[homer93]

hi
so i was looking at the makerbot replicator 2 and fancied having a go at designing my own printer. ive pretty much finished a solidworks model. dont want to do anymore until ive had some feedback on how ive done it. as im not sure its a very suitable/practical way.
i liked the style of the makerbot so i used that as a base for my design
the main chassis has been modelled to be some sheet metal, currently set to 1mm, then i though i could just sport weld it together in the corners.
for the linear bearings ive designed it to use bronze bushes, but im not sure if this will allow smooth movement. the bushes will just pr pressed into an aluminium block.
for the Y axis sliders ive got some nylon bushes to hold the bars for the X axis. im not sure if this is a good idea or if it will work with the sheet metal slider design ive got.
the y axis motor is in a similar position as in the makerbot, so ive got some shafts to move the motion to the other slider belt on opposite side of printer. the bars are suspended by some small bearings 5x10x4 which are held in some aluminium mounts which screw to the top, not sure if ive gone ab bit over the top with them though, thers 2 for every shaft

any feedback would be helpful, hopefully ill be able to build it one day

[Dean448]

Most of your drawings can't be displayed.
on bronze bearings vs ball bearings I don't think you can beat a ball bearing for accuracy (low clearance) and smooth rolling.
However I think you could get just about any type of bearing to work if you are willing to tune it. Ball bearings work well out of the box.

[homer93]

i thought if i used bronze bearings it would be cheaper and ide be able to make the design more compact

ive tried adding the photos again:

[Dean448]

Great models. The bearings should work as long as they arn't tight on the shaft. I'm not sure why you arn't considering the ever popular LM8UU or larger, which are very cheap. Just a comment on your design, why wouldn't you put the Y axis motor up near or at the center of the Y axis drive shaft? Also why wouldn't you put the X axis motor on the outside of the X axis range? Seems strange to let the extruder platform possibly hit the X axis motor.

[Pierke]

@homer
verry nice cad files.
Have you also cad files for the extruder?
The pictures are looking real nice, how much time to draw these files?
What types are the belt you are using?

Thanks,
Pierke

[homer93]

ill make sure to get them bored slightly bigger than the shafts. i looked at them, when i modelled them they were too big for the size of some of the sliders, and the bushes were easier to mount. ill try having a play round with the x axis motor mount and sliders, see if i can get it out of the range. dont understand what you mean about the y axis motor position though. with the setup at the minute it has a pretty big build area. dont know if the z axis slider will be strong enough but at the minute it has a build area of about 250 x 145 x 185 ish.

which bit of the extruder? ive made rough cad drawings for pretty much all of it. i havent found components for the extruder so i havnt been able to make proper models for it.
once i got into it it didnt take too long, a day at the most working on it properly.

Synchroflex® Timing Belts - T 2.5 / T 2.5-DL (6MM)
was thinking of using these belts the T2,5 ones, they small and there quiet cheap .

[cncadmin]

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looking good!

[Pierke]

We are looking to your next pictures.
Nice work! :-)

[homer93]

did some work on the z axis today.
again using sheet metal, ive changed to 2mm throughout the design. not sure if it will be able to take the weight of the models though
uses a nema 17 linear motor
the plate on the slider isnt the build platform, bolts will go through it so the actual build platform can be levelled off.
will be spot welded again, hopefully by using the shape i have it should make it stronger, and not bend when larger models are built on it
the lead screw will be fixed in at the top with a bearing so ive made a quick bearing mount for it, dont have a bearing yet so thats not its definite size

what you all think?

