Show all posts by user

Re: Core ZXZY Build Log - 1 year ago

Quotedc42 Looks interesting! As the kinematics is linear, RepRapFirmware supports it already, without even having to recompile. In theory, the kinematics are linear-- but with a floppy moving gantry and >3 independent motors, I've started wondering recently if a more generalized model that takes axial skew and twist into account might be a better approach for these types of machines (also Vor

by NathanaelXYZ - Reprappers

Re: A new design - CoreXrY - 1 year ago

If I'm understanding this correctly, doesn't it suffer from the same racking issues as an h-bot design?

by NathanaelXYZ - CoreXY Machines

Re: Diamond Nozzles, and the aftermath - 3 years ago

Quotethe_digital_dentist I wonder how they manage the difference in thermal expansion coefficients of the diamond and brass that it's mounted in... The kickstarter page mentions that the nozzles should not be used above 300C-- assuming they install the tips to an interference fit by heating the brass, perhaps this is the point at which the diamond is at risk of coming loose?

by NathanaelXYZ - Tech-Talk

Re: A Very Different Extruder - 3 years ago

Are you sure the "rollers" are... rolling? Based on the grooves in the filament and what appears to be filament dust on the roller threads in your posted image, it looks like your design is gouging rather than pressing the threaded pattern into the plastic. I remain skeptical that pure rolling contact would result in any net axial thrust on the filament. Of course, in the end, the proof is in th

by NathanaelXYZ - Tech-Talk

Re: A Very Different Extruder - 3 years ago

@obelisk79: I admittedly did not fully comprehend your post the first time around, but now I see what you mean It will be interesting to see the concept in action. My own "backyard engineering" idea, partially inspired by this bearing concept, is to replace the canted bearings with a helical coil (e.g. a compression spring) and bearing balls of an appropriate size as to create a recirculating b

by NathanaelXYZ - Tech-Talk

Re: A Very Different Extruder - 3 years ago

I don't see how this newer design actually drives the filament-- it seems to me that the threads on the bearing sleeves would simply impress a "///////////" pattern on the cylindrical surface of the filament (much like a knurling tool) as they revolve around it, without any of the desired axial movement. The design will only function if the bearings don't actually rotate-- at that point the whole

by NathanaelXYZ - Tech-Talk

Re: Building thoughts - 3 years ago

It has become standard practice among higher end 3D printers to use a 6-10mm sheet of cast aluminum tooling plate (goes by various trade names like ATP and MIC-6) as a bed-- quite flat, and doesn't warp much at all under elevated temps. The material can be purchased from most metal suppliers, and some vendors now also sell pre-machined beds. Lots of info/details to be found on these forums and el

by NathanaelXYZ - Tech-Talk

Re: A Very Different Extruder - 3 years ago

Since nothing is keeping the filament from twisting on its own axis, won't a given extrusion pressure always result in some amount of torsional rotation of the filament instead of purely lateral displacement? This would be most obvious in soft/flexible materials, as you mention, but I'm curious if it's significant enough to cause print artifacts in stiffer materials as well. The effect could be m

by NathanaelXYZ - Tech-Talk

Re: A Very Different Extruder - 3 years ago

That is awesome! Variants of this idea have been kicking around for a while (e.g. here), but your implementation is by far the most elegant I've seen. How hard can this design push before the filament slips?

by NathanaelXYZ - Tech-Talk

Re: Presenting Piper 2 - CoreXY on EMT conduit frame Single Dual extruder moving gantry - 6 years ago

Quotepiper3d What artifacts in the print should I be looking for to see racking force intrusion? If this is uneven layers than the only uneven layers I saw on this printer were coming from Z wobbling . I was imprecise in my comment-- I am imagining twisting forces around the x-axis that would skew the parallel x-rods out of plane with each other. My hunch is that this would, if anything, lead to

by NathanaelXYZ - CoreXY Machines

Re: Presenting Piper 2 - CoreXY on EMT conduit frame Single Dual extruder moving gantry - 6 years ago

