Project: A0TAZ - TAZ style X end bits for AO-10x series...

So, I have this here Lulzbot A0-100, upgraded to most of an A0-101, but I can’t help but notice there is this TAZ thingy running around with shiny new features. I would like to have some or all of those features on my 3d printer, so this project will attempt to do exactly that. Specifically this is an attempt to retrofit Taz style Acme Nut with Anti-wobble and anti-backlash, and offer people the option of going with Taz style-ish LM8UU bearings or the origional existing pillow block bearings. I dunno if its going to work, or end up being an actual upgrade by the time i’m done with it, but we’ll give it a shot anyways. I borrowed the Lulzbot AO x end pieces and 1013’s excellent Acme nut module for the basis of this evil plan, hopefully they don’t mind too much.

Base Premises for this project:

  1. The upgrades need to use the existing Acme screws and Bearing rods
  2. The upgrades cannot require major frame alterations
  3. The upgrades will utilize the existing horizontal X bed and x axis rod spacing, clearance, etc.
  4. The upgrades cannot narrow the existing build window at all.

So this is a very early stage of this project. I’ve modified the existing X idler and lower X clamp 2.0 to remove their Acme nut portions, and as much of the clamp surface as I dared. I also removed the rounded reinforcing hump on the Acme screw side. The theory being that the Taz style single piece bearing frame will provide the rigidity and support that hump previously provided. .

I then sliced apart 1013’s Acme nut holder (surgery is a work in progress, and mearly shows the basic premise i’m headed towards. it’s also missing the lower portion) to attempt to add a channel where the TAZ style acme nut holder will pass over the two Clamp pieces, and be secured above and below them. This may have the added benifit of constraining the motion of the anti wobble to the x axis plane. To compensate for the anti wobble spring pieces lost, I’ve extended the acme nut piece up another 10mm, and will extend it down slightly on the bottom clamp as well. The intent is to allow the Acme rod to move side to side as much as possible, but still maintain the upper and lower sections as a single unit so i don’t end up with spring wierdness. I’ll probably also beef up the side faces of the section around the cutout. The side cuts now become the replacement for the front Acme nut loading window since they have to be there anyways. At the final installation, the X end clamps on both sides would be sanded and polished top and bottom to allow the acme nut piece to glide back and forth maybe, unless that ends up being a pain to align in which case it will just get a .1mm clearance all around or something.

On the Idler side, i’ll also end up having to clearance for the bolt head. Not sure what that will entail yet.

Here’s some pictures so you can see where I think i’m going anyways. Work in progress, holes are in wrong spots, parts are missing, cats and dogs living together, etc. Non Euclidian Geometry may be in effect.

So, it’s a start anyways. I’ll actually not be able to work on it further until around friday or so, but i hope to have something somewhat ready to attempt printing by next weekend. I guess I’ll need to figure out where to get a pair of them spring thingies and another few Acme nuts though.

Any thoughts, ideas comments or better approaches to what I am attempting than what I am attempting, Please let me know. I’m still sandblasting the rust of my Cad skills, so there are probably things I’ll need to clean up, etc. Once I get things further along i’ll upload the desing files so people can play with them

Nice work, keep us posted. :slight_smile:

Will do!

Got to thinking about this some more last night, and I’ll probably shorten the acme screw clamp platform a bit more. With the reinforcing hump gone, there is no reason the build platform side X end rod clamp screws couldn’t be moved closer to the flat upright piece, which gives me enough clearance in theory to extend more of the plastic spring and frame on the front face. At the sime time, i’m also going to have to trim around the rods themselves, otherwise the bearing rods will lock the cage in place and make it really useless. So thats going to further weaken that area of the acme nut cage. On the other hand, since it will be anchored above and below, it may not need to be particularily strong there. It needs to be beefy enough to resist downward pressure from the spring, but it really doesn’t need that much lateral strength because nothing in the lower section is going to be fighting the ACME screw.

figuring out how to print the resulting acme nut holder is going to be fun too!

Question for someone that has a TAZ, how much side to side flex is actually likely to occur under average circumstances in the ACME nut carriage? Specifically how many MM does it need to be able to move to one side or the other?

Alright, just got back from training trip, so I’ll start working on this again. I’m thinking I’m just going to leave 1MM clearance either side for the spring section movement. If the threaded rod is out of true more than 2mm it probably needs fixing anyways.

There is also a slight amount of material in front of the thread side clamp bolts that I may be able to remove safely, and give the front section of the spring an additional 1mm thickness. Which doesn’t sound like much, but as close as I am probably to the limits of the material I probably need every bit I can find. I may actually have to end up reinforcing that a bit thicker than it currently is, which will cut slightly into the X axis potential travel range, but I’m not sure yet. I’ll know better after I print the first one and see how it holds up I suppose.

On the pulley idler side, I’m going to have to offset the bolt back slightly, maybe 1mm or so. The motor side should be pretty much standard, though I am debating reinforcing the motor mount itself while I am in there. Anyways, more to come now that I have my cad computer in front of me again.

Ok, some theoretical progress. The spring modifications to 1013’s design to theoretically make it fit on the modified X ends is done. The x end pieces themselves suffered a bit of corruption or something wierd, so I am redoing them. I’ll probably reinforce the nema motor mount at the same time since I do see a bit of flex in that part.

