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| What have I done here? http://mowrystrings.luthiersforum.com/forum/viewtopic.php?f=10101&t=53357 |
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| Author: | bcombs510 [ Sat Jul 18, 2020 11:53 am ] |
| Post subject: | What have I done here? |
I purchased the SM calipers a few weeks back to replace a broken set from Starrett (I think  )... this is a 1/4” drill bit. Did I perhaps choose some setting with the SM ones that is adding a specific amount to the depth measurements or something?  I feel like I’m missing something obvious. I know you can measure fret height with the notch, but I don’t think that’s what is happening here. Brad Sent from my iPhone using Tapatalk Pro |
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| Author: | bcombs510 [ Sat Jul 18, 2020 12:00 pm ] |
| Post subject: | Re: What have I done here? |
I just noticed the depth rod sits at the top of the fret notch, so of course it is going to read weird. Do people zero this thing out each time reading depth?  Sent from my iPhone using Tapatalk Pro |
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| Author: | SteveSmith [ Sat Jul 18, 2020 12:39 pm ] |
| Post subject: | Re: What have I done here? |
Yep, you have to zero it. No biggie as long as you don't forget to re-zero when you use the other end. |
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| Author: | bcombs510 [ Sat Jul 18, 2020 12:44 pm ] |
| Post subject: | Re: What have I done here? |
Got it. OK, will commit it to memory. Luckily I caught it, I was 100% sure the tuner bushing hole wasn’t deep enough just by eye. So I guess I can see 0.070 discrepancies in a hole. Such a useful skill. Thanks, Steve. Sent from my iPhone using Tapatalk Pro |
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| Author: | SteveSmith [ Sat Jul 18, 2020 12:58 pm ] |
| Post subject: | Re: What have I done here? |
![[:Y:]](./images/smilies/smiley20.gif "Thumbs Up") Just one of them things. It took me a while but I managed to train myself to verify the zero on calipers every time I pick them up.
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| Author: | Colin North [ Sat Jul 18, 2020 1:37 pm ] |
| Post subject: | Re: What have I done here? |
Only ever had one which doesn't need rezeroed. |
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| Author: | Tim Mullin [ Sat Jul 18, 2020 3:16 pm ] |
| Post subject: | Re: What have I done here? |
bcombs510 wrote: I just noticed the depth rod sits at the top of the fret notch, so of course it is going to read weird. Do people zero this thing out each time reading depth? Sent from my iPhone using Tapatalk Pro Yes. Sent from my iPad using Tapatalk |
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| Author: | Chris Pile [ Sat Jul 18, 2020 3:25 pm ] |
| Post subject: | Re: What have I done here? |
Unfortunately, most makers will tell you this is an incorrect method of using the calipers. And old machinists don't bother doing that anyway because to get a true reading you need take the measurement from at least 2 frets at the same time. Which is why I use a depth gauge.... https://images.carid.com/starrett/products/449az-3r.jpg |
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| Author: | Burton LeGeyt [ Mon Jul 20, 2020 10:15 am ] |
| Post subject: | Re: What have I done here? |
That would get sent back so fast in my shop. |
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| Author: | johnparchem [ Mon Jul 20, 2020 10:23 am ] |
| Post subject: | Re: What have I done here? |
I have run into the stewmac difference between the rod and the caliper and have almost got burned. Luckily for me the error was enough for my eyes to see. I figured it had some handy purpose involving zeroing out fret height that I did not quite get. I do not use it anymore. |
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| Author: | SteveSmith [ Mon Jul 20, 2020 10:30 am ] |
| Post subject: | Re: What have I done here? |
I (and probably most everyone here) have been using my calipers to measure fret height (and other stuff) for years. As most everyone knows, the problem with getting an accurate measurement that way is that the caliper must be perpendicular to the fretboard. I don't find that to be an issue but I have, on occasion, put a small square next to the caliper for what I thought were more critical measurements (not frets). It appears that StewMac has tried to make it more foolproof assuming you have the caliper re-zeroed. I will stick with my standard 6" Mitutoyo. |
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| Author: | DennisK [ Mon Jul 20, 2020 11:10 am ] |
| Post subject: | Re: What have I done here? |
Oh, I see what they did. You zero the depth measurement against a flat surface, and then measure the fret height as a negative number. By having the depth stick able to retract "below zero", you can hold the notched end of the main bar against the fretboard with the fret in the notch and end of the depth stick against the top of the fret, guaranteeing that it's perfectly perpendicular to the fretboard surface. Terrible as a general purpose caliper, but for this particular task it's a clever solution. Although in that closeup photo it doesn't look like the end of the depth stick is ground square, which would make it useless for anything. But you could grind it square yourself easily enough, since it's not synchronized to the other two measurements anyway. |
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| Author: | SteveSmith [ Mon Jul 20, 2020 11:14 am ] |
| Post subject: | Re: What have I done here? |
Yes, an interesting approach which might cause as many problems as it solves. And I agree, doesn't look square. |
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| Author: | bcombs510 [ Mon Jul 20, 2020 11:34 am ] |
| Post subject: | Re: What have I done here? |
I'm just glad I know what to do. For a minute there I was questioning my life choices up to that point. I could not for the life of me figure out why the two measurements were different.
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