WIP High Speed Tool Changer | 3D Printing | Page 1

vital steppe Feb 19, 2026, 5:34 AM

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The project goals are:
High speed tool changer (sub 1s) including prime time
High speed / accel: 1.25m/s @ 200k accel
Quality: motion accuracy of <0.2mm

If you want to read the project description docs that I edit regularly:
https://docs.google.com/document/d/1SREib88dPVpR_M2EuA4wHL5ssWTWWNBHmWd0cEk9nfE/edit?usp=sharing
but TLDR:
fast printer
good quality
tool changer
new materials
new methodology

GT3 RF 12mm belts
MGN9/12 rails
4x 0.8Nm closed loop steppers
Core XY
Electromagnetic Toolchanger

Id love to hear comments questions and advice

Google Docs

proj

Objectives My objective is to create a 3D printer that is capable of very high speed operation whilst preserving quality with a goal of 1.25m/s at 200m/s^2 acceleration; this means that the machine has to have a very stiff motion system where there is minimal deflection in any axis due to transi...

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And before anyone asks why i run dual canted rails is because it basically acts a preload and also more distance between balls meaning more rigidity. And yes the disadvantages are higher mass fighting and binding if you don't get the rails perfectly parallel.

Additionally I have completed V1 which has a resemblance to this but only hit 1m/s @ 100k and a 1.33s tool change time.

solid hollow Feb 19, 2026, 3:00 PM

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#1088579612096872632 yay more details yay sounds awesome

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@tawny ether @lunar portal

tawny ether Feb 19, 2026, 3:06 PM

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Goddamn

solid hollow Feb 19, 2026, 3:06 PM

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Also considering a Beryllium beam vaulthah nice

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Is this purely theoretical for a thesis or so or do you want to really build it?

tawny ether Feb 19, 2026, 3:08 PM

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I feel like you'd be better off running a single HGR rail on Y rather than dual mgn12

solid hollow Feb 19, 2026, 3:08 PM

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Also: Pics of V1

tawny ether Feb 19, 2026, 3:08 PM

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solid hollow Also: Pics of V1

And vids 👀

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Wanna see that tool change

lunar portal Feb 19, 2026, 11:26 PM

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vital steppe The project goals are: High speed tool changer (sub 1s) including prime time Hig...

Okay, so:
Your stiffness estimations seem to completely skip:
Contact stiffness
Rail stiffness
Twist
SiC AMCs tend to have really low strength as well, which can lead to threads shearing off
Your second FEA shows signs of meshing errors

vital steppe Feb 20, 2026, 2:56 PM

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lunar portal Okay, so: Your stiffness estimations seem to completely skip: Contact stiffness ...

Yea you make good points on the Al SiC MMC well theres around a 1.98x SF says fusion 360 FEA and the meshing thing im quite sure its an guide line or something but im happy to rerun the simulation additionally my later sims that i did today deal with this

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additionally i finally heard back from the people that make the al sic mmc and the price is off the charts like i expected expensive but not 2000$ - 3000$/pc lol

vital steppe Feb 20, 2026, 2:58 PM

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solid hollow Is this purely theoretical for a thesis or so or do you want to really build it?

Yes im building it however im swapping from Al SiC MMC to aluminum bonded with CFRP because of the stiffness requirements

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heres the theoretical just filling in the holes of the initial design with cfrp to see the deflection under load and asuming infinitely strong glue

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vital steppe Feb 20, 2026, 3:01 PM

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tawny ether I feel like you'd be better off running a single HGR rail on Y rather than dual ...

the initial reason for running dual MGN 12 was to let the belts run inbetween the rails making the system more rigid as theres nearly no torque on the rails

vital steppe Feb 20, 2026, 3:02 PM

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tawny ether Wanna see that tool change

il post a video of the 1.33s toolchange tmr or sm because ive taken apart the psu somewhat because im kinda afraid someone at homes gonna touch it and arc like 25A DC on accident and also the toolchanging at that speed damages the V1 dock mechanism which isnt yet descirbed in the docs

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no extrusion yet as no "poop chute" bc my main printer is experiencing some "issues" regarding some shot idlers after i swapped to GT3 RF

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but i have proven that i can prime in under 1s with the orbiter extruder which is kinda bad imo so im swapping to sherpa for v2 like i was pushing maybe 85mm3/s and the orbiter was dying so gotta swap to sherpa and hopefully will hit the spec'ed 95mm3/s and slightly more because of heat saturation of the core

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also this project is a personal extracurricular that im perusing to aid in my uni app

lunar portal Feb 20, 2026, 3:07 PM

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vital steppe Yea you make good points on the Al SiC MMC well theres around a 1.98x SF says fu...