I’m thinking at the moment since anyone contemplating this mod will have the igus pillow bblock bearings already, that I’ll stick with those and maybe add a LMU88 option later for the backplate when i get to it.

Anyways, here is the theoretically final A0-TAZ spring:

I haven’t even thought about printing this yet, there is no support material in the file yet. I suppose the generated stuff would work for the initial trial fit.

More to come!
spring.stl (1.65 MB)

Cool! :slight_smile:

I ended up having to move the mounting holes on the spring down some to clear the idler bolt. I keep forgetting about it. Here’s the updated part. I was able to get slicer to render gcode that looks usable, but I haven’t had a chance to print it yet.
spring3 (repaired).stl (1.67 MB)

Here’s the lower X end clamp modified.

Basically just makes room for the spring on the one side, and the backplate on the other. X idler and X motor up next, then Backplate variant 1 for use with existing IGUS pillow block bearings. from the AO-10x series.After that, if it works, we’ll maybe do some alternate variants.
lowerx.stl (103 KB)

And the X idler.

Please note that I did have to move the idler bolt mount point back about 7mm, which means you will need a slightly longer X belt to utilize it. It was the only way I could clear the spring side. Not entirely happy with the blending at the moemnt, and it will take some supporting to print properly most likely, but it’s there.

Next up, the motor mount
xidler.stl (146 KB)

The motor mount

Its basically the same thing as the idler, reinforced the motor mount itself with a 1mm extrusion at the same time.

Last part to go, the back brace. I’ll build that tomorrow though
xmotor.stl (133 KB)

Ok I lied I built it tonight

edit, it’s also upside down.

Basically that replaces the structure I had to remove to make the spring fit on the other side. The bolts for the spring itself go from the spring, through the x end pieces and out through the backplate, where they are tightedend down, theoretically resulting in a single uniform assembly. I’ll try printing it tomorrow and see if it actually works. But the design bit is at least most of the way done. I think. I dunno.
backplate.stl (49.7 KB)

Printing parts now. Everything seems to be working well, except for the internals of the spring section which are way too small to fit the actual ACME nut. I think what I’ll likely end up doing is replacing the center section with a simplified anti backlash core. There is definitly sufficient space, and the concept looks sound. It’s printing beutifully too. Oh well, at least the bulk of the rest of it is done now.

Some proof of concept photos. The spring still needs a redesign unless everyone wants to switch over to 1/4" acme rod, but otherwise it works, and everything fits mostly. I didn’t trim enough support off the spring, but I have to redo it anyways so ignore that part.

Corrected spring that shoulkd now accept acme nuts. One goes in the bottom, other one goes on top of the spring in the top, compress the spring on the rod to put it under tension, screw the bottom nut up to maintain tension, etc. Will print and verify it tomorrow. I’ll need to redrill the holes on the idler, backplate and the motor mount to compensate for the new mount holes, also the idler needs a bit more clearance for the bolt than I gave it on the last revision. This spring, and the lower x end clamps should be the final parts though
springrebuild2.stl (700 KB)

Updated the spring file yet again, along with the corrected and slightly thickened backplate. The lower x clamp file is also final at this point.

I don’t want to tear my machine apart at the moment to find out if the acme nuts fit, so I have another set on the way, which should get here wednesday ish. I’ll check them in the final spring nut holder thingy then, and update dimensions as needed.

The idler needs surgery around the bolt hole, and the relocated holes for the spring piece. The motor mount just needs the holes. i’ll likely fix them tomorrow. Assuming everything lines up, this should be a finished printable project by Friday.

I am wondering if I might need a bit more flex in these springs. they seem fairly stiff so far. If this doesn’t improve the wobble enough I may end up splitting the top spring section into 4 springs (2 per side), but that won’t affect the other parts.
lowerx.stl (103 KB)
backplate2_a.stl (76.9 KB)
spring4rebuild_a.stl (494 KB)

Final X-idler is finished. That just leaves the motor which I’ll fix next

By the way, if anyone wants the design files, just let me know what format you prefer, Happy to provide them.
xidler_2_a.stl (181 KB)

Motor mount side again:

also since I have them here, pictures of the latest spring

xmotor__a.stl (164 KB)

Gdang, this is looking rad.

Thanks! I’m happy with how it is turning out so far. I have high hopes that we’ll get something useful and usable out of it. If nothing else the anti backlash should help with z axis reset after printing back to home.

Edit: Also, officially located a spring that will work. A Handyman springs SP-9727 Compression Spring 5/8" x 1-1/2" x .041 915m.9mm x 3.8cm x 1mm) 5.52lb / 2.50kg maximum capacity spring (as found at ace hardware locally) is about perfect in terms of size, height, and tension for this. The theory will be one Acme nut on the bottom under the plastic spring in the socket, one threadless drilled out one to act as a force distribution bearing (optional) at the bottom of the long socket, and then the third acme nut at the top of the long socket on top of the spring. To assemble, thread the top nut, spring and lower threadless oversized washer (i suppose a stack of normal washers would also work) , stick the rod assembly in the plastic spring, pull it down to put tension on the spring (not too much, you just want some upwards force on the upper nut, not a huge amount) then thread the lower nut on and up into the socket to lock the tension into the spring.