Print Flattening Disk

[shadowfiend 9]

Hi guys,

I have been getting frustrated with sharp corners curling upwards and despite having a semi-working heated build chamber the problem persists. My usual solution is to intervene with an old butter knife to flatten and cool down the plastic, trying to avoid the nozzle as it zooms about.

Then I remembered reading that some of the nice wax printers for jewellery and dental applications have a flattening plate that comes over and smooth’s out the material before moving on to the next layer. This got me thinking.

I could mount a steel washer centred on the nozzle and mounted on the four M3 bolts of the hot end and use fixing nuts to adjust the height away from the nozzle tip, this might do the job for me. Think of it as a kind of circular iron ;c)

So I was wondering if anyone here has any experience of this and if so, what were your findings?

Best regards :c)

 

[tommyph1208 55]

Hi guys,

I have been getting frustrated with sharp corners curling upwards and despite having a semi-working heated build chamber the problem persists. My usual solution is to intervene with an old butter knife to flatten and cool down the plastic, trying to avoid the nozzle as it zooms about.

Then I remembered reading that some of the nice wax printers for jewellery and dental applications have a flattening plate that comes over and smooth’s out the material before moving on to the next layer. This got me thinking.

I could mount a steel washer centred on the nozzle and mounted on the four M3 bolts of the hot end and use fixing nuts to adjust the height away from the nozzle tip, this might do the job for me. Think of it as a kind of circular iron ;c)

So I was wondering if anyone here has any experience of this and if so, what were your findings?

Best regards :c)

 

That actually sounds like a cool idea... I would imagine that the washer gets hot from nozzle heat radiation though, so it wont actually be able to cool all that much... It the end it might only delay the curling...

 

[shadowfiend 9]

Thanks for your reply Tom,

I was kind of hoping that some of the heat may help to flatten out the layers. From my research the ideal temperature would be just below the glass transition point for any given material. If this happens it will be by good luck than good management ;c)

Also I'm experimenting with soldering the washer to some thin steel plate in order to mount it on the hot end blots. This will act as a heat sink, so it 'should' not get too hot.

I'm hoping to get some pictures of the design posted soon.

Oh and by the way, I will need to remove the cooling duct at the moment, but if this works, I might not need it :c)

Cheers,

Ian.

 

[tommyph1208 55]

You might also want to look into insulating the heater block/top part of the nozzle... Not only does it reduce the heat radiation but also helps the nozzle reach temp much quicker, and keep it more stable (takes longer to cool down as well though)...

Ive had great success using ceramic "tape"... Something like this (I got a roll of it somewhere, cant remember): http://www.ebay.com/itm/MakerBot-Replicator-2-Ceramic-Insulation-Tape-6-Pack-/261710227470?pt=LH_DefaultDomain_0&hash=item3cef25280e

Wrap it to the heater block with kapton tape...

Regarding the cooling, you might want to look into "The crossflow fan approach" as discussed here on the forums:

http://umforum.ultimaker.com/index.php?/topic/3890-the-crossflow-fan-approach/?hl=%2Bcrossflow+%2Bfan+%2Bapproach

 

[shadowfiend 9]

Update!

I have drawn up the designs and have built version 1 of the Print Flattening Disk! However, there are some issues.

I must have got some dimesions wrong beause when I assembled all the parts the washer plate and washer were touching the nozzle. Also the printed brackets could do with being a bit taller, but I tried a test print anyway and found that the washer was pulling too much heat from the nozzle and warming up the parts being printed, resulting in a bit of a mess.

Tom, I might invest in some Kapton tape and the ceramic tape you mentioned. The crossflow fan approach is very interesting and I have looked into this before, this flattening disk is a kind of side-step idea, but my main plan is to emulate the way the commercial printers work with the chamber heated to 70 degrees C. I have been on with this for months!

Picures to follow, possibly video :c)

Cheers.

 

[shadowfiend 9]

Here are some pictures, please let me know your thoughts.

CAD designs

 

 

 

All attached to the hot end

 

These are my first results

Ok so print No 1 was binned because the washer was touching the nozzle and everything got too hot and ended up a right mess. I made some modifications to the metal parts and ground down the hole in the washer plate to open up the clearance and the temperature was much better.

