My dual extrusion Idea - Nozzle covering

[MTG 8]

Dear Community,

the release of the Ultimaker 3 caused mixed feelings in the forum. On one side, there are a lot of members with much experience who turned out to be like beta testers which say the Ultimaker 3 is so good and on the other side there are a lot of people which feel a bit betrayed from Ultimaker, because they bought an Ultimaker 2 oder 2+ lately, not knowing that there was a new one coming or not knowing if there was ever dual extrsuion coming for ultimaker 2.

I did buy the Ultimaker 2+, I did think there will be an update for dual extrusion. A lot of people are saying things like "there never was dual extrusion promised" etc., but when you don't have an Ultimaker, you are not on this forum and in my opinion it was a bit confusing and unclear when you are new and considering to buy the ultimaker 2 or not. But also, I have to say, you really can't blame Ultimaker for that, you can't say that this was intended by them. They also have a business to run and bills to pay, if they announced a Ultimaker 3 in January coming in October, the sales numbers for the last 10 month would have decreased a lot and it would not have been an good descision.

To make a point here, the situation is like it is, you can't blame the costumers neither Ultimaker, and we have get the best out of that sitiuation.

I think the Ultimaker 2+ is a really good machine. We could afford an Ultimaker 3 too, but I already customized the 2+. I have build an enclosure and I did install an Raspberry running Astroprint with Camera etc, but we defenetily want dual extrusion now. I just made a design in my spare time which might work.

We have two possibilities now. We could sell our machine and buy the Ultimaker 3 or we could try to build that design I made. For making that descision I want to show you the Idea and hope you will give me feedback about it. We are able to manufacture the prototype, we have a CNC lathe and a 3 axis CNC milling machine. So if it works some day, I can offer you a kit. Maybe I will release it as open source, too, because in my opinion thats what an upgrade for an open source machine should be.

Lets come to the design:

My toughts were: prevent oozing, thermally seperate the heating blocks, take as few as possible of the build space and make the change as quick as possible.

The idea is that there is a nozzle lift system. When the nozzle is not used, it will be lifted and the ooze cover will be turned 90° under the nozzle and seal it, that no more material is coming out of it. In the same time the other nozzle will be opened and lowered.

The lift system is something like a "camshaft". The 90° turning mechanism turns the nozzle cover and the camshaft that lifts the nozzle.

The advantages that I see in this:

 

• It takes almost no build space. The X/Y-Size of the printhead is not changed, only the size in Z is slightly bigger.
  
• It's fast. You don't have to cool down the nozzles to prevent it from oozing. You might have to cool it a little to prevent it from clogging.
  
• You don't have to waste material, time and space for a wipe tower that might come unstuck during the print.
  

 

Where the problems might be:

 

• Heat transfer to the head might be too high, we could try making the isolator part out of PBI
  
• I don't know if the nozzles might clog, but as you can cool it down a bit I guess that souldn't happen
  
• Get the nozzles on the same height. Theoretically, my parts can be made precise enough. Maybe the mounting system from Ultimaker can be problematic. A workaround could be in the software, we could add different offsets to the nozzle. Maybe we have to build a mechanical height calibration for one nozzle. Calibrating would be the usual heat bed calibration and after that a calibration of the right nozzle with the paper trick.
  

 

For moving the machanism I have planned a NEMA 8 stepper motor. It should be contolled by an Arduino. The tool-change signal can be transferred via free PIN on the Ultimaker board and the M42 command in gcode.

An other solution might be like an mechanical one, like the solution of the Ultimaker 3. we could build something like a lever and place something like a lever hard stop on the frame. But that is going to take some build space. I don't know if you get me at this point, it's hard for me to explain that in english.

Aditionally, when we have an arduino in use, we could attach a sensor and some indicator for automatic bed levelling.

It's not an easy project and I can't make it on my own. I might need help especially on software side, because i'm more the hardware guy. The tinkergnome firmware should theoretically work, we just have to create a tool change script.

That's my idea so far. Please give me feedback about it, if a prototype will be made depends on your opinion about all of that. If you have questions or i have explained something poorly, please let me know. Maybe I can make a video, but it has been a time since I used the Inventor rendering thing.

