thereprapkitstore.com Prusa Mendel construction Notes/Discussions

I did indeed press the 'set' button. But alas, nothing

Thanks for the tips.....I'm excited to get this working....so close, yet so far away!

Keukpa

OK, the heatbed problem seems to be something to do with the thermister. Must be a short or loose connection, so I'll check that and all is a go!

One last thing, do I need to tune the pots on the drivers for the motors, anyone got a good link?

Thanks for all the help!

Keukpa

nophead Wrote:
-------------------------------------------------------
> I don't know why James doesn't respond to email
> from customers. I suspect they get caught in a
> spam trap or something.
>
That's a very charitable suggestion, in my experience (and as I can see from some others') James only ever replied when I threatened to open a PayPal dispute.

Did this in my previous post: -

Shim and screws to hold J Head still

However, I'm using two short screws to trap the top of the extruder between the screws and the shim. The aluminium plate still takes the extrusion force.

Nophead, I see what you mean about the two bolts holding the extruder to the X carriage taking the force. The design could be a bit better here as there is no room for a washer on these nuts as the linear bearings get in the way as my extruder is in the 'at an angle' position to allow access to the tensioning nuts on the extruder bearing holder. I might try and look at the the design of the carriage with the other guys going the the Ledbury RUG meeting on Saturday.

keukpa Wrote:
-------------------------------------------------------
> Hi Remondo, thanks for your offer...I might take
> you up on some advice at some point! I think I've
> got most of it sorted now. Just configuring the
> Sprinter config for my endstop positions, etc.
>
> Could someone post a picture of where they have
> put their screws to prevent the extruder head from
> wobbling. That would be cool!
>
> I just need to get my headbed working, and I'm
> good to test. When I use pronterface to turn on
> the heatbed nothing happens....I've measured the
> pins and no voltage out. Does anyone know what pin
> it should be in the pins.h for an Atmega644P?
>
> Many thanks,
>
> Keukpa

WRT James at thereprapkitstore.com, I noticed that he now lists his kits as sold out. I can only assume that, rather than taking orders and money in the hopes of having a full kit by a particular date, he is waiting for the kit being complete for advertising the sale. However, I guess his inbox is now full of irate asking when he is going to have stock rather than irate people wanting to know where the rest of their kit is!

People set and follow different priorities when running their own businesses. I don't know what the batch size was for his sales but I'm guessing he had to strike a balance between answering emails about where the remainder of kits were and sourcing, packing and shipping the remainder of the kits and batches. My suggestion to him was to use the blog on his website to give a daily update. We'd have all known what was going on and would have been confident that things were happening because the web site was being updated regularly. He didn't answer my email.

Anyway, I wouldn't write him off. The important thing is that were are getting our kits, all be it late and with poor communication. In my experience, there is no such thing as a free lunch. James' kits are over £100 cheaper than his nearest competitor. I'm guessing the main reason for this is that he keeps his overheads down by not employing someone to just answer emails for him. I'd happily save £100 in £500 if it meant I had to wait a couple of weeks for delivery any day.

Incidentally, I did open another thread in this forum when I was going through all this at the end of April.

I haven't 'tuned' my pots as such, I just increased the current incrementally until the steppers didn't skip anymore. There's a formula here but it's too complicated for my tiny brain and it's also for Sanguinololu which may differ from the Melzi.

Still having trouble with my prints, the main issue being a build up of excess filament around the nozzle which catches on the filament which has correctly stuck to the bed and peels it off. I've also found that I had to heat the nozzle to 190 to get anything to stick, I haven't checked my thermistor tables against a thermometer yet though because my mulitmeter thermometer is very slow.

I get this on my first layer as well. I think it's because the z axis home is below the level of the bed, if you get my meaning. The extrusion is squashed down too much onto the bed. This means the first layer filement is too wide. When the head does the adjacent pass, there is not enough room for the filament on the adjacent side so it puckers up. This excess sticks to the head and, at best, adds to the problem else where and, at worst, can result in the whole first layer being ripped off of the bed.