To attach the washer to the steel plate, I was going to try to solder it, but that proved a bit tricky without flux :c) so I ended up using some scraps of ColorFabb XT and heating it up on the gas stove. This worked really well and much cheaper than epoxy!

I can adjust the height by turning the pairs of nuts on each hot end bolt and I found that about .2 or .3mm above the bottom of the nozzle seems best so far. I am not using a heated bed, fans or any other heating. I'm using ColorFabb XT at 242C at 50mm/s. The prints are by no means perfect, but the washer really does keep the corners from lifting up and everything stays flat.

If I go less than .2mm the washer eventually starts dragging the plastic about causing dents in the side of each part and eventually a squeaking sound as the washer presses too hard against the plastic. This could be because I'm not currently using any fans though.

I'll keep you posted on any developments. :c)

 

[shadowfiend 9]

I have been doing some tests and have come to realise that Tom was correct:-

 

I would imagine that the washer gets hot from nozzle heat radiation though, so it wont actually be able to cool all that much... It the end it might only delay the curling

 

On the first few layers the washer is cool and works well to flatten any corners that dare to lift up. However as the washer heats up, it also starts heating up the plastic under it and it also becomes more sticky which is why I'm getting this dragging effect.

So I have decided to to make a water cooling ring from copper tube and solder it to the washer plate.

New design for copper pipe cooling ring :c)

 

This was my first attempt at making a cooling duct, but dicided to scrap it because it would be dificult to seal it water tight.

 

Can anyone please tell me if I can run a water pump from the hotend fan power cable?

 

Many thanks.

 

[shadowfiend 9]

I have ordered some bits from ebay so that I can make a start on the cooling duct, but I would like to be able to control the water pump as if it was the hot end fan. I'm not that experienced with electronics and would apperciate if anyone could offer advice on how to do this.

I don't need anything fancy like temperature control, just a way to vary the speed from the cooling parameters in Cura. Hell even if it is just on or off would be ok.

Many thanks.

 

[aviphysics 9]

I have been doing some tests and have come to realise that Tom was correct:-

On the first few layers the washer is cool and works well to flatten any corners that dare to lift up. However as the washer heats up, it also starts heating up the plastic under it and it also becomes more sticky which is why I'm getting this dragging effect.

So I have decided to to make a water cooling ring from copper tube and solder it to the washer plate.

New design for copper pipe cooling ring :c)

This was my first attempt at making a cooling duct, but dicided to scrap it because it would be dificult to seal it water tight.

Can anyone please tell me if I can run a water pump from the hotend fan power cable?

Many thanks.

 

The fan is just powered from a simple transistor that is right next to the fan header. I believe it is the main limiting factor in the current you can draw. When I get home, I can look up the part number.

I wonder if water is really necessary. You could try pumping air with an aquarium air pump. Water just seems like a mess waiting to happen. At work we use neumatics for cooling parts inside a vacuum chamber. They work pretty darn well and a small leak doesn't destroy the system.

For water cooling, I would suggest that you solder a copper tube to the top of your plate. Would be easier if they are both copper.

[shadowfiend 9]

Thanks for your reply aviphysics.

I have ordered this 12V pump from ebay:-

http://www.ebay.co.uk/itm/171555075839?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

Rated voltage: 12V DC

Max rated current: 400mA

Static flow rate: 240L/H

From what I read on the forum I think it should be ok, but I will bow to any information to the contrary ;c)

I did consider air cooling but I thought that there may be excessive noise and was unsure if it would be efficient enough to cool the part. It's all guesswork at the moment.

I take your advice about the risks of water leaks seriously and will proceed with caution. However I have already bought most of the bits I need, so I'm going to keep going the water cooling route for now.

Regarding the soldering, this will be a make or break for the project as I am trying out new things. I know that flux is the key to getting the solder to flow properly and getting the parts all lined up is going to be a challenge. I read somewhere in the forum that in order to bend the copper pipe without kinks, you can fill it with sand and this will minimise the localised stresses.

I'm just waiting on the parts to arrive now so I'll let you know how I get on.

Cheers.

Ian.

 

[aviphysics 9]

The sand thing sounds cool.

For thin copper tubing, I bet you might be able to get away with printing a pipe bender, or just buy one.

