Filament monitor for UM3/UM3E

[NikThemechanic 0]

@SandervG said they used a mechanical way of sensing the filament. Could you specify what exactly that was? Was it like a limit switch or an optical encoder?

[Labern 774]

it was a AS5048B chip magnetic rotary encoder

[NikThemechanic 0]

Coming back to this. Optical encoders might not be a very good solution to this problem. We have a bunch of Cubepros and the very main reason they breakdown is false error signal from the filament sensor/spool sensor. 

Making the filament detector module monitor the length being used or the length of filament remaining seems unnecessary, atleast for me. 

Having said that, I decided to go with a mechanical limit switch. Ideally, a NC limit switch would simply go off when the end of the filament passes through. This should pause the print. But there are 4 cables currently installed in the ultimaker 3 for filament detection. Could anyone help me figure out how I'd use these 4 cables and connect it to the limit switch such that every time the switch goes off, the print pauses.

Not from an electrical domain, hence the post. 

Thanks.

[tomnagel 126]

It is not so simple. The 4 wires connect to an SPI port in the printer. You cannot connect a simple on/off sensor, and get the behaviour (pause the printer) you want. You will have to create a simple IO connection on the Olimex board, and change the firmware. 

I have experience with electronics, and did some hobby projects with Arduino, but I would not try such a thing. The UM3 is too complex on the inside.

 

[geert_2 557]

I think it is very unlikely that you run out of filament unexpectedly, since before the start of a print you can see how full the spool still is. After a couple of prints, you know how much your models will consume. The risks are rather: a blocked nozzle, filament grinding due to too much retractions, a kink in the filament that can't get through the feeder (I had this once), flexible filament getting stuck in the bowden tube, or something similar. None of these are "end of filament" conditions, so none would be detected by a simple mechanical switch. You would need something that detects motion: a laser mouse (standard mouse sensor only works for opaque materials, not for transparant materials), or a non-slipping rubber wheel and high resolution decoder driven by the filament (which also might not work reliable on smooth oily filament like Ultimaker nylon).

 

[cjs 34]

On 12.1.2018 at 12:59 PM, geert_2 said:

I think it is very unlikely that you run out of filament unexpectedly, since before the start of a print you can see how full the spool still is. After a couple of prints, you know how much your models will consume.

I have to disagree. In the case of one person operating the printers you may be right, but in the case of multiple users and printers it gets tricky.

I think in a lot of cases a simple end stop is enough. Blocked nozzle, filament grinding and filament problems can be solved by using the right profiles,quality filament and the right filament.

Another option would be to save the length on the filament rfid chip and reduce it after printing/every stepper move

On 12.1.2018 at 12:13 PM, tomnagel said:

It is not so simple. The 4 wires connect to an SPI port in the printer. You cannot connect a simple on/off sensor, and get the behaviour (pause the printer) you want. You will have to create a simple IO connection on the Olimex board, and change the firmware. 

I have experience with electronics, and did some hobby projects with Arduino, but I would not try such a thing. The UM3 is too complex on the inside.

. What if you would guide us ? Couldn't you transfer the main shematics of  the ultimaker filament sensor?

[herbw 0]

I am not a mechanical engineer, but here is the approach I would use:

 

I would start with a gravity operated filament sensor in which the filament passes around a roller, causing a weight to be lifted. If filament is not present, the weight would drop. This mechanism would be mounted on a pivot. See diagram:

 

 

I would use an optical switch. The weight would either block or allow light to pass, detecting whether the weight is raised or lowered, thereby detecting whether the filament is present or absent.

 

The optical switch would be much more reliable than a mechanical switch, and the gravity operated sensor should also be reliable.

[NikThemechanic 0]

On 1/12/2018 at 6:59 AM, geert_2 said:

I think it is very unlikely that you run out of filament unexpectedly, since before the start of a print you can see how full the spool still is. 

1

How do we see how full the spool is? I can't see that information on Cura when I prepare my print.

