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Magic Probe digital thickness gauge

Discussion in 'Setup & Repair [DB]' started by james condino, Jul 28, 2012.

  1. james condino

    james condino Spruce dork Supporting Member Commercial User

    Sep 30, 2007
    asheville, nc
    I mentioned a few weeks back that I'd post a review of the new Magic Probe digital thickness gauge. As a disclaimer, I have no financial interest, this is not any business enterprise of mine, I'm not sleeping with anyone somehow connected to the company, blah, blah, blah....it is just an interesting new product that is applicable to our nerdy little world.

    I had heard about the Majic probe earlier in the year. They offered to send out one for testing, but it only went up to approx. 8mm. I told them no thanks; give me a call back when you develop one that will work for bass builders and go about twice as thick as that for the times we run into overbuilt tanks; I thought I'd never hear from him again.

    About six days before I headed out to the Oberlin Bass workshops last month, I got a call from Liam who makes these; he told me he had a new bass version and would send it out today via FEDEX overnight air. He did- and FIVE DAYS LATER, it arrived. Luckily, I wound up departing a day later than expected. We nerded out a little bit with it at the workshops, but to be honest, there was so much good stuff happening there that it was on the back burner.



    I've been putting it to the test this month and my overall opinion is that this is a great tool and something all luthiers have been wanting for quite a while. The basic principle is that you've got a handheld unit with a few options and a digital readout that uses the magnets inside along with another magnetized ball ( two size options included) that you drop in the holes of an assembled instrument for non invasive measuring of the top / back / rib thicknesses. I also have a Hacklinger gauge that does the same thing manually. The Majic Probe measure to two decimal points, rather than the 'hacks visual estimate by tenth of a millimeter. Both work within a tolerance that is acceptable for my work. I use both every day. I have no intention of getting rid of either one ( Liam, that means I'm keeping the demo model!!!)

    Since both of work with internal magnets, you've got to be a little careful not to get them near any internal metal parts; I've gotten both the 'probe and the 'hack stuck on internal pickups and endpins. That spices up your day a lot of you can't reach them inside....

    How do I stand one magic vs. hack? Simple- I first got my own Hacklinger gauge about seven years ago- after a decade of lusting after them and then cussing every day that a German company seemed to hold the global patent on $4 worth of scraps that they sold for $400!!!! That clearly said, as a builder, it revolutionized my work. Within six weeks, my new instruments took on a completely different voice and volume. When I checked some of my older instruments, the reason was simple using dial gauges and traditional making / depth systems and allowing for some final scraping /sandout /margin of error, what I thought was close wound up being off by sometimes 25-30% of my target goal with top and back thicknesses- almost always being overbuilt. Since joining the 'hack club, I still make them a bit over, but when everything is fully assembled and ready for the finish, I can measure very precisely what I want the final dimensions to be. I also use them almost daily in new building, restoration, writing, making blueprints, and studying all of the great older instruments that pass through my shop. As much as I hate the cost of the 'Hack I can honestly say that I would pay for its weight gram for gram in gold at today's market value and still feel like I was getting a deal.

    For a real world application today, I posted earlier about the "mystery Kay" with solid ribs. It has a 1941 label; I 'probed it alongside a 1939 model next to it for comparison:

    (all numbers in mm and I only use one decimal place)


    ribs: 3.0-3.1
    top: 5.1-6.2
    back: 5.7-5.9

    mystery 1941 numbers:

    ribs: 3.3
    top: 5.9-6.4
    back: 6.5-6.6

    For someone who takes a lot of notes on old instruments and uses them for publishing blueprints and such like I do, the Majic Probe has a fantastic feature where you can shoot a digital image of the instrument and then quickly overlay your probe results on to the image- a very cool and handy feature.

    Since I now have both and it is clear how I feel about using them. I can say this: GET ONE!!! If you are a crusty old Luddite who likes analog measuring tools and period music, probably the Hacklinger is the one for you; if you're a techgeek with a very latest electronics device, the majic probe is the obvious choice for you. If you're thrifty (a polite way of saying it...) the list price on the Majic Probe is cheaper than the Hacklinger, but my guess is that the 'hack folks can see the writing on the wall and you can get them a lot cheaper today while they are circling the drain....

    If I can offer one suggestion for future upgrades, that would be to skip the handheld part, sell just the probe and make it available as a reasonably priced app for the iphone / ipad systems and you'll sell thousands of them!

