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Working slider in aluminium extrusion on Z axis

Posted by joostvl 
Working slider in aluminium extrusion on Z axis
June 25, 2020 10:45AM

I am new to this forum but I felt to create an account and share this linear movement solution I created.

A few months ago I set out to custom build a new I3 style printer, out of an older and discarded machine. I decided to use 2040 extrusions because of its rigidity and the project worked out pretty well. While building, I learned a lot about linear movement and it basically almost always comes down to a bearing system fastened on top of a frame, where you see that the two functions (construction and movement) are handled by separate physical components (frame and linear bearings).

It dawned to me that the extrusions I was working with have these nice slots running over the full length and I started to wonder if I could integrate the construction and movement functions into 1 component: the aluminium extrusion itself.

After some experimenting and iterating, I came up with a working system which uses 4 of the 6 slots. It is very low on backlash as the 4 sliders compensate one another greatly. Further, because the little backlash, the fit is quite tight and to compensate I applied a bit of bearing grease to the slider and the slot itself. Finally, the moving carriage is fashioned with a piece of 4mm aluminum rod over the full length. This makes the carriage to mainly run metal to metal (with grease in between). The plastic is there, mainly for keeping the metal in the right place.
You can see the proof of concept working here: [www.instagram.com]

After this working proof of concept, I decided to use my custom I3 as the guinea pig. I redesigned the z axis to get rid of the 8mm aluminium rod and added the slot carriage to it. First, I did one side, with the original system remaining on the other side. After this proved to be successful, the other side was updated as well. After just minor fine tuning, the machine worked again. And to be honest, it is better at layer consistency than it was before.
You can see the I3 in action here: [www.instagram.com]

A couple of advantages of this system:
- It is more compact than a traditional system.
- It is quiet, as there are no bearing balls moving all the time
- It is durable for the same reason as above
- It is far cheaper than traditional systems
- I now have 2, 8mm rods that I have reused to further strengthen my frame cool smiley

I am very curious about what the community thinks of this idea. I am looking forward to your input and questions, and see if it can be improved further. Hopefully the I3 can be upgraded on the X and Y axis as well in the future.
Re: Working slider in aluminium extrusion on Z axis
June 25, 2020 12:53PM
So ? Already done. Igus and others market them with proper guides and bearings.
In fact better use the 8mm rods nested in the Al profile as tracks. The type of anodization of these Al profiles is usually not suitable for a track.
Of course Igus filament ot make proper sliders too. And NO GREASE, it is messy, collect debris and acts as grinding paste.

"A comical prototype doesn't mean a dumb idea is possible" (Thunderf00t)
Re: Working slider in aluminium extrusion on Z axis
June 25, 2020 01:05PM
Thanks for your feedback.

Do you happen to have a link to this product or concept? I am not familiar with Igus.

Edit: I think I found what you mean as it fits your description: [www.igus-cad.com]
I don't think that this is conceptually the same as this Igus system is also placed on top of the extrusion and not integrated in its properties.

I have been doing quite extensive searching before but couldn't find anything similar. Thanks for you (no) grease tip by the way.

Edited 1 time(s). Last edit at 06/25/2020 01:15PM by joostvl.
Re: Working slider in aluminium extrusion on Z axis
September 09, 2020 08:31AM
I'm curious how the slides are holding up after a few months. Any updates on this Joost?

Re: Working slider in aluminium extrusion on Z axis
October 27, 2020 01:27PM

The sliders are still doing very well and I get consistent prints without any noticeable artifacts on the Z axis. When it comes to dirt, potentially grinding in the rails, I haven't had that problem so far. Although I do appreciate that being a risk of this technique as MKSA fairly commented.
Of course, the Z-axis on an I3 type printer is not moving as much as the X and Y axis. Still, I am pleased with the current performance.

To put this to the real test, I am now building a huge Delta printer (107 cm high) and I am going to apply this slider technique to it. This will of course generate a lot more (quick) movements and I am really curious how it will cope smiling smiley.

Edited 1 time(s). Last edit at 10/27/2020 01:27PM by joostvl.
Re: Working slider in aluminium extrusion on Z axis
October 27, 2020 01:37PM
... for a "demonstrator" of a small delta system around 2007 I've used 30x30 aluminium extrusiongs and milled gliders from PTFE, what was working pretty well for some time without wearing ... but don't know, how long, until it will wear or develop play -- gave it away some years later ...

Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]
Re: Working slider in aluminium extrusion on Z axis
October 27, 2020 03:13PM
I'm using PTFE bearings sliding inside t-slot for my corexy sand table. The 45mm square rails are so long (180cm) that the belt tension causes them to bow outward (belts, pulleys, and motors are all mounted on the inside of the rails). I added a brace to prevent the bowing, but still had some variation in the spacing between the rails, so it sometimes made a clunking noise as the entire X axis shifted between the rails when the X motion reversed direction. I redesigned one of the bearings, spring loading it, so it keeps the X axis stable which stopped the clunk when it reverses direction. I don't know if I'd use it for a 3D printer, but for a low resolution application like a sand table, it works great.

I am now rebuilding the sand table as a coffee table in a slightly smaller size. The rebuild includes a redesign of the bearing/pulley blocks that include the PTFE bearings.

Son of MegaMax 3D printer: [www.instructables.com]
Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]
Re: Working slider in aluminium extrusion on Z axis
October 28, 2020 06:26AM
So if I understand correct. The actual extrusion started to bend because of its length combined with the force of the belt tension, causing the slider to jam upon direction changes. I wonder if a more sturdy and rigid frame will prevent this from happening as well.
By the way, in the solution I proposed. the slider is also rigged with an aluminum rod inside of it, resulting in extra strength and metal on metal sliding.

Of course I hope I won't be facing such problems so thanks for sharing your experience!
Re: Working slider in aluminium extrusion on Z axis
October 28, 2020 07:57AM
The X axis was sliding between the two Y axis rails. It didn't jam, it was a loose fit, so when the X motion reversed direction the whole X axis would shift maybe 1mm in the X direction. The spring I added pushes one of the bearings against the Y axis rail and takes out the slop. That stops the X axis from shifting and making the clunking noise.

You can see the mechanism here: [vimeo.com]

Here's a picture of the bearing/pulley blocks. One has two, 3 mm steel pins that the bearing slides on, and springs that fit over each pin that push the bearing.

I wouldn't recommend it for a 3D printer, but it's fine for a sand table where resolution in the sand is 2-3 mm at best.

Edited 1 time(s). Last edit at 10/28/2020 08:06AM by the_digital_dentist.

Son of MegaMax 3D printer: [www.instructables.com]
Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]
Re: Working slider in aluminium extrusion on Z axis
October 28, 2020 08:12AM
That's really amazing.. thanks for sharing
Re: Working slider in aluminium extrusion on Z axis
November 06, 2020 05:59PM
Today I assembled the core of the new Delta printer and wired up the stepper motors to a BTT 1.4 Turbo mainboard. After updating firmware and uploading a dry run GCODE file, this was the result: [www.instagram.com].

The new printer is running very smooth, silent and the sliders are doing their job well.
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