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  1. #1
    Join Date
    Mar 2015
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    Redmond, WA
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    Default GraverMax Question

    Hi GRS Guys and Ladies,
    I have an opportunity to buy a well used GraverMax, actually two of them, from an estate. The machines are disconnected from an air source and there is only one foot pedal. I suspect that one of the machines is broken, since there is only one pedal, but I've never used one and don't know how to test one. What happens when a machine is plugged in and the switch is turned on? Is there a way to check operation without connecting to a compressor? I'm not sure what happened to the compressor, probably already sold, but I'd love to buy one of these, or maybe both, but I don't know how to check them. Any suggestions?
    Thanks,
    Barry

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  3. #2
    Join Date
    Mar 2015
    Location
    Redmond, WA
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    48
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    Default

    Well Barry, if you'd known about the plethora of downloads available at GRS, perhaps you could have answered this question on your own.

    At GRStools.com navigate to the product manual download page and click on the link to download the entire manual for the GraverMax. [ http://www.grstools.com/PDF/004-041_MaxMate.pdf ] I've included the link to your manual in the brackets above for your convenience.

    You will find in the manual a caution about NOT running the GraverMax machine at all without an air source connected (40psi minimum up to 120psi maximum) however, it is possible to run the machine for a few seconds without causing damage.

    The machine itself is comprised of an electric motor that spins the ported barrel of a "rotating valve" which floats on a cushion of compressed air. When the ports align, puffs of compressed air find their way to the hand-piece, which is simply a pneumatic jackhammer driven by those puffs of air.

    Fluid of any kind in the system is a very bad thing so a coalescing filter in the outside compressor line is mandatory with oil lubricated compressors.

    The electric motor is what you will hear when you turn on the machine without an air source connected. Turn the "stroke speed" knob on the front panel and listen for changes in the speed of the electric motor. If there are no squeaks or squeals you probably have a machine that is serviceable, however, there are several hoses inside the machine that connect the rotating valve to the hand-piece connectors, the foot throttle, and the pressure gauge.

    After a relatively few years, ozone, heat, and vibration serve to harden and cause cracks in the hoses. The machine I recently bought suffered from complete degeneration of the tubing, so I replaced it all with new tubing. If that is the case with your machine, be sure not to just throw out the old tubing, because one of them, the line from the regulator to the pressure gauge on the front panel--#21 on the machine diagram, will contain a "sintered disk" (#26 on the diagram) that prevents fluctuations of the pressure gauge. Keep that disk and insert it into your new tubing.

    It is a good idea to remove the cover of the machine to inspect the hoses before buying because the replacement kit is $30-$40 depending on from whom you acquire it. GRS will also refurbish your machine if you send it to them, but the cost is $225 plus shipping for the GraverMax, foot control, and one hand-piece.

    I believe a reasonably well informed and experienced tool guy can do the refurbishing him/herself with a couple dollars of the correct tubing, a few minutes of study, and an hour or two of judicious work. My son has effectively, efficiently, and inexpensively refurbished two machines, three hand-pieces, and a foot-pedal by himself just today, in a couple of hours. He's down there right now, making beautiful lines in a practice piece of mild steel, and he never even held a graver until two weeks ago. Hope that helps...
    Last edited by BarryB; 05-22-2016 at 02:24 PM. Reason: Formatting

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