That's SF of 1,98 with taking bolt clamping force into account?
Got a mesh preview of these FEAs?

vital steppe Feb 20, 2026, 3:08 PM

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lunar portal That's SF of 1,98 with taking bolt clamping force into account? Got a mesh previ...

i didnt take into account bolt clamping force because A) didnt think of it and B) by that point the threaded holes were more of a fantasy

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because near diamond hardness gonna eat all the taps

lunar portal Feb 20, 2026, 3:09 PM

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Also, technically specific modulus (E / ρ) isn't the right metric here since the majority of the load isn't from the backer but from the stuff bolted to it

vital steppe Feb 20, 2026, 3:10 PM

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i dont quite understand what you mean but in the simulation the force is applied to the center bolt hole for worse case scenario

lunar portal Feb 20, 2026, 3:11 PM

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vital steppe because near diamond hardness gonna eat all the taps

Not really, you can machine threads in, but the results aren't stellar. Tool dislodges ceramic grains, which tumble around leaving deep scratches and gouges

lunar portal Feb 20, 2026, 3:12 PM

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vital steppe i dont quite understand what you mean but in the simulation the force is applied...

I'm talking about the parameter you call Ep

vital steppe Feb 20, 2026, 3:12 PM

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yes? elastic modulus per density

lunar portal Feb 20, 2026, 3:13 PM

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vital steppe yes? elastic modulus per density

The fancy name for it is specific modulus.
And it's not the main metric for your use case as the bending caused by the toolhead and stuff bolted to the backer is greater than the inertial load from the backer itself

vital steppe Feb 20, 2026, 3:14 PM

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yes but stiffness isnt just effecting the backer but any forces being applied to it?

lunar portal Feb 20, 2026, 3:16 PM

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vital steppe yes but stiffness isnt just effecting the backer but any forces being applied to...

Yes, but if you decrease the backer stiffness 2x, while decreasing its density 2x, you'll end up with higher deformation of the backer

vital steppe Feb 20, 2026, 3:20 PM

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yes your right but its somewhat counteracted by the fact i can make the backer larger taking advantage of the fact that when you make a beam wider by 2x it gains like 8x the strength (were not talking about strength but more beam length less deflection bc higher moment or sm)

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but yes your completely right in this regard

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i should explain that better in the docs

lunar portal Feb 20, 2026, 3:21 PM

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Well, 8x stiffer, and that's because of its second moment of inertia

vital steppe Feb 20, 2026, 3:21 PM

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yep mb

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i have a vid of 100k with tool and a tool pickup/dropoff pic but i need to figure out how to transcode it bc discord wont let upload 😭 and il try get a vid of v1 toolchaning soon no promises cuz i js realised ive broken all the tool docks but one lmao

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and the belt tension is very low bc im afraid of a temporary plastic part blowing up in my face

lunar portal Feb 20, 2026, 4:14 PM

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I wanted to check 2MGT3 RF stiffness, but I can't find it anywhere

vital steppe Feb 20, 2026, 4:18 PM

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good luck i havent found it either lmao

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but i have done some research and am considering swaping to the best on the market: polychain carbon

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but have to see bc of 5mm pitch

vital steppe Feb 21, 2026, 9:19 AM

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new Al 7075 CFRP composite beam

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vital steppe Feb 21, 2026, 1:25 PM

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1.6kg 😭

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still within spec tho barely

vital steppe Feb 23, 2026, 2:19 PM

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lunar portal Feb 23, 2026, 2:34 PM

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vital steppe

I wonder, have you tried to determine the force decay factor for these electromagnets?

vital steppe Feb 23, 2026, 2:37 PM

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lunar portal I wonder, have you tried to determine the force decay factor for these electroma...

i have not but the intention is to rewind as they do not apply sufficient force for 200k

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not really rewind like rebuild from the ground up with the same formfactor

lunar portal Feb 23, 2026, 2:38 PM

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vital steppe i have not but the intention is to rewind as they do not apply sufficient force ...

Beware of magnetic saturation of the core

vital steppe Feb 23, 2026, 2:38 PM

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Ah yes i havent covered that in the docs yet but probably FeCo core or smth

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my cnc machining vender of choice offers it

lunar portal Feb 23, 2026, 2:39 PM

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You can likely get high permeability cores to wind on

vital steppe Feb 23, 2026, 2:39 PM

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good point

vital steppe Feb 25, 2026, 9:54 AM

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hey @lunar portal i just came up with an idea for a seperate project and would like your view on it can i DM?

#WIP High Speed Tool Changer