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Thread: Belt sander/linisher - good or bad?

  1. #31
    Join Date
    Mar 2013
    Posts
    1,499

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    Europe, 50 Hz, about 2850 rpm from an AC motor without brushes. Small pulleys and you completely out of the grinding speed range. 4-1/2” grinder runs 10’000 rpm or more and so far I haven’t changed brushes in one.

    Build your own. Start with 4-1/2” grinder and put a drive wheel right on the spindle thread. Machine a slight crown on it using another hand grinder while it is running so it will be dead true diameter. Remove the guard and attach an arm for spring loaded idler wheel. Mount it or use it hand held. You can probably carry this one up the stairs. Add a backing bar to the arm if you want. Plenty powerful and the right speed.

  2. #32
    Join Date
    Dec 2016
    Location
    Helsinki, Finland, Europe
    Posts
    2,787

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    Quote Originally Posted by Cenedd View Post
    Oh wasn't planning to use it in place of the mill.
    I'm roughing to shape with belt grinder(5.5hp) and finish on milling machine (0.3hp)
    Talk about balanced combination..

  3. #33
    Join Date
    Oct 2014
    Posts
    329

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    Back in the 80s I built a 2x48. I used the contact wheel from a Baldor belt sander, bought it as a replacement for a Baldor. IT is about 7" in dia. 2" face and had a 3/4 bore if I remember. I had a 1/3 hp 3450 rpm flange mount motor from a water pump so I used it and it has enough power. I am using V belt drive at 1 to 1. If you push it to where the motor slows down it is heating up the part too much or making it too hot to hold. Briefly here is how I did it. About a 2 ft section of 4" sq. tube mounted vertical , at the top two ears extending forward, towards you, for two flange bearings. for the contact whell arbor. From a short section of 5" pipe I made a idler pulley with a very slight crown. This was mounted lower down on the 4" sq. column and was mounted on a spring loaded pivot so it could be adjust for tension and also for angle for belt tracking. The idler pulley has a sealed bearing pressed into a 1/4" flange welded into each side of the 5" pipe. There is a platen that can be mounted with cap screws to The column and a work stop that can be attached to that. I know it is unusual to have the contact wheel at the top and you are working on the loose side of the belt as you apply pressure to it but I am able to work on the contact wheel easily this way. The motor is mounted low down back on a 1/4" "flange" that extends forward to the side of the column and pivots for belt tension. This tool has been great. I use it almost anytime I am in the shop. It sits on the floor on small casters under a bench. I sit on a short stool to use it. A longer belt might last longer but this machine doesn't take up much room and 2x48 belts are common and a reasonable size for a home (and a lot of commercial) shops. The cost is little if you can scrounge some of the materials and parts. The contact wheel cost me $75 back then which I thought was a lot but it is still in very good condition, and the cost was probably because it was a "replacement part" and parts are always expensive. Possibly if I had had a way to buy it wholesale the price might have been a little better. Anyway I don't care, the machine has been great.

  4. #34
    Join Date
    Nov 2017
    Location
    Watford, UK
    Posts
    370

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    Thanks for the info WDTom44. A low-down setup sounds interesting for ideas. Any chance of a picture please?

    The idea of using spare parts for other machines sparked some thoughts. I have a mostly working (e-stop relay doesn't work but could maybe be replaced) control board for the 1000W brushless motor in my lathe. Only trouble is that when I checked, its priced at nearly 400 (nearly $500 USD) so that idea's not going to fly. Would something like the 48V version of this work? I specify the 48V version only because there is a controller available in that voltage - although only rated for 750W. Not sure which way round is ok: higher rated motor with lower rated driver or vice-versa. Could do with a bit of a point in the right direction when it comes to what I'm looking for to be honest.

  5. #35
    Join Date
    Nov 2017
    Location
    Watford, UK
    Posts
    370

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    Ok, have found a UK supplier for a 3-phase AC Induction motor. Think I got hung up on it being brushless before. Might need a face/flange mount rather than foot-mounting. Not really sure but figure that mounting off the face will make it easier to align it...?
    Motor: https://www.ebay.co.uk/itm/222432402799

    VFD from the same supplier: https://www.ebay.co.uk/itm/321059752566

    I don't really know anything about VFDs except that this one is about 1/3 the price and the same basic spec. Support/warranty is likely to be almost non-existent but is there any reason not to go for the bargain basement unit?
    Cheaper VFD: https://www.ebay.co.uk/itm/254033246766

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