Development corexy September 23, 2017 05:14PM |
Registered: 10 years ago Posts: 97 |
Re: Development corexy September 24, 2017 01:16AM |
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Re: Development corexy September 24, 2017 02:25AM |
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Re: Development corexy September 24, 2017 05:33AM |
Registered: 10 years ago Posts: 97 |
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prot0typ1cal
I like it
I'd put the steppers in the front and let the belts cross (or stack?) in the back over the centered Z screw.
Though keeping em in back helps tidy up wire routing.
Looking at your pic, If all 3 Z screws are anchored, makes me wonder if you need the Z rods at all?
Re: Development corexy September 24, 2017 06:23AM |
Registered: 10 years ago Posts: 97 |
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o_lampe
Interesting concept to put the z-lift in the hotend. Also using non-captive leadscrew steppers is new to me.
One thing I'd reconsider is the placement of the linear rails. I'd try to put them below the top-members to reduce the gap between bed and X-gantry. Especially when using larger extrusion cross section. I'd also rotate the X-linear rail 90°. A vertical mounting plate makes it easier to feed filament from above.
When you say tool change system, do you think of using one direct drive stepper motor and only exchange the filament guide / idler gear ? That system wouldn't require one stepper for each tool and oozing of the unused tool is non existant. But you'd have to solve the problem of controlling the idler gear tension. Maybe use an electromagnet?
Re: Development corexy September 24, 2017 08:11AM |
Registered: 11 years ago Posts: 5,780 |
Re: Development corexy September 24, 2017 08:41AM |
Registered: 10 years ago Posts: 97 |
Thanks for the feedbackQuote
the_digital_dentist
Mounting the motors on the bed plate means their cables have to move.
I may need to move the motors inboard slightly to accommodate the top cover, i envisage the cabinet to be part of the frame work, maybe attached using magnets.Quote
the_digital_dentist
Mounting the linear guides and A and B motors on top of the frame members means you won't be able to put a top cover on the frame itself- your enclosure is going to have to extend above the XY stage somehow. I can't tell from the image but the if the Y axis bearing blocks overhang the edges of the frame, you won't be able to simply attach the enclosure walls to the frame- you have to stand them away from the frame somehow. Attaching enclosure panels directly to the frame adds to the rigidity of the frame (but you probably don't really need the increased rigidity). Is the enclosure is going to be a larger cabinet that this mechanism goes into?
i am using a three screw system for bed levelling, the end supported round rails are only being used as torque arms to prevent the motors turning.Quote
the_digital_dentist
The Z axis will be much less prone to wobble if you use fully supported linear guides instead of end supported round rails. Using two of them at the front of the machine and just the screw at the back will provide all the stability and guidance needed.
Probably on the top or the back of the printer.Quote
the_digital_dentist
Where will the electronics and ventilation/filtration stuff go?
Re: Development corexy September 24, 2017 09:21AM |
Registered: 10 years ago Posts: 14,672 |
Re: Development corexy September 24, 2017 10:40AM |
Registered: 10 years ago Posts: 97 |
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dc42
My limited experience of using leadscrews suggests that it is very hard to eliminate wobble. So my choice would be to use two vertical linear guides or possibly round rods to define the horizontal position of the bed, one at the mid point of the left and right sides. Then one end of each leadscrew can be left unconstrained.
However, from your drawing, you appear to have the leadscrews passing through the motors. Is that right? If so then I guess that's why you have then mounted on the bed. I've not come across motors like that.
Re: Development corexy September 24, 2017 03:11PM |
Registered: 7 years ago Posts: 249 |
Re: Development corexy September 24, 2017 03:35PM |
Registered: 10 years ago Posts: 97 |
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prot0typ1cal
If you're going for totally enclosed, might suggest moving motors outside the enclosure.
The A and B steppers could be below, and have a shaft through the center hole of the extrusion to the top where you'd mount a pulley.
One of the premises behind coreXY is no moving motors...
Dunno about the hollow Z motors, sounds like something you want to try rather than being practical.
Again, mounting the Z steppers below remove them from the heated chamber and eliminates the need for cable chains, something worth considering.