I got the first layer spot on for a while and the problem went. Then one of my z axis bars worked its self out and I have yet to get things right again.

Z axis home position is a real pain in the butt. I also found it difficult to get right across the whole bed but, having bought a 300mm vernier, I now realise my frame wast not that accurate. I also think the machine has to stand on a very flat surface. We have a large marble chopping board in the kitchen that would be perfect but my wife does not agree.

Anyway, having now sorted my hot end wobble, twisted frame and bought a piece of 18mm mdf to stand it on, I'll see if things get better.

I am also thinking that the frame is very flexible in the x axis direction. I am looking into bracing it somehow. On the infill whilst printing a set of z axis motor plates, the machine was shaking left to right like a jelly!

remondo Wrote:
-------------------------------------------------------
> I haven't 'tuned' my pots as such, I just
> increased the current incrementally until the
> steppers didn't skip anymore. There's a formula
> here but it's too complicated for my tiny brain
> and it's also for Sanguinololu which may differ
> from the Melzi.
>
> Still having trouble with my prints, the main
> issue being a build up of excess filament around
> the nozzle which catches on the filament which has
> correctly stuck to the bed and peels it off. I've
> also found that I had to heat the nozzle to 190 to
> get anything to stick, I haven't checked my
> thermistor tables against a thermometer yet though
> because my mulitmeter thermometer is very slow.

I got a blocked nozzle soon after my first test prints and nearly two weeks later still haven't printed anything else

I then realised I was putting the PTFE inner on the hotend upside down and causing continual blockages by doing so.

It was just at that time that I broke the lead to the thermistor so ordered a few from RS, part no: 484-0183 - they're smaller than the ones James sent but it seemed to be working ok at first however, at some point, whether it was when the hotend hit a temperature or if I moved something about I don't know, but the pronterface screen showed it was disconnected from the printer. I've noticed this happen before when the power resistor shorted against the brass block, normally reset the power and reconnect and it's fine but this time it wouldn't reconnect. I started disconnecting wires and then at some point I managed to reconnect.

Anyway now I'm getting a weird result - when I connect and check the temperature, the head is showing 249 before I even start the heater. The really weird thing is that the bed thermistor, which I haven't changed, is showing 194 before applying any current.

The only thing I can think to do is to strip the head down again and recheck the resistor and thermistor connections but I'm really confused about how the bed temperature is screwy too. Just wondering if anyone had any thoughts.

FYI I've also posted my question here as after I posted I realised it was probably a more generic question than just about these kits...

Looks like your thermistor wires got shorted to the heater wires putting 12V into a 5V input of the CPU which damages it.

---

[www.hydraraptor.blogspot.com]

Mmm. I bought 528-8592 from RS. These fitted like the one that came with my head. You do need to warm the head to melt the PLA that build up on it but its handy because, as it cools, it hold the thermistor in place. In the head and running well now so the head temperature must be in the right ball park. The one thing to note is that I think the leads of these thermistors are insulated with enamel. I had the Devils own job cleaning up the ends to solder to them. Although I've used PTFE sleaving on the leads this might help prevent shorting to the head block which appears to blow the Micro.

MotoBarsteward I don't understand why you're having such trouble keeping the thermistor in place. I just wrapped each lead in kapton tape and bent them around the top of the nozzle and secured with a single layer of kapton. Here's a picture, it all seems to work fine.

Edited 1 time(s). Last edit at 06/20/2012 02:49PM by remondo.

The thermistor leads are not normally enamelled. They are Dumet wires (copper-clad FeNi). They normally solder easily but perhaps yours had tarnished.

Shorting to the block only damages the CPU if the resistor is also shorted to it.

---

[www.hydraraptor.blogspot.com]

I had no problem holding it in place with tape. I was referring to the PLA that had worked its way into the hole holding the thermistor in place for me while I taped it.



