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40mm t-slot large format printer

Posted by gmh39 
40mm t-slot large format printer
July 15, 2014 10:27AM
Here's the post from my site:

Quote

I’ve got a lot of junk laying around in my studio/office. And most of it is random/extra parts form past projects. So when I went through it all I was kindly reminded of plans to build a large format (300mm^3 +) 3D printer. With a few days of designing, tweaking, CADing, tweaking, CADing, re-designing, and more CADing, I was able to coming with a pretty nice design.



Here are some of the features*:

125,000,000 mm^3 build volume

That’s a 500mm x 500mm x 500mm build volume! I am planning on adding another ~150mm in the X direction and ~60mm in the Y direction later on, but for right now I just want to get the thing built.

100:1 geared extruder with MIG welder drive roll

Since I am an avid member of the reprap.org forums, I came across an extruder used by the user cnc_dick. He uses a a MIG welder driver roll in combination with a 100:1 geared stepper to get very high torque and an extremely reliable stepper. I redesigned his extruder to be a bit more user friendly, and I will definitely be putting his claims of swinging the extruder by the filament without any slippage to the test to really see how much this extruder can hold. There will also be a separate post just about the extruder.

Im the meantime, you can check out the discussion about his extruder design on the Reprap.org forum. (http://forums.reprap.org/read.php?14,361658)


40mm aluminum t-slot frame

This is was restarted with project. I had bought a lot of 40mm extrusion off eBay back in the fall, but that was about it. So I picked up some fasteners and fastening plates from 80/20 and finished up most of the frame. (I say “most” because there no bottom square yet. I only had 16 pieces of extrusion.)

FabTotum CoreXY gantry system

The guys over at FabTotum did a critical analysis of the CoreXY gantry system. They figured out that while the standard CoreXY is a good system, it can be even better by running the belts at 2 different levels and avoiding the dreaded cross over. (http://blog.fabtotum.com/blog/2014/04/04/belts-and-stuff-experiences-to-share/)

NEMA 23 stepper motors

NEMA 17 motors are great… for smaller sized printers. Since I want to go big, I need to go big on the motors as well. the recommended holding torque for a standard Reprap is 19.4 ozf*in (http://reprap.org/wiki/Stepper_motor#Holding_torque) although it is probably a little dated, so let’s say 40 ozf*in coming from a NEMA 17 with a current rating of 1.2 A. The motors are typically run at a max current of 0.6 A, so you would get approximately 1/2 the rated torque of the motor, 20 ozf*in.

Now by using a NEMA 23 that has a torque and current rating of 425 ozf*in and 3A, respectively, I can get a theoretical torque of 85 ozf*in at the same current as the NEMA 17. That’s over 4x the torque!


polycarbonate enclosure

Since this is going to be a pretty large printer, 52″ x 29″ x 29″, I wanted unnoticeable as possible. Instead of leaving the sides open, I decided to put paneling on them to give it much cleaner look. This will also keep the printing environment more controlled by blocking any drafts that might cross the build plate.

I also hope to add a full heated build chamber in the future, but like the enlarged build volume, the panel suffice for now.


storage cabinet

Last, but not least is the storage cabinet. Like I mentioned in the beginning, I have a lot of stuff for my hobbies, so having a large cabinet to store my filament, spare parts, and finishing tools would make my studio a bit more tidy.

*separate posts will be made about each of these features.

Right now I just have the basic frame built and I am double checking/planning placement of certain components.

Questions? Comments? Concerns?

I have been told that using parallel linear rails (15mm rails) can be problematic at large build volumes due to the tolerances of the parts. I've already ordered the rails, so hopefully they wont cause too much of a headache.


greghoge.com

HUGE 3D PRINTER PARTS SALE!!!
Re: 40mm t-slot large format printer
July 15, 2014 06:42PM
I love it. Very well thought out. Picking out the same good things I'm looking at. I've got nothing much more to add except an automatic fire suppression system [something I won't be starting with, taken with a grain of salt, it is costly]
Yes, yes, and yes with FABTotum's modified CoreXY. The instant I saw that I fell in love. As suggested here and there by I forget who, rather than expanding build size in both directions, I would expand in one. Most needs for a larger axis are typically elongated pieces. The larger you go the harder curving plastics will be to control in any form or fashion. Also, this can give you larger build volume without increasing your moving mass if you increase the right axis your gantry moves on.
Eh.. linear rails, especially [[b]especially[/b]] for larger build volumes is about as bad as it gets. I've chosen the V-Slot path for my linear motion system.

Otherwise, good choices!


Realizer- One who realizes dreams by making them a reality either by possibility or by completion. Also creating or renewing hopes of dreams.
"keep in mind, even the best printer can not print with the best filament if the user is the problem." -Ohmarinus
Re: 40mm t-slot large format printer
July 15, 2014 07:49PM
Quote
MrDoctorDIV
I love it. Very well thought out. Picking out the same good things I'm looking at. I've got nothing much more to add except an automatic fire suppression system [something I won't be starting with, taken with a grain of salt, it is costly]
Yes, yes, and yes with FABTotum's modified CoreXY. The instant I saw that I fell in love. As suggested here and there by I forget who, rather than expanding build size in both directions, I would expand in one. Most needs for a larger axis are typically elongated pieces. The larger you go the harder curving plastics will be to control in any form or fashion. Also, this can give you larger build volume without increasing your moving mass if you increase the right axis your gantry moves on.
Eh.. linear rails, especially [[b]especially[/b]] for larger build volumes is about as bad as it gets. I've chosen the V-Slot path for my linear motion system.

