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  1. #11
    Nice Job Steve :clap:

  2. #12
    Steve,

    Steve get one of these Constant Force springs .

    http://www.ondrives.com/springs-cons...-65n-load.html

    Like a gas strut but can't leak and always adjustable both ways if you cock up. Compact as well.
    John S -

  3. #13
    Quote Originally Posted by John S View Post
    Steve,

    Steve get one of these Constant Force springs .

    http://www.ondrives.com/springs-cons...-65n-load.html



    Like a gas strut but can't leak and always adjustable both ways if you cock up. Compact as well.

    I think I need more force than 9.55kg which looks like the biggest one they do, not weighed it but took some lifting when fitting back on the machine and I nearly broke into a sweat so it must be at least 20-25kg.

    Thats why I thought gas spring, the ones I am thinking of usually go up to 40kg with a little valve in the end to release the pressure. If you are dead against this idea then fair enough I will come up with something else, got any more idea's?? !

  4. #14
    Just ran the spindle again and still not happy with it.....

    The problem bearings at the moment are 2 x 16004's - dimensions OD 42mm x ID 30mm x width 8mm

    Decided to change them for some 6004's - dimensions OD 42mm x ID 20mm x width 12mm

    Will need to do a bit of a mod to the housing and make up a new spacer for the spindle but think its worth it as they have a higher load rating than the originals.

    Just rang my bearing man up and he has them in stock, apparantly they are used quite a lot for motorbike wheel bearings and he has plenty on the shelf. Price - 3.50 each for NSK's!

    Where's me van keys.........
    Last edited by HiltonSteve; 08-04-2010 at 04:17 PM.

  5. The Following User Says Thank You to HiltonSteve For This Useful Post:


  6. #15
    Isn't that motor just a tadge excessive?

    How on earth are you going to channel 1hp through such a tiny tool without blowing it to shards?

    If I was going to put in a 1hp layshaft I wouldn't go below 3/4"

  7. #16
    Quote Originally Posted by Robin Hewitt View Post
    Isn't that motor just a tadge excessive?

    How on earth are you going to channel 1hp through such a tiny tool without blowing it to shards?

    If I was going to put in a 1hp layshaft I wouldn't go below 3/4"
    Robin,

    When I got the motor i too thought it was a bit excessive but based on my simple calculations I ended up looking for a 1HP DC motor and was very suprised at the size when I collected it.

    Current Kress 240v AC spindle - 1050W = 1.408073 HP

    New big 180V DC motor - 750W = 1.01HP

    Then throw into the equation that I have geared the spindle up to increase speed from the 2000rpm motor max which will in turn reduce the torque, so in theory I will have less power than the Kress but I will have slower spindle speeds which is what I am after.

    I can't find a torque/speed curve for the Kress spindle but I imagine that when running at its slowest speed (10,000rpm) that it is not developing 1HP, hopefully when my spindle is running I should get decent torque at 3,000-6,000 rpm but time will tell....

    Swapped the bearings in the spindle last night which made an improvement but still got a vibration/resonance problem which looks like is coming from the toothed belt, tried different belt tensions which altered when the vibration came in. After a couple of phone calls I think it could be to do with the small amount of 'wrap' i have on the smaller pulley, will be making up an idler pulley to run against the back of the belt to push the belt further round the small pulley.

    Note to self - when feeling round for vibration on machine do not put hand on bare motor connections as it makes you jump and shout BASTARD really loud...!

  8. #17
    Maths isn't exactly my strong point, but...

    For sake of argument, consider a 6mm tool at 6000rpm

    6mm*pi*100rps=1885mm/s=6.18ft/s at the cutting edge

    1hp=550ft.lbf/second

    550/6.18=89 lbf=Whoops!

    Irving will now tell me where I went wrong :naughty:

    Best

    Robin
    Last edited by Robin Hewitt; 09-04-2010 at 12:18 PM.

  9. #18
    Quote Originally Posted by HiltonSteve View Post
    Robin,


    Swapped the bearings in the spindle last night which made an improvement but still got a vibration/resonance problem which looks like is coming from the toothed belt, tried different belt tensions which altered when the vibration came in. After a couple of phone calls I think it could be to do with the small amount of 'wrap' i have on the smaller pulley, will be making up an idler pulley to run against the back of the belt to push the belt further round the small pulley.
    Should have used a Polyvee belt

    Nar nar nar nar nar
    John S -

  10. #19
    Quote Originally Posted by John S View Post
    Should have used a Polyvee belt

    Nar nar nar nar nar
    I know your right and you know you are right.....

    Still got the tool to make them and the 2 sample pulleys that I borrowed from you! Where did you say to get the belts from?...... smart arse.

  11. #20
    Quote Originally Posted by HiltonSteve View Post

    Still got the tool to make them and the 2 sample pulleys that I borrowed from you! Where did you say to get the belts from?...... smart arse.

    See what I mean, BORROWED - huh, fat chance of even seeing those again.

    Belts ? try the belt company..............
    John S -

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