Re: Development corexy September 24, 2017 03:38PM |
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Re: Development corexy September 24, 2017 04:17PM |
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Re: Development corexy September 25, 2017 11:40AM |
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Re: Development corexy September 25, 2017 03:10PM |
Registered: 10 years ago Posts: 97 |
Re: Development corexy September 26, 2017 08:03AM |
Registered: 11 years ago Posts: 5,780 |
i am using a three screw system for bed levelling, the end supported round rails are only being used as torque arms to prevent the motors turning.Quote
the_digital_dentist
The Z axis will be much less prone to wobble if you use fully supported linear guides instead of end supported round rails. Using two of them at the front of the machine and just the screw at the back will provide all the stability and guidance needed.
Re: Development corexy September 26, 2017 03:03PM |
Registered: 10 years ago Posts: 97 |
Quote
the_digital_dentist
i am using a three screw system for bed levelling, the end supported round rails are only being used as torque arms to prevent the motors turning.Quote
the_digital_dentist
The Z axis will be much less prone to wobble if you use fully supported linear guides instead of end supported round rails. Using two of them at the front of the machine and just the screw at the back will provide all the stability and guidance needed.
Bolting the motors to the bed support plate is what will prevent the motor bodies from turning. That's not what guide rails do.
Guide rails are used to constrain lateral motion and allow motion along their axes. One rail will provide Z guidance, but will allow the bed to rotate around it in the XY plane. A second rail, parallel to the first, prevents that rotation. That's fully constrained motion, under ideal conditions. End supported rails flex in the real world, especially when unstraight lead screws start putting lateral forces on the bed support plate they are lifting. That causes Z-wobble in prints and is the bane of many poorly made machines that use two screws to lift the X axis in Z. Fully supported linear guides are much less prone to flexure than end supported round rails, and the bearings are usually better, too (no play). If the two rails and screws are placed on one end of the bed, that's a cantilevered arrangement that leaves the opposite end of the bed free to bounce when the machine shakes from movement of the XY mechanism. Adding a third screw at that end of the bed supports it and prevents the bouncing.
Re: Development corexy September 28, 2017 07:24AM |
Registered: 6 years ago Posts: 1,007 |
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andornot
I think there is a misunderstanding on how i propose the z axis will work, let me draw it properly in 3d cad and then i will post it on this thread.
Re: Development corexy September 28, 2017 09:47AM |
Registered: 10 years ago Posts: 97 |
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MKSA
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andornot
I think there is a misunderstanding on how i propose the z axis will work, let me draw it properly in 3d cad and then i will post it on this thread.
By the look of just your Z system, it is clear it is over constrained. Concepts you seem to misunderstand.
A proper CAD package will show you what is wrong when you assemble the parts.
Now, quite frankly, you should try to copy a well thought, based on a sound design, working machine.
The choice is simple as there are not that many due to natural selection (lucky here it only applies to the design, not the designer)
Re: Development corexy September 28, 2017 12:04PM |
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Re: Development corexy September 28, 2017 03:40PM |
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Re: Development corexy September 28, 2017 08:29PM |
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Re: Development corexy September 28, 2017 08:48PM |
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Re: Development corexy September 29, 2017 01:03AM |
Registered: 6 years ago Posts: 1,007 |
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andornot
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MKSA
You were the first to claim we misunderstand, isn't ?
OK, then I will wait for your proper drawing.
I have read several of your recent posts and all you have done is criticised their designs, what machines have you designed?
Re: Development corexy September 29, 2017 03:21AM |
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Re: Development corexy September 29, 2017 02:51PM |
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Re: Development corexy September 29, 2017 03:16PM |
Registered: 10 years ago Posts: 97 |
Re: Development corexy September 29, 2017 05:22PM |
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Re: Development corexy September 30, 2017 12:02AM |
Registered: 6 years ago Posts: 1,007 |
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the_digital_dentist
.....
Your CAD model looks like you have put bearings on the ends of the screws, but if I understand what you're doing correctly, the screws aren't going to rotate, so bearings won't be needed.
Re: Development corexy September 30, 2017 12:31AM |
Registered: 7 years ago Posts: 249 |