[homer93]

just had a look at moving the motor for the x axis too, decided that its current position is the best position i can get for the most range
i couldnt think of a suitable way to mount the motor easily

[EL34]

Looks good

Oilites work ok, but I found they sometimes chatter on really fast moves
If you plan on cranking up the X and Y axis speeds, you may end up going to ball bearings if you get some chatter
Maybe plan on being able to switch to a different type of bearing in your design if the bronze bearings don't work out

Definitely get the motors outside the frame
If you are using belts, use GT2 belts and pulleys

Leave more room than you think you need for the axis movements
If you only plan on a total working range of 8 inches, make the total travel on your rods a couple inches longer

Also, don't forget to take into account your limit switches cause they can eat up some of your travel

On my recent build, I found out later that I should have created my X axis a little bit longer than I did because of the limit switches

here's some info on my build

http://www.cnczone.com/forums/genera...ter_build.html
DIY 3D printer using T-Slot Extrusions

[wontpontificate]

I don't think you'll encounter any problems using oilites vs. ball bearings. Heck, I've even used cheap brass tube on hardened shafts as linear bearings, and they work beautifully. As long as they have zero lateral play on the shaft, you should be good to go! Buy the bearings that have been made to fit the exact diameter of the shaft (don't bore oversize) and you'll be happy with the motion. Anything even slightly bigger than it should be can skew and introduce binding and chatter.

Longer bearings will give you less trouble than shorter ones. The more shaft contact you have, the more tolerant your bearings are, with less chance to bind and chatter. When I do brass tube bearings, I tend to use a single piece of tube the length of the bearing block (2-3") and I tend to avoid any binding issues that way.

I tend to like using oilites better than LM series ball bearings. I find that they're smoother than the cheap chinese LM*** slides, and are very likely much more tolerant to gunk and goop that may end up on the rails than ball slides. No internal parts to go wrong, I think you'll end up with a very reliable machine.

Looks like you've already got plans to drive your gantry/Y-axis from both sides, which is awesome, and should also help eliminate any chance of binding on that axis. I don't see what bearing size you're using for your shaft rotation -- and you may have already done this -- but 608 (skate) bearings will give you best bang for your buck.

The mounts for your X-axis rods should work, but you might want to put a spacer in next to the tubes, where the bend is, in order to get that all shored up and solid. Presuming that you can keep the rods exactly parallel with each other in that arrangement, you should be doing dandy.

Your motor mount is a bit of a concern, as, depending on the size of the motor you use, it's dangling off of the centre of gravity, which could cause some peculiarities. There's no easy way to really remedy this, all options are tradeoffs. Some of them are:

Run a similar similar setup to your Y axis drive, with motor --> pulley, coupled to a pulley that drives your X axis belt. This would let you mount your motor somewhere possibly more convenient. Tradeoff: complexity, and figuring out alternative mountings. Adds a bit of weight.

Mount the X-axis drive motor on the extruder carriage, and use a stationary belt arrangement to drive it back and forth. Tradeoff: More weight and bulk in the extruder carriage.

Run a connecting plate across the top of your X axis, and mount the motor to that, having it drive the axis from above, with four idlers keeping a longer belt in a rectangle. Tradeoff: extra complexity, extra mass/weight to the gantry, larger part count, complex design.

Also: I found that in mounting limit switches, I had more flexibility in mounting the switch itself on the moving part (i.e. gantry or extruder carriage) and mounting the plunger to the frame. Plungers take up less space than switches, and I could home my axises right up against the extreme edge of their travel. requires more "flying wiring" but since you already have a bundle, another couple wires isn't going to be the end of the world.

-C

[homer93]

hi all, thanks for all the feedback, not been able to do anything on the design recently
had to get cracking on with some revision for uni, want to try and get a little bit done on it this weekend though

EL34

• if i dont do any test on speeds i can use different bearings before finishing the design i may try make the bearings interchangeable, or make 2 different sets of sliders to compare results.
• at the minute i dont have a specified build platform i want to try and achieve, so not too much problem with the limit stitches taking up space. but im going to design the switches into the design now so i know almost exactly what my limits will be, so hopefully no nasty surprises when i make it
• nice build, dont suppose you could give me some links for the electronics you used, im undecided if i should buy existing electronics or design the PCBs myself

wontpontificate

• i may try using both long and short bearings, currently in the design there quiet short but if the dont preform well i can always swap them for the longer ones, just with shorter ones it should cost a bit less.
• i wont have a problem with the bearings slipping out of the mount there in will i?
• the bearings im using are quiet small, MR105-ZZ 10x5x4, originally i had some larger shafts, but the pulleys had a smaller bore than i though so everything ended up smaller.
• what do you mean put a spacer in next to the tubes?
• im still undecided on the x-axis motor mount. i don't want to mount it to the slider since i want to be able to extra extruders easily. preferably i want to just move it in on the slider its on, but didn't have any look last time i tried, going to give it another shot at the weekend.
• ill have a look at mounting the witches to the sliders, but i think the limits are going to be mechanical obstructions rather than room for the switches.