I have never faced a blocked nozzle or any other issue during an ongoing print. We have 7 ultimakers installed in our makerspace and when someone starts a print overnight, it sucks to come back in the morning only to see the printer printing air.

5 hours ago, herbw said:

I am not a mechanical engineer, but here is the approach I would use:

 

I would start with a gravity operated filament sensor in which the filament passes around a roller, causing a weight to be lifted. If filament is not present, the weight would drop. This mechanism would be mounted on a pivot. See diagram:

 

 

I would use an optical switch. The weight would either block or allow light to pass, detecting whether the weight is raised or lowered, thereby detecting whether the filament is present or absent.

 

The optical switch would be much more reliable than a mechanical switch, and the gravity operated sensor should also be reliable.

We had Cubepros in the past and optical sensors they have pretty much gave it the bad reputation it has. Optical sensors gave a bunch of garbage values at times and we pretty much like the mechanical way which is why we preferred the Ultimakers over the Cubepros. Adding a mechanical limit switch is a foolproof way of sensing end of filament. 

[kmanstudios 1,120]

14 minutes ago, NikThemechanic said:

How do we see how full the spool is? I can't see that information on Cura when I prepare my print.

Peek around the back side? Ya gotta go to the printer at some point to get the print, place and clean the buildplate, etc.

 

Or, as I have now configured my print space, my two printers sit on endtable type of things with a polybox underneath to feed upwards into the feeders. I can see how much is there at a glance from the front.

[cjs 34]

7 hours ago, kmanstudios said:

Or, as I have now configured my print space, my two printers sit on endtable type of things with a polybox underneath to feed upwards into the feeders. I can see how much is there at a glance from the front.

Nice setup!

Regarding how much filament is left on the spool: I still think it's quite hard to differentiate 30m to 40m left on the spool and a filament present sensor would be useful. 

[kmanstudios 1,120]

27 minutes ago, cjs said:

Nice setup!

Regarding how much filament is left on the spool: I still think it's quite hard to differentiate 30m to 40m left on the spool and a filament present sensor would be useful. 

No doubt about that, but until we get one, this is whut we gots ta werk wid.....maaaaannnnnn.....

[cjs 34]

Hopefully this will be sometime sooooonish  

It's quite interesting as this is kinda a standard now on cheaper machines like the prusa mk3, zyyx, makerbot and more. 

Normally new technology/features is delivered first with the more expensive machines.  

[kmanstudios 1,120]

If I had to choose between the solid operations and robust engineering over things that can be implemented at a later time, I go with later time.

 

For instance, there was someone who kinda trolled the forums a while back about not having adaptive layering. Now that is becoming a reality. Out of all the things one can choose to implement, it can be dicey to choose which one right away takes priority. Nobody would be happy no matter which direction you go in.

 

Most of those other machines are also not making their own slicers either, so that is an added responsibility they do not deal with.

[foehnsturm 969]

Hi there,

 

There might be an external plug&play flow sensor for the UM2+/3 feeders in the nearer future 

It will detect end of filament as well as grinding and should be capable of monitoring real flow percentage precisely enough for some other (fancy) ideas. 

 

Firmware development right now focuses on the UM2+ for obvious reasons.  

However it'd be very exciting to find a way to integrate this into UM3 printers.

[cjs 34]

@foehnsturm do you mind to share more information? Are you using a laser sensor to monitor movement like Joseph Prusa does on the MK3 ? 

[foehnsturm 969]

No laser, I think it's not reliable enough regarding false alarms. This is the most annoying thing which makes the filament sensor useless as people will finally turn it off. Prusa as well as the Duet3D guys don't seem to be perfectly happy with the reliability.

 

Rotary is the way to go but maybe a little different, bent filament can be a beast.  For further information I've to ask for some patience.

 

Anyway, most encoders offer a quadrature signal which is relatively easy to connect to the UM2 electronics.

As @tomnagel mentioned the sensor originally planned for the UM3 was going to be connected via SPI port. This would be the first obstacle to overcome. And then there is the UM3 firmware ...

Edited March 29, 2018 by foehnsturm