Willera's SmartrapCore Build Hi Guys! So i have been following most of the smartrapcore projects on here, I thought i would post progress of my own! So a little timeline of my build progress so far......... [attachment 53787 2015-04-1719.55.12.jpg] [attachment 53788 2015-04-1813.30.05.jpg] [attachment 53789 2015-04-1923.06.33.jpg] [attachment 53790 2015-04-2208.07.24.jpg] [attachment 53791 2015-04-2400.07.34.jpg] [attachment 53792 2015-04-2423.56.30.jpg] [attachment 53793 2015-04-2500.22.11.jpg] However I am having a few issues. When setting up the electronics I cant seem to get the x y motors to move properly. z works but it doesnt seem to sense the inductive endstop and will continue to ram into the head or the bottom of the bracket. I know the motors work as i have used the Test firmware from reprap and everything runs well. I uploaded the firmware from the smartfriendz smartcore github website onto the arduino, using repetier host software to control it straight from my PC. Thermistor, hotend, fan, Induction sensor(the light comes on when the bed is manually moved up) all work fine with the software so far. X and Y endstops all light up when triggered, using the M119 (As shown on the smartfriendz video tutorial) command senses that they have been triggered. So all good so far. This is where the problems start. When i get the bed close enough to the induction sensor the light comes on, but running M119 shows that the endstop is not triggered. The Z motors work using manual control to go up and down, however seems to move 1cm when i press the +/- 1 control button (is this right?) The X and Y motors when set at home by the endstop location, do not respond when i press the manual move button, they just make a beeping noise followed by no movement. I have tried reuploading the firmware to the board to no avail, and swapping the motor connections round manually on the Ramps board. I am getting the stage now when im getting worried about the pins breaking on the ramps board due to me removing them and changing there position aha. I need some help i think. If someone could reply on exactly what they did (possibly with pictures) on setting this up to work, or sees where i am going wrong as i have followed the smartfriendz youtube tutorial but dont get to the same point he does when he starts moving the head. Thanks in advance! :) https://reprap.org/forum/read.php?344,503212,503212#msg-503212 Mon, 18 May 2026 17:14:44 -0400 Phorum 5.2.23 https://reprap.org/forum/read.php?344,503212,512437#msg-512437 Re: Willera's SmartrapCore Build https://reprap.org/forum/read.php?344,503212,512437#msg-512437 smerrett79 Smart_Rap Fri, 22 May 2015 19:26:46 -0400 https://reprap.org/forum/read.php?344,503212,508026#msg-508026 Re: Willera's SmartrapCore Build https://reprap.org/forum/read.php?344,503212,508026#msg-508026 willera Smart_Rap Tue, 12 May 2015 04:52:51 -0400 https://reprap.org/forum/read.php?344,503212,507301#msg-507301 Re: Willera's SmartrapCore Build https://reprap.org/forum/read.php?344,503212,507301#msg-507301
What is your VREF set to now and what did you have it on when you were getting drift? Also could you just confirm you're using A4988s with nema 17 motors?

The IRLB8743PBF is a MOSFET. They are the two switches which are near the heated bed and hotend terminal on the RAMPS board and look like this [uk.farnell.com]
They allow the pins on the arduino which can only supply 10s of milliAmps to turn on and off large currents and also at voltages which the arduino can't handle.

The MOSFET comes with its own resistance when on, called RdsOn in the datasheet, and this is the number you use to calculate how much heat will be converted from electricity in the MOSFET and need to be dissipated from the MOSFET, using the formula heat power to dissipate (unit Watts) = RdsOn x Current squared (^2 in spreadsheet formula). The MOSFET is only rated to a certain temperature so if you can't adequately dissipate heat the temperature may rise close to this limit and start to damage the component. You can add a heat sink in good thermal contact with the MOSFET (the hole in the aluminium tab is so you can screw it to a heat sink) and although this is standard practice for stepper motor drivers, in the brief period I have been following RAMPS I haven't heard of people doing this for their MOSFETS.

