Latching magnetic tool changer

1ri

Nice Job!.
I would greatly appreciate any information to start designing a toolchanger system for my Hypercube.
The printer looks sturdy and it seems that the change of tools works very well.

Thanks

fma

I'm thinking of a tool changer too, but what stops me is the Bowden configuration...

So I'm working on a design where the motor stays on the carriage; each tool has its own gears, which engages on the motor gear once the tool is selected. Only theory on paper, for now.

Martin1454

@fma said in Latching magnetic tool changer:

I'm thinking of a tool changer too, but what stops me is the Bowden configuration...

Zesty nimble ?

A Former User

Looks almost NSFW.. Nice work!

fma

@Martin1454, you would need a Nimble per tool...

fma

@pawPrinter, I'm also very interested in your magnet-based design.

pawPrinter

Thanks all for the kind remarks.

@Martin1454 I've dug out some pics of my changer's latching mechanism.
I CNC'd the rather elaborate brass guides, but it turns out that they are almost completely superfluous because of the way the magnets keep the head aligned even when not fully attached. Without the guides you would just need a stop to prevent the pawl from moving above horizontal when the head is docked. The shape of the pawls could easily be filed by hand.
You can look at my cad files on Onshape if you like but they are a complete mess.
I can't take credit for the magnetic kinematic mounts. They were based partly on commercial versions used in optical systems (such as these: https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=1546) and partly on material from an engineering book that I have which was published in 1934 and has two chapters on kinematics! It seems there is nothing new in mechanics!

@1ri The sturdy frame is just aluminium angle welded together, and is a nice cheap way to make a strong frame. It probably would have been easier/better to bolt the sections together, but I had just bought a new welder that I wanted to play with

@fma Your idea sound good. Gear mechs are fun. The four heads shown in my video are unplugable, and I have just made a version which carries a Bondtech BMG extruder so that I can print flexible material. I haven't properly tested it yet, but it looks like it will work ok.

@bearer Ha ha

gnydick

ingenious. would love to have one!

thwe

@pawprinter said in Latching magnetic tool changer:

You can look at my cad files on Onshape if you like ...

I think that's a very good system and would like to build it. Would you please provide the cad data?

Unfortunately I can not find the oneshape link.

fma

I think this is here: https://cad.onshape.com/documents/ee78eeb0f6b8aaf2d8eaeb6f/w/dcf1bccd45c5fcc6fbba5f9c/e/701e92f83c58894a4886d70a

Do you have to pull hard to disconnect the magnets?

thwe

@fma said in Latching magnetic tool changer:

I think this is here: https://cad.onshape.com/documents/ee78eeb0f6b8aaf2d8eaeb6f/w/dcf1bccd45c5fcc6fbba5f9c/e/701e92f83c58894a4886d70a

Do you have to pull hard to disconnect the magnets?

Thanks for the link, but i have no account and the link leads me to a login page.

fma

Mmm, I though it was possible to see designs even when not logged on (a recent feature); I may be wrong.

I suggest you create an account, it's free. Create a dummy one, just to see public designs (there are thousands) if you don't plan to use Onshape...

pawPrinter

Yeah, sorry, I have enabled link sharing now so you should be able to view without an Onshape account.

thwe

@pawprinter said in Latching magnetic tool changer:

Yeah, sorry, I have enabled link sharing now ...

Thanks

pawPrinter

@fma said in Latching magnetic tool changer:

Do you have to pull hard to disconnect the magnets?

Not once the plates have been angled apart by the wedging action of the latch. There is still some pull which is easily overcome. I was surprised how far the magnet's attraction is effective, but once the plates are split they are easy to separate fully. The remaining attraction is actually helpful to keep the heads aligned properly. Obviously there is a balance between the strength of the magnets and the size/angle of the wedged latches. I found it quite easily by trial and error.

fma

I see. Clever design!

pawPrinter

Here are some more heads that I've made for my latching tool changer.
Two are water cooled: One for a standard hot end, and one to fit a volcano. It turns out that water cooling is fantastic, and much less fuss than I thought it would be.
The other head is sporting a Bondtech BMG fitted for printing flexibles. It is a bit experimental to see if the magnetic mount can take the weight. So far it has worked very well, but it's perhaps not the most elegant solution. However, it was very simple to adapt the Bondtech in this way, and I get the advantage of a well proven feeder.
When you can easily swap heads over, it starts to get very versatile, but can be a configuration nightmare!

fma

Very nice work!

I'm thinking to make a system to be able to swap hotends but keep the extruder on the carriage. Or at least, just the motor, and use a quick shaft coupling...

pawPrinter

@fma Thanks. Yes, your idea would make a lot of sense. I might wait to see what you do, before I re-design mine.

fma

Don't hold your breath, as I need to re-design all my CoreXY gantry to be able to implement a tool changer