Mendel90 build

A little more progress today - things have slowed quite a bit here, I really need to step on the gas again!

I finally got the 3mm glass today - free of charge I've used 3 clips down each side, I guess time will tell if the middle ones are going to get in the road.

Spent the afternoon leveling the bed. I mucked around a bit with the original design of fixed standoffs and using washers as shims, but I soon tired of that game. I found a couple of springs and went for the arrangement as pictured below. After that it took about 5 minutes to get it right! I've dabbed a couple of small dots of nail poslish on the screws to (a) stop them from moving and/or (b) tell me if they have moved. It seems to work ok for now but I'm sure there are some better methods around (maybe?) I have the bed level to +/- 0.2mm over most of the area (assuming that my gauge is .01 mm per increment). I'm not sure if that is pretty good, or going to cause me problems with a 0.4mm hot-end and probably circa 0.3mm layer heights?? These tolerances seem mighty small and I don't yet have the experience to know how close I need to get it. I'm also not sure if the springs I have chosen are are heavy enough, they may sag under the weight of a heavy printed peice. I've seen some thumbwheel adjusters somewhere, I might hunt them down and give them a go. One thing is for sure - I won't be buying one of these warped heated beds again! Horrible things to deal with



Edited 2 time(s). Last edit at 12/03/2012 12:48AM by 41southrap.

Yes my last hotbed like that was warped too, these are very flat: [www.panucatt.com]
What is the big silver block under the glass?
Print some of these out when you get to printing, they hold an M3 nut on the underside and make levelling a bit quicker. [www.thingiverse.com]

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Richmond, New Zealand
Thingiverse ~ YouTube

Ah yes, those are what I had seen - thanks. The silver block is insulation between the heat bed and the arcylic base - in theory to stop it warping from radiated heat. Secondary to that I have read that it may also help to reflect the beat back up to the bed which resluts in faster heating time and possibly better temperature control.

Slow progress due to a number of things - not the least of which is electronics "issues". I finally powered up the ramps board the other day and I'm now fighting with limit switches being wrong in some way and an X carriage motor that just sits there and hums no matter what I do with the current pot on the ramps board. These limit switches have me a bit beat. I've downloaded the mendel90 firmware from Nophead which I thought was ready to roll - but so far the only way to get anything to move is to invert the switch settings in the firmware - and then hold my finger on the limit switch!! That makes no sense to me what-so-ever. I have the outer pins (n/c) wired to signal and ground. Is that correct? Or should it be + and S?? Any help much appreciated. Anybody in Wellington available for a diagnostics session?

maybe not quite right. For a ramps board, pull ups are enabled by default. That means that your signal pin is "high". So for normal operation the limit switch will be "off" which is N/O and C on the microswitch. So when the limit is hit the limit switch closes and pulls the signal line down to ground. Your connections should be N/O and ground. For the ramps config.h file
// The pullups are needed if you directly connect a mechanical endswitch between the signal and ground pins.
const bool X_ENDSTOPS_INVERTING = true; // set to true to invert the logic of the endstops.
const bool Y_ENDSTOPS_INVERTING = true; // set to true to invert the logic of the endstops.
const bool Z_ENDSTOPS_INVERTING = true; // set to true to invert the logic of the endstops.
//#define DISABLE_MAX_ENDSTOPS

also the next bit
// ENDSTOP SETTINGS:
// Sets direction of endstops when homing; 1=MAX, -1=MIN
#define X_HOME_DIR -1
#define Y_HOME_DIR -1
#define Z_HOME_DIR -1
Your home should be the minimum point for each axis so when X=) the it homes and stops. That is the setting above. Hope this helps a little, it is a lot to get your head around at the beginning.

It doesn't depend on the board. Switches should always be wired NC so they fail safe if they become disconnected and also so they are less likely to be false triggered by noise. The switch should normally short the signal to ground, when activated it opens and the pullup pulls it high.

My original settings are correct for a Mendel90. Your original problem might be that the max endstops inputs are active but you have nothing connected to them. Either short them to ground or change the pins in pins.h to be -1.

