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Discussion in 'Laser Cutters' started by silverchris, Mar 16, 2018.
Work in Progress of a laser cutter design. Based on the CoreXY build from https://makerstore.com.au
silverchris published a new build:
Read more about this build...
This is my first attempt at designing using v-slot or t-slot, so any feedback on my design would be appreciated. In my head it seems like it should be sturdy, and functional for a frame?
Looks great man, love the idea of the corexy for this system.
I would make a suggestion to make sure you enclose this system to be safe.
Keep up the the great work!
Thanks Mark, a sealed enclosure is planned
My current thoughts on the process is get the movement figured out, and get the optics and electronics all functional, and then get the laser tube as well as enclose it.
I updated the picture on the build page, as well as included a link to the sketchup 3d warehouse of the WIP 3d model.
Question? is this a two motors running the y axis or the x?
I am using a corexy design, which uses two motors and belts tied to the Y gantry, that when coordinated move both the X and Y with the two motors.
The corexy site has a good overview CoreXY | Cartesian Motion Platform
Some progress has been made, though I am having some issues.
I managed to get the frame assembled, though I am having a little bit of an issue with the X gantry having what feels like a lot of wobble/wiggle in it. E.G. when I grab one side of it, I can pull it back a little bit, or pull it forward before the other side starts to move.
I have a feeling that it comes from my frame not being perfectly straight, so this week, I think I am going to pull it apart, and check the squareness of the cuts on the ends of the t slot/v slot, and double check the lengths are all the same.
Also, this photo clearly shows that I need more shop space
What a great idea, im still wondering a miss step of a motor and safety, if a miss align of mirrors occurs ??
I have found a few examples of people using the core X-Y design. A slipped belt would just result in the cut being off, as the mirrors have to be in alignment across the whole table, the only way the beam would miss the laser head is if one of the mirrors was misaligned on the mount
For the size of what your are looking for, 20x20 have a lot of flex but, im also new to this so maybe a bigger profile will help to keep the motion system more strong, keep on going
or build the x y stages inside the frame with 20x60s , easy to hook it up with the frame, you will need strong support for a big fast moving machine.
I should have taken a video of the the wobble, but I think it's a bit excessive to be the flexibility of the 20x20, it might be a few centimeters each way, and the 20x20 doesn't feel like it would flex that much in the hand. I think the mini-v wheels aren't being allowed to sit flat in the v slot, letting them have a lot more side to side play in the v slot than they should? I will have to do some playing tomorrow, as I didn't really check if the amount of play changed when I rolled it along to a different part.
i should try modifying a bit your idea and build your motion system independent but attachable to the machine frame,
I think that before you start pulling it apart try screwing the frame to the table and installing some plates on the corners. You'll need about 20 of them and they will stiffen up the frame immensely.
I ended up taking it apart, and probably should have done this before I started... I checked the lengths of the pieces, and it seemed they varied a few millimeters from the company the cut the t slot, as well as the ends not being very square at all.
Having a local machine shop mill them straight, which will affect my finished size a bit, but at least it will be square
Still seems like I have excessive slop in the movement?
Actually remembered to record a video of it. The rest of the frame doesn't seem to flex at all during this, so I am not sure if its flex in the piece I have going across, or play in the mini-v plates?
It was suggested in a thread I made that having independent control of each axis is the way to go to avoid misalignment. Essentially, one stepper for X, and one for Y. I too looked into the CoreXY setup.
My initial reaction from looking at your carriage is that there isn't enough of it to not wobble. The mini v-wheel gantry just isn't wide enough to overcome torque inertia and your delrin wheels are compressing and unloading. in effect giving you some unwanted suspension.
I've always viewed the mini v-wheel gantry as being used for carrying something light, but you've got about 600-700gm of torque on a long lever arm without any damping and you are moving it from one end only - it's doing what its going to do.
But... that won't happen with belts in place.
I have a 1500mm run of 2060 Y-axis with a cantilevered 600mm 2020 X-axis carrying a mini-v gantry and 200gm of laser diode. It doesn't bounce or vibrate at all. When it was only a 2040 Y-axis, I used to get oscillation under stop/start. The wider stance I got by making the y-axis plates bigger to accommodate the 2060 and wider to give it more rigidity and a third pair of wheels means theres no slop or wobble.
Howdy. This is a great idea. Do you have your source yet? Are you going to use a DC or metal tube? Gonna be cool to see it go. On your X slop...the engineer above is right. You can get rid of some of that slop by changing X gantry mini v-wheel plates. Double their length along X and add a couple more wheels. This will spread the load more effectively and reduce the compression of the wheels. You could also try to replace the X gantry 20x20s with 20x40s with the longer axis aligned with the Y. You'd still have to replace the X gantry slide plates. Good luck.