For soldering, I would look at how plumbers do it and do it that way. That is the same as the way I have scene the pros do it for this kind of stuff. The only difference is that you are soldering the sides together instead of the ends.

[shadowfiend 9]

Apparently you can also use salt or fill with water and freeze it. In the end it was quite ease to bend by hand. I used an old bit of PLA that was just the right diameter for the tight bend. I also annealed it a couple of times which made it easier to bend. A printed bending rig would be brilliant :c)

I changed the shape to make it easier to attach the silicone tubing.

 

I have looked at a few plumbing videos and also tested the flux out on some scrapps and it seems to work well. I'm going to solder it today :c)

 

Will keep you posted.

 

Cheers.

 

[shadowfiend 9]

Progress has been made :c)

I Used some gardening wire to secure the 3 parts before soldering.

 

I covered everything in flux before holding the part over the gas stove and the solder flowed quite nicely :c) Not bad for my first attempt :cp

 

Cleaned up a bit.

 

All assembled and just waiting for the silicone tubing a water pump.

I warmed up the printer to 242C just to see how hot the parts got and it did get very hot, but I think the water cooling will bring the temperature right down to useful levels :c)

I'm hoping to get some video when it's all up and running, but it's going to be difficult to get decent close up shots, we'll see :c)

Cheers.

Ian.

 

[neotko 1,417]

Maybe a easier (not better ofc) approach could be using the aluminum that comes with the UMO+ and make it stay just 0.1mm (or lower) above the nozzle. With just some head sinks attached inside the cool should be ok. I mean on my UMO+ the aluminum after 8h of printing never goes beyond 50ºC (at least that's what my thermal camera says). One advance it's that it's already 'leveled' with the structure, so it should be flattening/cooling the printed results. The problem probably it's that if it don't works it will literally send the print flying

The only problem I see on your idea it's that unless the nozzle it's ptfe/klepton insulated the pla/abs inside the nozzle head 'should' cool and block.

 

[shadowfiend 9]

Hi Neotko,

As my machine is the UMO I did'nt have this option, also the washer that I made has been carfully ground very flat on a dimond sharpening stone and the edges rounded off. I suspect that the UMO+ shroud would get caught on the print as you say :c)

Unfortunately I'm having a problem with the water pump at the moment. Let me try to explain.

I have connected the pump to the cooling fan power and it runs fine and I can control the speed from Cura, but there seems to be some interferance with the temperature sensor when the pump is running. I have tried changing the firmware via this utility:-

http://marlinbuilder.robotfuzz.com/

I changed the 'Increase PWM frequency' to 'off' and 'on' and I'm still getting the problem.

Does anyone know if 'Increase PWM frequency' is the same as 'fast PWM'? I'm Drawing a blank on this one.

I will be able to test if the nozzle will get cooled too much after I fix this problem, but there is a small gap between the copper pipe and the nozzle. If there is a problem I'll buy some insulation :c)

Many thanks.

Ian.

 

[aviphysics 9]

I know the default UMO hot end fan PWM frequency is 30 kHz. Could you try using a separate power supply?

[shadowfiend 9]

Thanks Avi,

How does one go about changing the PWM frequency? I couldn't see that option on the robotfuzz web application.

I was hoping that I could run the water pump just like UM cooling fan, start stop and speed control. I might try to dig out an old transformer to power it though.

Cheers.

 

[aviphysics 9]

I don't know how to change it. I just measured it with an oscilloscope a while back.

I do however have my doubts that changing the pwm freq will resolve the issue.

I was thinking you could at least test an external power supply. If that resolves the issue, than we can put more effort into electrically isolating the pump, while still controlling through Marlin.

[shadowfiend 9]

That sounds like a a plan Avi, good thinking.

I'll report back soon to let you know how I get on.

Many thanks :c)

Ian.

 

[shadowfiend 9]

I figured out what the problem was :c)

It was caused by proximity of the wiring to the pump to the thermocouple. Being lazy just to test it, I just plugged the pump into the socket where the fan goes. I've now got the pump plugged into the UM mainbord and zero interferance!!!

Result :-P

Now comes the plumbing bit, which should be interesting and I can the do a test print :cool:

Cheers,

Ian.