Quoteo_lampe And last but not least, I don't like the Z-axis' 4-motor mechanic. If the four motors are controlled independently, then the system actually has the benefit of being able to de-rack the gantry automatically based on z-probing. I believe the Voron v2 does this. I'm not entirely convinced (yet) on conduit framing, but kudos on the design and execution. How far apart are the corexy be

by NathanaelXYZ - CoreXY Machines

Re: Black Beauty Build Log - 6 years ago

You mention that you're using CF-HTPLA for the printed parts-- I'm interested to see how that will end up working out in the long run. PLA is known for having high creep properties (see, for example, here), which typically make it a poor choice for structural and mechanical applications. However, it is possible that the fiber-fill helps in this regard (a bit of googling found this vaguely relevan

by NathanaelXYZ - Extruded Aluminum Frames

Re: E3D's tool changing CoreXY design - 6 years ago

I've been pondering ways to make the kinematic coupling more DIY-able. Perhaps three parallel pairs of drill rod embedded in a printed part could take the place of the v-grooves, with a similar setup for 3 ball bearings on the mating surface. It seems like alignment isn't as important as repeatability and consistency in this application. The locking mechanism is another problem unto itself...

by NathanaelXYZ - CoreXY Machines

Re: My coreXY design is progressing to the build stage - 6 years ago

@DigitalDentist, Apologies if this is a silly question, but is differential thermal expansion between steel linear rails and the aluminum they are bolted to a concern? It seems to me that the higher expansion of the aluminum could put stress on the rails in a way that tends to make them bow concavely. Though perhaps this effect is too slight to cause any significant deflection.

by NathanaelXYZ - CoreXY Machines

Re: My coreXY design is progressing to the build stage - 7 years ago

Impressive build log, almost impressive as the build itself. I respect the careful and well-reasoned design approach. Physics experiments involving lasers often have complicated optical setups where everything is mounted on adjustable tables for beam alignment: Typically the "middle" corner has a ball bearing sitting in a countersunk recess constraining it along three axes, as in your bed-mount

by NathanaelXYZ - CoreXY Machines

Re: Piezoelectric disks for Z contact detect and bed levelling - 8 years ago

How well would the system work if the piezo were placed between the hotend and its mount rather than beneath the bed? This has the benefit of only requiring one disk. It would obviously only help with z level detection, though, and not compensation.

by NathanaelXYZ - General

Re: Nyloc nuts everywhere? - 8 years ago

Thanks for your responses. Good to know that nylocs destroy printed nut traps, as that's the typical use case in my design. @the_digital_dentist I had assumed star washers would simply chew up the printed surface- do you have any personal experience with this setup? Maybe I'll just stick to regular nuts, and apply some thread locker if I notice any loosening.

by NathanaelXYZ - Mechanics

Nyloc nuts everywhere? - 8 years ago

I am in the process of designing a printer, and intend to use plastic-insert lock nuts everywhere. The only exceptions will be screws that are designed for regular adjustment (-ie bed leveling, belt/cable tension, and extruder spring pressure.) Are there any other exceptions, or general reasons NOT to use nyloc nuts for general fastening on the frame/bearings/etc? I have done some research on the

by NathanaelXYZ - Mechanics

Re: Best Z-axis configuration? - 8 years ago

Couldn't a cantilevered bed be "enhanced" by supporting more than one side of the bed on a single lead screw? Pulleys and cable could be used to transfer the load from one point to another, as in this diagram: I am currently gathering materials to build a printer using this system for z; I will report back with results.

by NathanaelXYZ - CoreXY Machines

Precision vs general-purpose ACME hardware question - 8 years ago

I'm looking to purchase a lead screw for the printer I'm putting together, and want better quality than can be achieved through plain threaded rod. What I'm thinking right now is a McMaster-Carr precision ACME screw (McMaster# 98940A305) with a general-purpose acme hex nut or two (# 95155A114). However, McMaster recommends their expensive precision acme nuts to go along with the precision rod.

