My printer hates me

Hi folks
I was tempted a while ago to post a message saying I hate my 3d printer but I've decided it's got it in for me

I went to the rewrap master cless in bath a couple of months ago. I had a great time and couldn't imagine a more knowledgable group ofeople to help you build a printer

However I live on the other side of the country so I printed a pig ( with some small problems ) then went home.

This is where the problems begin....

I just couldn't get the printer to work properly.
So I spent a long time fiddling with it and every time I tried to print I had to re-adjust the x-axis, I just couldn't get it setup correctly.

So I have a list of problems that I have overcome, not in the order I found them.
The y axis belt was too loose, Identified at the workshop, so the print bed came off ant the belt was tightened. Oh and re calibrate the bed to flat
The z axis smooth runner was loose and that meant the z microswitch kept moving and it wouldn't work the same way twice. Fixed and re calibrated
On the same side the stepper motor came partially adrift from the threaded rod so that needed re attaching, and of course re-calibrating
All that re calibrating showed me that the heated bed was not flat, so couldn't be properly levelled. This was fixed by adding a sheet of glass to prong on. Oh and then re calibrating the bed.
The extra weight of the glass meant that the springs couldn't hold the bed level so I added spacers to help compress the springs, now it can hold the bed properly, oh and then re calibrated the heated bed.
Then at the same time I kept adjusting the power to the x axis , did you know that if it's too low then things get a bit compresses in that direction.

These have all been frustrating but I've overcome them all.( then re calibrated the heated bed )

But I still have one set of problems that Is driving me mad. The belts on the x axis and, to a lesser extent, y axis keep jumping

Really I'd like to say I have a 3d printer but all I've ever done is use one model and never managed to get the same output twice.
I've no idea about how to use the software. I just have one gcode file that drives me mad

Of you want to see some of me many failed pig cookie cutters then have a look below
[picasaweb.google.com]

But even better would be if you have any suggestions to stop it driving me mad

Many thanks

Peter

(it was either post this or screen)

Quote
Mutant pig
The belts on the x axis and, to a lesser extent, y axis keep jumping

Can you elaborate on this.

Do the belts come off the idler bearings?

Do the belts come off the pulley on the motor?

Do they just skip teeth?

Can you provide a picture of where it happens?

Edit: Don't feel bad, we have all gone through our own troubles too.

Edited 1 time(s). Last edit at 08/03/2011 04:49PM by Sublime.

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FFF Settings Calculator	Gcode post processors	Geometric Object Deposition Tool Blog
Tantillus.org	Mini Printable Lathe	How NOT to install a Pololu driver

It looks like you have T2.5 belt and printed pulleys. T2.5 was generally considered too fine to print and so printed pulleys normally use T5 belt. I suggest you get some metal pulleys.

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[www.hydraraptor.blogspot.com]

Hi Sublime,
The belts skip teeth. this is apparent in some of the mutant pig pictures where the print continues just shifted 10 mm on the X axis (leaving some plastic strands un-supported)

originally the bottom belt (Y Axis) seemed to have a lot of slack while printing (spotted by Adrian Bowyer so who am I to argue) but didn't come off the idler or pulleys. I tightened the X Axis to match

the belt does seem to slide up against the stepper motor but only on the X, not Y axis

Nophead
I have suspected the pulleys but
a. they were provided like that so I would hope they were right.
b. though they look printed they were actually cast from resin
c. most persuasively they were being used by RichRap, of this forum, on the same day to get good prints

I am hoping that I don't have to buy new pulleys



I added a few more pictures. number 9 is what happens when the x Voltage is adjusted too low
numbers 10, 11 and 12 were all done without any adjustment in between so with the same setting.

all I can really say that's good about these is that, since the glass plate and spring adjustments, I have a nice flat base to them.

