General 3D Printing Thread


 
I designed and printed a little bracket that screws onto my X carriage then used this python script to run the tests. I had to hack up the python pretty good to work with the default Marlin though. I'll post the code when I'm done; my nut fell off as expected and messed up my leveling. I'm doing it again now with triple nuts on each screw. I wish M3 bolts were easier to come by because I need some longer ones. Amazon can't deliver until Tuesday? Dammit!

Edit: my clips are on the back and front right by the screws. My design for the switch bracket isn't ideal because it puts the switch about 20mm back from the print head so the whole setup isn't ideal. I may design another while I wait for screws.
 
Bryan,
I asked Colin at MakerFarm why there were not springs under the heated bed for leveling and he said they always had problems with them wiggling loose and going out of adjustment. It sounds like you are having the same experience?
What I plan on doing is supporting the heated bed with springs (no screws), then using a slightly over-sized glass (bigger than the heat bed) which will sit on top of the heat bed. The glass will sit on 4 mounts that can be adjusted up and down with a thumb screw, the thumb screws will lock in place by a lever that slots into grooves on the thumb wheel and keep them from rotating out of adjustment (outer edge of thumb wheel will be like a gear). So you can release the lever, adjust the bed height, then lock it in place. Meanwhile, the heat bed will be firmly pressed up against the glass by 4 (or more) stiff springs...
Does this sound like a good system to you guys? Is there perhaps something like this already in existence that I can print rather than design from the ground up? I looked at ThingVerse and didn't seem to find anything...
 
Tom Kole said:
I just used stiff springs with screws and nylock nuts. It's really as simple as that.
Click to expand...

...and they don't vibrate loose? Not sure what kind of printer you have, does the bed move? The bed on the i3 can really get going back and forth when its doing some of the fill patterns, with lots of vibration. I had thought the same, springs and nylock nuts... I decided to ask the guys at MakerFarm WHY they didn't include this with the kits and they said there was problems with them vibrating out of adjustment? I figured they have the experience...
 
Yea, the bed moves. I remember looking at your slic3r file and noticing that you are only moving at an infill speed of 60 mm/s, I'm usually over 100 mm/s so I'm not sure why you are having these issues. One reason could be that my machine is probably a lot stiffer than yours and has a higher frequency range. Do you find your machine resonating at certain parts of a print when there are high frequency moves?. If so, analyze the gcode at that part to figure out what frequency you are hitting and lower the frequency limit in slic3r. There are particular spots in the gcode for the HMPi case that can really ramp up in frequency (the wall parts).
 
Well, I don't recall posting my slic3r file so you must be referring to Bryan, but the information is still relevant so thank you for sharing....

You are right about the stiffness of the machine, this wooden i3 has way too much flex IMHO. I have added a base to the printer and used L-brackets to secure it down and the printer is WAY more stable now than the way it came stock. IMHO they should have either used thicker wood for the frame or include a bottom to tie everything together and make it more solid.

The next thing I am going to do is change the bed, I find this wood way too thin and flexible. The belt pulls on the center and if it's just slightly too tight you can see the bed bow, I think that has a lot to do with it. I've yet to choose a material for the bed, I saw one made of a plexiglass type material that looked cool, it was thick and really clear so I assume it was lexan or something like that, not regular plexiglass. I could also use some sort of metal... If you have a suggestion for a good choice of material for the bed (and a good source to purchase it) I would appreciate your input on that.

I can already see me going down the road of designing my own printer like you guys have done. Not that the MakerFarm i3 is a bad printer, but the thin wooden frame leaves much to be desired and there are other areas where I know I could improve upon the design. I bought this printer to dip my toe, and get an understanding of what is going on, it's been a pretty good introduction to 3D printing for me I would say...
 
You mentioned that you use the stock Makerfarm slic3r config so I checked it out...I use aluminum sheet for my bed. I purchase it online from a metals delivery shop.
 
The reason my screw + nut system didn't work was because the spring didn't put enough pressure on a regular nut to keep it in place. The spring wasn't very stiff and the bolt wasn't long enough to go all the way through the nut. I didn't have any lock nuts on hand to try. The triple nut system I cobbled together seems to be holding just fine so I'm not going to mess with it until I something else that will require the bed to be re-leveled.

I haven't had any problem with flexing that I've seen, and I've done 50mm/s print with 70mm/s infil. I still haven't tried to see how far I can push it though, because I've had about 40 minutes to play with it since the 4th.
 
I think because for whatever reason the bed on my printer ended up extremely close to the y-idler I was able to notice the bowing of the bed when the belt was slightly over tightened. I figure if I could see it bow in the middle from that little bit of extra tension there must be some sort of deflection happening as the bed jerks back and forth on the y-axis.

At this point I'm thinking I might replace the bed with a more solid material and try the stiff springs and nylock nut method for bed leveling. I'm gonna see what I can come up with for material on my own because I think $45 bucks before shipping is a bit much to pay for a 8" bed that I still need to figure out how to mount to my linear bearings...
 
