Mini wind barrier and stepper motor platform mod

Post improvements made for UP, and share ideas.
jeeplvr
Posts: 212
Joined: Sat Jun 08, 2013 5:26 am

Mini wind barrier and stepper motor platform mod

Post by jeeplvr » Thu Jan 16, 2014 4:50 am

My intent was to lower the extruder motor temperature to help stop some of the filament jam problems I am having. Here is the data I logged during the test.
Extruder stepper motor temperature taken after 1 hour of printing with all the covers off and door open. Same model printed for each test at layer 20.
Original stepper motor platform.
55-58c fluctuating.
*Stepper motor platform modified with air holes.
47-50c fluctuating.
Stepper motor platform with improved wind barrier sealing.
54.7 c steady.
New wind barrier design.
48.7 c steady.
New wind barrier design and **fan air flow reversed.
48 c steady.
*Perforating the stepper motor platform seem to have made the most difference.
**Reversing the fan seems to make no difference.
STL files are on thingiverse here http://www.thingiverse.com/thing:227206

roller
Posts: 1622
Joined: Sat Oct 06, 2012 9:09 pm
Location: Brisbane, Australia

Re: Mini wind barrier and stepper motor platform mod

Post by roller » Thu Jan 16, 2014 2:35 pm

The main thing to focus on is the temp of the extruder gear itself which you may find is a little cooler. If you are looking to print with any common PLA you really need to get to 40C or under. Many PLAs soften at 45-50C. It's tough. With air injection (fishtank pump) I get about 8C above ambient (28C-34C in my studio). With Peltier and heatsink ... well choose your temp ... but I its a bit more of a project and not really worth it.

So ... it would be good if you can work out a way to get enough cooling to get down to 40C.

jeeplvr
Posts: 212
Joined: Sat Jun 08, 2013 5:26 am

Re: Mini wind barrier and stepper motor platform mod

Post by jeeplvr » Fri Jan 17, 2014 5:48 am

roller wrote:The main thing to focus on is the temp of the extruder gear itself which you may find is a little cooler. If you are looking to print with any common PLA you really need to get to 40C or under. Many PLAs soften at 45-50C. It's tough. With air injection (fishtank pump) I get about 8C above ambient (28C-34C in my studio). With Peltier and heatsink ... well choose your temp ... but I its a bit more of a project and not really worth it.

So ... it would be good if you can work out a way to get enough cooling to get down to 40C.
The heat comes from the motor so I figured lowering the temperature of the motor would lower the temperature of everything associated with it. Its hard if not impossible to get a direct shot with the temperature gun on the gear itself. It seems to work much better now and I am even getting sucessful prints with the bad filament. Nothing is more frustrating than getting a third of the way more or less through a print and having to scrap the model because of a jam.
The wind barrier redesign moves some of the hot exhaust air away from the fan intake.

roller
Posts: 1622
Joined: Sat Oct 06, 2012 9:09 pm
Location: Brisbane, Australia

Re: Mini wind barrier and stepper motor platform mod

Post by roller » Mon Jan 20, 2014 3:38 am

Yes. In repraps we dial back the current on the stepper to cool it right down ... or never face the problem by having indirect drive which stops conduction of heat. For a long time I focused on cooling the stepper but without some active cooling I could not cool it enough to keep the extruder gear cool. If we could thermally decouple the extruder gear from the stepper we would be sorted.

jeeplvr
Posts: 212
Joined: Sat Jun 08, 2013 5:26 am

Re: Mini wind barrier and stepper motor platform mod

Post by jeeplvr » Mon Apr 14, 2014 3:59 am

I have designed a new bunch of extruder plastic that will allow me to fully expose the stepper motor and add another fan and possibly a heat sink. have no idea if it will work yet but I am so tired of the filament jamming during prints that I will try anything before I replace the entire extruder assembly.
assembly2.JPG
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assembly1.JPG
assembly1.JPG (58.17 KiB) Viewed 17514 times

caesar
Posts: 64
Joined: Sat Feb 22, 2014 1:32 am
Location: Romania

Re: Mini wind barrier and stepper motor platform mod

Post by caesar » Mon Apr 14, 2014 1:46 pm

Watching you closely for news.

