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WeldingRod Bot: Exactly Constrained 3D Printer

by Weldingrod1 Aug 24, 2015
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That cat you printed is so realistic!

Finally decided to pull my Cobblebot out of the closet and do something with it. Stoked I found your build. I don't have AutoCAD to open the DWG files, but do they contain everything I need to get the plates cut? When I open the files in other apps I don't see any dimensions.

Yes, the DXF files have all the parts you need cut. There are both metric and English sized drawings with the parts laid out full scale. With my local welders they like to have at least one dimensions left on the drawing, but they have to take it off before cutting. The rectangular plate with 6 holes in the lower right corner is 5.905" by 2.362" or 150 x 60mm.

Perfect! Thanks for the quick reply!

What material is the cat printed with green eyes?

You did a good job, the cat looks realistic. jk

I mounted the Nimble Dual remote direct drive cold end on my WeldingRodBot this weekend, along with a new E3D Cyclops. No complaints so far, although I lost about 40mm of build height (or alternately, 20mm of X axis) when allowing for the new drive cables to pass under the top of the frame. It’s a fair trade for improved quality and reduced jamming.

The conversion to Nimble Dual was trivial. Two of the triple-hole Cyclops heatsink mount pattern screws center up nicely against the inner centers of the arched cutouts in WeldingRodBot’s hotend plate, with the third hole centered along the outer edge of the section between the two arched cutouts. My plan was to have the 1/8” steel gantry plate clamped between the Nimble and the Cyclops heatsink, so to keep it from slipping around, I just drilled and tapped a single M3 hole and screwed the Nimble down against the plate with a shallow M3x6mm socket cap screw (using the fourth through-hole on the Nimble that wasn’t being used to mount the Cyclops heatsink. The other three screws were M3x10mm to accommodate the added plate thickness. The Bowden tubes needed to be 25.75mm long to take up the full length from Nimble to bottom of Cyclops. This configuration reverses the orientation of the Nimble, but it’s the only way I could get it to fit, and everything is still relatively accessible.

Hi Weldingrod1:

I'm starting to build a basic Cobblebot (kickstarter $299+$$$$$) and so far it's missing (only) the Solid V Wheels (http://openbuildspartstore.com/solid-wheels-precision-shims-28-pack/ ). Should I buy this pack and use the Cobblebot supplied spacer, precision shim, Wheel, etc or get the 23x Solid V Wheel Kit - http://openbuildspartstore.com/solid-v-wheel-kit/ ?
I downloaded your google docs and found that, to build a "good" printer I'll have to purchase a few extra parts (list on pag 4), most of them from Openbuilds and Amazon (no problem). I'm trying to find where to get those new sets of the plates here in Portugal (maybe hard to find where to cut them).
Do you have any other/new advise for a 3D printer noob?
Thanks for your help

3d printing is a blast; I love having minions out in my shop to do my bidding... Mwha ha ha ha! Sorry, my inner mad scientist sneaking out ;-) Seriously, it changes how you do things; you can make jigs and fixtures, custom containers, holders, hangars, art, all for only the effort of modelling (or finding a model to modify), then have the real thing in 30 min to 8+ hours. And, its all exactly what you drew!

If you have the second version of the Cobblebot wheels (shipped out MUCH later than the crummy moulded ones), there is nothing wrong with them. The bearings I got with my kit were fine, but some people's weren't. The Cobblebot spacers aren't the rights outside diameter; you need really skinny ones. I would either get the Openbuilds spacers or order them from McMaster: http://www.mcmaster.com/#98055a099/=13ixxcq

If you take the .dxf files to a welding shop that has a plasma cutting table, they should be able to run you out a set pretty cheaply. Waterjet or laser cut parts will also work well, but be more expensive. You want steel parts; Aluminum is going to flex more than steel AND cost more. Don't use acrylic parts, even if they are easier to get cut!

Get your mechanical stuff working smoothly first, then figure out where your wires need to go so they don't get caught in stuff anywhere in the range of motion. Extend your wires as needed, heatshrinking over the joints. You REALLY want to tie the two Z screws together with a single belt; if you get things running smoothly you will find that its a must-have to keep the Z stuff from sliding down!

Have fun, and welcome to the world of 3d printing!

Sorry, but no. I did all the modeling work in AutoCAD and my head. I didn't bother to model it in 3D.

Understood. Maybe some better pictures. I cant seem to get into your head with the ones posted, they are to small and low res

I've added a link to the google doc for the instructions and a fresh PDF of them. That might help, but let me know if there's something I can post for you. My printer is enclosed now, but I can take some photos of it. You might want to visit the Cobblebot group; I posted a lot of stuff on this printer design. https://plus.google.com/u/0/communities/101598858709677645162?cfem=1

Is there a complete 3d model of this printer?

will it give my cat lazer eyes?

Build in process (from a Cobblebot 1B). Couple issues so far:

  • My 500mm 20x60 cross bar rails are not perfectly squared on the ends, resulting in either a tilted box (meaning the ends don't line up, and the measured diagonals are not equal) or a squared base frame but with a curl/warp that won't sit flat on the work surface. Flipping the 500mm rails around a bit more found a configuration that was squared and flat.

  • After assembling the entire gantry, my Y side of the gantry with the X motor easily sinks under its own weight for about 10mm any time the gantry is moved into plane with the base (meaning the gantry is aligned and not starting to rack against the Z rails as only one side ascends/descends). I believe this is due to the placement of both X and Y motors on the same Z side of the Y axis. I modified the X idler plate and reversed its position with the X motor plate to balance out the overall gantry weight a bit more between the two Z lead screws.

how long does it take to heat your 3/8 with the silicon heater? im looking at 3/8 and 1/4 mic 6 right now with hopes to get the silicon heater later. i wont have any support under my plate after i mount my manual leveling screws so im leaning towards the 3/8

I haven't timed it; between 5 and 10 minutes to heat up.

I have a beast that I've gotten running and fully adjusted with the exception of proper leveling of the bed. I would be happy to take pictures or answer any questions about the setup to confirm these enhancements will work.

If you want to post some pictures on the google group or some other site, I can take a look at it.

I don't know enough about the Beast build! If it is a stretched Basic, then these plates should work fine. One caveat: elastic deflection of the Y rails is noticeable at the basic's 15" span. The beast will be worse. Mesh bed leveling should be able to deal with it by shaping the motion into a surface that matches your bed.

Thanks, appreciate the reply. So far, from what I can tell it is just a stretched Basic. I haven't seen anything anyone has posted about the Basic that looks terribly different other than the build plate and aluminum extrusions being bigger/longer. Do you still have sets of the plates made up that you're offering, in case I decide to try this configuration?

I've got some more plates on order. If you send $$ before they get cut, I can get you a set. Otherwise it will may take a while.

What do we know at this point in using this design on the Beast?