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simon

UM2 axis control Software

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I'd like to level my bed using a DTI, which makes it easy to get it within 10 microns. Is there any software out there I can use (for free), which always me to control the x, y and z axis independently. The UM2 bed calibration function moves a bit too far and the needle will fall off the edge or hit one of the clips. I couldn't find a away to control it in Cura or via the UM2 control panel. Thanks.

 

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Hi Daid, looks quite involved... (difficult) for a newbie. Is this the right link for me 'printrun-win-slic3r-12july2013' to run on windows 7 64 bit?

Is there anything else that would do it that looks easier to use? Not wanting to sounds ungrateful for the info of course.

 

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Pronterface is the most "low level" you can get, it gives you lots of control for moving the head and manual heatup and stuff like that. It's not as difficult as it looks, as you can ignore most features and only use what you need.

I'm using an old version (2 year old or something) myself for when I'm testing. So I'm not sure what download you need.

 

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Daid... the wizard for bed-leveling on a UM2 suggest leveling to a 'papers-width' from the bed. Does it actually treat the point that you set using the wizard as zero, or does it assume that you are at z=0.1 or something after running the wizard?

Also, has the firmware been fixed yet - when I tried to level the other day, it put the head over the front right clip during the leveling, which made it hard to position the bed accurately. Secondly, it still doesn't home properly on 'abort'. This is with the firmware from the Mac Cura13.11.2.

 

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Daid... the wizard for bed-leveling on a UM2 suggest leveling to a 'papers-width' from the bed. Does it actually treat the point that you set using the wizard as zero, or does it assume that you are at z=0.1 or something after running the wizard?

Also, has the firmware been fixed yet - when I tried to level the other day, it put the head over the front right clip during the leveling, which made it hard to position the bed accurately. Secondly, it still doesn't home properly on 'abort'. This is with the firmware from the Mac Cura13.11.2.

 

The wizard assumes you are at Z0.1, accounting for the paper.

It should put the fan cap over the clip, but this cap should clear the cap just fine (some of the first machines have some minor bending issues with the cap) but I think I'll put the head back 5mm just to be sure it clears the clips always.

Aborting and homing then is kind of a hit/miss sometimes, haven't looked into the details yet, seems to be some buffer-full problem. Aborting by pulling the SD card always causes homing as far as I know.

 

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The wizard assumes you are at Z0.1, accounting for the paper.

 

Ah!! Smart! This is the first I read about that but have been wondering.

Daid, is there any way to set the home position with a gcode?

I mean in pronterface could I

1) move z to -.03 and then

2) send a gcode to set this has "home"?

I'm hoping I can at least do #2 but I suspect I can't do either. Instead I think I would have to re-run the homing procedure or turn the 3 screws a bit.

 

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Thanks guys, sorry for not getting back promptly, child care commitments and supper took priority. Right, what I'd like to do is set the z-axis height so it compresses the plunger on the DTI a few mm's and then drive the x and y axis independently keeping the plunger over the glass. This is perhaps over kill for levelling, but I've read many times that bed levelling is v.important. Seems more so on glass. I already have a DTI which I use on my Afinia and measuring microscope so I might as well use it for the UM too.

Although paper is fine I find it more accurate and easier using a DTI.

 

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One thing I forgot to ask is.. Could I accidently drive the x or y axis into a position beyond the limits of the machine using pronterface. Or does the UM2 'know' it's physical limits to prevent me from doing that by accident?

 

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Ok, have tried Pronterface now and it does look pretty simple to use. The look of the website made me think it was going to be some kind of horrible text based unix type thing, but it seems to have a nice GUI. Unfortunately because I have the duff 5A PSU presently, each time I try to connect, it trips the printer and it re-boots. I've turned the bed temp down to 0C for everything, but it still trips. So I'll have to leave it until my new PSU arrives.

BTW what values should I use for Baudrate, x y and z mm/min, etc.

 

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Baudrate 250000

x and y speeds can be anything up to maybe 200mm/s = 12,000 mm/min. But 60mm/s = 3600 mm/min is probably a reasonable starting point.

for z, I'm not sure of the absolute upper limit - probably 30mm/s or more. But if you are doing precise positioning, you probably want to limit it to maybe 2mm/s or less at least in the finer parts of the adjustment process. So that's 120 mm/min.