    If anyone is interested, I'll offer up that you can stop by the shop with a malt beverage and have a geek-o-rama and check things out in person.

    I was going to use this writeup for American Lutheire magazine, but Mike Doolin, someone who has written a number of articles on how to build your own thickness gauges, beat me to it in the current issue.

    For more information, check out the Majic Probe website:

    'Hope this helps you develop your skills better. The more tools and knowledge we as individuals have, the better the bass community as a whole gets.

  2. tonequixote

    tonequixote Supporting Member

    Feb 6, 2004
    The magic probe is on my short list of tools. When used with graduation mapping software, database building just took a quantum leap forward.

    Any idea when the bass version will be available ?
  3. drurb

    drurb Oracle, Ancient Order of Rass Hattur; Mem. #1, EPC

    Apr 17, 2004
    Thanks for this review. I'm not a luthier but read this with interest because of my interest in technology (and basses, of course). I know far more about electronics than I do bass-building. One reason that it may not be feasible to sell "just the probe" is because the conversion to units of thickness based on the signal from the transducer (the probe) apparently takes place within the handheld unit. That is, that's where the brains are. So, it seems that in order to interface with an iPad or the like, the "brains" would have to be built into the probe along with the means to format the output to a data-stream recognizable by the iPad, etc. That could all be accomplished by having a small box at the end of the probe but it's not clear whether that would make it all more or less costly. Again, thanks for taking the time to provide all of the detail.
  4. james condino

    james condino Spruce dork Supporting Member Commercial User

    Sep 30, 2007
    asheville, nc
    This is the new bass version.:)
  5. drurb

    drurb Oracle, Ancient Order of Rass Hattur; Mem. #1, EPC

    Apr 17, 2004
    I think he wanted to know when it will be available for sale. :)
  6. Jake deVilliers

    Jake deVilliers Commercial User

    May 24, 2006
    Crescent Beach, BC
    Owner of The Bass Spa, String Repairman at Long & McQuade Vancouver
    Liam already makes a version that will plug into the USB port of your laptop and use the processor for the calculations/display. Its a really smart little tool either way. ;)
  7. drurb

    drurb Oracle, Ancient Order of Rass Hattur; Mem. #1, EPC

    Apr 17, 2004
    Ah... smart...very smart. :) That may be a bit more than an "app" often does but makes sense.
  8. Jake deVilliers

    Jake deVilliers Commercial User

    May 24, 2006
    Crescent Beach, BC
    Owner of The Bass Spa, String Repairman at Long & McQuade Vancouver
    Given that you have to pay Apple to sell an iPhone app...

    He's also got a version with Bluetooth, but that's just a little too much for me! ;)
  9. drurb

    drurb Oracle, Ancient Order of Rass Hattur; Mem. #1, EPC

    Apr 17, 2004
    Good point! Yes, I saw the Bluetooth version. Hmm... maybe he's willing to build pre-amps. :)
  10. JoeyNaeger

    JoeyNaeger Guest Commercial User

    Jun 24, 2005
    Houston, TX
    Bass Specialist, Lisle Violin Shop
    This is definitely on the wish list. I didn't really get to see it in action at Oberlin, glad to see it turned out well.
  11. lsnyman


    Aug 2, 2012
    Dallas, TX
    Produce electronic thickness gauge
    Thank you James, I am glad you like the unit so far.
    Just to clarify, The standard unit will actually measure to 15mm using a 1/2" ball but the resolution is a little lower in the 10-15mm range. For James I constructed the probe using a 5/8" ball to provide more resulution in this range.
    You are correct about the iphone App, I am ready but Apple makes it very difficult to get data in to the device, they block both the serial and bluetooth ports, i am playing with other methods. I use the same electronics in the "probe Only" model, all surface mount so it fits inside the tube. Someone mentioned a gradation Mapping software, I have been searching for one, any suggestions?
    Jake, I think we may have the same heritage.....Verstaan Jy? :)
  12. Jake deVilliers

    Jake deVilliers Commercial User

    May 24, 2006
    Crescent Beach, BC
    Owner of The Bass Spa, String Repairman at Long & McQuade Vancouver
    No, I don't understand you. ;) The name may be of Huguenot origin but its been English since 1066.

    Congratulations on your thickness gauge, by the way!

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