meh. Not gonna try the SSR. they are expensive Mosfets would be the way. buying some 2.5 miliohms mosfet for the extruder and some super low 1.2 milliohms mosfet for the heatbed. the 1.2 mOhms ones are expensive :/

if anyone is interested, the cheaper 2.5 mOhms mosfet is IRLB8743PBF (http://my.element14.com/international-rectifier/irlb8743pbf/mosfet-n-ch-30v-78a-to220/dp/1740785) roughly RM 5 each

the better 1.2 mOhms ones are IRLB3034PBF (http://my.element14.com/international-rectifier/irlb3034pbf/mosfet-n-ch-40v-195a-to220/dp/1698299) roughly RM 14 each.

The current one i have on the RAMPS board is 18 mOhms. So its a big difference.

This post has been edited by izzudinhafiz: Jun 27 2015, 04:56 PM

Either MOSFETs should work as long as the gate turn-on voltage threshold is below 5v (its 1.8v and 2.5v for the two). To keep cost low, I would recommend the IRLB8743PBF (2.5 mOhms) which is good enough for reprap use and does not necessarily require a heatsink to keep cool. The thermal power loss would be about 7 times less compared to your existing one.

You can calculate the thermal power loss of a MOSFETs by following the example at: http://reprap.org/wiki/Basics_about_switch...ds_with_MOSFETs

Obviously you can reduce thermal power loss by about 14 times with the IRLB3034PBF (1.2 mOhms) but the two MOSFETs would heat up to roughly to the same temperature and it cost 3 times more. Just my 2 cents.

Yeah maybe you're right. I'll only get the IRLB8743 only. Get three of em and replace all 3 MOSFETS on my RAMPS.

Good luck!

Just ordered the new MOSFETS. Will let you know if it fixes it

BTW anyone else with high temperature problem MOSFETS should read this

http://reprap.org/wiki/Gen7_Research

There's a correlation between PWM switching frequency on the MOSFETS and the heat ouput. The lower the switching frequency the lower the temp.

A suggested fix is for high load system (ie the heatbed) the Bang-Bang method is more suitable rather than the PID which switches at really high frequecny

Guys!

I bought a new extruder which has a longer j-head compare to my previous extruder (almost twice the length). This has reduce the printable area for the z-axis by quite a lot. Is there anything i can do to reclaim those printable area?

Thanks in advance.

you can move up the extruder mounting higher to reclaim the space. What kind of printer and extruder setup is it?

P/S: if you have the original extruder STL file i can edit it for you to move the mounting holes. (there is a limit of how high you can go before the weight of the extruder becomes a huge enough lever that the mounting would bend)

This post has been edited by izzudinhafiz: Jul 9 2015, 05:29 AM

Hi bro,

Thanks for the help in advance! That is what i like about this little small community of ours. Everyone is willing to help each other to keep the community growing.

Anyway, im using a Blomker Prusa i3. The STL can be found here. The new extruder which i bought is similar to this.

Once again thanks in advance.

P.S. By the way, anyone know if there is a way to remove a broken barrel from a j-head?

Good news, the change of MOSFET has done alot to fix my issues. The MOSFETS now are at 56 degrees celcius at LOAD. Which is nothing for the MOSFET running 11 Amps to power the heatbed.

I would recommend anyone to change their MOSFETs. You can buy it at element14, and they dont charge delivery (well they dont for me).

Also the heatup time has been reduced dramatically. Before this it took me roughly 7 mins to get to full heat, now its 1 min 20 seconds. Im super happy about it. Also now with the reduced heat (and therefor less resistance on the MOSFETs) the stepper drivers also seems to have reduced in temp. Before this it was averaing 70 celcius. Nowadays its at 52. I've been running without fan on the controller boards since before but this is remarkable.

P/S: my room temp is at 22 celcius with the aircond on

where can i buy abs filament here in malaysia?

you can contact Blomker. He sells them

or Lelong. there are a few seller

Finally back from an event and I am surprise to see some on going activity here.