Given that the power is proportional to the square of the current and only directly proportional to the RdsOn, the current is the most significant factor in this issue and I understand that the heated bed currents are much higher than the hotend (and certainly the fans) so we ought to focus on the heated bed first.

You could reduce the current going to the heated bed (through firmware) and insulate it better (underneath mainly!), or accept longer heating times and lower maximum temperature. I have just bought a Mk3 bed with the shiny aluminium side facing up, which will minimise radiant heat loss. Enclosing the print space might allow higher air temperature in contact with the heated bed and reduce convective heat loss but then we're into a balance with print layer cooling requirements etc. The print cooling fan will also have an impact. So what else can we do to reduce the thermal stress on the MOSFET (assuming you also don't want hot components near you or a thermoplastic enclosure)?

The stock RAMPS MOSFETS are designed to be cheap and don't have a great RdsOn, whereas the IRLB8743PBF has a very low RdsOn at the voltages and currents we are interested in (RdsOn varies with current, voltage differences between MOSFET pins and ambient temperature). Here's some good research on the best MOSFET for our needs [reprap.org]
You will notice that the pulse width modulation frequency is also relevant and I don't know what marlin uses but arduino pwm functions are usually about 400Hz IIRC, so on the end of the spectrum which is good for MOSFET switching. The datasheet attributes which are relevant to the frequency impact on heating are the times to switch on/off, given as rise time and fall time (usually in nanoseconds).

There are a few other factors to consider when selecting a MOSFET for RAMPS, max DC voltage, max current (note this can be limited by the package or physical size of the MOSFET and need a heat sink to reach the level stated in the datasheet - our needs should be fine with a TO220 package without a heat sink) and VgsThreshold, which is the voltage needed from the switching controller to start turning the MOSFET on (for N channel MOSFET) or off (for P channel MOSFET). This voltage is just the start of the turning on/off so a good rule of thumb is to double this to be confident that the MOSFET can be fully switched on/off by your controller. The IRLB8743PBF has VgsThreshold of 1.8V and we're confident our 5V arduino can achieve double that (3.6V) when it switches a pin to a high state.

Sorry if that was too much detail or patronising.]]> smerrett79 Smart_Rap Sun, 10 May 2015 09:10:01 -0400 https://reprap.org/forum/read.php?344,503212,507249#msg-507249 Re: Willera's SmartrapCore Build https://reprap.org/forum/read.php?344,503212,507249#msg-507249
yeah i am in the UK, what does that part do?]]> willera Smart_Rap Sun, 10 May 2015 06:17:08 -0400 https://reprap.org/forum/read.php?344,503212,507135#msg-507135 Re: Willera's SmartrapCore Build https://reprap.org/forum/read.php?344,503212,507135#msg-507135
Are you in UK (you used £ costs)? I'll be getting some IRLB8743PBF to upgrade the RAMPS soon from a bigger Farnell order and am happy to get some for others and post at cost. They are 65p each on Farnell and £2 on eBay but I know I'm getting genuine parts from Farnell - ebay is a counterfeit lottery as far as I'm concerned. Let me know if you are interested.]]> smerrett79 Smart_Rap Sat, 09 May 2015 19:54:20 -0400 https://reprap.org/forum/read.php?344,503212,507106#msg-507106 Re: Willera's SmartrapCore Build https://reprap.org/forum/read.php?344,503212,507106#msg-507106
[attachment 54388 _20150509_225439.JPG]]]> willera Smart_Rap Sat, 09 May 2015 18:18:30 -0400 https://reprap.org/forum/read.php?344,503212,506854#msg-506854 Re: Willera's SmartrapCore Build https://reprap.org/forum/read.php?344,503212,506854#msg-506854 smerrett79 Smart_Rap Fri, 08 May 2015 19:35:14 -0400 https://reprap.org/forum/read.php?344,503212,506843#msg-506843 Re: Willera's SmartrapCore Build https://reprap.org/forum/read.php?344,503212,506843#msg-506843
it's just two 10k resistors to have a 5v signal .]]> smartfriendz Smart_Rap Fri, 08 May 2015 18:58:02 -0400 https://reprap.org/forum/read.php?344,503212,506720#msg-506720 Re: Willera's SmartrapCore Build https://reprap.org/forum/read.php?344,503212,506720#msg-506720 smerrett79 Smart_Rap Fri, 08 May 2015 11:40:03 -0400 https://reprap.org/forum/read.php?344,503212,506709#msg-506709 Re: Willera's SmartrapCore Build https://reprap.org/forum/read.php?344,503212,506709#msg-506709 willera Smart_Rap Fri, 08 May 2015 11:22:14 -0400 https://reprap.org/forum/read.php?344,503212,506643#msg-506643 Re: Willera's SmartrapCore Build https://reprap.org/forum/read.php?344,503212,506643#msg-506643
Quote
willera
[attachment 53995 _20150502_193825.JPG]