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[www.hydraraptor.blogspot.com]

Are you keeping a running cost-sheet for the parts? I'm curious how it compares to the kit nophead sells

No I haven't, but I could probably delve back through the receipts. There was no kit when I started this, so it's been done from scratch. I'll be adding some of the kit features once I get these issues sorted and get it printing. I actually don't even know how much the nophead kit is.

Hi,

I have just rounded up all the bits required to build the machine, my total so far is 624nz , in saying that I have used alot of my trade discounts for bolts etc, the rest I have brought from ebay as they have been ALOT cheaper than sourcing locally.

Electronics were the same kit as 41southrap, I managed to get a fixed price offer from ebay for the same kit for 160us including shipping.
Motors from alibaba for 57us including shipping these are the 70oz version
acrylic from trade me 17$ 8mm+6mm
Parts I have got vik at diamondage to this will be around 150nz
hot end was 51nz

The balance was for bearings, gears , couplings etc.

Xmas project so more pics to come.

Welcome to the club Stubbie! What will you be making the frame out of?

Hi 41southrap,

Pretty much identical to yours


Just completing the wiring at the moment, more pics tommorrow.

Cheers, Stubbienz

Quick update after alot of messing aroun and getting my head around marlin I finally had success



41south if you run into any problems with marlin more than happy to send you the files.

Didnt have much luck with getting nopheads version to work so used the LCD version and rewrote it to work with the mendel90.

Got to say very impressed so far qualiy can only get better from here.

Cheers, Stubbienz

Edited 1 time(s). Last edit at 12/30/2012 05:09AM by stubbienz.

Well unfortunately my printer is still just a pile of parts sitting on the desk that does nothing. I really do suspect that the Ramps board is faulty so it's all coming apart today. Many thanks to Stubbienz for his help, emails and advice

If anyone in or around Wellington has a spare hour or three (and/or a spare Ramps board!) to help me fault find this it would be much appreciated.

I'm happy to pack it all the car for a road trip

hi 41southrap,

All of your post have been really cool , I was heaps disappointed when I found you didn't finish it. I was just wondering if you found what the problem was with your ramps board . I'm considering building a mendel90 ( I have never built a 3d printer b4) and I have no experience with electronics or basic level programing ( I can follow a tutorial though ) , do you have to know basic programing and do most people have troubles with their boards like u .

Thanks so much

41southrap's build is what inspired me to build my own Mendel90!
It did concern me that he seemed to get stuck and not finish as I was in an almost identical situation - First build, Mendel 90, and ramps!
A few other people have Mendel90's in NZ now and there's a whole forum just for it, so I'm sure you'll be able to get the help you need if you get stuck.
Nophead has a great step by step build manual, and a lot of people seem to have built his kit with little mechanical or software experience.

The easiest path would be to buy his kit, it comes with everything and forum support.
Next easiest would be sourcing the same parts as he has especially the same electronics - a "Melzi" board.
Harder would be using Ramps like 41south and I. It'd need a version of Marlin to match which takes a little text editing, but not exactly "programming". I've got a working version now so that'd help.
The majority of Mendel90 owners bought the kit, so the further you deviate from the standard parts the harder it is to find help.

I feel the real fun of reprap is doing it yourself. I sourced the parts, changed the model to GT2 belts and pulleys, made my own Z couplers and hot end as well as using Ramps so that I could use and LCD screen.

I'm pretty happy with the result



Edited 1 time(s). Last edit at 09/05/2013 06:05PM by isolt.

41southrap Wrote:
-------------------------------------------------------
> Slow progress due to a number of things - not the
> least of which is electronics "issues". I finally
> powered up the ramps board the other day and I'm
> now fighting with limit switches being wrong in
> some way and an X carriage motor that just sits
> there and hums no matter what I do with the
> current pot on the ramps board. These limit
> switches have me a bit beat. I've downloaded the
> mendel90 firmware from Nophead which I thought was
> ready to roll - but so far the only way to get
> anything to move is to invert the switch settings
> in the firmware - and then hold my finger on the
> limit switch!! That makes no sense to me
> what-so-ever. I have the outer pins (n/c) wired to
> signal and ground. Is that correct? Or should it
> be + and S?? Any help much appreciated. Anybody in
> Wellington available for a diagnostics session?
>

Sounds like your copy of firmware is wired for NO switches, best to recompile it as nophead has a good point about NC circuits being better in this sort of application.

