From RepRap
Jump to: navigation, search

--MrJohn 20:01, 2 February 2012 (UTC) I am currently building this model and will release some build instructions and directions on how to correctly cut the rods to get the dimensions you would like.

Jan 31- Second build night. Parts printed- 1 base, 1 Y idler, 1 set of 4 feet, 1 set of 4 bearing idlers, 1 x carriage, 1 x motor end and 1 x idler end.


Base- Bug: The base wasn't tall enough for my NEMA 17 motors and was a bit loose in the mounts. Fix: Measured the NEMA 17 motors and adjusted the openscad file to fit. 50mm base height, 43.5 motor casing.Update: After printing the second base I can confirm the above measurements work very well. The motors fit snug into the base and are level with the bottom.text --MrJohn 20:07, 2 February 2012 (UTC)

Y Idler- Bug: I only have 608 bearings on hand as do most Prusa builders. The idler was designed for 623 bearings. Fix: Measured the GT2 pulleys I will be using at 26.2mm and the 608 bearings at 22mm OD. An idler that fits would need to have a hole spacing of 48.20mm with 8mm holes. I'm not sure if this will get in the way of the current threaded rod spacing joining the two bases together.

Feet- Bug: None really. I printed them at M6 settings and they won't fit my design. Fix: Print at M8 and use threaded rods twice as long as the Y rods. This will basically out line the foot print of the machine, ensuring nothing is bumped by the bed.

Bearing Idlers-

Bug: They won't fit the 608 bearings I plan on using. Fix: I will see if I can adjust the scad file to scale them up. Or design my own.

X-Carriage Bug: The bearing fittings went in fine but were a task to remove. Also, the belt clamp system is a bit confusing. Fix: Adjust the file to loosen the bearing space by 0.25mm. Write up a belt mount instruction with photos.

X-Idler Bug: Again the bearings were incredibly tight. I couldn't even get one in. Next, the hex nut was loose. Fix: Loosen the bearing space, tighten the hex space.

That’s all for now.--MrJohn 20:01, 2 February 2012 (UTC)

The bearings slid right in for me with just enough friction to keep them from falling back out. If you have some Z wobble or your flow rate is a little too high, it may constrict the holes. Shaving a little plastic off of the edges at the ends of the channels may make it easier to get them in if the problem is just getting the end of the bearing in and the part will bend a bit to make it fit once you get it started. The X and Z bearing channels have slits in the sides to take up the slack. You can also push a screwdriver into that slit to force the sides apart a bit, thus widening the circle in order to get the bearing in more easily. Worst case scenario, you can add that .25mm fudge factor to the bearing size parameter before exporting the parts for printing. The channels are supposed to be tight, though, and I intentionally did not add these types of fudge factors in the code because the amount of fudging required, if any, is COMPLETELY different for different machines and gcode generator settings, and compensating for miscalibrations that make parts too tight on one machine will make them too loose on another. Drill or ream your parts after printing if necessary.
BTW, please sign and timestamp your posts on talk pages. You do this by ending with four tilde marks (~), and the wiki software will insert the proper information. There's also a button for it above the edit box. It comes out looking like this: --Whosawhatsis 18:43, 1 February 2012 (UTC)

--MrJohn 20:01, 2 February 2012 (UTC)I've added the signature, thanks for the hint.--MrJohn 20:01, 2 February 2012 (UTC)

I'm building this myself at the moment, here's my own feedback:

  • Feet: Personally I think these should be a bit thicker to make it easier to put felt strips on the bottom.
  • X Ends: I suggest allowing the bars to extend through the end pieces. The separation of the end pieces is already fixed based on the size of the print bed, so having to cut the length of the bars to fit adds an extra thing that can go wrong during construction i.e. cutting them too short or too long. The two bars that hold the base pieces together do just this, if you're in any doubt you can just cut them a bit longer than you think you need.
  • X carriage: the M4 holes are really close to the diagonals, a potential problem with poorly calibrated machines (or hand-cut pieces).
  • Y bearing retainers: the M3 holes on one side (the same side as the bearing loop) don't quite have enough free space for an M3 washer.

