On Mounting things.

So since I can’t find the box i put all the fillament sensors in, I’ve decided to revisit the extruder mount instead. So, this is officially “the mount project” until I come up with a better name for it.

The stock lulzbot mount works pretty good. it is easily removable, it holds the extruder mostly in place to a reasonable degree of accuracy for most people, it’s easy to produce, and its pretty hard to break. Where it falls down in my oppinion is that it doesn’t hold the extruder as tightly to the mount plate as it could. In my admittedly modified Taz, I can move my extruder in and out from the plate at least 0.01mm. Thats not much, but for me I think we can improve on it by adding more mounting surface. The other problem is the midpoint of the mount isn’t anchored to the structure of the back wall. Does it matter? for most people, again probably not. But what that would help alleviate is the nozzle bed drag condition where the nozzle moves in and out on Y in response to friction with the part. The upper bed anchor helps eliminate most of that, but there is a little bit that can still occur. The goal here is zero possible flex, with as little as possible additional weight.

The other area the extruder mount could use improvement is the quick release. A threaded bolt isn’t bad, but there are camera mounts that use a sliding dovetail latch with a pin on a spring to undo very expensive camera equipment quickmounts, so I think we can do something similar with the top of the mount without taking too much extra space and the possibility of adding additional interface to structure.

My final goal is to also incorporate mill max spring pins into the mount. 2 banks, one on either side about where the cables terminate now to allow for a dual extruder setup.

Here are my initial thoughts on a design. At the moment since I’m dealing with the openbuilds variant of the Taz X mount plate, and I have a big metal plate back there, I’m considering using that as the base for this. The Stock taz can utilize that without too much modification, and if i do it right it will actually result in a weight reduction over stock. I’m ignoring the Taz 6 X max limit switch entirely for now.

So i’m thinking of basically adding a dovetail in the middle and on the two sides. Those can be printed pretty easily to a high degree of usefulness, would have mounting area to bolt down to a plate up the middle, and would hold a mount tightly to the part. It may need “gun breach” style slots in it to accomodate easier mounting. Not sure yet. The surface can also be angled to allow for a better friction fit towards the bottom.

I’m also thinking that the mount can be narrower than stock aside from where it interacts with the limit switch. Even a wade extruder doesn’t need that wide of a base. I’m tempted to go with the same ring base mount I used for my nova pro instead of the stock mount plate, since I am changing everything anyways, and possibly the novapro fan duct and fans too while i’m at it. Not sure yet. The closer to stock i keep it, the more it will be utilized. But the more rigid and compact I make it, the more actually useful it will be.

The end goal is a more secure mount and an extruder package that is more rugged and less mass than the stock one. If you have any thoughts or ideas, please feel free to share them here!
mount2.stl (128 KB)
mount1.stl (8.87 KB)

The top concept:
Not fully glued together yet, the basic idea is that middle piece slides over 10mm to reduce the upper fingers, then the whole extruder plate lifts out. I’ve added some relief cuts to the lower mount to hopefully let it clear, but that may need a bit more surgery. I may also add a mid latch of some sort if i can figure out how to fit it in.

Concept is a bit up in the air right now., If it ends up being the entire mount interface I will probly thicken it a bit. if I end up bolting on a mount overlay to allow easier swapping in of different extruders, it may stay about the same. Need to see how stout the fingers are when printed and run some wear tests before I decide.

Either way, there will be a bolt on cable path and spring pin mount section that goes from the removable section to the fixed section. I will probably extrude another 20mm up to accommodate that, and another few mm forward. Logistically though i’m thinking this might work. The tricky bit is going to be the long M3 bolt, i may end up making that M4 if I thicken things just to make supply chain easier. Buuuuuuut, that adds weight. Not sure yet. As is right now it’s about the same amount of plastic as the existing openbuilds x mount without the back relief cuts.

I think what i’ll do next is look at adding some trapezoid head bolts sticking up from the metal plate in the middle, maybe an M5 6mm thread with a bolt on the backside to act as a midpoint mount stud, and then cut a recess into the mount plate so that when it is placed on the mount and slid down, it locks in place.

I’m not sold on my sliding lock design idea. It looks like alot more mass than a single bolt. But, it does also serve to help anchor the mount down. I’m debating making it smaller, or even going back to the bolt for now since that seems to be the lowest mass solution.

the plan next is to figure out where I put my spare backplates, and make some testing prototypes. I’m thinking a flat plate with some mounting lugs in it to attach weights and see if I can get it to deflect in the middle or shift at all in any direction. But, i probably won’t get a chance to print those this weekend.

Is quick change really necessary?
One COULD drill holes through the extruder mount and x carriage, then through bolt them. Not elegant, but likely effective. :wink:
Of course, a modified extruder mount and x carriage could be printed with holes for bolts and heat inserts, if you want to be fancy.

