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Thread: Was going well...

  1. #1
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    Was going well...

    I decided I'd try to replicate our mission statement from the institute's lobby on a plaque.
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    I received the paint mask that I ordered earlier this week and decided to give it a go on a plaque that had some corner damage as a test.

    All was going well, however I lost steps on my Y axis after about an hour. I'm thinking the motor over heated as I could hear some chirping, and it's possible the threaded nut was sticking. I think I may have lost some steps on the Z as well as the lower text and some of the tree lost definition as it worked from the center area out.
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    Other than that, the detail was looking pretty good. I went ahead and painted it to test out the paint mask, we'll see if I need to do anything different there.

    I do plan to build a new enclosure for the controller and add another axis to it, so will be checking all my voltages at that point, the current enclosure is entirely too hard to get into for doing maintenance and and too small for any updates.
    Darren

    To a small child, the perfect granddad is unafraid of big dogs and fierce storms but absolutely terrified of the word “boo.” – Robert Brault

  2. #2
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    Quote Originally Posted by Darren Wright View Post
    All was going well, however I lost steps on my Y axis after about an hour. I'm thinking the motor over heated as I could hear some chirping, and it's possible the threaded nut was sticking. I think I may have lost some steps on the Z as well as the lower text and some of the tree lost definition as it worked from the center area out.
    Probably a dumb question, but if you're loosing steps over a long period of time would it make sense to periodically re-zero? I mean not loosing steps is obviously the goal, but it seems like a lot of these systems that ends up being somewhat of a long-path-to-get-there so in the interim..

  3. #3
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    Quote Originally Posted by Ryan Mooney View Post
    Probably a dumb question, but if you're loosing steps over a long period of time would it make sense to periodically re-zero? I mean not loosing steps is obviously the goal, but it seems like a lot of these systems that ends up being somewhat of a long-path-to-get-there so in the interim..
    Not a dumb question or suggestion. I plan to do that on the next attempt, but this was such light work for the cnc and all with the same bit that I didn't think I would need to. For most of my other files I've ran, most operations are about 20 minutes long, this was over an hour and 20 minutes, so heat hasn't been much of an issue. Will be doing some voltage measurements/adjustments this weekend to verify that isn't an issue.
    Darren

    To a small child, the perfect granddad is unafraid of big dogs and fierce storms but absolutely terrified of the word “boo.” – Robert Brault

  4. #4
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    Still, once you lose steps, unless you catch it, it's game over.

    Would have to have limit switches installed though so you could go back to an accurate machine zero, then go to the workpiece zero and start over.

    Seems like it'd be a lot less hassle just to get to the reason why the steps are getting lost and fix that. There's usually a reason, unless I miss my guess.
    Programmer - An organism that turns coffee into software.
    If all your friends are exactly like you, What an un-interesting life it must be.
    "A door is what a dog is perpetually on the wrong side of" Ogden Nash


  5. #5
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    Looking at your third photo, are you sure the board is flat? It appears everything in the middle of the board is carved pretty well, but the farther from the center, the lighter the carve got. As to the circle being so far off, that has to be a bad case of losing steps on the Y axis.

    I've had issues with a board being flat but not perfectly level on my base board. I have now started flattening my waste board using a 1.25" bowl bit; makes a ton of difference.
    Bill Arnold
    Citizen of Texas residing in Georgia.
    NRA Life Member and Member of Mensa
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  6. #6
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    Was going well...

    Quote Originally Posted by Bill Arnold View Post
    Looking at your third photo, are you sure the board is flat? It appears everything in the middle of the board is carved pretty well, but the farther from the center, the lighter the carve got. As to the circle being so far off, that has to be a bad case of losing steps on the Y axis.

    I've had issues with a board being flat but not perfectly level on my base board. I have now started flattening my waste board using a 1.25" bowl bit; makes a ton of difference.
    Yeah, the carving started in the middle and worked its way outward. I think it lost steps on the plunge.

    Sent from my SM-G920P using Tapatalk
    Darren

    To a small child, the perfect granddad is unafraid of big dogs and fierce storms but absolutely terrified of the word “boo.” – Robert Brault

  7. #7
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    Quote Originally Posted by Brent Dowell View Post
    Still, once you lose steps, unless you catch it, it's game over.