All help appreciated

Peter

I have had the occasional; stepped print too usually when I leave the printer on and go out seems to be when it happens but not always, I don't think mines a slipped belt but suspect when I get around to checking it in the next few days that the pulley might be slipping on the motor spindle. Been too busy and not had anything to print for the last week so it's looking like a weekend job

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__________________________________________________________________________
Experimenting in 3D in New Zealand

Could you post the gcode file? I am curious as to what speed you are trying to print at. (may just be you are trying to print to fast)

Do you know what firmware you are using?

Have you seen it actually skip teeth on the pulley? or does it just sound like its skipping?

With the power off and the motors unplugged do the axis move easily and smoothly?

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FFF Settings Calculator	Gcode post processors	Geometric Object Deposition Tool Blog
Tantillus.org	Mini Printable Lathe	How NOT to install a Pololu driver

Are you sure the belt is slipping teeth? With the right tension and correct pulleys to match the belt that shouldn't happen. Does the belt sit in the teeth properly, or is there a pitch mismatch?

More likely the motor is missing steps, or the pulley is slipping on the shaft. Did you file a flat on the motor shafts? A grub screw does not grip enough without a flat. You can put a pen mark on the shaft and the pulley to see if it slips.

If the belt slips it will always produce a multiple of 2.5mm offset. If the motor slips it will be a multiple of 0.8mm (4/200 * 40mm). A pulley slipping will give arbitrary offsets.

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[www.hydraraptor.blogspot.com]

Thanks Nophead, a couple of new things to check.
the motor came with a flat side though I hadn't thought about it so I suppose the grub screw might have come loose I'll have to check that this evening.
similarly I can see if there's a base common offset to the errors though that's not always easy to measure because of the way it fails.

I've attached the gcode file. this is actually the only file I've ever tried to print and again I've seen it working better from the day of the reprap course in Bath.
I'm not sure about the firmware version I'm afraid

If we look at your prints we see that the layer prints fine and the problem is during the layer change. And after having a look at the Gcode I noticed it sped up at every layer change. On average it went from printing @2400mm/m and then for one move at each layer change it sped up to 6000mm/m which if it were my machine would cause it to skip steps.

To test this I changed the speeds in the Gcode file for you to try. Hope it works

I lowered all of the moves faster than 3000mm/m

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FFF Settings Calculator	Gcode post processors	Geometric Object Deposition Tool Blog
Tantillus.org	Mini Printable Lathe	How NOT to install a Pololu driver

Hi Peter, its RichRap.

I hope you are getting more luck printing?

I had a few similar issues but it's printing well after doing the following -

My skipping was a combination of overheating pololu modules and the filament catching on the top rods.
I found The supplied hobbed bolt did not do a great job at filament transport and the hot-end requires quite a lot of force even at high temperatures so if you have any drag on the filament it will cause problems. As soon as i used a filament spool holder i had good printing with PLA.
I did change the hobbed bolt in the end and now get perfect printing at 60mm/sec to 100mm/sec using skeinforge 41 and pronterface.

Did you get an SD card interface? Printing with SD will also help keep things moving smoothly but it's not essential.

I still have small heatsinks on the pololu modules but I dont use a fan now.
I have tightened everything and not had a single problem with the cast polyester 2.5mm gears on the belts so I doubt it is actually slipping, more likely a pololu current issue? Or the igus bushings are not well aligned?

Do you see the problem on x axis or y? I have not looked at the pictures as im typing on my phone

Keep us updated, i'm sure we can help you get it working well.

Rich

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[richrap.blogspot.com]

I've added three more mutant pigs to the gallery...

[picasaweb.google.com]

Sublime,
many thanks for tweaking the gcode I gave it a go this morning and have three more pigs to show for it.

Mutant Pig 13 was created from the slow version and is a lot better. there is a bit of a shift between the base and the walls, indicating an initial problem but afterwards it is far and away my best pig - almost not a mutant.

so for reference I ran a fast pig - mutant pig number 14 - and it looks as bad as ever, so far so good it looks as if you might be on to something.

then I went off to do the washing up after breakfast and set off a new slow pig - mutant pig number 15 - confident that it would look as good as number 13...
It looks so good up to the last few rows that I hope something specific happened but overall it looks like we have some progress.


