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Discuss any sort of mechanical stuff here: positioning systems, gears, extruding methods, etc.
Re: Steel sheet metal frame? - 4 years ago
I wouldn't recommend welding the frame together. Even if it starts off square and flat it wont end up that way. Bolted connections with some angle brackets are a better idea in my opinion. One thing to consider though is that while sheet metal may be strong and rigid in some respects, it can buckle. Not so much an issue with smaller structures like the solidoodle, but on a half meter cube the sidby Trakyan - CoreXY Machines
Re: Hephaistos - IDEX Ultimaker style - 4 years ago
Some carbon fibre tubes are fairly weak in torsion, the extruded sort with fibres only parallel to the tube I've heard are prone to splitting in torsion because the parallel carbon fibres provide no strength. You're left with the resin which is weakened by the inclusion of the carbon fibre similar to particle filled filaments. The other sort with carbon fibres going in multiple directions both axby Trakyan - General New Machines Topics
Re: Independent X Axis & Control Board - 4 years ago
Have you considered a nozzle lift mechanism like the ultimaker? Seems like a much simpler solution to me, and it also takes away the weight of an extra motor to drive the second X axis. You would be able to use standard firmware, with just a short "toolchange" gcode for when you want to print with a different color. You could even add more than 2 nozzles with this sort of design.by Trakyan - General New Machines Topics
Re: Unsupported lead screws/ball screws/cantilever questions - 4 years ago
Cost is the main reason we don't see them used much, but they also aren't necessarily a better choice anyway. Leadscroews (trapezoidal or ballscrew) are used mostly just for the z axis, where the lower backlash of a ballscrew is a moot point, and the fact they are sometimes back drivable is a disadvantage. And yes, one end is often left free to avoid over constraining. If you fix the leadscrew aby Trakyan - Mechanics
Re: Another version of dual-wire gantry - 4 years ago
I've thought of this as well since I saw the DWG/Slid3r to make both axes behave the same, and get the 2:1 benefit on the Y axis as well. Unfortunately I think it might suffer from racking issues and binding as a result. Technically it would be self squaring since any racking would stretch the belt/cable which would result in it trying to pull itself back into square, but for small angles out ofby Trakyan - General New Machines Topics
Re: Cantilevered dual wire gantry - 4 years ago
You can simplify and shorten the belt path for the X axis if you go for a moving X rail design like this: You'd shorten it by a factor of twice the length of your x axis. Just fix both ends of the belt to one end of the Y axis, the motor to the other end and run the belt following the perimeter of the X and Y rails. You maintain the 2:1 gearing from the block and tackle, and the X axis movementby Trakyan - Mechanics
Re: Linear rail choice for advanced CoreXY design - 4 years ago
For a chamber getting up to 100C, make sure you isolate the motion components (rails, ballscrews) from that heat by putting them outside the heated chamber (try wrapping them in bellows that have cool outside air pumped through them). The thermal cycling wouldn't be good for those parts and will probably cause warping/distortion of your motion system, and would mess with the tolerances of the balby Trakyan - Mechanics
Re: Cad for printing...?? Moving On? - 5 years ago
Solvespace is another open source option. It's very minimal and lightweight but can do a lot. I believe it's still missing a chamfer/fillet option though which I'm sure is a deal breaker for many. I found it easier to use than FreeCAD from both a computer requirements and UI point of view, but coming from openscad the lack of variables for constraints and chamfer tool leaves me wanting more.by Trakyan - General
Re: Power Generation (not sure if this belongs here) - 5 years ago
Ahh, makes sense that it's already been implemented. I wonder why it's not more widely used though.by Trakyan - green talk
Power Generation (not sure if this belongs here) - 5 years ago
Feel free to delete this if it doesn't belong. So I've always had a side interest in power generation. Specifically renewable energy, not so much for the hippie aspect of it but because it seems like a fun "puzzle" to work within the constraints renewable sources impose (reliability, accessibility etc.). Anyways, here's the idea. You can build a sea wall extending from the shore and encapsulatinby Trakyan - green talk
Re: Filament homeproduction fails due to lack of good spooling? - 5 years ago
You can use laser measurement to avoid the problems calipers can cause. Or cool the filament quickly with a water bath after exiting the nozzle so you can have the calipers right after without causing deformation.by Trakyan - green talk
Re: DiffBot - Differential Screw-Driven XY Gantry - 5 years ago
I get you on not wanting flexibility from cables, but what I'm talking about the cables are very short, they are only enough to wrap around the two drums that are almost touching in a figure 8 type arrangement, they serve to take out backlash/slop more than transmit force. It was just a suggestion for some ghetto low backlash gears. Why would the worm need to back drive the pinion? All the motivby Trakyan - Look what I made!
Re: DiffBot - Differential Screw-Driven XY Gantry - 5 years ago
Well someone came out from under the bridge. Anyways, the "parasitic" effect I was meaning mostly is if friction between the nut and screw causing the nut to spin with the screw (thus not moving axially as it should) rather than stay stationary when you want it, or vice versa friction in the bevel gears stopping the nut from rotating freely with the lead screw (and thus causing it to move axiallby Trakyan - Look what I made!
Re: 3D Printed Home in Austin, Texas - 5 years ago
Ahh, I see now I think. A sort of modular design where the end-of-life sections can be individually replaced. I was imagining some large, monolithic island where the only way to restore/repair would be "patches", and there is only so many times you can patch something.by Trakyan - General
Re: box frame prusa i3 - 5 years ago
Ahh, so that's what he meant by box frame. I thought he meant box as in a cube coreXY or similar. To me that's still a gantry/portal style machine even if the XZ gantry is built slightly thicker. But yeah, I wasn't really into these sorts of things back when that was more common.by Trakyan - Reprappers
Re: DiffBot - Differential Screw-Driven XY Gantry - 5 years ago
Very interesting. I don't think I've fully grasped the way it work yet. but most of it makes sense. A couple of possible issues is that but bevel gears and trapezoidal lead screws have backlash, and you have them setup in series with each other, so their backlash is cumulative. Aside from the usual backlash issues that would normally cause, since both motors need to work together and sometimes iby Trakyan - Look what I made!
