Re: Anybody hear of this - 3D printers for every FIRST team
 

Thanks I like the effort put into the comparison.

I am not sure one actually needs to have dual Z motors as a "critical feature" (page 4) as long as they can achieve the resolution and movement with one: does it really matter?

After all: often times the dual Z stepper motors are in parallel (with respect to a RAMPS 1.4 system for example...not in the general sense of stepper motor windings) and you are actually sending less power to both motors. For something like a Prusa I3 it makes sense because the dual Z lifts the carriage over the width of the printer. In a design like the MakerBot, Duplicator 4, or others of that type the table moves the print in the Z axis of the printer instead of the potentially heavier head assembly. Keeping in mind the head assembly moves in the X from side to side so at any one time the increased weight of the head is on one side of the other of the Prusa I3 design. That issue does not exist in the other design: the prints weigh less and really should not extend over the bed, while the extruder may extend out over the bed surface increasing the leverage of the head weight in the Prusa I3 system.

Re: Anybody hear of this - 3D printers for every FIRST team
 

Good point on the other designs. I should have noted that designs that move the bed vs the X-carraige in the Z would not need dual motors. My main concern was both the weight of the Xcarraige and the resonance/vibration from the unsecured end as the carriage moves.
Rostocks are yet another example where the Z motor does not apply.

The reality is that the overall stability of the entire system is the key. Rod driven versus belt driven systems tend to have better absolute resolution in the X and Y.

Re: Anybody hear of this - 3D printers for every FIRST team
 

Our 3D printer got here. I think I'm starting to get the hang of it.

Re: Anybody hear of this - 3D printers for every FIRST team
 

I'm jealous. The color variety of print material available is impressive! Have you tested Plumber's Putty?

Re: Anybody hear of this - 3D printers for every FIRST team
 

A. In the presentation and your comments it notes the importance of a heated bed for ABS. One of the First choice items in the presentation comparison chart shows no heated bed but notes it is ABS compatible. Is a heated bed absolutely necessary or desired for ABS?

B. You mention belt vs. motor driven. What is the case with the First choice items?

Thanks!

Re: Anybody hear of this - 3D printers for every FIRST team
 

LOL - And all sorts of pre-built stencils.

Re: Anybody hear of this - 3D printers for every FIRST team
 

James:
ABS will tend to warp without a heated bed in general. Warping can range from aesthetic to ruining long running prints. Warping can cause the print head to hit the object (because it is higher than planned) and knock the object loose from the bed. Without, heat ABS does not seem to stick well at all to the build surface.

So to me, unless you want a TON of frustration don't try ABS without a heated bed. Most likely on the First Choice item referenced it means the hot end is rated for ABS temps and the vendor will not void your warranty if you print with ABS. It would have to do further research to make sure on that.

When ever I have had the heated bed go out during a print I have lost that print due to warping or the print just separating from the bed.

[quote=J
B. You mention belt vs. motor driven. What is the case with the First choice items?

Thanks![/QUOTE]

Great question.
I meant to say Belts versus LeadScrew driven I think.

It looks from what I can Google all 3 FIRST Choice options use belts for at least one or two axis.
And so do almost all RepRap models I am familiar with.

Belts are not bad per-sea they just need to be tensioned regularly to avoid backlash.

I have only seen a couple home 3D printer designs that use lead screws. Most of those are derived from CNC machine designs. In fact, when I visited the folks at ShopBot in Oct they showed me a printer built directly on their Desktop CNC platform.

Lead screws have less backlash, are generally more accurate, and require less maintenance than belts.

So unless you want to spend serious money, belts will be what you get.

Re: Anybody hear of this - 3D printers for every FIRST team
 

I've built plenty of CNC machines so I will chime in on this.

There is still backlash with a mere nut and screw, the issue is that it's easier to create situations that limit backlash with a lead screw.

Belts, even ones reinforced with steel, will stretch and depending on their profiles they may have more backlash limiting their resolution. For example the GT2 tooth profile is more accurate than the MXL.

To limit the backlash of a lead screw there are several simple choices. One simple trick is to heat a section of the screw up till it can melt it's way into a block of nylon cut in half. The resulting 2 halves of nylon will tightly grip the thread and reduce the backlash until wear increases the backlash again.

Backlash compensation nuts exist and generally they work on a variant of 2 nuts pushed against some spring tension so that there is less backlash regardless of the screw drive direction.

In the case of an all lead screw design the Prusa I3 should not be all that difficult to convert to all leadscrew economically. The bed axis is already supported it just needs a lead screw down the length. The X axis with the head assembly will be heavier but the Prusa I3 design is already a dual Z stepper. So if the mechanism got much heaver with a lead screw across just add another Pololu driver, split the drive signal from the controller board and run both Z steppers at full power (that's something you could do by making a module to plug into the existing Pololu driver socket).