Other than that, great design! I struggled getting most of my linear bearings in place but that was mainly due to printing the pieces on a poorly calibrated machine. Nothing a dremel wasn't able to fix.

--Myndale 02:23, 2 February 2012 (UTC)

Feet: I could probably add a parameter for that.
X Ends: I had them that way at first, but it made them a lot weaker and allowed the tension of the X belt to bow the Z rods inward. I might experiment with it again now that the top is braced.
X Carriage: That part needs some work, and I'm thing of getting rid of the 45-degree-rule friendly angles and switching to something that takes advantage to the ability to bridge gaps.
Y bearing retainers: They're intended to be used without washers. I wanted to keep the inset for the head small to avoid compromising the integrity of the arch.
--Whosawhatsis 12:43, 2 February 2012 (UTC)

@Whosawhatsis Could you share your last name the same way the other designers of the previous RepRaps have? ie. Sells-Mendel, Prusa-Mendel, Whosawhatsis-Wallace.

And a follow up question. How do you pronounce your nick? Is it Whosa? Whats? Is? or Who SAW, What SIS?

MrJohn 20:16, 2 February 2012 (UTC)

"Who's a what's 'is?" all run together into one word so it sounds like "HOO • zuh • wut • sis".
As for preceding the machine name with that of the designer, that was started by Joseph when he used his name to denote his version of the Mendel design rather than giving it its own name, thus necessitating adding Ed's name to the original Mendel to minimize the confusion between the two. It's a practice I don't agree with, and I don't want to encourage it. --Whosawhatsis 21:38, 2 February 2012 (UTC)

Design Requests

I cannot design parts well. So, this page is my way of putting ideas in the minds of those that can.

Makergear compatible hot end mount.

I am currently working with a Wades Extruder that has a Makergear hot end interface countersunk into the extruder. It, however, is much too short to reach from the mounting plate on the x carriage to the bed as-is.

Would it be possible to create a mounting block under the overhang of the x carriage to then mount the MG hot end to?

So from top to bottom it would be:

Wades extruder (standard)

X carriage (Wallace)

---This mounting block or extender----

Hot end


Print bed

I think it would be a good idea to create this type of adaptor for now until someone designs an extruder with the Wallace in mind because builders can use the components they already have laying around to build this model. They can print up the parts to the Wallace, a few other adaptors and build this machine in no time.

Please, feel free to comment below.

MrJohn 20:28, 2 February 2012 (UTC)

I'm using a Makergear hot end with mine. They work if you assemble it with the 50mm barrel instead of the 36mm barrel. The reason there hasn't been much movement on the existing Wallace parts recently is because I've been experimenting with extruder designs and I'm going to release my own. This will be the recommended extruder for Wallace, and may even be optionally integrated into the carriage as an alternative to the current style of mounting.
Mounting the hot end lower is more problematic than you might think, because the mounting would have to fit into the extruder in a way that would make it completely incompatible with any other hot end OR extruder. Extruder issues are at the top of my list, and I would like to make it work with the shorter hot end, but just tacking on a spot to mount the hot end 15mm or so below the extruder is not the answer.
This is just a taste of what I'm working on: [1]
--Whosawhatsis 21:38, 2 February 2012 (UTC)

Extruder looks great, I was going to print off a Wade's accessible but I think I'll hold off now. One more suggestion that may or may not work: with the current design you have to remove all three steppers on the base in order to get to the screws and nuts that hold the Z bars in place. Would it make more sense for the hole that holds those to run parallel to the Y axis so you could get at them whenever you want without removing those steppers? If done properly then I think it would also help further secure the Z axis and X carriage from back and forth movement in the Y axis direction. Or would that just introduce instability along the X axis? Myndale 10:22, 3 February 2012 (UTC)

I wanted to do it that way, but in the end I decided it was too important to make sure the rods were braced as well as possible in the direction of the forces that will be applied to them. --Whosawhatsis 12:18, 3 February 2012 (UTC)