MotoBarsteward Wrote:
-------------------------------------------------------
> Mmm. I bought 528-8592 from RS. These fitted like
> the one that came with my head. You do need to
> warm the head to melt the PLA that build up on it
> but its handy because, as it cools, it hold the
> thermistor in place. In the head and running well
> now so the head temperature must be in the right
> ball park. The one thing to note is that I think
> the leads of these thermistors are insulated with
> enamel. I had the Devils own job cleaning up the
> ends to solder to them. Although I've used PTFE
> sleaving on the leads this might help prevent
> shorting to the head block which appears to blow
> the Micro.

Wooohoooo! My printer actually started extruding today!

Just some software issues to iron out and I think I'm good to go. So, a few questions if I may:

1) What software (for windows) do people recommend? I'm using pronterface, whilst this is excellent, as soon as I switch on my heatbed (via the software) it crashes it....

2) Any ideas why pronterface crashes when enabling the heatbed?

3) Does anyone have software configuration files for the ABSPrusa that I could try?

Many thanks again,

Keukpa

2) Maybe a poor ground allowing some of the bed current to flow through the USB cable.

---

[www.hydraraptor.blogspot.com]

I find pronterface crashes some times if I pause a print. The point of the crash appears to be when I click Z up 10 or some other move after pausing.

The scenario is that I see the first layer is going bad so I pause, Z up 10, remove the stuff from the bed and then restart. This is something that I find I do quite regularly. If it doesn't crash on the Z up 10 the first time I do this then it will always be ok. Obviously, then, it only crashes the first time I try to pause a print.

I think I'll raise a bug on Pronterface seeing as it's reasonably reproduce able for me.

Once pronterface survives my first attempt to do this, its ok until the program is closed.

Thanks for all the tips and info, it appears by changing to a different laptop and windows 7 (from XP) it all working lovely now. I've printed my first object, and much better than I thought it would turn out, it's just a little squished on the X-Axis, I think the belt is slipping, so a few little adjustments and I think all will be good

Exciting times!

Cheers,

Keukpa

I get this too, motobarsteward. Just wait a couple of seconds before clicking the z-axis controls after you pause it.

And here it is....my first sucessful print! Amazing stuf!

Keukpa

OK, to improve my prints, I've just tried to extrude 50mm of filiment to calibrate my extruder, and it only extruded 20mm!!

Way off! And prints are still OK!

Interesting.....time to tune things up!

Keukpa

Hi all,

I only now get to calibrate my machine (3rd batch with sangulino board). The first test print looked OK but obviously not great.

Many here suggest to calibrate the extruder as a first step, I'm trying that but I cannot upload the sprinter firmware.


"Binary sketch size: 45444 bytes (of a 63488 byte maximum)

avrdude: stk500_getsync(): not in sync: resp=0xce
avrdude: stk500_disable(): protocol error, expect=0x14, resp=0xae"


I tried the following:

I used the Arduino version 1.01, 0023, 0018,
each with the sprinter file which somebody posted here and with a fresh git download

I tried to change boudrates and the ports

I don't get any compile errors, I did change the board number in the config files... and I tried to hold down the reset button while uploading.


is there any trick I'm missing?

Thanks

Peter

Haha... writing this post solved my problem!

I found the thing which I hadn't tested yet... there are a couple of versions of the Sangulino software 0023r4 doesn't work, 0023r3 works just fine!

So my working setup right now:

Arduino 0023
Sangulino 0023r3
Sprinter from Github including changes for the board

Thanks

Peter

So, has anyone got one of thse ABSPrusa's printing good quality prints?

What software are people using?

Would anyone be willing to share their settings?

I've got some good decent prints now, but still not perfect, so would like to do some tweaking.

