In case others like me don't know, I just figured out that the Ramps 1.4 bd has 2, TWO outputs for the Z motors connected in parallel.
I guess, depending on ur motor, u might need the higher pwr drvr for that. no wiring necessary - though I have decided to go with one motor and 3 screws.

 

The lead screw bases are fully parametric, if you let me know what bearing you are using I can change it for you.

I also have a new gantry plate, for two end stop switches. I am adding a line in my ending g code to send the print head to x max after the extruder is cool, triggering the end stop switch will power off. As soon as I print it I will post it.

 

Thanks Carl. My J-head(genuine) will probably be a little bit shorter but I think there is enough threaded rod still, worst case I'll redesign the stepper mounts or use my E3D clone but I prefer my J-head.

Got a big box of bolts yesterday from the greatly overpriced mcmaster and I just placed my order at openbuildsstore.

Your Order Contains:

• 12 x Aluminum Spacers
  (Size: 1/4")
• 7 x Tee Nuts (25 Pack)
• 7 x Black V-Slot 20mm x 40mm Linear Rail
  (Length: 1000mm)
• 20 x Delrin Mini V Wheel Kit
• 2 x 8mm Metric Acme Lead Screw
  (Length: 250mm)
• 2 x Nut Block for 8mm Metric Acme Lead Screw

I now need to begin printing the parts needed on my Mini Kossel. Biggest issue I see is a miter saw to cut the extrusion. Anyone have tips on how to ensure the cuts are equal? I'm considering trying to cut four 20x40 at one time but I'm not sure how well that will turn out.

 

When using a reasonable length Z length, why not use a integrated leadscrew / stepper, instead of a flexible coupler. Is there a benefit to using the flexible connection?

 

I FINALLY was able to place my OpenBuilds order in the 30 second window when everything was in stock. I am going with 345mm leads (1m OB screw/3). I figure that will give me about 275mm build height. I can also invert the Z motor and raise the screws about 15mm if I need to. Most other parts have arrived from China - still missing a few. I will drive the 3 screws with a belt similar to Adam's arrangement and only use 1 wheel on each end (4) of platform. I am still working out the XY build area with endstop placement. I shaved about 40 mm off the width and I am mounting the Y stop on the rail. For the X stop, I think I am modding the H end to hold that. Extending the width if I need to isn't an issue as long as I do it before I cut the rails. LOL.
I found that there is one issue with the left idler (if u r looking at it from the XY motor side) - the void for the bearing screw hole below the nut is much off center. I am posting my fix if anyone is interested. Warning, I'm not an expert and it isn't perfect, I'm sure, but much closer. Hopefully they will screw into the plastic and I won't have to wrestle with a nut. Not much extracting force on them anyway.
thx Carl again - now to impress myself with my assembly skills.

 

thx Carl.
I didn't notice the rt one - I may have adjusted it a while go but the left one u posted is still off by that much

 

Yep, should have just told u about it in the first place - but I guess I learned more Sketchup doing it.
Looks like a pro fixed it now. thx - what program do u use?

 

Thats interesting, I didnt notice that. After remodeling all your parts, I really have to say, I am very impressed with what you did in 123d. I found it kind of clunky and not very revision friendly. I am pretty much finished putting parts into Fusion360, Triple-C , I am down to modeling endstops and extruder fans. I still have to learn how to make a belt . Thanks again for all the work you did in revisions and iterations.

 

I have no idea if this is useful to anyone, but since u guys/gals have been so helpful to me I want to give u first shot at it. An Excel spreadsheet to calculate the PID averages for running Repetier-Host M303 Autotune function. Just run it and copy paste results into spreadsheet and view the results. It will average multiple runs also. And is easily expandable if u need to. It may work for other programs but it depends on what their output look like. But I am sure u can adapt it easily. It simply parses the output to extract the data. Instructions included at top along with a couple of my runs for examples - DON'T delete anything but the first column as the rest of it contains formulas. Just overwrite the log data and everything else will chg magically.
thx again

 

Hey Carl,

Just giving your BOM a closer look with regards to the extrusion cuts needed. When compared to your C-bot photos I noticed you are using 20x20 extrusion horizontally in the front of the printers frame but it's not mentioned in the BOM and I only ordered 7 1000mm 20x40 extrusions(according to BOM). Do I need to order some 20x20 or did you change the design after building your machine?

 

Thanks for posting the model. Gives me a better idea of how the regular C-bot is assembled. I see now that you can likely use 20x20 or 20x40 extrusion for the two front horizontal braces. It also looks like adjusting the Z axis stepper height would be fairly easy if my threaded acme rods end up being a little too short.

