask what radius did you decide on for the front bumper?
I've read differing opinions on this, some say there is a specific method to determine the correct radius while others say that's it not particularly crucial. I'm inclined to think the latter is correct as long as the chosen radius is precise.
Simon
Sent from my SM-G970F using TapatalkGirl, I don't wanna know about your mild-mannered alter ego or anything like that." I mean, you tell me you're, uh, super-mega-ultra-lightning babe? That's all right with me. I'm good. I'm good.
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19th Feb 2021, 11:11 AM #4Novice
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19th Feb 2021, 11:19 AM #5Most Valued Member
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Cheers!
Sent from my SM-G970F using TapatalkGirl, I don't wanna know about your mild-mannered alter ego or anything like that." I mean, you tell me you're, uh, super-mega-ultra-lightning babe? That's all right with me. I'm good. I'm good.
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19th Feb 2021, 09:42 PM #6Most Valued Member
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That's a beautiful piece of work John - you should be very proud.
Steve
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22nd Feb 2021, 11:35 AM #7Senior Member
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That's a beautiful job, John
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22nd Feb 2021, 11:07 PM #8
Hi Guys,
I'm probably wrong, but shouldn't the radius be centred on the centre of the column ?
I do agree that it is a very nice piece of work !Best Regards:
Baron J.
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23rd Feb 2021, 08:35 AM #9Most Valued Member
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I initially had a similar thought John. After thinking about it a bit I came to the conclusion that the column is just a structure to hold the indicator in a fixed position.
The pointer of the indicator is pretty central to the nose radius in this design, but its not critical as the reference points are the base plane, the contact point on the nose and the indicator pointer. Swinging the indicator off center will indirectly shift the contact point on the nose as that stays vertically below the indicator - but when zero'd to a reference square it will still function correctly.
That's my take on it anyway. Since I haven't actually made or used one I could be completely off track.
Steve
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23rd Feb 2021, 11:17 AM #10Most Valued Member
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I've put some thought into it as well.
Since its a comparator, it's not critical as long as all the dimensions stay the same (as they would) when moving from one measurement to the next.
Equally, there is no real need to have the indicator facing out radially from the centre of that bumper radius. Adjustment by eye is close enough.
Considering the level of accuracy you can achieve, if the radius was as critical, it would be difficult to make this tool at home.
Simon
Sent from my SM-G970F using TapatalkGirl, I don't wanna know about your mild-mannered alter ego or anything like that." I mean, you tell me you're, uh, super-mega-ultra-lightning babe? That's all right with me. I'm good. I'm good.
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23rd Feb 2021, 09:23 PM #11Golden Member
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As already mentioned the stylus of the DTI does not have to be accurately aligned but it does help to have it reasonably central, I had to make an offset adaptor to get the indicator located on the centerline of this gauge that I made a few years ago.
I used a 50mm radius on the bumper but I think it could have been larger.
Surface Gauge.jpg
Surface Gauge.jpg1.jpg
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