Otherwise, good choices!

Yea I wish I had known about the linear rail earlier... But hey, I'll give them a shot just see for myself. a switch to rollers wouldn't be too hard and may make my end goal of a complete repstrap easier.

As for enlarging the build volume I would be moving the NEMA 23s to the outside of the extrusion frame (they would get covers to hide them) and doing either switching to a L bracket for the top corners or just getting rid of them all together.


greghoge.com

HUGE 3D PRINTER PARTS SALE!!!
Re: 40mm t-slot large format printer
July 31, 2014 03:39PM
hi,

i'm new here, this is my first time posting with reprap so please bare with me. that said, your choice of four lead screws is a healthy one. would it be possible to move the screws to the corners? after mounting, the screw takes on a structural role, stiffening the frame, and you could compensate easily for bed sagging. you might have to play around with some custom brackets, but the structural bonus is well worth imho.
Re: 40mm t-slot large format printer
August 23, 2014 04:18PM
Wow, very cool design.
I'm doing something sort of similar - here's a shot of the first iteration of my frame.

It's going to be expanded to allow a 1m x .5m x .5m build area, and I'm planning on using ballscrews for all the axial movements, 1 for X, 1 for Y and 2 for Z.
The design is based on Mendel i3 electronics. Jhead and Bowden extruder ordered and on their way!
I'm going to use 80/20inc linear bearings instead of the 12mm shafts for the X axis too.
Fingers crossed!
Re: 40mm t-slot large format printer
August 24, 2014 03:43AM
I've built plenty of machines with 8020 and linear rails you should be fine. I don't know how good your skills are what tools you have a dial indicator with a magnetic base helps a lot. Usually on the bearings you'll see a machine groove on one side this is the accurate side and also on the rail you will be a small machine groove on the side or on the bottom toward the side that is meant to be measured from. But I have ran across others that don't have this feature I am assuming both sides are accurate enough for these that are un Marked

Edited 1 time(s). Last edit at 08/24/2014 03:45AM by cnc dick.
Re: 40mm t-slot large format printer
August 24, 2014 10:09AM
Yea, I've been really busy with other projects lately and haven't had a chance to work on this.

I do have it wired up and have gotten motion, albeit slightly messed up. I think only one of my motors is rotating (ie. my carriage moves diagonally when I move it). Either that or when I tell Repetier to move the X, it moves just the X motor. I'll have to investigate it a bit more.

I also have the extruder motor and printed parts ready to go. I just need to assemble them and test it out. I am hoping my version of your design CNC_dick works out as nicely as yours!

What are some tools that can I can use for alignment? Right now I have a bubble level and an L ruler...

Edited 1 time(s). Last edit at 08/24/2014 10:16AM by gmh39.

greghoge.com

HUGE 3D PRINTER PARTS SALE!!!
Re: 40mm t-slot large format printer
August 25, 2014 10:20AM
I've been running a 40mm extrusion framed, ball screw, nema-23 driven design for 4 months or so now (I'll try and get a real picture, but it basically looks exactly like Cinnerman's above).

I used cheap 1204 ball screws, but compensated for slow screw rate with fast nema-23 steppers (low resistance, low inductance coils, run them at 48volts) and decent stepper controllers from massmind.org.

Here's the actual limitations in my setup:

the ball screws whip at around 115mm/second on a 400mm shaft (a little over 300 usable for me)
reducing to 100mm/second on both X and Y works reliably except in rare cases (I think where the head collides with excess plastic buildup)
acceleration and jerk are a lot lower than I'd like - 600mm/second^2, jerk around 10-12, IIRC
at that speed and acceleration, a print big enough to fill the space will take forever to print - I bought a .6mm nozzle and will try it, but have usually been using my .4mm/.2 layer height.

I actually spent a lot more time fighting the E3D V5 head, which had a lot of problems with PLA until I drilled out the nozzle core. Also, ABS worked well for it.

What I'd do differently:

Build a delta with very low mass on the effector plate - very, very fast, reliable speeds appear possible
Instead of a 1204 ballscrew, use a 5-start ACME thread - saw some on ebay - those would give much better torque/speed tradeoffs with the steppers available
build a smaller printer - 200mm x 200mm x 200mm would suffice for everything I have the patience to print

What I'm worried about, but haven't gotten to yet:

ABS is tough to print to any great height - I'd enclose the cabinet for ABS for heat retention
Delta printers are trivial to enclose compared to my build, so another big vote for Delta there

Overall, I'm glad I did it, and I can now print complex, large PLA prints, and after I work out some more problems, I expect to be able to print complex ABS prints, but not very tall ones.

For what it is worth, it is fun watching and listening to the steppers screaming along at 1500RPM... no idea how long they'll last...
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