Stratasys's mojo : throw-away hotends
May 10, 2012 04:17AM
"since the Print Engine now includes the print head right on the end of the filament"

fabbaloo.com/blog/2012/5/8/the-mojo-3d-printer.html

I'd be curious to see their hotends in real smiling smiley

(otherwise it seems a huge machine with less than a huxley print surface, and ressource-expensive (no density control), reprap ftw :p)


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Re: Stratasys's mojo : throw-away hotends
May 10, 2012 02:23PM
WOW. $300/kg for material.


www.Fablicator.com
Re: Stratasys's mojo : throw-away hotends
May 10, 2012 05:25PM
With their wording I just glazed past that point. $300/kg Yikes. Thanks for transforming the numbers and putting it into perspective.

From looking at the pictures of the cartridge I'm not sure the print head is actually integrated into it. It looks like it is more of a gimmicky filament loading cap to make it look more professional than a loose filament end.

Edited 1 time(s). Last edit at 05/10/2012 05:33PM by billyzelsnack.
Re: Stratasys's mojo : throw-away hotends
May 10, 2012 05:30PM
wow, throw away extruders? But it's more expensive than new makerbot extruder+filament.. and this is what they are throwing away? Who the heck would buy this.. its not THAT much cheaper than uPrint is it?

What takes up all that space inside? This thing makes little sense....
Re: Stratasys's mojo : throw-away hotends
May 10, 2012 08:00PM
wow thats pricy. but the idea of leaving the hot end on the filament is not all that bad i think,


[mike-mack.blogspot.com]
Re: Stratasys's mojo : throw-away hotends
May 11, 2012 01:24AM
Based on some recent patents I've been snooping, the hot end consists of just the metal part of the nozzle with a gap for the "hobbed bolt equivalent" to poke through and grip the filament. I bet all heating/heat-sinking is done on the machine and not on the cartridge. Also looks like the anti-refill chip is built into the print head.

The rest of the space is taken up by the~ 800W power supply, insulation, chamber heater/air circulator, and 2 cartridges. It looks similar in size to a replicator if you include the external filament spools and filament guide that pokes out the top.


www.Fablicator.com
Re: Stratasys's mojo : throw-away hotends
May 11, 2012 01:31AM
Quote
The article
Only solid printing is permitted, ensuring very strong printed parts, but also using more material. The software does not provide an option to select a density percentage.

Yikes, that sounds terrible. This thing will be mega slow. It's also kind of funny how 0.17mm layer height is touted as if it's some kind of achievement for a commercial 3D printing company confused smiley
Re: Stratasys's mojo : throw-away hotends
May 11, 2012 06:06PM
Ok so according to this [www.engineering.com] it takes five hours to print a 2x2x2 inch cube. Anybody have time estimates for the same job on their machines?
Re: Stratasys's mojo : throw-away hotends
May 11, 2012 06:53PM
I wonder if the guy actually wrote that article or if Stratasys wrote the article and the guy was paid to put his name on it. Geez.
Re: Stratasys's mojo : throw-away hotends
May 11, 2012 07:45PM
"In addition, the consumer printer couldn’t build a usable part."

"Contrary to what consumer-class 3D printers lead you to believe, the extrusion tips must be replaced at regular intervals."

Glad to see the review is fair and unbiased winking smiley


www.Fablicator.com
Re: Stratasys's mojo : throw-away hotends
May 11, 2012 09:27PM
Forget the fact that we are spending $300/kg on plastic...

...did anyone else notice the fact that this is a $10,000 machine? Ten Thousand bucks!

Last I checked, that was the price of a good used car.

Sorry, one more time through... ...$10,000 --Does it come with gold coins or maybe a big bag of crack?
I am the author and Stratasys did not write, edit or direct any of the content.

I won't try to change anyones' minds here. But I will note that many of the assumptions noted in this thread are incorrect. Let me just leave it at this: If you find (through actual experience, not passing on someone else's assumptions) that anything in my article is not factual, please let me know.