After adding up all of the cuts including the bed, I think 7 pieces of 1000mm extrusion will be fairly close but may end up being sufficient as long as I get everything right on the first try. I'm printing the 90* corner brackets now out of PLA @ 60% infill 0.1 layer height while waiting for my order to ship.

 

I used the Popsicle stick method of planning my cuts

 

I was wondering what others were doing to keep track of everything as this build is much more involved then my Mini Kossel that I pieced together myself. After seeing your Triple C 3D model I decided to try Fusion 360 and I am really enjoying it so far. Will you be posting the files for the completed model once you're finished? I'd like to take a stab at modifying it to reflect my build of a regular C-Bot.

After reading other reviews on the standard C-Bot I'm really considering using two 20x40 Z sliders positioned on each side of the frame with two Acme threaded rods possibly connected via a belt similar to the Triple C. My main concern is flex in the bed due to the weight as I eventually plan to scale my build up to a 300-500mm print bed.

 

@haxored, PM me your email address and I will give you the keys to the fusion castle. I will be putting up all my .stl's and fusion files ( .igs or step) . I just ran all the stl through netfabb and havent put them back up yet. Sorry my inbox moves at the speed of my toddler.

 

I was considering 2 screws but after a couple comments from adam decided 3 would be much better. My planned arrangement is much like adam's but I don't have the extra wheel on my adjustment bar. I may need to add a wheel someplace to give more wrap on the 2 opposite the motor. Actually, I just thought of a better idea. Since I have an extra bar in the center anyway, if I mount the motor to it (instead of on the side) I have adjustment, don't need the idlers, AND have high wrap on all pulleys. I must go model that..........thx for making my brain work.

 

you may be able to use a 20x40 crossmember and put two idlers on it. That was my original plan, , that pic is not very good, can be seen here http://www.thingiverse.com/thing:588277 . I decieded to add a second cross member , thats why one of mine is 20x20 and the other is 20x40. I could also probable make it work with the ganrty plate as i had it in the photos.

Same for anyone else, if you want access to the Fusion files, just send me a pm with your email and i will invite you to my project.

 

BTW - I ordered 5x 1500mm and 1x 1000mm rails - I have a sq bed so i need a little extra. But if u use the longer pieces I think u might find that it comes out the same cost wise and u may have longer more useable scrap pieces. just a thought.

 

Actually would like bigger but I consider myself reasonable and plan to start small . I eventually hope to print full scale engine blocks but for now I'm going to slice them into pieces and test out the CoreXY design vs my Delta(the two fastest printer designs) and decide which way to go for a much larger build. I definitely agree about the 3 screw system and would probably use 20x60 everywhere except the print bed frame where 20x40 will likely still work and keep things as light as possible.

So far I've got ten 90 degree corners printed @ 60% infill, 0.1 layer height and four 5 bolt 90 degree plates with 100% infill and 0.1 layer height. I'm considering reprinting the 5 bolt 90 degree plates in ABS @ 100% infill to compare strength I just wish I had some extrusion here cut already so I could test the printed plates under actual load but I think openbuilds is out of stock on the 250mm Acme threaded rod even though it showed in stock at the time of my order.

 

Just trying to keep this thread active...

I've managed to get a bit of working done on my 12" ^ 3 C-Bot today. I cut and mounted my 20 X 60mm v-slot for the z axis/print bed. I decided to go with eight mini v wheels per side. It definitely seems solid enough. I also decided to give this extruder a try: http://www.thingiverse.com/thing:711401. I know from my experience with the Airtripper with a mk8 hobbed gear it should work ok on a direct drive NEMA 17 stepper.

Here are some pictures:

 

Got my order from Openbuilds finally. Everything looks pretty good except the Acme threaded rod blocks have a little slop in them (one more then the other) and a few Delrin Mini V Wheels were machined poorly/out of round. Tried to take some pictures but the flash on my phone is hiding the quality problems.

I'm slowly printing the parts now but the Sainsmart fluorescein green PLA I'm using is almost gone and Amazon is out of stock. I'm hoping to have the machine mostly built by the end of the month.

bhalkett, that looks great! I wish my build was that far along. I really like the red on black as well, hopefully my green on black turns out as good. I'm also considering the same V wheel layout for the Z axis along with the 20x60 extrusion. How long are your Z axis wheel bolts?

 

I used the 60mm low profile bolts for the z axis. I also used the 9mm spacers and two extra washers on each bolt for proper spacing.

 

Yup...I think the 20x60 will work out just fine. I don't know if the extra wheel are helping or not but they seem to work fine. The extruder...you're right there is now adjustment. I've also had some challenges getting the correct diameter springs. Either too small or too big. I just made a small change to the arm so it will accept a slightly larger diameter spring.