Re: Anybody hear of this - 3D printers for every FIRST team
 

Good points about how you still have to deal with backlash on lead screws.
One neat design I saw on a small CNC used two wing nuts (one fixed and one floating) with a spring between.

I have seen some posts about modifying the I3 to be all lead screw and there is at least on kickstarter running to build something similar. You are right doing the Y bed would be easy. Unless you use a really screw and mechanism
I don't think you need to add another Pololu driver. As is my driver is set at less than 50% current so unless the weight is doubled.

I am looking forward to see some of these designs in action and how fast they are able to print accurately.

Re: Anybody hear of this - 3D printers for every FIRST team
 

This experience has been awesome. We got our 3D printer, almost entirely donated by MakerBot, last week, and since then we've printed parts for use in my robotics class, had several students (not on my FIRST team) designing parts for curricular use and figuring out the best way to print them, FIRST students printing parts and testing their durability under different situations, art students and teachers manipulating objects for practical production....

And a whole heap of kids inspired by really cool technology.

Thank you, MakerBot, and DonorsChoose, and those who contributed. This is fantastic. :D

Re: Anybody hear of this - 3D printers for every FIRST team
 

We got ours yesterday and I can already see a similar situation building here.

Re: Anybody hear of this - 3D printers for every FIRST team
 

We got ours last week. Just got it out of the box and set up this week.
Going straight to big parts. This part will take 13hrs to complete.

Its our first part printed using ReplicatorG, sliced by skeinforge

http://youtu.be/UIyJ3P3pPtU
http://youtu.be/UQH6Ev4iBsE

We'll have more info up on what it is we are printing in these videos in a few weeks.

Re: Anybody hear of this - 3D printers for every FIRST team
 

We've been doing a lot of little experiments, testing the applicability for every class: Earth Science, Art, Social Studies, etc, etc. The art teacher is ecstatic over the 3D printer, so we've been testing what kind of supports are needed, and whether or not it's easier to let the MakerBot software handle them, or to add them in ourselves.

It's pretty cool to get the whole school involved in the technology wow-factor!

Re: Anybody hear of this - 3D printers for every FIRST team
 

I have to completely agree with everyone else here on the forum that 3D printing is fascinating. Since receiving our Makerbot last Thursday we have put over 40 hours of printing time on it even though our school was out last Friday and all of this week due to weather. My favorite story of 3d printing so far was that one of our seniors Designed a lightning bolt handout for regionals. Instead of putting a value of 4 inches for the height she put .04 inches. Needless to say that was a very quick and small print, but it still held up :D .

Edit: I also want to thank FRC team 981 and Rob Steele for providing a stl. file for a denso window motor adapter. http://www.thingiverse.com/thing:190429. If we use the window motor worm gearboxes at anytime during next year's game we plan on using these adapters.

This technology has really given our team some incredible oppurtunities. Last year, we integrated 3D printing with carbon fiber technologies, and the attention we got was surprising. This technology provides for a lot of creativity an possibilities in FIRST. I can't wait to see what teams will come up with next year using this technology!

Re: Anybody hear of this - 3D printers for every FIRST team
 

Our project just got randomly funded!
Yay!

Re: Anybody hear of this - 3D printers for every FIRST team
 

If there is a small amount remaining (for us there was $98.00), make sure you fund that remainder quick - I've seen others loose the Makerbot Contribution as quickly as it came.

Re: Anybody hear of this - 3D printers for every FIRST team
 

Luckily it was an anonymous donor so we didn't have to have the $100 additional.

Re: Anybody hear of this - 3D printers for every FIRST team
 

Reviving this dormant thread as a reminder to teams that the 3D printer project continues!

Team 2122 just received notification that their school's application for the Makerbot Replicator bundle has been fully funded! A huge thank you to the donors that made this possible especially Makerbot and Autodesk.

If your team has not applied, do so now...:)

Re: Anybody hear of this - 3D printers for every FIRST team
 

I thought it was interesting that dictionary of numbers showed me this

Re: Anybody hear of this - 3D printers for every FIRST team
 

Thanks for the heads up. My project expired a couple weeks ago. I just resubmitted it. *fingers crossed*

Re: Anybody hear of this - 3D printers for every FIRST team
 

As I was preparing my Thank You package today I noticed that the team number of a donor had been changed from 330 to 3309 on the DonorsChoose account. I accordingly need to switch my public thanks to the Friarbots. Again, Thank You for your timely donation. The 3D printer has been an incredibly fun way to allow students to work on some small design projects.