Heated Build Chamber; Flip stepper motor direction

[pauldutch 0]

People,

Over the last while I have researched how "professional" FDM printers prevent warpage and they all seem to prefer the "heated build chamber" approach. Now, I know that Stratasys hold the patent for it (How they got approved such a generic beats me..) and I think that that is the reason why people stay away from it.

But I do think that best results are achieved with a heated build chamber so I'd like to incorporate it in my UM.

I reckon that cooling off layers with a fan as they get built is counter productive. It is a bad fix to make up for not having a proper support material. Since my UM has dual extrusion I think the Heated Chamber is the way to go. A support material fixes the overhang and bridging issues where a fan would be needed otherwise. A cooling fan only makes warping worse.

To heat the Build Chamber I'd need to flip the XY stepper motor to sit outside the build chamber otherwise they'd get too hot. It seems to be an easy exercise, but if flipped they run the axis opposite towards where they would normally go.

Does anyone here have an easy solution to swapping the motor direction? Ie. which wires would I have to swap around?

The extruder motor in an UM luckily is already outside the chamber. Only issue would be to try and cool the Bowden Tube to prevent the filament from softening. A secondary sleeve with blown cool air should do the trick.

[joergen 1]

I put my steppers on the outside... To reverse direction, i swapped the left pair if wires with the right pair of wires

[pauldutch 0]

Aha! Thanks Joergen for your input. So just a straight swap? Does it matter if the order of the wires in the pairs are swapped?

[joergen 1]

Aha! Thanks Joergen for your input. So just a straight swap? Does it matter if the order of the wires in the pairs are swapped?

yes, it matters (at least it mattered when I did the swap), just swap the left and the right pair, but keep the direction of each pair intact.

when you are done. move the head into the middle, and use the Ulticontroller in 10mm steps, to verify they move into the right direction.

[destroyer2012 0]

Alternatively, just swap the axis direction in the firmware.

I have done a similar thing in that I have enclosed my ultimaker completely using cut up oven bags to keep the warmth from my heated platform in. I think it definately helps, at least with PLA. I think the fan is still important because what you want is to quickly cool the plastic down to the ambient temperature inside the chamber. Commercial printers do this by basically being a convection oven.

So you could keep the fan around the nozzle or mount a big fan on the bottom that blows all around the inside. You definitely don't want your plastic to stay molten after it gets extruded or else it will sag/move around after being printed.

[joergen 1]

Alternatively, just swap the axis direction in the firmware.

Yes, but then you have to remember doing this every time you upload a new firmware. switching the wires is a onetime thing.

[pauldutch 0]

Cheers Guys for your feedback.

I will try and swap the wires.

The firmware update seems easier, but will have to remind myself to do it every time I update firmware.

This patent of Stratasys is a good guide when building a heated build chamber:

http://www.google.com/patents/US6722872

It says that the heated chamber really should be between 70-90 degC for ABS and all the steppers etc should be outside of it.

I reckon that the uM is idealy made to convert to this, apart from the structure being made of wood.

Just swap the motors to the outside and all that is really left is to make sure that the bowden tube gets cooled.

Perhaps wrapping insulation around it plus blowing cooler air into the tube would work.

Ideally the PCB underneath should be transferred to the back with some insulation in between.

Quick fix obviously is a heated bed, but seems to me that that is only half of the solution..

[joergen 1]

Cheers Guys for your feedback.

I will try and swap the wires.

The firmware update seems easier, but will have to remind myself to do it every time I update firmware.

 

Totally up to you... I personally don't see much difficulty swapping the wires

 

This patent of Stratasys is a good guide when building a heated build chamber:

http://www.google.com/patents/US6722872

It says that the heated chamber really should be between 70-90 degC for ABS and all the steppers etc should be outside of it.

I reckon that the uM is idealy made to convert to this, apart from the structure being made of wood.

Just swap the motors to the outside and all that is really left is to make sure that the bowden tube gets cooled.

Perhaps wrapping insulation around it plus blowing cooler air into the tube would work.

Ideally the PCB underneath should be transferred to the back with some insulation in between.

As with all patent stuff, don't think about commercializing it... You will get away with personal use.

You don't need to cool the bowden... Remember the Tg of ABS is 110C, and since the chamber is way below that, you don't have any problems. Heat rises, so the electronics underneath should be fine as well. You could use a hairdryer and yet another TC/PiD/SSR to make a quick heater for the chamber, a frame to cover the top, and to hold the material you are planning to use to seal the sides (turkey oven foil?)...

But, you have tried, and a heated bed in conjunction with brim and pads doesn't work for you?

[am001 0]

Hi,

I enclosed my Ultimaker, and just using the heated bed at 70deg for ABS or 50deg for PLA is plenty enough to keep the distortion down. I haven't moved my steppers anywhere, Yes they are at about 50deg, but they were anyway and that's well within their operating range, and they haven't caused any problems.

The air in the build area is about 40-45degC and this completely eliminates cracking and de-laminating such that I can build an ABS model to the fullest size of the machine without problems. I highly recommend it. My enclosure is simply bubble wrap and sticky tape. One day I'll make something more permanent, but it works so well that there isn't really much incentive to mess with it.

One thing I do suffer with is stretching belts. I suspect that the higher temperatures makes this problem worse. Something to look out for. Anyone have a source of higher quality reinforced belts in the UK/EU?

