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  1. #1
    Join Date
    Aug 2010
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    Default Biax motor change

    As mentioned elsewhere on this forum, I managed purchase a Biax scraper in Germany at 'the right price'. This one is a 'Type IV' - an early model - and was a compressed air motor version.
    Sadly, the compressed air motor is worn and not really convenient for me anyway. However, the scraper end and gearbox is in excellent condition.
    So the plan is to 're-engine' the scraper, using a low power electric motor with variable speed control and convenient size.
    The electric version of the Type IV Biax used a 180W universal motor, for which spares have not been available for a long time. So trying to convert to the original motor was not an option.
    I chose to use a easily available 'multi-tool' made by Ozito for this project. It runs a 250W motor. The process of conversion will be the same for any suitable motor.
    One of the requirements is that the tool's gearbox is detachable in a single plane at right angles to the armature and is screwed on to the motor body.
    First a photo of the Biax as it arrived:
    $_57 (3).jpg
    Here is the gearbox and scraping mechanism taken apart and cleaned up:
    IMAG2963.jpg IMAG2964.jpg IMAG2965.jpg
    The original motor spindle, removed from the air motor and photographed in place in the gearbox cover:
    IMAG2966.jpg
    Cheers, Joe
    again completely retired - more time to contemplate projects and spend more shed time....

  2. #2
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    Default

    Next, here is the donor motor's armature with and without fan for comparison with the air motor:
    IMAG2968.jpg IMAG2969.jpg
    So then I cut a suitable piece of aluminium and turned it to register in the new motor housing, accommodate the fan and the drive end bearing.
    IMAG2971.jpg
    Then I cut the small off-centre drive pin off the armature and the drive pinion and 8mm section off the air motor spindle.
    In the process of figuring out how to join the two spindle parts, I decided that the bearing needed to be fitted into the Biax gearbox cover, rather than the adapter plate. This will allow better integration and registration of the adapter plate to the Biax cover.
    IMAG2973.jpg
    Next will be to join the two spindle parts. I have a collet suitable to accurately hold the pinion stub for machining.
    IMAG2976.jpg

    More progress reports to follow as I go....
    Cheers, Joe
    again completely retired - more time to contemplate projects and spend more shed time....

  3. #3
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    Aug 2010
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    Default Biax conversion lives - and dies....

    Firstly a small correction: the Ozito multi tool motor produces 300W, not 250W as posted at the top.
    Anyway, I finished the conversion. It works and looks the part.
    Unfortunately, I had a little accident during final assembly - I dropped the Biax gearbox very awkwardly on the armature on the workbench.... and damaged one of the windings irreparably...
    However, since this was to be a re-motoring demonstration and proof of concept, I did what I could to keep it alive for a while and continued reassembly.
    Sadly - or maybe gladly - I learnt that there are no spare parts available for many of the Ozito range of tools! So that wasn't a good choice anyway...
    Once assembled and everything moving the way it should, I ran the motor despite the damage. It works as expected: a bit slower than intended (due to the damaged winding) and gets hot quite quickly. However the soft start and variable speed works nicely.
    I'll decide at some point if I buy another Ozito tool to use the scraper or keep looking out for a more "industrial strength" powertool to do a final conversion, preferably a brand that keeps spares for a while...
    If anyone has any good suggestions for a suitable drive motor, I'm all ears!

    The little Biax air motor pinion and shaft was through hardened, but I managed to turn the plain end down to 4.5mm with a ceramic insert to fit into the electric armature spindle. It turned out very well. Sorry, I didn't take a photo of that step.
    Next I drilled and bored the armature spindle end to a nice tight fit for the pinion 'peg' and Loctited it in. Checking concentricity turned out to be very good at less than 0.02mm at the gear end.
    The adapter plate was registered on the boss of the Biax gearbox cover and screwed on with 3 screw that used to hold the air motor in place.
    I then drilled the 4 screw holes to fit the motor housing and milled the register bosses and angled ventilation slots. Then I marked the body shape of the Ozito housing on the adapter and shaped it (sanding disk) to transition to the Biax gearbox housing to look right.
    Next I painted the adapter plate to match the Biax parts.
    Here are the photos of the completed conversion:

    IMAG2977.jpg IMAG2979.jpg IMAG2981.jpg IMAG2984.jpg IMAG2991.jpg IMAG2992.jpg IMAG2988.jpg IMAG2987.jpg
    Cheers, Joe
    again completely retired - more time to contemplate projects and spend more shed time....

  4. #4
    Join Date
    Aug 2008
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    Default

    I thought parts for Ozito tools would be not possible to get, as you generally just swap for another one as they rarely last warranty anyway.

    It is hard to say what to use, anything decent is going to be $$, you would have to trawl ebay to find a seldom used appropriate power tool that might have parts backup. Or at least common enough that you could buy a couple of them, one for spare parts. Hitachi seem to be one manufacturer that still sells models that are decades old, like their spade drill and their nibbler. Their nibbler motor would be a nice Biax replacement motor, but they are very expensive power tools, even second hand.
    Gold, the colour of choice for the discerning man.

  5. #5
    Join Date
    May 2012
    Location
    Victoria
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    Default

    G'day Joe,
    Great work, looks just like a factory job.
    Regards
    Bruce

  6. #6
    Join Date
    May 2011
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    Murray Bridge S Aust.
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    Default

    Hi Joe,
    As Bruce said Looks like a factory fitted job. Excellent workmanship.
    Thanks for the write up and pics on how you did it.
    Kryn
    To grow old is mandatory, growing up is optional.

  7. #7
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    Aug 2006
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    Melbourne
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    Default

    Hi,

    What are the requirements for the motor? What power output, rpm and is variable speed necessary?

  8. #8
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    Quote Originally Posted by Com_VC View Post
    Hi,

    What are the requirements for the motor? What power output, rpm and is variable speed necessary?
    Given that the motor on the original Type IV was 180W, anything above that would suit. So as not to load the motor to capacity, I'd say somewhere above 250W would be better. Variable speed is not critical but very handy indeed. If the perfect tool didn't have variable speed built in, I'd make an in-line speed control for it. So built it is more convenient and preferred.
    What do you have in mind?
    Cheers, Joe
    again completely retired - more time to contemplate projects and spend more shed time....

  9. #9
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    Aug 2006
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    Default

    What about rpm?

  10. #10
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    Default

    I would calculate 15000 and up rpm would be right.
    I haven't checked the actual reduction ratios and can't right now (I'm in hospital until at least tomorrow).
    Because I intend using variable speed, anything above 15k would be OK.
    Cheers, Joe
    again completely retired - more time to contemplate projects and spend more shed time....

  11. #11
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    The 7EL motors do around 23 000 rpm for 1200 strokes/min.
    Gold, the colour of choice for the discerning man.

  12. #12
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    Thanks Richard. That's useful. I will check the ratios when I get home.
    Cheers, Joe
    again completely retired - more time to contemplate projects and spend more shed time....

  13. #13
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    May 2011
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    Murray Bridge S Aust.
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    Did you end up finishing the Biax Joe? Or is still on the to finish list?
    Kryn
    To grow old is mandatory, growing up is optional.

  14. #14
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    Default

    It still works as it was, but I bought another Ozito Multitool to try again when it gives up the ghost. Haven't done much scraping in the past few months....
    The other thing I got hold of is a Metabo jig saw - with the correct motor for the current model Biax. I may reconsider pushing on with that motor instead when I get to it.
    Cheers, Joe
    again completely retired - more time to contemplate projects and spend more shed time....

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