Finished yoda, one ears abit funny bit otherwise good!:) happy

That's an awesome first print!

Which version of voltage regulator or voltage divider for the inductive sensor signal did you use?]]> smerrett79 Smart_Rap Fri, 08 May 2015 08:21:30 -0400 https://reprap.org/forum/read.php?344,503212,506615#msg-506615 Re: Willera's SmartrapCore Build https://reprap.org/forum/read.php?344,503212,506615#msg-506615
however added up the cost for all my parts and it comes to £160! not bad tbf for the piece of kit I now have! (when it works of course aha)]]> willera Smart_Rap Fri, 08 May 2015 06:46:29 -0400 https://reprap.org/forum/read.php?344,503212,504459#msg-504459 Re: Willera's SmartrapCore Build https://reprap.org/forum/read.php?344,503212,504459#msg-504459 djinn5150 Smart_Rap Sat, 02 May 2015 18:50:11 -0400 https://reprap.org/forum/read.php?344,503212,504455#msg-504455 Re: Willera's SmartrapCore Build https://reprap.org/forum/read.php?344,503212,504455#msg-504455 willera Smart_Rap Sat, 02 May 2015 18:22:58 -0400 https://reprap.org/forum/read.php?344,503212,504447#msg-504447 Re: Willera's SmartrapCore Build https://reprap.org/forum/read.php?344,503212,504447#msg-504447 djinn5150 Smart_Rap Sat, 02 May 2015 17:49:53 -0400 https://reprap.org/forum/read.php?344,503212,504439#msg-504439 Re: Willera's SmartrapCore Build https://reprap.org/forum/read.php?344,503212,504439#msg-504439
ah thats a nice design for the fan, ill print one off and try it.