Great,now I have ideas for an integrated X/carriage extruder mount truss thingy… :smiley:

I have found it of value to be able to easily remove the hotend for servicing, and I definitly need to do something cleaner than my current mess of 32 plugs. I don’t really like the pin block approach the Taz 6 uses mainly because there isn’t an adequate latch on the connector. I’ve had pin blocks vibrate loose on me mid print before. I kind of like the approach the toranado extruder took with JST connectors, and i think i’m going to eventually do something similar to that for the fan connection points, but usually if I have to remove the hotend, the cold end needs looking at too. My new spare metal frontplate for an openbuilds setup arrived today, so I can start building my prototypes once i’m done printing commission work.

I do think that someday it will be feasible to add a nozzle swap system to the Taz frame as well similar to how project Athena is setup, but with a mechanical mount instead of the magnet (mainly due to available space and mass) and I kind of have an idea how to go about it, which is one of the things that prompted the slide latch design.

Another option i’ve considered is going with a rifle scope mounting system and a pitcany rail. they are everywhere, they are inexpensive and highly precise, they make ready made high mass capable quick release mounts designed to lock back in to a fraction of a mm repeatedly, and you can get them everywhere. Ultimatly that may end up being the cheapest and lowest mass option., but I think it’s cheating so i’m avoiding that. Also the whole “gun part on a 3d printer? now your gonna make a gun oh no run away!” controversy. Even with that its probably not a bad option.

Put a mock up x carriage section together to test some of these ideas on. I also picked up a picatinny rail section, which happens to line up with the stock plate holes exactly. I have a couple quick disconnect carriages on the way as well

this is the direction i’m leaning right now. I don’t think I can print something as compact, solid, cheap, and plentiful as that, and if I make the adaptor plate right, it will be a much better interface into the stock extruder with a significant weight savings, resulting it a more rigid and more structurally integrated piece that still allows for quick change mounting. Though likely not auto extruder change.

The cable integration still is planned to be some sort of mill max spring pin. I’m thinking i’ll also need some printed guide posts to ensure the extruder ends up in the correct rail slot. If it works out, I’ll probably make some adaptor plates and make a hexagon / e3dv6-ish mount plate and possibly an adaptor plate for existing extruders. The nova pro Mk II (or possibly the Mk III by that point) may be the first one mounted.

My home selling and move project is still in process, but the holidays may kind of scuttle the whole thing until warmer times. so i’m not sure yet how far i’m going to get on this before I have to stop and move. but its making progress!

Lots of progress, I have a prototype. Quite a few things I need to change in it, but it fits, it latches, and it doesn’t move. So it’s viable! It’s also lower weight than my current openbuilds X axis mount.

On top of that, i finally received my MH860 crimping tool and mill max spring pins and targets - crimp style. You can see my first crimp here. They are about 6mm long, so fitting them in will be a little tight, but this is going to work. I’m thinking either one long patch of 22 pins, or 2 patches of 11-ish to accommodate a future dual extruder.

The spring pin block prototype:

I think i’ll end up adding a few more pins and shrinking the block down a bit, and I still need to adjust the base a bit, but it’s working!

Very cool.
That’s coming along nicely!

Thanks! I’m printing the new pin block while the turkey bakes right now, should be able to start on the upper target block tomorrow and get that finished.

Redid the pin block to add 4 pins for future servo position sensors, shrink it up and added two somewhat oversized but smallest i could find guide pins. I also added the carriage version that contains the mounting points for the upper pin receptacles. Still a bit of flex in the mount, I think i need to make the block interface another 4mm thicker when I get a chance. I’ll reprint it with the changes once I know the upper pin block will fit.

I started work on the last major piece, the upper pin block. Technically there is a cable shroud piece that I’ll do later as well, but this is the last piece required for functionality. So I’ve ran into a bit of a dilemma. The crimp targets have to be inserted from the front of the mount. unlike the pins that go in from the rear. Apperently I should have swapped them in the design, but I’m not about to waste that many pins. So what that effectivly means though is that I have to have some sort of join between the pin targets and the hotend compoenents. I kind of like the idea of just running crimp ferrules in there to save mass. I may end up going that route, but I do have the room to add a connector box as well, which is what you see modled here. I basically need to get 4 fan leads, 4 motor leads, 2 heater core and 2 thermistor leads to the block (as well as possibly a ground lead) so the cable bundle will be just over half of what is seen on the carriage. But, i also need to have disconnect fittings, which will occupy roughly 12mm x 15mm x 32mm with a bit of extra space for wire . I then have to run those wires under the belt section, and up to where the pin targets go. I have plenty of room for most of it, and I think i can print an enclosed duct of some sort to make it look clean. The pin target block itself is also going to be tricky. I have to print it face up unless I want to drill out a bunch of holes (and I do not want) which means support. The good news is building it will be really simple. The bad news is I haven’t the slightest idea how its actually going to attach in that limited space. It’s getting there, but its one of those parts that isn’t going to be fun to design until its almost done heh.