i could do with starting looking for some electronics now. was hoping some people could guide me in the right direction of whats best. should i custom design, or buy ready made. i want to get a small lcd display on the body somewhere, the build area to light up since I've taken out the side openings, and then some simple controls on the body with the lcd as well as an E-stop. i haven't looked for anything yet, thats a weekend job too, any help would be good though.
also does anyone know of a good supplier for components, belts and motors, stuf like that. found a few places online, but maybe someone else could give me some places with better prices

thanks, will update soon
rob

[EL34]

I added links to my electronics on my build page here
DIY 3D printer using T-Slot Extrusions

I just went with the same Probotix stuff I used on my CNC machine because it works and is trouble free
Also, I would have backups if anything failed on either machine.

I am using Mach3 to drive my 3D printer and so I stayed with what I know
Mach3 and CNC electronics

I am not familiar with any of the arduino type stuff the reprap guys use

[wontpontificate]

i may try using both long and short bearings, currently in the design there quiet short but if the dont preform well i can always swap them for the longer ones, just with shorter ones it should cost a bit less.

What sort of bearings are you using? What's the part number/dimensions?

i wont have a problem with the bearings slipping out of the mount there in will i?

You shouldn't -- it would depend of course on how they're fixed. I've found that even finger-pressure insertion of oilites can work, provided that everything is square and there's no racking.

what do you mean put a spacer in next to the tubes?

I modified one of your images and attached it. The crude drawing on the left is shows a grey square where you'd have a spacer to fill the void around the bearing mount. Would help stiffen the whole shooting match and prevent flex. A block with a hole through it for the shaft mounting tube to run through.

im still undecided on the x-axis motor mount. i don't want to mount it to the slider since i want to be able to extra extruders easily. preferably i want to just move it in on the slider its on, but didn't have any look last time i tried, going to give it another shot at the weekend.

I worry that the flap you've got your motor mounted to in your design will flex/bounce with a tight belt and quick direction changes, compormising your accuracy, and introducing "wobble" into your print layers.

ill have a look at mounting the witches to the sliders, but i think the limits are going to be mechanical obstructions rather than room for the switches.

How do you mean here? Are you planning on avoiding the use of limit switches in entirety? You -can- technically get away without using them, but there's nothing quite like that moment of clenched AARGH and panic when you make a mistake while jogging it, and ram an axis into an endstop, the motor fervently trying to drive it past.

From a practical everyday standpoint as well, you'll want your machine to know where it is, and be able to home itself reliably. Makes life a lot easier!

i could do with starting looking for some electronics now. was hoping some people could guide me in the right direction of whats best. should i custom design, or buy ready made. i want to get a small lcd display on the body somewhere, the build area to light up since I've taken out the side openings, and then some simple controls on the body with the lcd as well as an E-stop. i haven't looked for anything yet, thats a weekend job too, any help would be good though.
also does anyone know of a good supplier for components, belts and motors, stuf like that. found a few places online, but maybe someone else could give me some places with better prices

Most of the reprap/3d printer folks use a combination of Atmel microcontrollers (Arduino stuff) and Pololu stepper drivers for movement. There are any number of different boards out there, the most common is the Arduino Mega (or cheap clone therof) with the RAMPS shield. Theres also the Sanguinololu, the Printrboard, and a whole host of others that pop up. Pretty much all of them support, either natively or through add-ons, LCD displays, SD cards, etc. Most of them (all the ones I've mentioned for sure) use Pololu/Stepstick drivers, which are often sold separately. They're on separate little daughterboards, so in the event that you blow one, you can just replace it to the tune of about ten bucks, without scrapping your entire board. Features vary, some support dual extruders, some only single, some have other geegaws and whatsits, so compare a few before you pull the trigger. Just remember that when it boils down to it, they all do about the same thing, just at different price points, with different feature sets.

