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X,Y mechanics

Posted by smithhear360 
X,Y mechanics
June 20, 2017 01:36AM
Hi all. I am about to build my first 3d printer, and have decided on building a printer with a bed that only moves on the z-axis and the print head that moves on the x-y. I am avoiding the i3 mechanics due to the double lead screw motor sync issue and the moving bed on the y axis. I am noticing many makers are using of the core x-y "etch a sketch" style movement, and then came across a video on youtube where a guy is taking apart a Stratasys Dimension BST printer and it's motion system has the x-axis motor moving on the print head gantry (via gears and belts) and the y motor is controlling movement (via a linear rod, gears and more belts). Although this design has more pulleys, gears and 2 closed loop belts (from my count) it appears a lot more straight forward to trouble shoot (since all the motion systems are at right angles). Other than the increased cost required with building a rigid frame, and extra parts Is there any reason to stay away from this design that I am not seeing?Stratasys 3d printer rebuild


I plan having a 12x12x12 inch build volume and I am prioritizing reliability of printer and print quality over speed. I will also be using Hiwin 15 linear rails for the xy, and 2 16mm linear rods for the z.
Re: X,Y mechanics
June 20, 2017 04:43AM
There's no good reason to mount the X motor on the print head- you can mount it on one of the Y axis bearing blocks and use a smaller extruder carriage. That will allow your 12" x12" build space in a smaller frame. It's easier and cheaper to make a smaller rigid frame than a larger rigid frame.

Watch out when buying HiWin linear guides. Most of the stuff sold as HiWin on ebay is actually cheapo knock-offs that are poor quality. As far as I can tell, the only way to be sure of getting real HiWin guides is to buy them directly from HiWin. There are plenty of other quality brands- IKO, THK, NSK, Bosch-Rexroth (and some others) are all good, industrial quality stuff you can buy used, or sometimes NOS, for reasonable prices on ebay.


Son of MegaMax 3D printer: [www.instructables.com]
Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]
Re: X,Y mechanics
June 20, 2017 05:37AM
Thanks for the advice DD. Having read your instructables multiple times, I will just take your word as law and mount the x motor on the y carriage.

No worries about getting ripped off on the rails. I bought them a 6 months ago for this project and they slide fine.
Re: X,Y mechanics
June 24, 2017 06:09PM
I recently took on the challenge of building a 3D printer that was 12 by 12 with a xy moving head and a z-axis bed. I chose to do an h-bot setup, I will include a CAD model of the design.

[cad.onshape.com]

Maybe you can find similar ideas to use between the two.
Re: X,Y mechanics
July 18, 2017 10:02AM
Alright the printer is not pretty or well thought out, but it works.. I have ordered a total of four 4040 by 1 meter aluminum extrusions, a 12x12inch mic6 aluminum plate(build plate), as well as thicker right angle aluminum for version 2. Here is the printer. I will apply all I have learned from my errors in this build and take into account space for enclosing the printer as well as a location for the electronics. I am very impressed with the mechanics of not having a moving bed on the y-axis. It has definitely been worth the extra effort of figuring out how make the more complicated x, y movements happen on the print head.

Edited 1 time(s). Last edit at 07/18/2017 12:06PM by smithhear360.
Re: X,Y mechanics
July 19, 2017 11:26AM
Stratasys machines tend to be over designed (note, this does not mean they are the gold standard, just that it cost more money!). They prefer machines that can't break, are simple and can withstand abuse from customers. This leads to heavy machines.. the weight of a moving X axis motor does not mean much to them when the axis already weighs so much.

We tend to deal with desktop sized machines with smaller motors, making lightweight CoreXY perfectly suited to our needs. CoreXY is simple and only slightly more difficult to diagnose problems (Just check an extra motor....). Perhaps stratasys aims to idiot proof their printers and so stick to ultra simple Cartesian machines? Even the new F170, F270 and F370 seem to be simple Cartesian machines.
Re: X,Y mechanics
July 20, 2017 10:21AM
After experiencing a gantry that moves on the (x,y) I am definitely going to buckle down and learn to perfect a core (x,y) with two stationary motors. I really didn't think the headache would be worth it but the simplicity of not dealing with a moving bed cannot be understated.
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