This has made me think about what might cause this sort of problem and I'm wondering about the grease I put on the runners.
If the speed matters ( and it looks like it does) then I'm sure that it's not an absolute issue of it can't go that fast.
it must be related to inertia in changing direction and getting the head up to speed. this would also make friction an issue.
I had used a little Teflon grease to help make sure they were running ok but I think it might have caused more trouble than it solved. I just didn't notice at the time because of the other problems I was having.
I've wiped off as much of the grease as I can and added a little silicon spray lubricant (with a cloth) and Ill try the same on the other axis later this evening (think it feels better).


Cheers

Peter

Ahhhh yes, they are looking much better.

Since slowing it down fixed it a little we can now say it is just loosing steps and can be caused by friction as you have already figured out.

If you disconnect the motors or take the belts off you will be able to check for tight spots and areas of high friction. It may even be possible you have tweaked the shape of the machine a little during the travel home and this is causing it to be sticky.

You also mentioned the belt rubbing against the motor and this could be your cause. I find if my belt rubs against the washers on the idler and I am running my machine at full speed I can have issues.

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FFF Settings Calculator	Gcode post processors	Geometric Object Deposition Tool Blog
Tantillus.org	Mini Printable Lathe	How NOT to install a Pololu driver

Hi Rich,
it's good to hear from you again, we wouldn't have got past our software problem without you in Bath.

I'm hoping that the catching problem you mention is the reason why the second slow pig had problems, it certainly sounds promising. it also matches the way that I occasionally see slightly uneven levels

after running for a while the board did seem to get hot so I added a fan to the spare power pins (ideally I'd print a little enclosure to keep it all together ...) I may get some small heatsinks but every time I go to maplin I forget to buy any, I've done this a few times now

I did buy the SD card but I have absolutely no idea how to use it (after all I only print mutant pigs ) I kind of assume you put a gcode file on it and away it goes but I was going to worry about that when I could print more reliably. I didn't expect that it might improve quality though.

As far as other things are concerned I've looked at skeinforge and it scares me. there are such an insane number of options that I look at it and don't know where to start. there are lots of settings that don't mean anything to me and the ones that I do understand aren't that clear. I did run the pyramid you used through it to see what happened (with default settings) but there were already a couple of minor issues like it not wanting to print in the centre of the board so I haven't been back to it since.

currently my plan is to get two good pigs in a row (to prove 1 isn't a fluke)
then try to print something else from thingverse
then look at doing my own stuff

i just wish this was as un-impressive as it sounds, but getting a level bed that lasts for more than one print was already too much hard work


Cheers

Peter

Hi Peter,

With the bed, get it level and flat once and then don't touch it again, just move the Z-endstop switch up and down if you need it (you really should not need to do this very often). I have not touched or adjusted the bed a single time since I got it home, but I have moved the Z-endstop to get a good nozzle distance from the print surface, it's stayed level even with a few changes of Kapton.

If you are finding that the nozzle is on a slant then maybe the whole X axis is not moving up and down on the Z rails smoothly? check that your Z motors are in sync and not binding or stalling. I had problems with the Igus bushings on the Z rails, they are very tight and easily bind, my solution was to add Rod stabailsers (see the Blog) and also to use PTFE oil on the Igus bushings.

With Skeinforge if it's in the Pronterface directory with the default settings from the Bath Masterclass then actually you do not need not touch it (Skeinforge), just load the STL in Pronterface and it will call Skeinforge and slice the file for you in the background, and give you an output Gcode.

Make sure Bottom and Multiply is enabled in Skeinforge (They should be like that with the default MendelBath profile)

Tighten the belts, mine 'ping' and make sure you lubricate the bushings (both PLA and Igus) Don't be worried if you need to use a heatgun to soften plastic (slightly) and make things (bushings / rods) fit a little better as long as you think you have binding and you have all the mechanics lined up well first.

