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Precision tools for measuring precut lugs?

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Precision tools for measuring precut lugs?

Old 09-16-21, 05:19 PM
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bikingman
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Precision tools for measuring precut lug angles?

This might be an easy answer, but are there any precision tools for measuring angles of precut lugs? I'd like to be able to measure the angle of cast and mitered/brazed lugs before they've been customized.

​​​​​​Thanks!
Dan
​​​​​​

Last edited by bikingman; 09-16-21 at 05:23 PM.
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Old 09-16-21, 05:46 PM
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GrayJay
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Mock-up the joint with tubes in the lugs an measure the angle of the protruding tubes. Most lugs will have a bit of slop in the fit to the tube so it is not exactly a high-precision measurement.
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Old 09-16-21, 07:55 PM
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Originally Posted by GrayJay
Mock-up the joint with tubes in the lugs an measure the angle of the protruding tubes. Most lugs will have a bit of slop in the fit to the tube so it is not exactly a high-precision measurement.

Thanks! Could you clarify by what you mean by a bit of slop? Is that in the realm of one or two degrees or between five and ten?
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Old 09-17-21, 05:53 AM
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Yes, 1-2 degrees of slop is there depending upon the tubes and lugs being used.
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Old 09-17-21, 07:19 AM
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Search for bevel protractor, it'll make the angle between tubes easy to measure.
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Old 09-17-21, 09:14 AM
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You don't say why you're measuring this or what precision means in your context but to increase the accuracy of your measurements you could turn some chunks of tube/bar (delrin, alum, etc) in a lathe to slightly oversized for each socket's tube size. Then mock up the joint as GrayJay suggests. This will remove most of the slop and give a more precise fit and measurement. I would add to Ti's comment that the socket will have 1-2* of 'slop' and it's pretty easy and common to manipulate the socket (up to another 2-4*) with some basic blacksmith techniques. I don't think I've used a set of lugs that didn't need some tweaking.
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Old 09-19-21, 03:52 PM
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Thanks duanedr and GrayJay - I bought a set of pre cut cast lugs and noticed the sockets are slightly ovalized, which got me wondering if the angles between the sockets are correct. I thought I'd ask if there's a special tool for the job. I don't have access to a lathe yet for turning delrin, AL, etc - but I do have a few spare tubes that I could use to mock up the join.
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Old 09-19-21, 04:34 PM
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When I try to measure lug angles as accurately as possible, I use the biggest tubes that will fit I can find (they are never exact but always + - to their theoretical size). When I lay the unit on my flat alignment table, I like to put some kind of similar lug on the other end of the tube. That means the tube is now laying parallel to the table. I then lay 1/2/3 blocks against the tubes so that my bevel protractor is laying flat on the table and up against the blocks. The mostly solves the problem of when the protractor is at a slight angle to a tube, it will read a slightly different angle than true.
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Old 09-19-21, 05:43 PM
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Originally Posted by GrayJay
Mock-up the joint with tubes in the lugs an measure the angle of the protruding tubes. Most lugs will have a bit of slop in the fit to the tube so it is not exactly a high-precision measurement.
That's what I do. It's not rocket surgery, after all. And you can use the tubes to adjust the angle to more closely match what you want.

Originally Posted by bikingman
Thanks! Could you clarify by what you mean by a bit of slop? Is that in the realm of one or two degrees or between five and ten?
It depends on the lug. Bulge-formed/stamped lugs are less precise and easier to manipulate than investment cast lugs. In desperate cases, you can cut a slot in the crotch of the lug to make it easier to adjust. Best for brass brazing, as you'll want to fill that void with brazing material.
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