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IndustryArena Forum > CNC Electronics > Servo Motors / Drives > Figuring Out the Weight of my Gantry
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  1. #1
    Join Date
    May 2011
    Posts
    104

    Question Figuring Out the Weight of my Gantry

    I have a large gantry machine with two servos moving it. Well it will have two servos once they get here in a few days

    I need to figure out a way to get the weight of my gantry so I can tune the servos independently.

    Short of removing it from the machine and weighing it does anyone have a suggestions for a way to estimate it closely? I'll tell you it slides very easily back and forth with no motors installed so I'm not sure putting a scale on it to see at what pounds it starts moving would do it.

    Click image for larger version. 

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    Thanks in advance.

  2. #2
    Join Date
    Jan 2013
    Posts
    474
    Quote Originally Posted by Dbl_Tap View Post
    I have a large gantry machine with two servos moving it. Well it will have two servos once they get here in a few days

    I need to figure out a way to get the weight of my gantry so I can tune the servos independently.

    Short of removing it from the machine and weighing it does anyone have a suggestions for a way to estimate it closely? I'll tell you it slides very easily back and forth with no motors installed so I'm not sure putting a scale on it to see at what pounds it starts moving would do it.

    Click image for larger version. 

Name:	CNC4.jpg 
Views:	0 
Size:	17.8 KB 
ID:	489608

    Thanks in advance.
    Find a similar sized piece of metal or motor and weigh that, then use your best guesstimate:-)

    You can then monitor the drive responses and current to tune the acceleration and deceleration ramps.

  3. #3
    Join Date
    Jan 2005
    Posts
    15362

    Re: Figuring Out the Weight of my Gantry

    Quote Originally Posted by Dbl_Tap View Post
    I have a large gantry machine with two servos moving it. Well it will have two servos once they get here in a few days

    I need to figure out a way to get the weight of my gantry so I can tune the servos independently.

    Short of removing it from the machine and weighing it does anyone have a suggestions for a way to estimate it closely? I'll tell you it slides very easily back and forth with no motors installed so I'm not sure putting a scale on it to see at what pounds it starts moving would do it.

    Click image for larger version. 

Name:	CNC4.jpg 
Views:	0 
Size:	17.8 KB 
ID:	489608

    Thanks in advance.
    The servos tuning and Parameters will have to be identical when using a Master / Slave setup.

    This should have been calculated before you brought the servo motors as they have to be sized to suit. most Cad programs if you draw the parts can get the weight calculated from there, you could measure all the parts and use a weight calculator also, which will get you close. https://www.specialtysteel.com/steel-weight-calculator/
    Mactec54

  4. #4
    Join Date
    May 2011
    Posts
    104

    Re: Figuring Out the Weight of my Gantry

    Quote Originally Posted by mactec54 View Post
    The servos tuning and Parameters will have to be identical when using a Master / Slave setup.

    This should have been calculated before you brought the servo motors as they have to be sized to suit. most Cad programs if you draw the parts can get the weight calculated from there, you could measure all the parts and use a weight calculator also, which will get you close. https://www.specialtysteel.com/steel-weight-calculator/
    Mactec54, these servos will be fine. Teknic helped me with sizing them and if anything I went overkill.

    The problem with trying to use a comparable steel comparison is this is a Chinese machine and I have no clue what quality steel they used but tapping any of the steel in the gantry assembly was like going through butter.

    I was brainstorming with my buddy that is a mechanical engineer and it hit me. I can move the gantry all the way to the front, lift the machine slightly and set it back down on a scale of appropriate range to weigh it right where the gantry sits. Then slide the gantry all the way to the back where it sits over the back legs on the ground and measure the weight in the same spot at the front and see what the difference is. I know it won't be exact and there are a million different variables affecting the true weight but it will at least give me a place to start.

  5. #5
    Join Date
    Jan 2005
    Posts
    15362

    Re: Figuring Out the Weight of my Gantry

    Quote Originally Posted by Dbl_Tap View Post
    Mactec54, these servos will be fine. Teknic helped me with sizing them and if anything I went overkill.

    The problem with trying to use a comparable steel comparison is this is a Chinese machine and I have no clue what quality steel they used but tapping any of the steel in the gantry assembly was like going through butter.

    I was brainstorming with my buddy that is a mechanical engineer and it hit me. I can move the gantry all the way to the front, lift the machine slightly and set it back down on a scale of appropriate range to weigh it right where the gantry sits. Then slide the gantry all the way to the back where it sits over the back legs on the ground and measure the weight in the same spot at the front and see what the difference is. I know it won't be exact and there are a million different variables affecting the true weight but it will at least give me a place to start.
    No, Mild steel weight is all the same 41.82 Pounds per square Foot at 1" thick, Chinese steel is no different from anywhere else, your buddy being a mechanical engineer should be able to measure the sections of steel and give you a very accurate weight of the Gantry. the only variable is the welds and by the size of the weld you can measure it also, the Gantry would have to be removed to measure the weight with a scale, and I don't think that would be a good idea.
    Mactec54

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