by NathanaelXYZ - Mechanics

Re: Best Z-axis configuration? - 8 years ago

What about a compound approach-- use a single leadscrew + linear guide to actuate an effector to which three cables are fixed. A system of pulleys could then be used to transfer the motion along this single lead screw to support three points on the bed. This way you would get the benefits of a single lead screw without the downsides of cantilevering.

by NathanaelXYZ - CoreXY Machines

Re: Fishing line traction drive - 9 years ago

Wow, I should probably update the first post with all the things I've forgotten to note The spacers I'm using don't have holes for set screws, and I don't have the tooling to drill/tap holes, so I came up with a printed solution: The slots are for m3 nuts, and the motor shaft and the spacer are each secured into the coupler with two screws. Though this should theoretically center the spacer o

by NathanaelXYZ - Developers

Re: Fishing line traction drive - 9 years ago

Quotejbernardis I wish I could visualize this a little bit better. I see in the photo that one side of the assembly has 4 bearings and the other 3. I guess this is to allow for a downward spiraling. On the side we cannot see, what is the arrangement? You say your prototype has 5 loops around the center, but in the diagram I only see three. I assume that the diagram is simplified, and that yo

by NathanaelXYZ - Developers

Re: CoreXZ - 9 years ago

Another option is to move away from spools entirely, and instead use a traction drive-- I pursued the idea specifically to address the same problems you are facing. My current version has six windings instead of the five shown in that post, as much for the resulting cable path as for the additional traction, and I have not experienced any slippage when the line is tensioned.

by NathanaelXYZ - Developers

Re: New firmware for printing directly from the Raspberry Pi's GPIO pins - 10 years ago

This is really cool. Have you thought of using a Beaglebone Black? The PRUs would probably come in handy.

by NathanaelXYZ - Developers

Why are max endstops disabled for CoreXY in Marlin? - 10 years ago

I was reading through the Marlin source to try and understand how it works (I'm currently tinkering with CoreXZ support), and came across the endstop handling code in stepper.cpp. Even though MAX_ENDSTOPS are force-disabled for CoreXY, it seems like it would be trivial to enable them with an additional "if else" statement--almost too trivial. Is there any reason why this has not been done before?

by NathanaelXYZ - Firmware - mainstream and related support

Why are max endstops disabled in marlin? - 10 years ago

edit: The code formatting appears to be broken. I'm tinkering with a coreXZ version of Marlin, based off of the already included coreXY code. I noticed that max endstops are forced off if coreXY is enabled, but I need both min and max endstops on the z axis so I can home to max and then use a z-probe to auto bed level. In the stepper.cpp file, however, I noticed endstops are tested like this:

by NathanaelXYZ - CoreXY Machines

Fishing line traction drive - 10 years ago

Sorry for the blurry image. This is a design that is inspired by/based off the ideas discussed in this old thread. The drive shaft (center) is a 13mm od aluminum m5 spacer, and the idlers (corners) are stacks of 608 ball bearings. I am using 1mm dyneema line. (top-down: red = top loop, blue = middle, green = bottom) My prototype has five loops around the drive shaft, for the equivalent of ab

by NathanaelXYZ - Developers

Re: CoreXZ - 10 years ago

@Nicholas Seward: Thanks for the numbers, and for checking out my blog! The friction drive is just an experiment. It only cost ~$5 to throw in some m5 aluminum spacers with my mcmaster order, vs. $21 plus shipping for three spools from tridprinting. I will switch to spools (especially in light of what you have said) if it doesn't pan out. I have also thought of a way to reduce the size of the x-

by NathanaelXYZ - Developers

Re: CoreXZ - 10 years ago

@nicholas Brilliant design, just started planning a reprap variant. What is the behavior of the z axis when the printer is powered off? Does the gantry stay in place, or fall towards the print bed? Is there any noticeable error from the fishing line "walking" on the spools as they wind/unwind?

by NathanaelXYZ - Developers