Have fun

Andrew

[pauldutch 0]

Thanks guys for the feedback!

Yesterday I have swapped my stepper motors to the outside of the UM and it is working fine.

I have swapped the pairs of wires around as suggested and it works perfectly. The wires to the connector are easy to push out and in again, so permanent swapping is no problem.

Today or tomorrow my heated bed will show up that I bought from Ebay and in the meantime I will enclose the sides and figure out what power supply to use for the heated bed.

In essence it will have upgraded the UM to be similar to the MB replicator 2X without too much extra effort.

[joergen 1]

Hi,

I enclosed my Ultimaker, and just using the heated bed at 70deg for ABS or 50deg for PLA is plenty enough to keep the distortion down. I haven't moved my steppers anywhere, Yes they are at about 50deg, but they were anyway and that's well within their operating range, and they haven't caused any problems.

The air in the build area is about 40-45degC and this completely eliminates cracking and de-laminating such that I can build an ABS model to the fullest size of the machine without problems. I highly recommend it. My enclosure is simply bubble wrap and sticky tape. One day I'll make something more permanent, but it works so well that there isn't really much incentive to mess with it.

Can you please elaborate a little bit on your findings?

What surface material are you using that allows a bed temperature of 70C, since glass needs 115C-ish, for ABS prints (and 70C for PLA)?

What cooling profile (fan power) and min layer time are you using?

[am001 0]

Hi,

The heated bed is 6mm aluminium, with Kapton tape. I started with 3mm, but couldn't get it flat enough so I had to go thicker.

&0deg seems optimum for ABS, any higher than 90deg, and it shows some distortion between 2 and 4mm up into the part, as presumably that is where the higher temperature reaches. At 70deg it is straight.

I spent a long time figuring this out for exactly the reason you mention, all the published figures are over 100deg. My only conclusion is that these high numbers are for glass surfaces, and the top of the glass is not actually that hot, only the base where the thermistor and heater are.

I don't use a fan at all for ABS, and for PLA if I have something with significant overhangs, I use the on for loops setting in Kisslicer.

Andrew

[joergen 1]

Hi,

The heated bed is 6mm aluminium, with Kapton tape. I started with 3mm, but couldn't get it flat enough so I had to go thicker.

&0deg seems optimum for ABS, any higher than 90deg, and it shows some distortion between 2 and 4mm up into the part, as presumably that is where the higher temperature reaches. At 70deg it is straight.

I spent a long time figuring this out for exactly the reason you mention, all the published figures are over 100deg. My only conclusion is that these high numbers are for glass surfaces, and the top of the glass is not actually that hot, only the base where the thermistor and heater are.

the main difference is Kapton, probably, since ABS will not stick to glass under 110C. if you don't have glass, then the heater core temp is pretty much equal to the top of the kapton tape.

I measure my temperature with a TC on the top glass surface, since the top surface needs longer to reach temp than the heater core, for obvious reasons, and I like my measurements to be very very accurate.

but good to know that ABS straight to kapton needs lower temp. can you confirm the 70C works without the chamber as well?

[pauldutch 0]

That's odd..

I am sure all of you have seen the new 3DS printers, the improved Cube and the CubeX.

Both able to print ABS..

BUT.. no heated bed or enclosed chamber?

From

http://fabbaloo.com/blog/tag/3d-systems#.UPNV02-R949;

"We asked 3D Systems Rajeev Kulkarni how the Cube can print ABS successfully when it no longer has a heated build platform? Why doesn't the ABS warp? Kulkarni explained they've changed the formulation of the plastic and combined with software changes ABS warp is reduced significantly. And the glue you apply to the print bed helps, too. "

Anyone got any experience with the new Cibe printers to confirm warpage with ABS??

And what's in the CubeStick glue?

[am001 0]

Hi Joergen,

Yes the 70 works the same without the chamber, but there is of course more distortion.

I generally wipe it clean with acetone before printing but that is all.

Mine is controlled with a 100k thermistor pushed into a small hole in the aluminium.

[joergen 1]

I generally wipe it clean with acetone before printing but that is all.

Hmm, I think you should not hide such mission critical info all the way at the end. If you wipe down with acetone, you are leaving a very thin film of ABS in the kapton, which is basically the ABS juice method.

[am001 0]

I'm not sure that it is so significant, the heat level, z calibration and the thickness of the first layer are much bigger factors. If I forget to wipe it over then I don't see a big difference, and if I put fresh Kapton on, I don't need to add 'juice'.

A.

[cora111 0]

Hi. I'm still not sure which cables have to be swapped.

One stepper motor has 2 cable pairs with 2 wires each of them. Red/Blue and Green/Black.

Which cables/wires do I have to swap?

[pauldutch 0]

Hi. I'm still not sure which cables have to be swapped.

One stepper motor has 2 cable pairs with 2 wires each of them. Red/Blue and Green/Black.

Which cables/wires do I have to swap?

I swapped the cable pairs but left the order of each cable pair as they were..

Ie.. If from left to right the plug is: Red-Blue-Green-Black

This will then become: Green-Black-Red-Blue..

[cora111 0]

Thanks Paul, my stepper motors work like a charm - now outside of the case.

[pauldutch 0]

Wonderful!