    Would have to have limit switches installed though so you could go back to an accurate machine zero, then go to the workpiece zero and start over.

    Seems like it'd be a lot less hassle just to get to the reason why the steps are getting lost and fix that. There's usually a reason, unless I miss my guess.
    Yeah I wasn't thinking it would be a long term solution so much as an interim work around.. since it ?appears? that sometimes tracking down lost steps can be a bit challenging. It seems that for most things if you loose ~1+- step~ you can probably fudge it on a lot of projects (like this one) with a little hand work. If its a lot more then its probably hosed so this might save you in that case.

    You might also be able to get it to report when zero wasn't zero and then see how far off you were from zero with a wee bit of clever programming... basically step into the limit switch (machine) zero and then record the delta of how far off you were from where you thought zero was.

  8. #8
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    Quote Originally Posted by Brent Dowell View Post
    Still, once you lose steps, unless you catch it, it's game over.

    Would have to have limit switches installed though so you could go back to an accurate machine zero, then go to the workpiece zero and start over.

    Seems like it'd be a lot less hassle just to get to the reason why the steps are getting lost and fix that. There's usually a reason, unless I miss my guess.
    Well...maybe. I know I'm a bit of a renegade at times and this is one of them. I don't use a machine zero. Early on in my CNC adventure, I decided I like using the center of a project as my 0,0,0 point. Having that point marked in some way means I can always get back there. To start a project, I move the spindle XY manually to the center of the project, then adjust Z down to the surface. I use UGS for everything; it sets machine and work to 0,0,0 when you open the connection.

    As to fixing the problem with why steps get lost, I finally whipped that by measuring the stepper voltages on the drivers and adjusting to the recommended level based on the stepper spec sheet. To keep the driver chips from overheating, I added a small fan about 2" from them.
    Bill Arnold
    Citizen of Texas residing in Georgia.
    NRA Life Member and Member of Mensa
    My Weather Underground station

  9. #9
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    Quote Originally Posted by Bill Arnold View Post
    Well...maybe. I know I'm a bit of a renegade at times and this is one of them. I don't use a machine zero. Early on in my CNC adventure, I decided I like using the center of a project as my 0,0,0 point. Having that point marked in some way means I can always get back there. To start a project, I move the spindle XY manually to the center of the project, then adjust Z down to the surface. I use UGS for everything; it sets machine and work to 0,0,0 when you open the connection.

    As to fixing the problem with why steps get lost, I finally whipped that by measuring the stepper voltages on the drivers and adjusting to the recommended level based on the stepper spec sheet. To keep the driver chips from overheating, I added a small fan about 2" from them.
    I'm still trying to figure out how my work flow will go. So far, I've been doing similar, with the exception of centering. I'm using the lower left corner. In my work the origin is always the lower left with x going left and right and y going up and down, so I've adjusted my axis accordingly. Not sure my brain would like having something that fundamental changed on it.

    Once I get the limit switches on it, I like the idea of zeroing out the machine, and being about to get back to the workpiece zero without having to do it manually. I can just have the workpiece zero (x, y, z) numbers recorded and go their without having to eyeball it.

    My steppers can use more juice than the tinyg driver can provide, so was pretty simple just to twist the pots all the way to max. I did have some issues with missing steps when the pots were set to the midway point. Now the only time I've missed steps is when I've hit a clamp or something, but I haven't done a piece yet that requires a lengthy run time.
    Programmer - An organism that turns coffee into software.
    If all your friends are exactly like you, What an un-interesting life it must be.
    "A door is what a dog is perpetually on the wrong side of" Ogden Nash


  10. #10
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    Quote Originally Posted by Bill Arnold View Post
    Well...maybe. I know I'm a bit of a renegade at times and this is one of them. I don't use a machine zero. Early on in my CNC adventure, I decided I like using the center of a project as my 0,0,0 point.
    More questions illustrating my lack of knowledge How would that work if the center is part of what's being removed? Specifically thinking about the Z axis ...

    Naively it seems like having the project center indexed off of the machine center would be more repeatable in the general case but I can see that being annoying in some cases.

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