About your broken barrel (or was it melted barrel?), you can use a spanner on the j-head heating block and a large pliers on the barrel to dismantle them.



Good report on the MOSFET mods, I didn't think the MOSFET change could have an effect on the entire Ramps board.


Lelong? I always thought there were lots of dishonest sellers and scammers at Lelong.

The barrel practically snapped into 2. I will snap a picture later when i return home from work.

Thanks again.

any other suggestion bro? i open to other member suggestion,

from the day i received my printer i not yet successful finish 1kg of abs since the bad experience with abs that i received with my printer, so i think i want to try printing with abs

are rm90 include shipping to sarawak is best price for abs 1kg?

This post has been edited by Prosperer: Jul 14 2015, 09:12 PM

you can try PLA. they are easier to print and i assure you its less headache.

how are you unable to print ABS? I;ve just started my first roll of ABS and as far as that goes my experience is print on Kapton tape at 110C and 240C on the hotend. the 110C bed temp helps adhesion, and if you still fail, turning on brim can help really well against lifting on the edges.

240C on the hotend is so i get better bonding between layers of ABS. I tried 220 and 230, but layer strength isnt so good.

RM90 is about okay, Blomker sells for 90 as well not including shipping, i think its 10 bucks for shipping to semenanjung. I suggest Blomker because he is trusted and his materials are okay. Customer support also top notch and he's local. (helps alot when we have local suppliers so i try my best to support him!)

@altan , the reduction in stepper temp is probably on the reduce heat from the mosfet. When mounted on the printer, the Mosfets are below the stepper so convection probably bring the heat up to the stepper drivers. since the Mosfets were at 100C-ish before, that is alot of heat. (btw how do you reply to multiple people in a single post?)

Btw anyone know any reason as to why my hotend jams mid print? Both PLA and ABS. tried increasing Temp, didnt work. The motor didnt seem to skip and there wasnt any filament grinding. I let off pressure from the idler bearing and let go again and it continued printing like nothing happened (except now im missing a layer or two). Happens on long prints only..

This post has been edited by izzudinhafiz: Jul 15 2015, 03:22 AM

my abs that i got with the printer is really bad, you can find the pictures i post here couple page back, my problem is not adhesion, it cloging my nozzle even on 260C, from there i just print with pla until now, so i think i want to try abs again

No wonder the steppers are heating up from the result of the previous MOSFETs...

For replying to multiple quote, just click on the quote button (bottom right and can select more than one) of each post then click on add reply button at the end of the page.

Its really strange to see the extruder motor not skipping and not grinding the filament at the same time. Usually if it grinds, its means the stepper drivers are still doing its job and its likely caused by the hotend or the filament. As for skipping, this happens when the stepper driver are overheated or the pot adjustment is too low. Since it is long term, most probable answer for skipping is the stepper drivers are overheating.

Another thing I suspect for those symptoms is the extruder motor cables could have come loose during prints (on the motor end). I had a faulty extruder motor that sort of fidgets (not turn properly and doesn't cause grinding) early or halfway through the print and it was caused by the repetitive loosening of the cable on the motor side. I push and press the cable end into the stepper and it magically works and this means one of the wire in one of the four is probably damaged. I think since we normally don't tie down the motor cable end to the motor/platform and we leave it hanging free, the movement in the Y or X axis causes the cable to wear internally and causes the wires to disconnect from the stepper.

Anyway long story short, try to change your stepper motor for the extruder and also cable tie the cable to the motor. Make sure to leave some slack on the cable motor end.

My advice for you is to get an all-metal hot end and not use the PEEK barrel J-Heads which are not actually spec for ABS printing. Some all-metal have a teflon tubing inside and it will still work for ABS but you might have to buy the teflon sleeve replacements.

I suspect the J-Head PEEK barrel doesn't form a proper thermal barrier between the hotend and the filament input end and causes the whole ABS filament to soften and jam up mid barrel. Another solution to try is to add a small fan pointing towards the barrel so it will assist in dissipating the heat and forms a good heat gradient profile.

I'll check on the stepper wiring issue. Thanks for the suggestion

thanks for the advice bro