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Discussion in '3D printers' started by Marshall Peck, Sep 27, 2015.
An open source 3D printer design with a sturdy V-Slot frame
I finally finished my Voxel Ox build. Here are some pictures:
When I built mine, I considered a single motor z axis. Lately I have experienced layer problems utilizing 2 color printing. No problem with single color, two color requires a lot of z axis movement. So one variable is the Z axis dual motors staying in sync. I test them with a block off of the edge of my build plate. I am seeing variations, but don't know why. One issue may be my moving the z axis as I load and unload my twin Bowden extruders which are mounted on the z axis support. Another is the fact that if you turn your machine off and on you run the chance that one of the motors will zero differently.
So I have been engineering a simple and realistic method to convert my machine to a single motor dual lead screw machine. After some thought, I decided to keep the lead screw flexible connector and bearing. Placing a belt pulley directly on the top of the lead screw will put a bending moment on the screw when the belt is tightened. My design leaves the flex connector and adds a 5mm shaft upward that is supported by two 16 x 5 x 5 mm bearings. The 20 toothed pulley will be pushed up against the first bearing and this will provide thrust support in both up and down directions. The design will bolt into the same position as the current lead screw brackets. I call them my Z towers and I will need both a left and right side version.
I plan on mounting the single motor shaft down on a plate that will mount to the 20 x60 mm upper extrusion. With four idler pulleys, I can use the motor as the tensioning device on the closed belt. Here is a picture of the right side tower.
I'm not seeing too much z axis variation between the two motors. I check it once a month or so. That being said, a single motor solution that can drive both sides would be interesting..
Don't see your picture...
Here are the pictures
No spam, Photobucket has raised their rates.
I am having trouble measuring the belt length. It will look like the drawing above.
I just recently converted my dual z to a single z with dual belts and it is working out well. Disregard the outside motors they are not actually coupled, I kept them in place in case this didn't work. I was having issues where the two motors were not staying timed causing serious frustration.
How do you tighten your belts? I intend to use a single 1000mm belt with the motor acting as the belt tensioner. Also, I am not sure putting belt tension on the 8 mm shafts is not going to cause vibrations from binding. Let us know how it works.
What quality filament have you guys used for the printed parts? Apologies if this has already been asked.
I generally use ABS. I don't like the strength of PLA.
I have now completed both towers, the idler pulley block and motor mount. Waiting on pulleys, bearings and belt.
Ok thats great, I struggle to notice the difference but have never really printed anything where strength is required so it is good to know.
On my first printer I had a direct drive Wade extruder on my machine. It was supposed to be ABS, but whoever printed it used PLA. I took it to a different location and stopped at a fast food and gas station. It sat in the back seat for about 25 minutes. This was in Washington State. When I came out the motor on the extruder seem off and I checked it and it had slumped about 3/4 of an inch and was completely unusable. Fine for a prototype, but really worthless for something that needs lasting strength.
Wow, I didnt realise there was such a difference, thanks for the advice.
I did not get the belts "piano string" tight. I just shifted the z-screw mounts outward till tight enough. Since the pulleys are high I do not have any bowing on the 8mm screws. Here are some pictures of prints i did yesterday. I little bit more tuning but so far so good.
Looks pretty good to me!
I am still waiting on the belt, but the idlers and motor mount are now installed.
Finally got the conversion completehttps://www.thingiverse.com/thing:2464919:
Looks great, let us know how it works..
It seems to be working very well. My prints have less ringing, but otherwise the quality remains very good.
Here's my lasted printer base on the Voxel OX
Marshall, what dimensions would I use for the X and Y axis to get a 12" X 12" build area?
I have read the entire thread and haven't found my answer, along with a few others who have asked. I love the design of this printer, few changes I will make is using a single z motor like this. I know I can move the lead screws to the outside but would like to leave as is.
So the question a few have asked is - What are the measurements needed on extrusions for a 12x12 build plate?! I know I could just add length how I see fit but would be nice to know what other people have done before hacking expensive extrusions!
This is the only thing stopping me from ordering parts and building this!! please help!
It is pretty straight forward. You can take the frame lengths on the 8 inch BOM (200mm) and extend them by 100mm. The structural parts are 2080 so there won't be a problem with rigidity. So the frame horizontal (called out for 475mm) would be 575 for top and bottom.
The X gantry needs to be extended as much as you extended the horizontal, normally called out as 430mm, it needs to be 530.
The height you can make as tall as you want. But I think Marshall P. mentions a limit of about a meter. You might be able to go higher since you have a bigger base. Verticals are normally called out at 380mm, add 100 to 480mm. I made mine 500mm so I would not have to make any cuts there.
The Y axis is a bit different, it will need 300mm both in front and behind plus an extra 100mm for motor and idler mounts so a minimum of 700mm.
Make sure your lead screws for the Z are the matching length for your height.
Wouldn't hurt to model things up in CAD. Maybe you want some extra length to mount the controller or power supply. It's good to have a plan as to where you want to put these.