Re: box frame prusa i3 - 5 years ago
A prusa isn't typically what people would call a box frame. It's more of a gantry/portal type framework. Secondly, they aren't very expensive, on the contrary. They're probably the cheapest frame design possible short of taking a prusa style printer and cantilevering the XZ axis. Are you actually after a boxframe/cube style printer or a prusa/portal based design?by Trakyan - Reprappers
Re: 3D Printed Home in Austin, Texas - 5 years ago
VDX, you mention "lifetime of the material". Wouldn't a floating island eventually break apart and degrade? A lot of existing artificial islands suffer from this issue, combined with the fact that repair is very costly and difficult. I imagine a floating island would face these issues but on a more extreme scale. Is there a solution to this problem? That and I could be completely ignorant here, bby Trakyan - General
Re: CoreXY or Delta ? - 5 years ago
I'd recommend going for a coreXY. For a beginner, especially if you're thinking of self sourcing/self designing, a coreXY is much simpler, more intuitive and forgiving. If something is off with the print, like squareness, dimensions, flatness etc. it's much easier and more intuitive to diagnose. I'm not saying deltas are bad, or can't achieve good results. More so that they are more "fussy" mechaby Trakyan - General
Re: Alternatives to Steel? - 5 years ago
Aluminium and carbon fibre are common replacements for steel rods. I'd avoid carbon fibre for the perimeter rods as they need to transfer a torque, and depending on the fibre directions they can be prone to cracking when a torque is applied. I'd go for aluminium, using reinforced plastics as a linear rail and bearing surface has always seemed weird to me. That being said, if you're just concernedby Trakyan - Mechanics
Re: 4-axis IDEXY printer for prosthetic sockets? - 5 years ago
You could angle the toolheads (like angled belt printers do) with the nozzles pointing towards each other, that way they're have less interference. With a large enough angle/thin enough nozzle you could get the minimum gap between the extrusion lines down to a few mm. Would a small hole in the top of the print cause any issues for the functionality? I think varying extruder speed should work fineby Trakyan - General
Re: Best way to make use of these Powdered Bronze Bushings? - 5 years ago
Wouldn't allowing the second bushing to float rather than the second rail to float be easier? One smaller component that is attached at a single point, rather than a larger component fixed at two ends? There could be something I'm missing here but on most machines I've seen the rails are fixed rigidly and the second bushing is allowed to move perpendicularly across them, like the flat way on a laby Trakyan - Mechanics
Re: Best way to make use of these Powdered Bronze Bushings? - 5 years ago
Those would allow for the bushings to rotate, but I don't think that's what's causing the binding here. If the rods are out of parallel, or bent etc. the distance between them changes and thats what I think causes binding. There is some binding if you try to force the bushing itself out of paralle with the rail, in which case the spherical bearings would help, but I don't think thats the whole isby Trakyan - Mechanics
Re: 4-axis IDEXY printer for prosthetic sockets? - 5 years ago
Since the two toolheads are basically printing the same thing (except 1 wall thickness difference on the radius), and if you print in vase mode (i.e. continous, unidirectional rotation), you could just make the second toolhead echo the gcode of the first one, with a 180* delay and a 1 extrusion width offset. This could be done in the firmware possibly (i.e. every time a command is sent for the roby Trakyan - General
Re: Best way to make use of these Powdered Bronze Bushings? - 5 years ago
You're right, you're sort of pushing the limits of the sort of tolerances an FDM printer can hold. Something like a bushing can be unforgiving with alignment, and a sufficiently bulky and stiff part that isn't to the correct tolerance will force it out of alignment and cause it to bind. You can either design more flexibl (less rigid) parts, which isn't the best solution, or design in "slop" thatby Trakyan - Mechanics
Re: Best way to make use of these Powdered Bronze Bushings? - 5 years ago
You could try and "float" the sbushings on the second rail of each axis. Since the only reason you need two rails is to prevent rotation about the axis of the first rail, the second one can have a bit of "slop", ideally a slot that is parallel to the plane created by the two rails. If you look at lathe beds and saddles, ton the bed here is usually one V way (or similar), this is where the saddleby Trakyan - Mechanics
Re: 3pod - a simple printer - 5 years ago
It looks like you're using the ballscrews directly to hold your X and Y axis on the perimeter. Ballscrews (and leadscrews in general) are not meant to be a rail and constrain motion, they're just meant to actuate. They're probably not perfectly straight and any eccentricity or bend willl create print artifacts as they spin.by Trakyan - General New Machines Topics
Re: Mounting linear rails on plywood/acrylic/whatever? - 6 years ago
Please don't give up MKSA, just learn to recognise that not everyone can afford to or wants to spend a large sum of money to get "perfect". Most people can only afford or are more than happy with "good enough". Anyways, I'd recommend MDF over acrylic and plywood. It's usually cheaper than both, and more isotropic than plywood, plus I think it's actually more temperature and humitity stable. Downby Trakyan - Mechanics
Re: How do you seal your heat block? - 6 years ago
Not much point in using an all metal heatbreak if you'll wrap the threads with plumbers tape (teflon).by Trakyan - Reprappers
Re: scaling - 6 years ago
Repetier has a scaling option, just above the list of objects in the workspace.by Trakyan - General