Probe_basic Toolchanger

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02 Apr 2023 20:26 #268111 by spumco
Replied by spumco on topic Probe_basic Toolchanger

With 3d printers,  trial and error is pretty painless and cheap.

Very good point.  And maybe if the wheel is printed strong enough it'd work as-is on a lightweight platter.  I'd certainly use a roller bearing for the drive pin, but having a little bit of compliance in the rotational position is a benefit.

We'll see where CNC_ANDI wants to go with the mechanical side and keep nudging him to glory...

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02 Apr 2023 20:48 #268114 by spumco
Replied by spumco on topic Probe_basic Toolchanger
CNC_ANDI,

Here's a CAD model of a geneva wheel:

grabcad.com/library/geneva-mechanism-mkii-1

It could use some improvements for use on an ATC, but it's parametric and should get you going.

Things to consider:
  • slots wide enough to use a roller or needle bearing on the drive pin
  • Mount the drive wheel above with the pin pointing down
  • Print the driven gear wheel with a continuous diameter for a few layers (i.e. make a solid circle for it to 'sit' on) to help support the gear teeth/tabs
  • Add a bunch of screw holes to the driven gear so it can be screwed tight to the main carousel platter

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04 Apr 2023 13:24 #268263 by CNC_ANDI
Replied by CNC_ANDI on topic Probe_basic Toolchanger
ok...

i ordered a mesa 7i78 for more step/dir Ports...

for the future i need more axis anyway.

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04 Apr 2023 21:34 #268292 by spumco
Replied by spumco on topic Probe_basic Toolchanger
Do you think you want to try a geneva mechanism?  It'll make the software side much, much easier.  The stepper can be driven in velocity mode through th Mesa you just bought.

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04 Apr 2023 22:17 #268295 by tommylight
Replied by tommylight on topic Probe_basic Toolchanger
Anyone know of a usable 3D printed ATC?
Not the rack one, that is easy in hardware and software.
Something more complicated, say, something with a Geneva mechanism?

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05 Apr 2023 10:36 #268326 by CNC_ANDI
Replied by CNC_ANDI on topic Probe_basic Toolchanger

Anyone know of a usable 3D printed ATC?
Not the rack one, that is easy in hardware and software.
Something more complicated, say, something with a Geneva mechanism?


don´t find anything, hoping my Printred ATC runs good....

Do you think you want to try a geneva mechanism? It'll make the software side much, much easier. The stepper can be driven in velocity mode through th Mesa you just bought.


i don´t know... i thnik im to stupid to create a geneva mechanism....
found one for a 10 tool changer... but 10x don´t work on my machine. or i have to do the plate much bigger.

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05 Apr 2023 11:07 #268328 by tommylight
Replied by tommylight on topic Probe_basic Toolchanger
This is the best representation, some are just plain unusable for real life
en.wikipedia.org/wiki/File:Geneva_mechan...6spoke_animation.gif
Now lets see if gifs can be attached here:
Attachments:

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05 Apr 2023 11:40 #268331 by spumco
Replied by spumco on topic Probe_basic Toolchanger

Anyone know of a usable 3D printed ATC?
Not the rack one, that is easy in hardware and software.
Something more complicated, say, something with a Geneva mechanism?

don´t find anything, hoping my Printred ATC runs good....

Do you think you want to try a geneva mechanism? It'll make the software side much, much easier. The stepper can be driven in velocity mode through th Mesa you just bought.

i don´t know... i thnik im to stupid to create a geneva mechanism....
found one for a 10 tool changer... but 10x don´t work on my machine. or i have to do the plate much bigger.

The one  I linked to earlier on GrabCAD is parametric.  You can easily edit the number of slots.

There are also plenty of YT vids on creating a geneva mechanism in F360 and other CAD software.

Finally, if you post your existing design as a .step file or .f3d file I'll have a go at making one for you.  I think that an internal geneva mechanism would be better for a 3d printed application.

Where are you located and what materials/suppliers are available to you?  You mentioned Germany, right?  So you can easily get bearings, pins, stuff like that?

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05 Apr 2023 12:06 - 05 Apr 2023 16:45 #268333 by CNC_ANDI
Replied by CNC_ANDI on topic Probe_basic Toolchanger
hello yes bearings all so are i can get it... i´ve tried my luck but i must change everything on the prototype to get it work.
yes for sure... 

added the actually status from my atc project... i have tested to place in my 63mm Facemill and it works with that motor position...
 

File Attachment:

File Name: ATC.rar
File Size:99 KB
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Last edit: 05 Apr 2023 16:45 by CNC_ANDI.
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06 Apr 2023 03:38 #268374 by spumco
Replied by spumco on topic Probe_basic Toolchanger
I've got a present for you...

 

Internal geneva drive, obviously not detailed out... but works in F360.
  • All contact is through rolling elements (bearings), so no plastic wearing out or requiring lubricant.  The drive wheel pin is a 10mm needle bearing on a 6mm shoulder screw, and the outer anti-rotation pins are the same.
  • Driven wheel should be easy to print
  • Drive wheel should be easy to print, but should really use a metal flange to attach to the Nema 23 (?) motor.
  • Yellow driven wheel will get mounted to the tool carousel from below using slotted holes to permit slight alignment adjustment to the spindle.
  • Outer pins can also double as pocket sensor flags, and one can be longer for a home flag.
  • Everything in the model is in 'Murican units, but I've got the constraints and relationships sorted out.  For reference, the driven wheel is about 150mm.
If you want this now let me know and you can work out the details (size, mounting, motor, etc.).  My intention was to model a sliding pneumatic mount to move it in and out of position so you don't have to move the gantry and lose some cutting area.

In addtion, I plan to (or suggest you) add a spring-loaded hinge on the carousel mount.  BT/ISO30 spindles will push the tool down as the drawbar grabs it and you need some compliance in the system.  You also want a little compliance in the rotational position and the clearance between the driving wheel and lock pins will set that.
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