Cheers,

Keukpa

I'm getting some excellent quality parts now. I'm just trying to fine tune calibration so that they come out the correct size. My inside holes are too small. I've just printed a herringbone cog (picture below) the only problem I have is that the hole for the bolt is too small. Measuring the part using MeshLab would be pretty tight but my inside holes are about 0.5mm in diameter too small. I've just printed off a thin wall part and I see why. The extrusion is starting of wide at 0.9 to 1mm at the first corner after each layer start. Each side then gets thinner with the last side stable at 0.4mm. The extruder is not retracting properly, I think or is not recovering from the retraction. I've attached a photo. What does everyone think?

The outside trace of my cog is spot on. The holes through the cog are all much shorter traces, which is where my problem is. I can't help thinking the blops are part of the prom. The odd thing is that I only get these plobs at layer start on small parts.

Anyone got any ideas what I'm doing wrong? I'm using Sprinter with a J Head Mk4 B and Earl Grey Faberdashery PLA.

; generated by Slic3r 0.8.3 on 2012-06-24 at 15:03:30

; layer_height = 0.3
; perimeters = 1
; solid_layers = 1
; fill_density = 0
; nozzle_diameter = 0.4
; filament_diameter = 2.84
; extrusion_multiplier = 1
; perimeter_speed = 30
; infill_speed = 60
; travel_speed = 130
; scale = 1
; single wall width = 0.42mm

I'm using 2mm of retraction, 0.6mm Z lift, Speed 30, no extra length at restart and minimum travel after retraction of 2mm.

Cog 1
Closeup showing quality is excellent
Thin wall calibration showing blob and slow to stabilise walls

keukpa Wrote:
-------------------------------------------------------
> So, has anyone got one of thse ABSPrusa's printing
> good quality prints?
>
> What software are people using?
>
> Would anyone be willing to share their settings?
>
> I've got some good decent prints now, but still
> not perfect, so would like to do some tweaking.
>
> Cheers,
>
> Keukpa

---

Using ABSPrusa Mendel Zaphod with Pronterface and slic3r 1.3.0. Printing well with 3mm PLA and ABS through 2 x J Head Mk IV b and Wade Geared Exruders. Controlled using RAMPS1.4 board running Marlin_v1.1.9

MotoBarsteward that is an EXCELLENT print.

Would you mind attaching your Slic3r config.ini file?? So I can use that on my printer and see what I get as an output

I've pretty much got exactly the same setup (in terms of hardware and firmware) as you!

Cheers,

Keukpa

I assume that you are not describing the thin wall calibration as Excellent?

Quallatively, the parts are excellent. I'm just trying to get the dimensions correct.

If anyone can tell me why my bead width is unstable on short runs, I'd be a happy man.

I've attached the config file that I used for the cog.

---

Using ABSPrusa Mendel Zaphod with Pronterface and slic3r 1.3.0. Printing well with 3mm PLA and ABS through 2 x J Head Mk IV b and Wade Geared Exruders. Controlled using RAMPS1.4 board running Marlin_v1.1.9

Thank you for the config file, I will try this now

As for your print, it is EXCELLENT when you look at mine! Attached!



Cheers,

Keukpa

Print

How big is the part that you are printing? I'm finding that big things print really well. Where I have problems is with small things. I think there should be a pause between layers to allow the whole thing to cool down a bit. I also use a desk fan after the first layer has printed. Have you calibrated your extruder?

keukpa Wrote:
-------------------------------------------------------
> Thank you for the config file, I will try this now
>
>
> As for your print, it is EXCELLENT when you look
> at mine! Attached!
>
>
>
> Cheers,
>
> Keukpa
>
> Print

---

Using ABSPrusa Mendel Zaphod with Pronterface and slic3r 1.3.0. Printing well with 3mm PLA and ABS through 2 x J Head Mk IV b and Wade Geared Exruders. Controlled using RAMPS1.4 board running Marlin_v1.1.9

Yes, extruder is calibrated.

The part is 30 mm x 35 mm x 15 mm (WDH).

I've found using your config file that it's a little better now (although not perfect), see attached picture. So I'm going to play a little and see if I can improve it further.

Cheers,

Keukpa

slightly better part