[DidierKlein 729]

Hi!

Interesting idea!

I'm nothing close to an engineer so i'll just give you some thoughts about your idea

About the lifting, it's a good way to go obviously i would not put the two nozzles at the same height though because it might cause some crashes in the print, when the second nozzle is lowered i would add an offset to it (like on the UM3 or the magnetic tool changer).

Z calibration would take the two different heights and software could to the trick (i believe this can be done with Tinkergnome dual firmware already).

I would try to something mechanical like the switch for the UM3 because you don't need extra motors or electronics. The extra motor would add extra weight to the head which i think can lower the quality of the prints (if you want to print fast).

The cover could be somehow moved also mechanically i guess.

I don't know how the pressure build up in the nozzle could go, i guess you have to do a good retraction before cooling down the second head (this is critical for PVA!).

[MTG 8]

Hi DidierKlein,

thank you for your feedback.

Atm, the nozzle is lifted 3mm and the nozzle cover has a thickness of 2mm, so there is an offset of 1mm.

I did also think of the extra weight of the stepper, even if it's just a small NEMA 8, it will probalbly decrease the maximum accelleration. You might tbe right with the mechanical solution be the better one, it would require less components, modding and also cost less than with stepper+electronics..

The lifting of the nozzles and the turning of the nozzle cover is already one mechanism, it requires just one shaft turned to do both of these actions, so one lever for that will work for that.

A retraction is needed in any way, the cover should just prevent the small amount of material coming out after the retraction.

Edited October 20, 2016 by Guest

[Chiranjeevi 0]

Hi guys,

Even I have been thinking about something like this . And I think using something like a solenoid or electromagnet would be more simple than using a motor for the nozzle lif ting mechanism .

And if the nozzle height difernce is 3mm , I think that is sufficient enough not to have a cover for the nozzle.

And using a solenoid type actuator we can use spring return type mechanism . that is, when the solenoid is energised the nozzle comes down . De energise it and the spring will pull it back.

What I am thinking is whether I should put the solenoid for both the print cores or just one . Putting it fir both would be like making it more symmetrical , putting it fir only one is like making it more simpler (?) And cheaper .

[MTG 8]

Hi Chiranjeevi,

I also thoght about that. But the solenoid consumes power all the time when activated, because you need a current to create the magnetic field. I'm not sure if that is a problem (maybe heat or power supply) but I didn't like that.

The 3mm might be enough that the unneeded nozzle doesn't influence your print, but the main Idea behind the covering is that you don't need to wipe and you wont have a wipe tower. Additionally, you don't have to cool the nozzles down. That consumes a lot of time.

My design is easier with two moving nozzles, because the cover can keep it's height. If you don't need a cover I recommend you to move only one nozzle. It saves you a lot of parts and effort and that's more important than a symmetrical design. With the Tinkergnome Firmware you can configure a height for each nozzle seperatly, as far as I know.

To my project: I replaced the stepper with a lever. Engineering 90% done, but our cnc-machines are not free atm. Expecting to make the prototype in Feb' 16.

Edited December 21, 2016 by Guest

[seriousCADninja 0]

Hey hello there! Really nice idea!

How is it going any news about the prototype?

I am eager to see the results!

[MTG 8]

Hi,

thank you!

The engineering is done, I just dind't find the time to build it! Working hard on my bachelor thesis right now, finishing at the end of July.

I'm checking if someone of our employes has the time right now to make the parts as I can't at the moment. But if you are interested, I could show you some more detail of the latest design. Maybe someone has any advice?

[mhusmann 0]

@MTG - I sent you a PM. Please check. 

[mariuszem 4]

Why not use lightweight servo instead of stepper motor? Servo could be easly attached to for ex. pin 13 (like BL Touch).

[MTG 8]

Hey,

I just came back to this topic and worked on it. Prototype is currently in the making. Guess I'll update within 2 weeks with photos

Edited October 8, 2019 by MTG

[MTG 8]

Update: As the initial design was bad and would not be able to be manufactured, I decided to postpone  this once again into winter and start from scratch, so I could choose this topic as a masters thesis.

 

The outcome is a pretty functional prototype. Here are some pictures.