I just burnt my finger when I touched the stepper motor after a 3h print. Anything to get down that temp would help (besides opening enclosure).

Are they really supposed to run at over 50-60C?
Maybe current through them is a little too much or even more than needed?
Anybody tried to lower current through motors?
I'm afraid that they will fail right after warranty expires...

jeeplvr
Posts: 212
Joined: Sat Jun 08, 2013 5:26 am

Re: Mini wind barrier and stepper motor platform mod

Post by jeeplvr » Mon Apr 14, 2014 9:20 pm

One of the things I forgot to mention was that I opened up a passage for heat to escape from the extruder gear. The gear is nearly completely enclosed in the factory configuration. I will have to drill a few small holes in the small gear enclosure to utilize the passage in the stepper platform.
stepper mount.JPG
stepper mount.JPG (83.65 KiB) Viewed 17492 times

jeeplvr
Posts: 212
Joined: Sat Jun 08, 2013 5:26 am

Re: Mini wind barrier and stepper motor platform mod

Post by jeeplvr » Mon Apr 14, 2014 9:27 pm

Its an electrical motor and the cooler the better. There is really no cooling other than convection. The fan setup on the front of the assembly is nearly useless. Like roller said, the gear gets too hot and melts the filament. The only way to fix this problem is to cool the gear or remove enough heat from the stepper that the stepper doesn't transfer its heat into the gear. Also the hot end is directly below the stepper and this has to add to the heat problem. I have some thin header wrap material that I want to make a shield out of. I really don't have a lot of problems with small models it just with the larger models. The Mini just print big with out some sort of problem.

jeeplvr
Posts: 212
Joined: Sat Jun 08, 2013 5:26 am

Re: Mini wind barrier and stepper motor platform mod

Post by jeeplvr » Tue Apr 15, 2014 9:19 pm

Here are some pictures of the results
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Last edited by jeeplvr on Tue Apr 15, 2014 9:28 pm, edited 1 time in total.

jeeplvr
Posts: 212
Joined: Sat Jun 08, 2013 5:26 am

Re: Mini wind barrier and stepper motor platform mod

Post by jeeplvr » Tue Apr 15, 2014 9:25 pm

More
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Last edited by jeeplvr on Tue Apr 15, 2014 9:30 pm, edited 3 times in total.

jeeplvr
Posts: 212
Joined: Sat Jun 08, 2013 5:26 am

Re: Mini wind barrier and stepper motor platform mod

Post by jeeplvr » Tue Apr 15, 2014 9:26 pm

And more,
DSC02441.JPG
DSC02441.JPG (36.64 KiB) Viewed 17456 times
Exposed gear
DSC02442.JPG
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Last edited by jeeplvr on Tue Apr 15, 2014 9:31 pm, edited 2 times in total.

jeeplvr
Posts: 212
Joined: Sat Jun 08, 2013 5:26 am

Re: Mini wind barrier and stepper motor platform mod

Post by jeeplvr » Tue Apr 15, 2014 9:27 pm

Last one
DSC02450.JPG
DSC02450.JPG (60.89 KiB) Viewed 17456 times

jeeplvr
Posts: 212
Joined: Sat Jun 08, 2013 5:26 am

Re: Mini wind barrier and stepper motor platform mod

Post by jeeplvr » Tue Apr 15, 2014 10:46 pm

Here it is on Thingiverse
http://www.thingiverse.com/thing:300335

roller
Posts: 1622
Joined: Sat Oct 06, 2012 9:09 pm
Location: Brisbane, Australia

Re: Mini wind barrier and stepper motor platform mod

Post by roller » Wed Apr 16, 2014 7:43 am

caesar wrote:Watching you closely for news.

