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IndustryArena Forum > WoodWorking Machines > DIY CNC Router Table Machines > Weight of my gantry is *45Kg*or*100lb*
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  1. #1
    Erfahrener Benutzer
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    Weight of my gantry is *45Kg*or*100lb*

    Hi all.

    I am having some weight issues with my gantry. I wish to use stepper motors that are direct drive to a rack via pinion. The weight of the gantry is 45kg or 100lb at the moment. I then have to add on the stepper motors, a rack and bits and pieces. So basically it is HEAVY!


    As you can see the in the photo I have used angle iron to support the round bars on which the truck slides along. The weight of one round bar support (ie 2 lenghts of angle ) is 12kg. So I have two of them which is 24 kg.

    I am thinking that I can save weight buy using aluminium angle as supports.

    Maybe I should just use some aluminium shs and bolt on some of those duel'vee guides and use the groved bearings. If I was to do that, then I would eliminate the heavy steel angle iron and also the heavy round bar as well.

    The idea of me reducing the weight is so that I can use small/cheaper stepper motors.

    What do you all think of this?

    Also what size steppers would I need to drive this system. It is only for a plasma cutter so there will be no contact. It is going to be driven on one side only. I have been thinking of using stepper motors in the 400oz range. Could I go smaller or should I go bigger. What speeds could I expect to reach.

    Cheer Peter
    Attached Thumbnails Attached Thumbnails gantry 1.JPG   gantry2.JPG  

  2. #2
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    hi
    With the motors that possess (270 oz) , the force on leadscrew, of my cnc mills, is 305 kg = to 2998 newtons!!!! , (push gotten with leadscrew of 2 mm, with bronze dual nut ).
    or 152 kg with leadscrew of 4 mm
    hi
    my steppers turn to 17000 step/s, my stepper drivers arrive to more than 50000 step/ses :- (

  3. #3
    Community Moderator svenakela's Avatar
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    The table is horiziontal and runs with no friction, the only thing your motors need to do is accelerate the thing, not lift it. After all, you can push a fork lift with tons of load and more friction. Don't worry about the weight.

    Cheers,
    Sven

  4. #4
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    45 kg is not extremely heavy. The gantry on my router weighs about the same and I use 270 oz steppers 1:3 geared on a 3/4 inch diametre pinion. It accelerates to 500ipm within 2 inch of travel. If you use 400 oz steppers I think you can direct drive a pinion up to 1/2 inch diametre with roughly comparable speed & accel.
    The number of theeth is not relevant in these parameters, only diametre. However, pinions with less than 12T are said to run less than smooth.

    John

  5. #5
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    My gantry is easily that heavy. Maybe 150 pounds with the Z and router. It rides fine on just 4 roller skate bearings. I am using a rolled ball screw and nut. The weight is only an issue to accelerate and to decelerate, but it works well with 270 oz. motors. I get 70 IPM easily and can get a little more. The X is the slowest axis though, because of the weight.
    When I watch the thing moving quickly back and forth, its hard to imagine that it weighs as much as it does.
    Those little steppers are amazing. :wee:
    Lee

  6. #6
    Erfahrener Benutzer
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    Thanks everyone

    Thanks everyone. That's AWESOME. I was thinking of using like 400oz steppers. But maybe now I can get buy with some smaller ones. Meaning that provided that they are under 3AMP max draw, I can runn Xylotex or other cheaper board.

    Limbo: Yeah 500imp in about 2 inches of travel! That's brilliant. I can slowly see the power of these little motors now.

    Yeah The gantry although it is very heavy, It realy just glides along quite easy.

    Umm, Do 270oz steppers have a current draw of less that 3Amps ?

  7. #7
    S.N.A.F.U.
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    After all, you can push a fork lift with tons of load and more friction
    hhehehehhe LOL you made my day!

    I have two forklifts and I cant push either of them with no weight and 3 guys pushing them...

    but the steppers are probably good
    thanks
    Michael T.
    "If you don't stand for something, chances are, you'll fall for anything!"

  8. #8
    Community Moderator svenakela's Avatar
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    Quote Originally Posted by miljnor
    hhehehehhe LOL you made my day!

    I have two forklifts and I cant push either of them with no weight and 3 guys pushing them...

    but the steppers are probably good

    Pallet truck, mini stacker, hand lift... It's still a fork.




    Cheers,
    Sven

  9. #9
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    The 270 oz steppers from automation direct have a max current draw of 2.8A. I run them at 2A with a xylotex board.

    BUT:

    They need to be geared to drive a large pinion. I think the largest practical pinion size for direct drive with these steppers would be around 1/2 inch. To have more than 12 teeth on such a small pinion you end up with 24 pitch rack. This is probably much smaller than you planned for, or would want to use in a production environment.
    Without gearing it might be better to stay with the 400 oz steppers.

    John

  10. #10
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    Re: Weight of my gantry is *45Kg*or*100lb*

    I would say 45KG weight is not so heavyweight but still, if you want to reduce the fat of body then you need to follow the diet plan and health tips which can provide you lightweight of your body. Most of the people getting the http://careyourbodynow.com/ site option to following the best diet plan with the tips of staying healthy options as well.

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