yeah loving it! what have you guys made with your cores yet? just mods or any projects going?]]> willera Smart_Rap Sat, 02 May 2015 16:54:27 -0400 https://reprap.org/forum/read.php?344,503212,504430#msg-504430 Re: Willera's SmartrapCore Build https://reprap.org/forum/read.php?344,503212,504430#msg-504430 djinn5150 Smart_Rap Sat, 02 May 2015 16:05:07 -0400 https://reprap.org/forum/read.php?344,503212,504418#msg-504418 Re: Willera's SmartrapCore Build https://reprap.org/forum/read.php?344,503212,504418#msg-504418
Finished yoda, one ears abit funny bit otherwise good!:) happy]]> willera Smart_Rap Sat, 02 May 2015 15:03:32 -0400 https://reprap.org/forum/read.php?344,503212,504413#msg-504413 Re: Willera's SmartrapCore Build https://reprap.org/forum/read.php?344,503212,504413#msg-504413
What ideas do you guys have for the redesign?]]> willera Smart_Rap Sat, 02 May 2015 14:52:05 -0400 https://reprap.org/forum/read.php?344,503212,504409#msg-504409 Re: Willera's SmartrapCore Build https://reprap.org/forum/read.php?344,503212,504409#msg-504409 djinn5150 Smart_Rap Sat, 02 May 2015 14:31:07 -0400 https://reprap.org/forum/read.php?344,503212,504408#msg-504408 Re: Willera's SmartrapCore Build https://reprap.org/forum/read.php?344,503212,504408#msg-504408 madmike8 Smart_Rap Sat, 02 May 2015 14:29:40 -0400 https://reprap.org/forum/read.php?344,503212,504404#msg-504404 Re: Willera's SmartrapCore Build https://reprap.org/forum/read.php?344,503212,504404#msg-504404
Doing a yoda tho now
[attachment 53993 _20150502_184446.JPG]
[attachment 53994 _20150502_184419.JPG]]]> willera Smart_Rap Sat, 02 May 2015 14:09:33 -0400 https://reprap.org/forum/read.php?344,503212,504358#msg-504358 Re: Willera's SmartrapCore Build https://reprap.org/forum/read.php?344,503212,504358#msg-504358 madmike8 Smart_Rap Sat, 02 May 2015 11:50:06 -0400 https://reprap.org/forum/read.php?344,503212,504355#msg-504355 Re: Willera's SmartrapCore Build https://reprap.org/forum/read.php?344,503212,504355#msg-504355 djinn5150 Smart_Rap Sat, 02 May 2015 11:44:47 -0400 https://reprap.org/forum/read.php?344,503212,504293#msg-504293 Re: Willera's SmartrapCore Build https://reprap.org/forum/read.php?344,503212,504293#msg-504293 willera Smart_Rap Sat, 02 May 2015 08:24:37 -0400 https://reprap.org/forum/read.php?344,503212,504208#msg-504208 Re: Willera's SmartrapCore Build https://reprap.org/forum/read.php?344,503212,504208#msg-504208
Thanks for all the help! My current was wrong also so i changed that. Kept thinking it was the firmware as I could use other firmware like a delta, bur realised it wasn't steppstepping. So happy and I can now goto bed a happy man.]]> willera Smart_Rap Fri, 01 May 2015 21:25:01 -0400 https://reprap.org/forum/read.php?344,503212,504174#msg-504174 Re: Willera's SmartrapCore Build https://reprap.org/forum/read.php?344,503212,504174#msg-504174 Marlin

There you go, do not try to heat anything with this, you will have to modify configuration file to match motherboards, i have fwretract enabled so keep that in mind if you want to move forward with it, you will also need to change the number of extruders and disable the heated bed if you don't have one otherwise you will error out with min temps Better change steps on the Z axis too I am running a lead screw so my steps are 2560 not 80 that is just a crash waiting to happen, also did you try motion after running the 501? Sometimes weird numbers get loaded into eeprom on initial firmware load, that might be problem too, 501 loads factory(firmware) values then you can change those how you need to...but if you didn't run a M500 afterwords it wont save them...]]> djinn5150 Smart_Rap Fri, 01 May 2015 18:09:24 -0400 https://reprap.org/forum/read.php?344,503212,504168#msg-504168 Re: Willera's SmartrapCore Build https://reprap.org/forum/read.php?344,503212,504168#msg-504168
Output of M501
[attachment 53952 _20150501_222949.JPG]]]> willera Smart_Rap Fri, 01 May 2015 17:52:43 -0400 https://reprap.org/forum/read.php?344,503212,504149#msg-504149 Re: Willera's SmartrapCore Build https://reprap.org/forum/read.php?344,503212,504149#msg-504149 djinn5150 Smart_Rap Fri, 01 May 2015 16:16:58 -0400 https://reprap.org/forum/read.php?344,503212,504143#msg-504143 Re: Willera's SmartrapCore Build https://reprap.org/forum/read.php?344,503212,504143#msg-504143 Also when homing all the motors do wait 15s then hum and nothing else. All the videos I've seen the head moves towards the endstops]]> willera Smart_Rap Fri, 01 May 2015 16:13:16 -0400