 

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Well actually I found out after I read Illuminarti's post and changed the baud rate. I didn't realise that the clonk/blackout was normal. The errors I was getting were a result of the baud rate being incorrect. I just assumed the blackout was the power supply failing again, but thanks for making sure I didn't slip through the net of ignorance :-). I have to say I'm really impressed with pronterface.

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I have to say I'm really impressed with pronterface.

 

:-P Yes, it's very nice. Notice that when it connects it determines all kinds of things about your printer. For example the PID values of the nozzle and the max acceleration and so on.

 

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I did my little test today with the DTI and here are the results.

Setup

DTI 1

DTI 2

 

Video

UM2 X axis with DTI

(not sure how to get the video in) Its on the low res side, but you can make it out.

Here's a mov version

 

https://dl.dropboxusercontent.com/u/11059439/UM2/UM2%20x-axis%20with%20DTI.MOV

 

Anyway, its quite interesting (to me). If you level the table by following the UM2 procedure (could be the UM1 as well but I don't know) then you are leveling it using the 3 point paper thickness alignment method. Nothing wrong with that. The head stops next to the adjustment screw which is the right way to do it. However we are using the paper thickness of 0.1mm to gauge this distance, which can be a bit subjective. As the video shows, if you traverse across the middle of the table in the x-axis the deviation is about 220 microns (on my machine).

 

The difference will be a combination of the distortion in the glass and the rails. I don't have an engineering flat standard that would fit inside the UM2 so can't isolate how much of each there is, but my gut says its mostly the glass. I've only done one test so far and could probably isolate it further if I did, but I don't think its necessary. I just did it for interest because I can't print anything until I get the new PSU.

 

Possibly because of the clips, the glass bows very slightly. During the calibration the table drops between positions so you are not aware that, in fact, the nozzle would come into contact with the glass if it didn't. This is not, in any way, a criticism of the UM2. I'm mechanical engineer and design stuff like this all the time. Nothing is flat, straight or in fact anything you want it to be. It's just one big compromise. The interesting thing for me is wondering what is happening when you print in the middle of the table which is normally where you would print. I guess that the molten plastic pushes the glass away a bit like an air bearing (but with plastic) or pressurized oil bearings. If it didn't the plastic would be unable to get out until the head had moved to a position where there was sufficient clearance.

 

However, its also easy to see how, if you've leveled you platform on the tight side with paper (which is easy to do for a new comer), you could easily have increased the contact force between the nozzle and glass where the plastic could not extrude properly.

 

If we're trying to maintain a 0.1mm clearance in the center to start a print, maybe a final clearance should be checked there as well. Perhaps the calibration process should consist of 2 phases, one to get the level and one to set the clearance in the center.

 

It obviously works as it is, so I'm just chewing the fat really. I'd be interested in the opinions of our more experienced users (you know who I'm talking about). However, as it works for people as it stands, I won't be offended if the post finishes here.

 

 

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To fix your images, do this: Edit your post, in the top middle of the editor click the button that says "My Media", in the window that pops up click on "Gallery images" on the left and then click once on each image you want to insert into your post and close the window by pressing "Finished". I'd fix it for you but I only have access to my own media of course :)

I've also noticed that the glass is higher in the middle. I only used my calibrated eye ball so I don't have any measurements though.

 

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I just did it for interest because I can't print anything until I get the new PSU.

 

You can't? You don't need to heat the bed to print - but you *do* need to heat the nozzle. I would think there is enough power for the nozzle and the steppers. No? You can print cold on the blue tape (you have to relevel of course) and there are tricks for printing on cold glass here:

http://umforum.ultimaker.com/index.php?/topic/3404-printing-on-glass/

 

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I guess that the molten plastic pushes the glass away a bit like an air bearing (but with plastic) or pressurized oil bearings. If it didn't the plastic would be unable to get out until the head had moved to a position where there was sufficient clearance.

 

Probably not. More likely the later - nothing comes out and pressure gets high enough that the extruder motor simply "clicks" and jumps back and misses steps. No big deal as long as there are a few more layers with similar foot print. The default for cura I think puts the bottom layer at .3mm.

 

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I understand that you're frustrated that you can't print with the material you planned on right now. But, look at it as an opportunity to experiment and learn in the mean time. You might not be able to use your parts in production but you can at least check if they come out the way you expect. Or you could just print silly stuff for fun in the mean time ;)

 

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