By the way, I successfully built four parts on Mojo from my 2011 benchmark. My RapMan 3.1 couldn't build any of them (that pesky issue of supports while preventing parts from warping/delaminating). Sure I could build them all in PLA (with PLA supports), but there was no way to remove supports in a reasonable amount of time.
Re: Stratasys's mojo : throw-away hotends
May 13, 2012 10:59AM
Todd,
Could you share the test part you printed? From the photo in your article I don't see any reason why it couldn't be printed with a consumer or hobbyist printer. I am curious why you said the consumer printer was unable to print a usable part. Are there unseen details on the bottom of the part?

In my own experience after a couple years and well over 20 pounds of filament pushed thru my main printers nozzle, I still haven't needed to replace the nozzle. Can you share why you believe they need to be periodically replaced?
Re: Stratasys's mojo : throw-away hotends
May 13, 2012 12:31PM
Sorry Todd. It just seemed overwhelmingly glowing as if a marketing person wrote it.
Re: Stratasys's mojo : throw-away hotends
May 15, 2012 03:12PM
Todd Grimm Wrote:
-------------------------------------------------------
> I am the author and Stratasys did not write, edit
> or direct any of the content.

It is all about the transparency isn't it? People today are aware of marketing techniques like astroturfing, and are right to be skeptical. How and why does anonymous guy on the internet get hold of a $10,000 printer not yet on sale in order to write a glowing "review", in which there is no mention of actally using the machine in person? For all anyone knows, the author could well be an employee of the marketing dept.

But the article linked is misleading, a quick search shows who you are and who you work for. It would have helped if that info was in the open.

Even so, I think people are aware of how magazine reviews work. The reviewer writes nice things about the company product, so the magazine gets advertising and more products to review. Does that make the review false? Not necessarily, but there is clearly a bias there which people nowadays are wise to.

As for comparing the $10,000 custom designed printer versus the Rapman 3.1 commercialized hobby printer, it is perhaps not suprising that the expensive one wins. Especially if you did not have to pay for it winking smiley

Clearly, this machine is designed for pro users not hobbyists, so $300/kg is quite a reasonable price. My company pays double that price per piece to get samples of custom moulded parts made. In fact, my colleague who orders the parts asked me if I could print samples "for free" on my Rapman, but I declined winking smiley
Anonymous User
Re: Stratasys's mojo : throw-away hotends
May 15, 2012 07:10PM
Are not all the hobby 3d printers based on patents by this company? If so shouldn't we show them a little more respect?
Re: Stratasys's mojo : throw-away hotends
May 15, 2012 07:58PM
gerards1111 Wrote:
-------------------------------------------------------
> Are not all the hobby 3d printers based on patents
> by this company? If so shouldn't we show them a
> little more respect?

HA HA HA HA HA ......

Just because some company can afford to have a legal monopoly that has held back technology we are supposed to respect them. I may have some respect for the guy that originally came up with the idea but not the company that kept it out of ours hands for thirty years while other people came up with the same idea independently but could not do anything because of big corps control over an IDEA. Screw them!

Your argument is kinda like saying we should respect Apple computers because their OS works so well. But really it is all the hard work of the linux and free bsd community that made the super great foundation that apple has put a bunch of fluff on top and called it theirs.


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Anonymous User
Re: Stratasys's mojo : throw-away hotends
May 16, 2012 12:38PM
No it isn't the same as praising apple.

Also with your argument no one should be able to retain the rights of what they create.

It's all about making money, even reprap. Just because it's hidden under the guise of being open. The difference is stratasys pay the ones who help create the final product. In this setup everyone contributes but the main ones make the money.

Look at the front page and how it now links to machines to benefit a few. And on top of this not all the machines are fully documented with schematics and suppliers.
Re: Stratasys's mojo : throw-away hotends
May 16, 2012 01:05PM
gerards1111 Wrote:
-------------------------------------------------------
> It's all about making money, even reprap. Just
> because it's hidden under the guise of being open.
> The difference is stratasys pay the ones who help
> create the final product. In this setup everyone
> contributes but the main ones make the money.

You are sounding like a corporate shill. It is difficult for some people to believe, but it is not always "about making money".

You also seem a bit confused. If Stratasys are all about the money, and have paid the engineers whose ideas they exploit (I'll bet they didn't see much of the profits), then why do we owe them respect?
Re: Stratasys's mojo : throw-away hotends
May 16, 2012 01:53PM
Now Brad, that's not exactly true....Apple has openly mentioned it's opensource roots and unlike the others in the same space, gives away all their development tools. You're sounding like someone that's never used the platform and is basing your assumptions on myths and FUD.