 

I was able to print without the need to cool down the nozzles. They could stay on printing temperature without dripping on the print. But I had to print a prime tower. If the software was abit more customized, I possibly won't need that either, saving more time...

 

If anyone is interested in this I might share more details or a video.

 

 

Edited May 4, 2020 by MTG
added pictures

[Turbo-Power 3]

 

Hi. Video would have been nice :-)

[MTG 8]

Here you go

 

https://photos.app.goo.gl/9dEHmZxp5MxA1K87A

[drayson 75]

22 hours ago, MTG said:

Here you go

 

https://photos.app.goo.gl/9dEHmZxp5MxA1K87A

 

Whow - great design!

would be interested in more detailes as I plan (ok, since more than a year) to upgrade my dual UMO to something more reliable...

Are you willing to share the design?

 

Greetings from Austria!

[MTG 8]

21 hours ago, drayson said:

 

Whow - great design!

would be interested in more detailes as I plan (ok, since more than a year) to upgrade my dual UMO to something more reliable...

Are you willing to share the design?

 

Greetings from Austria!

 

Yeah I was thinking about putting it on Github or something like this, but I would need to take some time to clean it up a bit. For example the software that I forked - the lever switch position is currently hard coded.. also there are some other things that could work smoother. Mechanically, it's a pretty solid construction (might be because I'm a mechanical engineer and not a programmer 😅).

If someone wants to make their own, be aware that the core parts have to be made out of metal because they get quite warm. Most of the core is made from aluminum, the lever and shaft is stainless steel. Only the fan duct and the parts to connect to the x- and y-axis are printed. If someone is willing to work on the software side - I also have some spare parts lying arround that should add up to another complete printhead

[drayson 75]

2 hours ago, MTG said:

 

Yeah I was thinking about putting it on Github or something like this, but I would need to take some time to clean it up a bit. For example the software that I forked - the lever switch position is currently hard coded.. also there are some other things that could work smoother. Mechanically, it's a pretty solid construction (might be because I'm a mechanical engineer and not a programmer 😅).

If someone wants to make their own, be aware that the core parts have to be made out of metal because they get quite warm. Most of the core is made from aluminum, the lever and shaft is stainless steel. Only the fan duct and the parts to connect to the x- and y-axis are printed. If someone is willing to work on the software side - I also have some spare parts lying arround that should add up to another complete printhead

 

I'm mechanical engineer too so that's the reason I'd like to make most things "hardware" 🙂

I have two UM3 cores with Olsson blocks laying around which I want to use for redesign the Ultimaker Original head, but there is just limited progress.

In my design I thought of lifting the unused nozzle just by 0,5mm via a simple camway made of brass and with very small pitch to reduce friction. Unfortunately I have no access to a CNC mill so all parts are designed for conventional milling or handmade.

Your implementation is a way better...

 

Which design SW have you used?

If the UM3 core parts can be applied in your design, I would be interested in your spare parts...

 

[MTG 8]

It's made in Inventor.

The UM3 cores won't fit, the design is similar to the UM2 head size (´35x35mm) , the UM3 head is way bigger..

[drayson 75]

2 hours ago, MTG said:

It's made in Inventor.

The UM3 cores won't fit, the design is similar to the UM2 head size (´35x35mm) , the UM3 head is way bigger..

Hi!

that shouldnt be a problem. I already disassambled both cores and from your design, it seems that part 5 and 24 might be similar.

I have UM2 head parts laying around too. Tried a lot but not found an suitable design up to now.

I'm especially interested in your parts 7, 8, 25, 26 of the above shown assembly.

 

I work with SolidWorks, so if possible and you're willing, it would be great if you could share the design e.g. as iges...

 

b.r.

chris aka drayson

[enabler 0]

So what’s the status on this?

 

Github?

 

I’m eager to build one!

[enabler 0]

What about using a solenoid to actuate the lever / spindle / camshaft assembly? As opposed to a stepper motor on top or running the mechanical switch by some fixed point (I believe that’s how you’re currently doing it?). Having to run the unit past a fixed point is time consuming for sure. 
 

I would imagine the solenoid would be operating parallel to the build plate.  Or possibly implementing two solenoids working to push away the lever and throwing it into the second position?