I just burnt my finger when I touched the stepper motor after a 3h print. Anything to get down that temp would help (besides opening enclosure).

Are they really supposed to run at over 50-60C?
Maybe current through them is a little too much or even more than needed?
Anybody tried to lower current through motors?
I'm afraid that they will fail right after warranty expires...
60C should be ok and not take too much out of the life of the stepper motor itself and they are easy to replace with an aftermarket part. The issue is they need to be pushing every once of torque out of that little stepper because of the direct drive design and the fact they chose such a small stepper. Most open sources printers either use a gearbox to increase the torque from these little NEMA14s (like Makergear) or use a bigger NEMA17 motor which naturally has more torque. This allows the motor to run on less currently and therefore cooler.

I can't help but wonder if a stainless steel extruder drive gear would be a sufficient solution - being a poor enough conductor that it doesn't push sufficient heat into PLA to melt it.

PS and good work on the subsequent experimentation.

caesar
Posts: 64
Joined: Sat Feb 22, 2014 1:32 am
Location: Romania

Re: Mini wind barrier and stepper motor platform mod

Post by caesar » Wed Apr 16, 2014 1:16 pm

roller, I get it. I will try and use it as much as possible until it makes 1 year.
Regarding the stainless drive gear, I doubt it. The shaft of the stepper is still made in stainless steel and the temperature is also creeping through it and through the whole stepper motor.




Nice one, jeeplvr.

I wonder if printing a spring loaded mechanism for the ball bearing using the highest temperature material (will have to look at something even better than ABS for this) could solve the probelem?


I just took my extruder apart today (had some failed prints), cleaned the drive gear and applied two tapes of kapton on the stepper, under the radiator, before tightening it all back together. Will see how this works out and if it helps even a little bit.

jeeplvr
Posts: 212
Joined: Sat Jun 08, 2013 5:26 am

Re: Mini wind barrier and stepper motor platform mod

Post by jeeplvr » Wed Apr 16, 2014 11:14 pm

I have printed a number of models after these modifications and it seems to be better. I tried to print the full print board sized model and got about 2/3 of the way through before jamming the filament. Before I tried several times to print this model and couldnt get it to print more than a 1/4" tall before it jammed.

jeeplvr
Posts: 212
Joined: Sat Jun 08, 2013 5:26 am

Re: Mini wind barrier and stepper motor platform mod

Post by jeeplvr » Fri Apr 18, 2014 11:20 pm

I waited to post this one. I have been printing almost non stop for 24 hrs. and not one jam. I removed the small brass filament guide tube from the heating element and opened up the entrance with a small centering drill. If you don't know what a centering drill is, it is a tapered drill bit for use on a lathe to drill a tapered hole in the end of a shaft for the lathe centering support mechanism. The entrance of the brass guide is the point where the filament jams every time on my machine. With the centering drill I basically doubled the chamfer diameter and depth of the original chamfer. The combination of the plastic mods and increased chamfer has , for now, solved the problem of filament jamming. I am currently using the plastic parts shown above above but have redesigned them once more. I will post the newest design once the printed model is done.

jeeplvr
Posts: 212
Joined: Sat Jun 08, 2013 5:26 am

Re: Mini wind barrier and stepper motor platform mod

Post by jeeplvr » Sat Apr 19, 2014 1:21 am

Pictures
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Last edited by jeeplvr on Sat Apr 19, 2014 5:58 am, edited 2 times in total.

jeeplvr
Posts: 212
Joined: Sat Jun 08, 2013 5:26 am

Re: Mini wind barrier and stepper motor platform mod

Post by jeeplvr » Sat Apr 19, 2014 1:23 am

more
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jeeplvr
Posts: 212
Joined: Sat Jun 08, 2013 5:26 am

Re: Mini wind barrier and stepper motor platform mod

Post by jeeplvr » Sat Apr 19, 2014 1:25 am

and more
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