They are a hardware company first with the software being very much secondary....and in the case of their OS, realized BSD was a better choice years ago and abandoned their previous platform to better position itself and kill off the legacy issues that MS continues to deal with.

A fork is not exactly fluff.


[johnbiehler.com]
Re: Stratasys's mojo : throw-away hotends
May 16, 2012 02:10PM
johnbiehler Wrote:
-------------------------------------------------------
> Now Brad, that's not exactly true....Apple has
> openly mentioned it's opensource roots and unlike
> the others in the same space, gives away all their
> development tools. You're sounding like someone
> that's never used the platform and is basing your
> assumptions on myths and FUD.
>
> They are a hardware company first with the
> software being very much secondary....and in the
> case of their OS, realized BSD was a better choice
> years ago and abandoned their previous platform to
> better position itself and kill off the legacy
> issues that MS continues to deal with.
>
> A fork is not exactly fluff.

I wasn't trying to say there is anything wrong with Apple. They do make reliable well built devices. I was just saying we need to respect the people behind the OS not the company that claims ownership of it. Apple deserves full credit for the concept of GUI and many great additions to the world of computing. Just like statasys has done good work but it is not the company that had the great idea, it was the people that had the ideas that the company has taken advantage of. Just think of the machines we would have today if statasys had not stifled creativity with its patents.


FFF Settings Calculator Gcode post processors Geometric Object Deposition Tool Blog
Tantillus.org Mini Printable Lathe How NOT to install a Pololu driver
Re: Stratasys's mojo : throw-away hotends
May 16, 2012 05:17PM
Steering this abortive discussion back into productive territory:

the mojo seems like a good goal for reprap. Make a small device which can produce high quality objects, and do it for much less than 10K. What does the mojo have that warrants that price tag? Why can't we do what it does? Several differences I see off the bat:

1)support material

-two-headed repraps are in the wild, the software is trying to catch up
-PVA seems like a great candidate. 90$/kg is a pretty good price compared to $300


2)heated chamber

-I haven't heard of any reprap incorporating this... Seems complex because reprap is made of parts that will become soft inside the chamber. Solution: Make the chamber out of a turkey bag with only the heated bed and nozzle inside? Is that even possible?


3) no strings


-Do they have a valve? How do they accomplish ooze-less printing?
Re: Stratasys's mojo : throw-away hotends
May 17, 2012 01:33AM
Is there a difference in software as well? Slic3r and Skeinforge settings need to be tweaked at times depending on the geometry, while with the Mojo you are supposed to hit print and expect a perfect result. Is the Stratasys software able to analyze the model and adjust the speed, flow, temperature, cooling etc. for different parts of the model?

Having fans or orbits activate based on a minimum layer time is a start, but it seems like it could go further. Suppose I have something like a statue on a pedestal which has a wide fillet on the top edge. The simple base could use sparse fill and high speeds. It would need extra perimeters in the fillet to prevent gaps, but not so many on the legs of the statue, which will need cooling and maybe slower speeds and less flow for the fine details.

Then there is dimensional accuracy. Inside diameters would need to be printed exactly as designed, with the slicing software compensating for thread width, corner cutting, or whatever causes holes to come out too small.

Is the platform self leveling? Is it a closed loop system, so the extruder always knows its position no matter what? Does the printer know how much material has been used since the spool was changed, and how much should be remaining?

Mainstream adoption of 3D printing will depend on machines like the Mojo coming into consumer price ranges. I bet that the first machines that do will print smaller models at slower speeds and less quality than the hobby printers of the time, because some functionality will be sacrificed to preserve ease of use while maintaining a low price point.
Re: Stratasys's mojo : throw-away hotends
May 17, 2012 02:28PM
I have a feeling that a lot of the software tweaking that we do is a consequence of having to account for environmental effects. If we had a heated chamber and if the tip of our hot end was regulated at the chamber temperature (a temperature gradient, perhaps? Top is at 220 to melt ABS then the bottom is at 100C, chamber temp) then we wouldn't have to worry about cooling, etc. Since they use support material they don't have to worry about overhangs since they don't have any.