Your X motor only hums ?
Try only powering up one coil at a time, try swapping coils. check coil resistance and also pus some ear muffs on and check for coil output by briefly connecting an 8 ohm speaker in place of a coil. Compare with the other outputs. Try your X stepper motor on another axis to prove if it works or not.

Check your X limit is correct for your X stepper. Correct wiring ?

Great posts. Really useful.

Edited 1 time(s). Last edit at 02/04/2014 04:47PM by Carson1616.

Hi all, long time no post.

Unfortunately I never did get this project finished, so it's still sitting in the bottom of a wardrobe gathering dust. I wouldn't mind selling it as-is-where-is, I'm sure it won't take anyone much time at all to figure out the missing puzzle piece(s).

My reason for selling? - a lack of momentum and financing another project.

I'm very pleased that the build log was useful and has inspired others to follow though

Cheers
Colin

Edited 1 time(s). Last edit at 02/11/2014 11:02PM by 41southrap.

Now up for sale on Trademe

[www.trademe.co.nz]

And now sold

Quote
41southrap
Now up for sale on Trademe

[www.trademe.co.nz]

Hi 41southrap, I am the one who bought your unfinished build.

I think you may have just had some very minor issues - I unplugged everything from the RAMPS board to connect a psu, and reconnected everything as it seemed to me it should go based on the schematic, and all the axes are working fine - homing to the endstops on x and y work fine. I have a small amount of work to do on the Z axis endstops but it moves just fine. its possible you only had 3 out of 4 motor pins connected on your X axis, because I can't find a problem with it.

you may also have had the wrong two pins on your endstop jumpers connected, since they also work fine for me, and all i did was unplug and replug everything.

I wired the hotend today, and it heats up fine and reads out from the thermistor, so this machine will be printing soon ( just waiting for some filament to arrive)

I'm really impressed with the build quality on this, and would like to invite you to come and see it in action once I get it printing. You obviously put a lot of love into this machine, so if you would like, I would be open to loaning it back to you for some time so you can see it working on your own parts.

Pretty sure you should have my details from the trademe auction, but if not I will check this thread if you want to get in touch.

Cheers,

-Pete

now that is a kool story bro, dragons or not.
good to see this went to a good home

41southraps machine is now extruding plastic - There is an issue with the Y axis periodically 'ticking' which seems to be the RAMPS board resetting the driver due to overheat. This is currently ruining actual prints, but I expect tuning the pots on the drivers, and possibly adding a cooling fan for RAMPS will fix this.

Running nopheads modified Marlin firmware, homing to max endstop on Z. Its all pretty much working now.

Aaaaaaaand... Success!



Still have an issue where the bed switches on and this causes major step loss in the x axis - suspect either interference issue or just excessive current draw - will try tuning the bed max PWM value, so I can keep the bed on while printing.

Another minor thing is the top layer of my cubes don't seem to be completed.. i guess this is a slic3r issue or something.. few things to fix, but pretty happy with where it is at the moment.

That is a really nice looking build from 41southrap - I only just noticed this subforum - maybe post pics to the main Mendel90 section? :-)

This Mendel90 has just printed it's first part - a fan bracket for the RAMPS board. Seems pretty accurate in terms of dimensions, I measured everything up, drew up the bracket in blender, printed it out and it fitted exactly as it should.

One day I will get some white filament so the colour matches.

I am currently printing on masking tape with an unheated bed at the moment while I await the arrival of a beefier PSU. The XB360 PSU just can't handle the instantaneous current-draw of the heated bed, it seems.

Wow was just reading back through this old thread - it was so great to see the printer finally sorted and running!

Would you believe I'm going to build another one just tossing up between another M90 and an i3 ...... stay tuned.

Pete, hope you are still printing.

Colin.

Edited 1 time(s). Last edit at 01/29/2015 05:00AM by 41southrap.