The firmware I find seems to work the best for standard cartesian motion is Repetier. It's fairly easy to use, has a neat desktop software package (repetier host) and seems to work very well. Marlin is another good choice, but getting it going is a bit more complex.

Mach can work well, but I think it's a bit more cumbersome and expensive for 3d printers, especially since you can pick up a complete set of electronics with bells and whistles for less than two bills. If you're used to Mach though, more power to you, but I'd give Repetier/whatever hardware strikes your fancy a shot.

For the sort of stuff for a 3D printer, I'd check ebay for motors and electronics. Keep an eye out for an established seller with good feadback who deals mostly with motors (Long Motor or Wantai are a couple that come to mind) and publish all of the specs for their motors on their page (including inductance, which is a figure often left out) -- the sweet spot for price seems to be about $40 for a set of 5 steppers (most sellers aiming at the 3d printer market sell in packs of five, since the popular reprap designs use 1 each for X, Y, and extrusion, and two for the Z)

There are also a lot of ebay sellers selling the brainboards as well. Most of the 3D printer electronics out there are open source hardware -- you'll find that most of the differently named boards out there do the same thing, with the same hardware, compatible with the same software, and based on the same architecture, but with slightly different features. You'll also find a lot of chinese knockoffs of the boards, often for much less money. Beauty of it is that the chinese knockoff boards are often clones of the real deal, and have just been manufactured using the published board designs. No worries about crappy design (like the infamous TB6560 "blue board" cnc controllers all over ebay). If you do buy a chinese knockoff though, I do suggest figuring out where the original design is, and kicking a few bucks donation to the designers.

Hope this helps!

Cheers!

-C

[homer93]

at the minute ive got some custom sized ones, id'e have to get them machined, just brass tube i think i put it. so ill try it with 2 short ones in either end of the block and just one long one. if i remember right i put 8mm shafts in.

ide try and get them to be a tight fit, preferably, i haven't put any grub screws to gold them in place since i didn't think they would be necessary

ahh ok, understand now. i thought with 2mm sheet metal i wouldn't get much flex or distortion. ill have a play, see what i could put in, preferably something quiet light, but would rather avoid aluminium, to keep machining costs down.

if the belt pulley is inline on the opposite slider it shouldn't flex should it? ill have the motor bracket spot welded to the main slider bracket, i think it should hold it securely.

i mean ill have plenty of room for the switches, when i positioned it to its extreme positions in the cad model it came into contact with brackets and mounts, so ive got plenty of room to mount the limit switches, without having to add extra space for them.

ill have a look at the firmware later if i get chance. don't want anything too ridiculously complicated.
ill try to start sourcing parts too, may take me quiet a while to gather everything i need if i build it.

any tips what features i should include in it, to go with the short list i have so far: LCD, simple navigation, e-stop, light up build area, SD card, what else is liked by the people?

thanks
rob

[homer93]

not done much on the design ive got recently, but i hav made some progress with electronics.

ive decided im going to use the arduino electronics. this way i can personalise it to my design and look i want to get, as well as make the design more compact.
ive made most the schematics for the parts i need, and found the components im using for them. ive just got to make the schematic for the motherboard, whiich shouldnt take too. then ive just got to make the pcb layouts and find the rest of the components ill need.

is it best to have the power supply converter built into the printer or have it as a separate box? dont know if that makes sense

will put another update soon ish hopefully
rob

[Pierke]

Are the Arduino pcb not ready?
Can you put a few pcb together?
I'v read elsewhere that some guys use a temp. controller from Velleman Kits.

Nice work!
Pierke

[homer93]

well i was going to but the arduino and boards ide need, but when i was making a layout for the navigation and lcd panel i got a bit carried away and changed my mind and decided to make layouts for everything

rob

[Pierke]

Hello Rob,
can you make the platines by yourself (engraving or so?)
Pierke