I wouldn't be surprised if the reason why Mojo and other professional 3d printers are so expensive is because they have engineering solutions to the problems that we try to solve in software.

Also, they use rafts so i bet you they don't worry about leveling the bed. Dissolvable support, remember.

I do wonder what plastic they use. Probably it's not ABS, but some proprietary mix that has good properties like not shrinking, not being runny, etc.

Our approach is better: Software is cheaper to mass produce than engineered solutions.
Re: Stratasys's mojo : throw-away hotends
May 17, 2012 02:35PM
destroyer2012 Wrote:
-------------------------------------------------------
> I wouldn't be surprised if the reason why Mojo and
> other professional 3d printers are so expensive is
> because they have engineering solutions to the
> problems that we try to solve in software.

> Our approach is better: Software is cheaper to
> mass produce than engineered solutions.

As far as I am aware their "engineered solution" is to go really slow compared to a RepRap which results in no need for cooling. I think I remember reading in the RepRap wiki that commercial machines run at 15mm/s max and we run from 30mm/s to 300mm/s.


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Re: Stratasys's mojo : throw-away hotends
May 27, 2012 01:08AM
Here are some pictures of the innards of the mojo, and in particular, the disposable print head. Courtesy of Bertho Boman, who took them at the Rapid 3D trade show in Atlanta, GA. Thanks Bertho!






This is what he had to say about it:
Quote
Bertho Boman
Following the usual trend, “low-cost” printer and custom ink, this model has taken it a step further: A cartridge filament system interlocked with a throw-away print head. The design makes it convenient though, just drop in a cartridge and snap a head in place and go.

As can be seen in the first picture, there is a filament cartridge on each side and two blue print heads in the center. There is a sample head the left side. The heads just snap in place like loading an inkjet cartridge.

The strange black boxes at the rear corners triggered several questions in previous posts. They are simple mechanical retainers to keep the feeder tubes in place. There is a little blue ring on the tubes that snaps in place and it just locks it in position. I asked the design engineer and was told it is a prototype and they will simplify it. The whole top of the machine is actually a 3D print for the prototype.

The inside of the machine can be seen in the second picture. It has a usual heated build chamber. Note the big blower in the back with a wide horizontal slot near the top. The two white rectangular objects in the top center are the print head tips. They have what appears to be a silicone rubber cover.

The most intriguing part to me is the head design. It is extremely small!! Besides the thermal heater function it also has the drive circuit inside that small case. I managed to get an opportunity to look inside it. It is very nicely made, considering it is a throw away item.

· The filament is non-standard size: 1.3mm
· The drive motor is a low-cost brushed DC motor with what appears to be a simple magnetic encoder
· The motor is geared down with a worm-gear.
· The heater with the thermocouple is extremely small, about 6mm in diameter.
· There is a small PCB with an IC on it and a few extra components. Presumably it is the interface for the thermocouple, the shaft encoder, and I would guess an internal serial number to prevent reuse if someone manage to find filament that would fit.
Re: Stratasys's mojo : throw-away hotends
May 27, 2012 02:29AM
Good thing the extruder is disposable. I can't imagine those crappy brushed motors lasting much longer than a roll of filament.
Re: Stratasys's mojo : throw-away hotends
August 25, 2012 01:25PM
Those crappy brushed motors typically have a specified life of 2000 hours life which is a lot of printing.:-)

Unfortunately I did not want to take pictures of the inside of the print-head. They were getting suspicious of me taking all the pictures.
Does anyone know where I can buy a Mojo print-head? Preferable a used one since I do not want the custom 1.3mm or so filament and pay the full price.
Here is a link to the rest of the review:
Mojo Printer review
Bertho
Re: Stratasys's mojo : throw-away hotends
August 25, 2012 04:03PM
2000 hours? Under load? Amazing. Nevermind my comment then.

btw. Very cool blog. PS. Your link is broken.

Edited 1 time(s). Last edit at 08/25/2012 04:05PM by billyzelsnack.
Re: Stratasys's mojo : throw-away hotends
August 25, 2012 04:49PM
Thanks Billy,
Which link is broken? I just tried them all and they worked at least for me but I might have missed something obvious.
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