Re: Overengineered CoreXY January 29, 2017 12:59PM |
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Re: Overengineered CoreXY January 29, 2017 02:45PM |
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Quote
the_digital_dentist
This is what I am thinking would make using a steel frame pretty easy. The XY stage (red) rests on leveling adjusters either welded or screwed into the frame (I'd screw them in):
The only thing in the machine that needs to be accurately aligned is the XY plane relative to the Z axis- the guide rails must be orthogonal, and the bed parallel to the XY plane- via the usual bed leveling system. The frame can be out of square and it doesn't matter as long as the XY and Z orthogonality can be adjusted and the bed can be leveled. If you used 3 point mount (pitch and roll adjustments), you could bolt the Z axis into the frame then just adjust the XY stage pitch and roll to ensure orthogonality, though having some adjustment capability on the Z axis would probably be a good idea too, depending on how it is made and on whether you can count on it maintaining rail to rail parallelism when you bolt it into the frame.
Leveling things accurately with 4 screws is a problem as we have seen with many poorly conceived print bed levelers. Using 3 point leveling would require adding a cross bar on one side of the frame for the XY roll adjuster.
Fitting the XY stage into the frame as I have drawn it would require removing a couple of the levelers. If you opened the top of the frame you could make it so the XY stage can just drop in from above and sit on the levelers. That would make servicing and swapping the XY stage into another frame pretty easy, and theoretically, let you put the XY stage back without having to make any adjustments.
You could add more adjusters above the XY stage to tighten down as clamps so it doesn't vibrate or shift when transported, or do something similar to my CoreXY bed levelers with one point fixed, one leveler in a slot, and the third free to slide in XY, and use springs (or clamps) to hold it down.
Re: Overengineered CoreXY January 29, 2017 02:55PM |
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Re: Overengineered CoreXY January 29, 2017 04:12PM |
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Re: Overengineered CoreXY January 29, 2017 05:23PM |
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Re: Overengineered CoreXY January 29, 2017 05:29PM |
Registered: 9 years ago Posts: 238 |
What do you mean by floating linear guide in this case? It will be bolted down at both ends, but I don't see how to make it less "floating" since it'll have to bridge the Y axis.Quote
Dutch_Razor
Also a note on the X axis, you have a floating linear guide there which does not create a stiff gantry. For linear guides, a stiff gantry can even out errors in the individual linear guides, so I would personally go for a tooling plate the width of the Y carriages, then mount the guide on there.
Re: Overengineered CoreXY January 29, 2017 10:27PM |
Registered: 11 years ago Posts: 5,780 |
Quote
anvoice
Thanks for the detailed advice! I'll definitely revise my design with that in mind.
Do you think the levelers for the XY stage are necessary? As you mention as long as XY is orthogonal to Z, it's fine. Wouldn't it also make sense to fine-adjust Z relative to XY?
Re: Overengineered CoreXY January 30, 2017 01:21PM |
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Re: Overengineered CoreXY January 30, 2017 02:03PM |
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Re: Overengineered CoreXY January 30, 2017 04:11PM |
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Re: Overengineered CoreXY January 30, 2017 04:24PM |
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Quote
SatorCodex
But lapping only take elbow grease, gritpaper. Gives a good exercise and produce a better
result than grinding. Flat surface and you are set.
Re: Overengineered CoreXY January 30, 2017 04:53PM |
Registered: 7 years ago Posts: 2 |
Quote
anvoice
What do you mean by floating linear guide in this case? It will be bolted down at both ends, but I don't see how to make it less "floating" since it'll have to bridge the Y axis.Quote
Dutch_Razor
Also a note on the X axis, you have a floating linear guide there which does not create a stiff gantry. For linear guides, a stiff gantry can even out errors in the individual linear guides, so I would personally go for a tooling plate the width of the Y carriages, then mount the guide on there.
Re: Overengineered CoreXY January 30, 2017 05:09PM |
Registered: 7 years ago Posts: 94 |
I know what you mean.Quote
anvoice
Quote
SatorCodex
But lapping only take elbow grease, gritpaper. Gives a good exercise and produce a better
result than grinding. Flat surface and you are set.
Thanks, I learned something new. I'd definitely be willing to give that a go, though probably on a machined surface as otherwise it'll likely take forever. There happens to be a service with a large mill around so I'll have the top of my steel angle milled flat first.
As far as welding goes, it seems like the easiest solution. I don't see finding a lot of joining brackets/corners for the steel angle as easily or making it as rigid as a welded structure.
Re: Overengineered CoreXY January 30, 2017 05:11PM |
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Re: Overengineered CoreXY January 30, 2017 11:16PM |
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Re: Overengineered CoreXY January 31, 2017 12:55AM |
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Re: Overengineered CoreXY January 31, 2017 05:35AM |
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Re: Overengineered CoreXY January 31, 2017 07:28AM |
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Re: Overengineered CoreXY January 31, 2017 08:58PM |
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Re: Overengineered CoreXY February 17, 2017 02:07AM |
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Re: Overengineered CoreXY February 17, 2017 09:47AM |
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Re: Overengineered CoreXY February 18, 2017 06:59AM |
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Re: Overengineered CoreXY February 20, 2017 09:55AM |
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Quote
anvoice
I'm not that concerned about speed, my main issue is print quality. Although I already have some 2A 0.9 degree Nema 23 steppers as well as a couple of 68 oz-in 0.9 Nema 17 steppers that I can use for the XY. I'll go with the Nema 17's if they can pull the axes fine.
I think I'll fully support my Z linear rails, so using 4 rails per corner plus 2 ballscrews should be good enough I hope.
Re: Overengineered CoreXY February 20, 2017 05:44PM |
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Re: Overengineered CoreXY February 20, 2017 07:41PM |
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Re: Overengineered CoreXY February 21, 2017 12:29AM |
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Quote
napierm
So my point (yes, there is one) is that it is hard enough to get 2 rails to run parallel with each other. I sure wouldn't want to try fighting 4 of them. The 2 rails just have to hold the Z-table square to the frame in the X-Y plane. Use 3 screws hold the table level and drive them all from the bottom with a common endless belt.
Re: Overengineered CoreXY February 21, 2017 08:54AM |
Registered: 8 years ago Posts: 15 |
Quote
the_digital_dentist
Actually, my X axis rail is mounted so that the Y axis rails can move apart as the printer frame heats up and expands. It's a completely different issue from aligning two rails parallel to each other. One advantage of linear guides is that they are relatively easy to align parallel if you mount two of them on a common base plate. Then they can only be out of parallel in one dimension and that can be corrected by using one rail as the reference for the other, as you have described. It becomes more complicated when the rails are not mounted on a common base plate.
Re: Overengineered CoreXY February 21, 2017 11:51AM |
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Re: Overengineered CoreXY February 22, 2017 04:05AM |
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Re: Overengineered CoreXY February 23, 2017 03:26AM |
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