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  1. #41
    How big are the bolts for the rails? Will they fit in the profile that you've drawn? As Jazz says the profile is looking a bit small and weak, you could do with beefing them up a bit. It's looking like you're putting the Y axis ball screw on the front of the gantry, you'd be better putting it on the back and bringing your spindle nearer the front of the Y axis otherwise it could be quite a way off the front and a way in front of the X axis bearings. Are all the rails the same size?
    Neil...

    Build log...here

  2. #42
    What Dean is saying is you have very small clearance from gantry to bed. You need sth like 230mm distance for a 200mm Z axis travel, if well designed. Do you have that space as drawn?
    project 1 , 2, Dust Shoe ...

  3. #43
    I'm adjusting to lower Z depth, around 80mm would be ok for me

  4. #44
    Quote Originally Posted by njhussey View Post
    How big are the bolts for the rails? Will they fit in the profile that you've drawn? As Jazz says the profile is looking a bit small and weak, you could do with beefing them up a bit. It's looking like you're putting the Y axis ball screw on the front of the gantry, you'd be better putting it on the back and bringing your spindle nearer the front of the Y axis otherwise it could be quite a way off the front and a way in front of the X axis bearings. Are all the rails the same size?
    can't I just reduce the space I reserved at back of gantry from 80mm to 40mm? so that the plates and spindle come within the bearing range

  5. #45
    Hey everyone, I'm in the process of redesigning the gantry and need your input, I will probably need to use pulley and belt for both Y and Z based on the new placement of motors.

    can you please help me in figuring out the belt length I require based on distance between motor and ballscrew? I prefer 1:1 ratio and based on what was recommended to me I think HTD pulley 5mm pitch 15mm width is good?

    many thanks, will try to post design photos soon

  6. #46
    Quote Originally Posted by Noplace View Post

    can you please help me in figuring out the belt length I require based on distance between motor and ballscrew? I prefer 1:1 ratio and based on what was recommended to me I think HTD pulley 5mm pitch 15mm width is good?
    Here is the belt length calculator , sorry, busy now but later will take a look if nobody does before

    http://www.product-config.net/catalo...an/config.html
    project 1 , 2, Dust Shoe ...

  7. #47
    thank you very much!

  8. #48
    Just a preview render, if you have comments please let me know.

    Based on center distance I got around 292.2mm belt length, but in the site it says next available length is 295mm , i assume that is a standard length increment across all vendors, so is it ok to get that length ?

    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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    Last edited by Noplace; 08-04-2015 at 06:08 AM.

  9. #49
    You will need to put slots in the motor mounting to enable you to have adjustment to tighten the belt. It is quite normal to have 30 - 40 mm adjustment. >clive

  10. #50
    Quote Originally Posted by Clive S View Post
    You will need to put slots in the motor mounting to enable you to have adjustment to tighten the belt. It is quite normal to have 30 - 40 mm adjustment. >clive
    The slots need to be 1mm wider than the OD of the motor mount hole. Some servo motors will not allow that movement because the center part is bigger than nema 23 for example, but i can assure you that even 5 mm possibility to move is ok if you use that calculator. Just tested that theory with my servo motor mounts where it was not possible more play. So on a Nema 23 +-10mm both side from center hole is more than enough. Care should be taken if the mount is milled deep into a plate and the motor needs more play just to pass through and enter at its spot.
    project 1 , 2, Dust Shoe ...

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