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  1. #1
    Join Date
    Apr 2015
    Location
    Sydney, Australia
    Posts
    23

    Default Macphersons Reciprocating Saw.

    Hi folks,

    I am interested in running my Macphersons Reciprocating Saw at the correct number of s.p.m for cutting Stainless Steel Rnd bar (3").
    Any info appreciated re ideal speeds and where blades may be bought?. Presently it cuts light steel ok but it is running to fast. A variable speed would be ideal but perhaps not easy?

    Thanks

  2. #2
    Join Date
    Nov 2017
    Location
    Geelong, Australia
    Age
    57
    Posts
    2,651

    Default

    If its a 3ph motor then variable speed should be pretty easy/cheap using a VFD.

    Blades can often be had on eBay for a decent price, and some engineering/tool supplies places still stock them. I think I may have bought a blade from Totaltools when I had my Parkanson saw.

    I haven't found any specific power hacksaw references online, but this one for bandsaws might be useful: https://austechsaw.com.au/documents/Speed Chart.pdf
    For bi-metal blades they're recommending around 250SFM for mild steel, and for stainless its around 70-130 SFM (ie 2/3 to 1/2 of mild steel)

    Steve

  3. #3
    Join Date
    Apr 2015
    Location
    Sydney, Australia
    Posts
    23

    Default

    Thanks for the info,
    Blades are not easy to find, I will look at ebay.
    The motor is a 1/2 hp single phase. the saw is in good working condition.
    Cheers

  4. #4
    Join Date
    Apr 2018
    Location
    Perth
    Posts
    168

    Default

    What about Dc motor. Use a treadmill DC motor and a cheap dc controller. Most treadmills are 170V dc so easy to match with a controller and can keep single phase. I fitted one up to my BIL's old clunker of a power hacksaw.

  5. #5
    Join Date
    Apr 2015
    Location
    Sydney, Australia
    Posts
    23

    Default Dc motor

    Hi Sparksy,

    This sounds a very good approach, Thankyou.

    Are the treadmill motors able to be sourced at a good price? Are the DC treadmill motors rated in HP similar to my existing 1/2 hp single phase motor?
    Is Ebay etc the way to go?
    Is doing the controller wiring complex?

    Regards

  6. #6
    Join Date
    Oct 2008
    Location
    Cairns, Q
    Posts
    666

    Default

    Quote Originally Posted by Grahamross View Post
    Blades are not easy to find, I will look at ebay.
    Cheers
    My hacksaw uses 12 inch blades which are not easy to find now. A year or so ago I got 6 HSS blades via Ebay post free from the UK for less than the price of a single blade quoted by a local supplier. They were UK manufacture and seem to be OK. I don't use it much now, but still on the first blade.

    Frank

  7. #7
    Join Date
    Nov 2017
    Location
    Geelong, Australia
    Age
    57
    Posts
    2,651

    Default

    Buying longer bi-metal blades and cutting them down is always an option. It’s only the teeth that are HSS so shouldn’t be too bad drilling another hole.

    Steve

  8. #8
    Join Date
    Apr 2018
    Location
    Perth
    Posts
    168

    Default

    Quote Originally Posted by Grahamross View Post
    This sounds a very good approach, Thankyou.

    Are the treadmill motors able to be sourced at a good price? Are the DC treadmill motors rated in HP similar to my existing 1/2 hp single phase motor?
    Is Ebay etc the way to go?
    Is doing the controller wiring complex?
    I use a KB brand kbic controller https://www.motordrives.com.au/kb_dc_drives.aspx but only because they were obsolete stock from work. Ebay has them, just look for the voltage of the motor ,

    Simply connects from 240v through controller and then from armature connections on board to the motor. The speed is handled by a 10K pot connected to board.
    Easy to get treadmills free on gumtree or verge collection. Some others on here have used them for similar applications. If you are handy electrically with a simple one you could use the existing controller.

    Any large treadmill has a motor at least 1/2 hp. Some like one i fitted to BIL's saw have double ended shafts, so left the original cast iron pulley on as a flywheel and put new pulley on other end. Motor is like any dc motor so just revers polarity to change direction.

  9. #9
    Join Date
    Apr 2015
    Location
    Sydney, Australia
    Posts
    23

    Default great information --thamks

    Hi Sparksy,

    Many thanks for your reply and information, I will follow up with your advice.
    The old saw is worth is worth getting it running at its best.

    Regards
    Grahamross

  10. #10
    Join Date
    Apr 2018
    Location
    Perth
    Posts
    168

    Default

    Quote Originally Posted by Grahamross View Post
    Hi Sparksy,

    Many thanks for your reply and information, I will follow up with your advice.
    The old saw is worth is worth getting it running at its best.

    Regards
    Grahamross
    Checked out the treadmill motor I have in shed and its 180V 3HP with a 20mm shaft on both ends and foot mount . about 400 mm long and 200 mm diameter

  11. #11
    Join Date
    Apr 2015
    Location
    Sydney, Australia
    Posts
    23

    Thumbs up DC motors.

    Sparksy,

    Another project to go, but this has great opportunities for other applications, perhaps a drill stand?

    Thanks

    Grahamross

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