Another problem I've just encountered during my build is that the Z axis rods aren't sticking up straight either due to inaccuracies in my print or maybe I just didn't drill them out straight when cleaning them up. The end result is that my X axis bars aren't perfectly perpendicular to Y. The Z axis bars also seem to move (wobble) along the Y axis more than I like. I can fix both problems by wedging something into the base holes that hold them, but something like the following might be a better idea i.e. a receptacle for an M3 nut on either side of each Z bar and holes extending out the sides of the base for screws to be inserted and adjusted accordingly:


Admittedly it does make the design a bit more complex but they would only have to be used if these problems were encountered and it would really stabilize the Z axis bars in the direction of Y (a weak point for all printrbot-like machines). Myndale 11:20, 10 February 2012 (UTC)

The problem is that by drilling them, you made them too loose and destroyed the mechanism I put in place to self-align them. You see the little rectangular outcropping in the side of the octagonal hole? The screws push the rod against that so that it makes contact at the edges of it so that it can't move around. Drilling the hole out will destroy those and make it not work. The hole should be tight to make the rod even more secure. You can taper the end a bit with a knife to help you get it started, but if you can't get it in at all, you should re-print with a small fudge factor added to the diameter of those rods (remember what will happen if it's TOO loose, though) or better yet fix whatever calibration issue is causing the holes to be printed smaller than spec in the first place. --Whosawhatsis 12:13, 10 February 2012 (UTC)
Ah, ok, I see the problem now. It's not so much the drilling, it's the fact that the machine that my pieces were printed on had a small amount of backlash. Looking closely it looks as if that has caused those notches to shift ever-so-slightly in the direction that the print head was moving. Since both base pieces are rotated copies of each other it means one z-axis rod leans one way and the other one leans the opposite way; net effect is a skewed x-axis. It's a clever trick but I don't think it's very fault tolerant. Even on properly calibrated machines I can't help but wonder if the compression forces on the plastic around the edges of those mounting holes will eventually cause the z-axis rods to loosen up over time. Myndale 19:44, 10 February 2012 (UTC)
I've got the same problem with the Z-axis smooth rods, the holes have been printed around 1mm too small all the way through. Reprinting isn't an option so can you recommend anything? I'm using M8 rods all over on this. I'm loathe to taper it then force the rods in because I don't want any damage as it goes in (Splitting etc.). Plainnash 14:15, 16 February 2012 (UTC)
Definitely consider tapering the ends both of the hole and the rod. It's not uncommon for the bottom layer of a print to be squashed a bit, pressing the perimeter outward slightly and constricting holes only at the end.
If your parts are so inaccurate that you can't assemble them, I'm not sure you will be able to make it work. The only suggestion I can think of is if you use a drill press (NOT a handheld drill) and a vice (NOT your hands) and drill it in line with the center of the octagon (NOT the entire hole), and use a 5/16" drill bit instead of 8mm so that the hole remains tight enough to keep the rod from moving, that might just work. No guarantees, but if you're careful, you might be able to make proverbial lemonade. I'll see if I can think of a way to make the parts a bit more tolerant of printing errors, but anything that will make the part more adjustable will also make it weaker. Maybe I should just design a calibration block that you can print and test all of the tolerances before printing the actual parts. --Whosawhatsis 18:32, 16 February 2012 (UTC)
Excellent, that's worked fine, you were right about it only being a first layer problem. I tapered the first layer or two of the hole then placed the rod on the floor and pushed the base onto it. The print quality is top notch, just waiting on some linear bearings from China to finish the build now. Oh, and a hot end... Plainnash 18:45, 16 February 2012 (UTC)

M6 Nylock nuts

Do the Nylock nuts go on the bottom ends of the Z-leadscrews into the leadscrew_coupler ? DaveX 22:11, 2 February 2012 (UTC)

Yes. --Whosawhatsis 22:12, 2 February 2012 (UTC)