I also looked at the photo of the machine, remove all the spiral wrap from the top bars and don't have any cables going along them, this was what was catching the filament on my machine before I had a spool holder and also causing the X carriage to skip. If possible try to hold the filament up with minimal drag, and you should get a good clean pig print.

You are very close to a good working machine.

Good luck, I want to see lots of perfect pigs before the weekend is out!

Rich.

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[richrap.blogspot.com]

Hi Rich,

the bed is good and level and flat now. it just wasn't before now due to my many problems (see above)

I was thinking of hand cranking a bit of gcode to move the print head about (a lot of to and fro) and so help lubricate the runners but I'll hold that off until I see if hand lubricating it makes it any better

in bath we put the software on a friends netbook so I'm starting again from scratch. as for skeinforge though trying to run it from pronterface doesn't seem to work; the DOS window just reports an error and nothing happens. I can't test this from here so I'll have to play again later and see what happens.

Anyway that's for later, first we have Pigs to print.

cheers

Peter

Hi Folks,

We seem to have progress.

I got some time over the weekend to make more mutant pigs. to begin with i removed the print carriage, cleaned the X axis runners, filed the lugs that hold the bushes and lubricated the runners with more silicon lubricant. The carriage moved beautifully and freely to and fro. I re-attached the toothed belt a little tighter than before (thanks Rich for telling me that yours 'ping'). I was feeling confident that I'd be making progress. I even noticed that my belt was no longer trying to rub against the motor housing.

and then I produced Mutant Pig Number 18. it wasn't good and I aborted it before the thing ran of the edge of the hot plate.

However the comments by Nophead about the degree of slippage and some of my earlier problems gave me something to work with. the belt was Ok so the problem must be the stepper motors. in this case I needed to adjust the voltage up and slowly the pigs got better and better. in fact so slowly that the printer overheated and stopped working just when I thought I'd got it.

as I've gone through it took adjustment on both X and Y axis to get it going well.

eventually I've managed to get the thing running and produced a good pig!!! (Small picture attached)

the other pictures as ever are here:
[picasaweb.google.com]

there are still some slight problems with the smoothness of the layers but I think I now have an essentially working printer (famous last words). I'm hoping that the imperfections are caused by the same problems Rich was talking about earlier in getting the plastic to the head.

the next step is of course to see if it works as a cookie cutter

after that I need to find out why the skienforge software doesn't work for me. I've read the pronterface source code and thought i don't have any Python experience I think I can see what it's upset about so maybe I'll be able to get that working (fingers crossed and all that). having a working pig is good but it would be nice to be able to print something else.

Many thanks for your patient help. there were pointers to questions that i didn't even know to ask at the beginning

Regards

Peter

Yours was a thread I gravitated to as I'm just beginning to build, good to read your sorted (fingers crossed!) as it gives confidence to others like me!

What voltage are your steppers up to now?

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Andrew

Based in Slough, United Kingdom

Hi Andrew,

truth be told I don't know what voltage my stepper motors are running at because I've not measured it.
what I have done is adjust the little trimmer pot on the printer driver daughter boards until things started working.

this is based on two things. first of all when the system was first plugged in the X axis shuddered across and this was fixed by another Andrew when he turned down the voltage. at the same time he mentioned that things were obviously too hot from the temperature of the stepper motors.

then an idiot came along(me) and turned them down a bit too much so I had problems. what I was assuming was that the shuddering i had originally seen was related to the skipping I saw when I tried to print a pig. this meant i tried to fix it by turning down the power and eventually that led to me building a squashed pig as the carriage couldn't make it across. So I upped the power by small increments until the problems went away.

I was told by someone that you could measure the voltage by putting a meter between the pot and a little silvered hole on the board near the chip but as soon as i touched my meter to the hole the printer behaved oddly so i stopped. I may try again with a 'scope later.

Now I'm looking at my next problem, getting python to behave. I think there's something wrong with my install

Regards

Peter

Sounds like you have quite a zoo going!

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Andrew

Based in Slough, United Kingdom