 

A design like this would eliminate the need to hold current on the solenoid.  Just actuate it momentarily to “throw” the setup into the other nozzle.  Keeping the central vertical spindle intact, possibly having to modify the cam design.   

Edited December 28, 2020 by enabler

[gr5 2,173]

I could talk about this for many hours but the head changer method is the best of all possible dual printing designs I think.  The mark2 for example that works on UMO and UM2 printers here: https://magnetic-tool-changer.com/

Or the e3d-online version.

 

If you have a bowden printer (you probably don't) then you really want to keep the print head as light as possible.  Every gram you add to the print head degrades quality.  The bowden design has plusses and minuses.  The most important plus is that the print head is light.  Adding a servo or solenoid would hurt.  With a feeder right on the print head, now having a solenoid or servo is fine.

 

[enabler 0]

What I like about the dual extruder is the minimizing of time required to travel for a tool exchange.
 

After the first layer, there are two tool changes for each layer of the print.  That’s a lot of additional wear on the machine and the added time for printing.  

 

It seems like having two extruders mounted as closely beside each other as possible would be ideal.  So long as the switching can occur internally while also minimizing overall weight of the assembly.  
 

That Mark 2 looks slick regardless. 

Edited December 28, 2020 by enabler

[gr5 2,173]

The problem with 2 in the same head is that the inactive one always drips a little but Ultimaker got this to work pretty well with really good temperature control where the inactive head cools.  Combined with a tower to get rid of the tiny string/hair/hotdog before continuing the print.

 

So the extra time to change the head is about 3 seconds.  It's not major.  It's usually significant but if you are doing a large print - say a sneaker - that is 5 minutes per layer then it's not significant.  There is also the extra time to heat up the cold nozzle - UM printers have this down so that this time is typically less than 1 second as the nozzle is preheated at the right moment.

 

The wear and tear is small as well.  I've seen printers that have printed 10 kilometers of filament and still going strong.  The extra bit to change nozzles seems to be the smallest issue on a UM3/S3/S5.

 

With the e3d-online changer: https://e3d-online.com/blogs/news/toolchanger-the-update-youve-all-been-waiting-for

you can have 4 filaments (e.g. support material, 2 colors and a flexible material).  Or other tools (paste extruder, level sensor)?

[MTG 8]

Hi,

 

sorry I'm very occupied by work at the time - the printer with printhead is running but thats all 3d-prining stuff I do at the moment. Status on it is unchanged - working fine for me, not really ready for other persons. Sure could put the CAD on GitHub but I would have to check on patents and stuff so I wont get sued. Also the parts are kind of hard to manufacture - advanced cnc-machines are required, so I don't think the design would be accessible for many people.

Thought about making an commercial upgrade kit, but interest does not seem high enough.

 

Yeah, toolchangers are great, but in my opinion it should switch the tools like a cnc machine. In Ultimakers it really sucks that you can't move the printhead out of the buildplate, so a toolchanger will occupy space and its not possible to mount a wiping device and you still have to print prime towers. Yeah I know, the printer would be bigger at the same build area, but a wiping device is really nice and it saves a lot of time if you don't have to do prime towers. Sure for many people thats no issue, but I don't like that. If I would build an fdm printer from scatch it would probably have a toolchanger comparable to cnc milling machines with a magazine of tools. Also I think about working on other technologies like SLS to make that more affordable and less of a mess.

 

I did indeed think of using a servo, but the electronics part is not exactly easy on that because the UM Board is not equipped for that. You would have to find an unoccupied pin and modify a lot in the firmware,. I think its doable, but not easy. Also I did not like the additional weight.

 

On 12/28/2020 at 8:24 PM, enabler said:

After the first layer, there are two tool changes for each layer of the print.  That’s a lot of additional wear on the machine and the added time for printing.  

Actually, thats not true. If you switch the order of printing the filaments in each layer, you have one only toolchange, like -> A,B/B,A/A,B/B,A where "/" indicates the toolchange.

[chanyork 0]

Hello,

 

Would you be able to share the design?  I am using Duet 2 so hopefully software wise may be easier for me.  No need to fiddle around the firmware but just adding extra steps in between tool change.