Tom,
Looking though the website at lulzbot.com I noticed their "wood" filament, I'm wondering if you have ever tried it? Seems interesting and different..
 
Tom Kole said:
You mentioned that you use the stock Makerfarm slic3r config so I checked it out...I use aluminum sheet for my bed. I purchase it online from a metals delivery shop.
Click to expand...

Thanks for digging in that far, I did indeed mention I loaded the MakerFarm slic3r config file... I have to assume if the infill speed is set on the low side in their default config they must know higher speeds cause too much vibration and flex on the stock printer the way they ship it. I certainly don't think cranking up the speed at this point is the direction to go until I finish stiffening this unit up a bit more. The base added a lot of stiffness to the structure, after I replace the bed and do some test prints I will crank up the speed and see if she can handle it....
 
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BTW, I'm wondering what you have found to be the best source for quality filament? I was looking on Amazon and was surprised to see the majority listed was 1.75mm, far more than 3mm.

Also, what are you guys using for belts? I've been wondering if stiffer belts on the X and Y axis might be an improvement to my printer that could help me get the infill speed up higher...
 
I have never tried the wood filament. I usually stick to ABS or PLA. I used to get most of my filament from ultmachine.com. They make great filament, but are expensive. I have tried some of the amazon stuff and agree that there is much more 1.75 mm filament on their site than 3 mm. Recently, I started buying from http://www.newimageplastics.com/ as per Matt's suggestion. They are great, but you have to buy 10 lbs at a time.
 
Ralph, when redesigning your bed, you need to balance rigidity with mass. If you make your bed too heavy, you will run into another set of problems because of the difficulty accelerating the bed.
 
Tom Kole said:
Ralph, when redesigning your bed, you need to balance rigidity with mass. If you make your bed too heavy, you will run into another set of problems because of the difficulty accelerating the bed.
Click to expand...

OK, thanks for the advice. How thick was the aluminum you used for your bed? Seems aluminum is one of the better materials to balance strength VS weight... I did like the look of that clear plexi/lexan bed though, but I know it would be heavy..
 
13.5"x12"x3/16" aluminum base with some holes drilled in it and a 13.5"x12"x1/8" piece of aluminum acting as a heat spreader above that attached using springs and screws. I then have a 12"x12"x4 mm piece of borosilicate glass on top of that attached with bulldog clips. I have pretty high torque nema 17s and a smooth linear rail system so it moves very nicely. However, it is probably at the mass limit for my system and I would caution against going heavier without finding out what your motors can handle.

I would start with sturdying up your frame first though, because adding more mass to your bed will only exacerbate your vibration issues if your frame is already a problem.
 
My frame has been secured to a base and is about as sturdy as it can git without getting rid of the wood altogether, it is MUCH more rigid right now than it was without the base the way the kit came. At this point the bed is the remaining issue, cause it is very thin wood and I have seen it flex easily, and it gets jerked around pretty good while printing. It was never level from day one, not sure if I got a bad one or what, but the front end on the single bearing side is VERY low and even hit the Y-idler before I made a bushing to raise it up a hair. In short, I am really sick of this bed, it has been a thorn in my side since I built the machine. Frankly, a rectangle hole in soft wood with a single linear bearing isn't enough to keep a bed level IMHO. The two bearing side is fine, the single bearing side not so much. Wood dents, bearings dig in, bed moves, I get frustrated. I want to use a material for the bed that isnt soft wood like this one....

I'm thinking 8X8X3/16 aluminum for the bed, heater mounted to that with spacers, then the double strength window glass I have here on top of that. I don't think that would be too much weight...
 
I was playing with some Slic3r settings today and stumbled across some pretty interesting relationships.

I'll start with the default settings, 0.40mm layer height, 0.35mm first layer, 200% first layer extrusion width.
Calculated extrusion width: 0.53mm
First layer extrusion width: 0.70mm
First layer extrusion volume: 20% more than other layers

Makes sense to me, right? You put a little more down on the first layer to help it stick right? Well what happens when we change parameters to a 0.3mm layer height for both?
Calculated extrusion width: 0.70mm
First layer extrusion width: 0.60mm
First layer extrusion volume: 13% less than other layers

It gets even worse as the layers get smaller, 0.2mm layer height:
Calculated extrusion width: 0.85mm
First layer extrusion width: 0.4mm
First layer extrusion volume: 59% less than other layers

The reason for this is the percentage is a multiplier on layer height, but the extrusion volume cross section is a square function (actually an ellipsoid). If you want 20% more plastic to be laid down on the first layer regardless of layer height, there is no value you can put in the "first layer extrusion width" that does that.

What's really odd about the first layer extrusion volume, if you set it to 0 for "default" you don't get the same extrusion width or volume you do on the other layers. You actually get about <1% less than other layers. I think this might be due to rounding errors, and this error decreases as the layer height gets smaller-- <0.1% at 0.2mm layer height.
 
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