Does this work?

Hi!

I'm currently in the designing process of building my own CoreXY custom 3D printer.

The main issue I have is that in order to build a 3D printer, most people use an existing 3D printer to print parts for the new one.
In my case, mine just broke... So I don't have the option to do so.
Therefore, I will build my 3D printer all in wood. MDF and solid wood to be precise.

I have acces to professional grade woodworking machines since I make furniture for a living.

My questions are:

- Is it possible to support a heated bed using two linear rails at the sides on the back of the bed and two lead screws at the sides on the front. See image for reference

- Whitch way should I mount the linear rail for the x axis? Vertical or horizontal?

More troubles will surely come so I will probably post updates as I go.

Thanks in advance!

Edited 2 time(s). Last edit at 11/28/2019 02:39PM by Morbi.

You're putting the screws far from the bearing blocks. The bed is a lever with the fulcrum at the screws/nuts. There's nothing supporting the bed at the bearing blocks, so it's going to pivot on the screws and droop at the bearings. The screws have the full length of the bed to act as a lever to tilt it more. It will probably bind and won't move.

The screws should be put as close to the bearing blocks as possible. If you're only going to use two screws, it's probably best to put them and the bearings near the center of the bed.

Edited 1 time(s). Last edit at 11/30/2019 03:02PM by the_digital_dentist.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Ok! Thank you for your response!

So basically, I keep the linear rails where they are and put the lead screws on the sides at the center of the bed.

I'm torn between spending 35$ to get two additional linear rails or to just stick with what I got...

Anyway, thank you again. I will take this into consideration moving forward with the designing process

"Does it work ?"

NO
and I suggest you just copy a known working machine, even if it costs a bit !

Do a search of the many similar "projects" here and see their outcome.

Edited 2 time(s). Last edit at 11/29/2019 08:27AM by MKSA.

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"A comical prototype doesn't mean a dumb idea is possible" (Thunderf00t)

I haven't found anyone building a 3D printer without using printed parts.
But you're right.
Why I wanted to assemble the bed that way is because I'm unsure if the bed would be stable enough using only 2 linear rails. I'm leaning towards buying an extra pair but as you know, they can be quite expensive.

Try two linear rails, and three lead screws.

I currently have two screws and rails in the center of the bed(left and right sides) I find there is a small amount of wobble during the faster movement speeds.
I'm going to relocate them to the front of the machine (but still on the left/right sides) and the third screw center in the back. Should be supper stable then.

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Custom all metal CoreXY
- Duet 2 Wifi w/ PanelDue 7i
- 330mm x 360mm x 500mm
- 750w Silicon heater

Custom Mendel90
(Backup printer - Old reliable!) - Sold

Quote
Morbi
Ok! Thank you for your response!

So basically, I keep the linear rails where they are and put the lead screws on the sides at the center of the bed.

I'm torn between spending 35$ to get two additional linear rails or to just stick with what I got...

Anyway, thank you again. I will take this into consideration moving forward with the designing process

Reread my post.

Edited 1 time(s). Last edit at 11/30/2019 03:03PM by the_digital_dentist.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

That little jumpy flaming emoji thing is really annoying.

Edited 1 time(s). Last edit at 11/30/2019 03:02PM by the_digital_dentist.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Quote
the_digital_dentist
That little jumpy flaming emoji thing is really annoying.

Be patient, in a couple of weeks it will be buried down the page !

PS: NO answer to this message !

Edited 1 time(s). Last edit at 12/01/2019 03:43AM by MKSA.

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"A comical prototype doesn't mean a dumb idea is possible" (Thunderf00t)

Update:
I bought two extra linear rails. This should eliminate any potential wobble.
The four linear rails will go on the corners and the two leadscrews in the middle at each side of the bed.

So sorry for the emoji xD This is my first time posting on this forum. I will take note and never repeat again.

You can remove it from your posts by deleting the "X" followed by "(" from the subject line in your posts and replies.

The concern for wobble is vertical motion, not horizontal motion. Two rails provides all the horizontal control and vertical guidance you need. Now you have to figure out how to align 4 linear guides within a few microns of parallel to each other, and how to keep them that way with temperature changes and through moving the machine from one place to another. It's very hard to do that, and the result is that the bed will tend to walk up and down (tilt back and forth as it goes up and down) the Z axis. The result is poor Z axis print quality.

Edited 2 time(s). Last edit at 12/03/2019 09:23AM by the_digital_dentist.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Linear rails mounted on a wood frame will "self align" and with enough lubrication may not grind much. Besides, they are cheap.
Anyway ...
Wait and not see !

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"A comical prototype doesn't mean a dumb idea is possible" (Thunderf00t)

Oh, that's right, this will be made of wood. Add humidity changes to the things that will move the linear guides around...

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

DD said "The screws should be put as close to the bearing blocks as possible."

so move the screws and rails together to a spot that supports the bed best.

Alignment of 4 rails is tough -- self aligning? bed wobble around?

Good engineering -- accepting design that works and using it!

Quote
Morbi
Ok! Thank you for your response!

So basically, I keep the linear rails where they are and put the lead screws on the sides at the center of the bed.

I'm torn between spending 35$ to get two additional linear rails or to just stick with what I got...

Anyway, thank you again. I will take this into consideration moving forward with the designing process

I built Carl Feniak's design and modified it to use 3 screws driven by one motor.
He had 2 screws with a cantilever bed. I didn't like having one end hanging in the air.
The above appears to be his updated design which I just saw and I have no idea why there is now 5 screws.
This is his original design
This is pretty much what mine looks like and I have no problem with stability. It is solid as a rock.


What I liked most about his design is that the belts do not cross and are enclosed in the frame tracks.

Without a 3 point landing, you will always have a problem.
You could use 4 screws, but a solid bed will negate any effect of tipping of the frame with 3 screws.
For bed leveling 4 points is not good, contrary to many peoples belief.
IE, you need to make the bed leveling separate from the screw drive
4 points will try to bend the bed or bend the frame rails. Not a good thing = been there, done that.

Edited 1 time(s). Last edit at 01/06/2020 05:40PM by ruggb.

Why bring back this dead thread/project and have this annoying title again at the top !

No answer please !

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"A comical prototype doesn't mean a dumb idea is possible" (Thunderf00t)