Juki nozzle tip changer

[chende...@gmail.com]

Hi all,

I need a bit of advice, again.

For my current setup I use 2 of these assemblies:

https://www.aliexpress.com/item/32807025833.html

They use juki 5xx series nozzles on a shaft with 3 balls to retain the nozzle tip.

Initially I did not wanted to use tool changer from openpnp but it seems I have to.

These assemblies do have a problem. The mechanism they use to connect the nozzle tip to the stepper requires high force to insert or detach the tip. I'm not sure the Z stepper has enough force to couple with the tip when the shaft is pushed to the table and when the tip must be detached, only the spring pulls the shaft upwards and it definitely does not have enough force to pull the tip out when the tip is retained in the tip holder magazine.

So I must replace that shaft with something which is compatible with the tips magazine. So far I was not able to find a suitable shaft available somewhere. On aliexpress they are all with balls or with screws which permanently fixes the tip on the shaft. Before I start thinking how to build one, can you recommend me a shaft for this purpose? It must have a 5mm hole on one end for the rotation stepper and to couple with the tips with lower force compared to my current shaft. I must use 5xx juki nozzles, I already have a bunch of them. 

Thanks.

[chende...@gmail.com]

Ok, I just found this one, but it seems to require an odd construction for the holding mechanism:

https://www.youtube.com/watch?v=KRR3bC9j_3s&ab_channel=JuhaKuusama

Is there an easier way?

[Ian Arkver]

I have the same head and the same problem with a changer. My current plan is to have a servo/stepper driven lever which pushes on the bottom of the Z rail assembly (i.e. the bottom of the C stepper mount bracket) via a lever. The lever is positioned in the right place for the tool change carousel load/unload point and supplements the spring force, which as you say isn't enough on its own to pull the nozzle tip out of the holder.

I've not yet tested this to see if it works though. I'm hoping the Z-cam stepper has enough torque to push the shaft back onto the new nozzle tip though. Maybe that will fail and it will be back to the drawing board. :-(

All the best,
Ian

[Ian Arkver]

Posted at the same time. :-)

That mechanism uses a wedge to pull the tip off as the axis motor moves the head. This would work, I guess, but I was going for a rotating tip carousel, so the head just parks the nozzle into it and then the lever pushes the Z rail upwards.

Not sure that my plan is any easier though, and we still have the problem of attaching the new tip.

CU,
Ian

[chende...@gmail.com]

Hi, thanks for tips. I think I'll buy one or two of those spring shafts to test them (if nobody have a better suggestion) , cause I have a hell lotta things to do now than designing a new shaft. I would also like to avoid magnetic types, as they create other issues.

[Ian Arkver]

Spring shafts? Got a link?

CU,
Ian

[chende...@gmail.com]

https://www.aliexpress.com/item/4000890839985.html

but they are not direct replacement for 5mm rotation motor. Also much longer than I wanted, but it is the only one found so far.

[Ian Arkver]

Yeah, ok. I think I've seen those before. 6mm bore as you say is a problem, and length. Plus you still need some kind of wedge to push the outer shell up against the spring to release the tip. Not a great solution imho.

CU,
Ian

[chende...@gmail.com]

You're right. Search continues...

[Ian Arkver]

What we want, though sadly I don't recall ever seeing one, is some kind of twist lock. Where the retaining ring was (for example) a hexagon shape, held by the toolchanger, and you could rotate the shaft (using the normal C stepper) to lock/unlock the retainer.

I wonder if this is something you could 3dprint in PETG to replace the stock holder's bit of clear plastic tubing. Something that applied spring force to the retaining balls when locked, but released that force when rotated slightly. Hmmm.... rubs chin....

CU,
Ian

[mike....@gmail.com]

This Oil Seal could be the simple solution - still some force is needed to take the nozzle out. With removal of spring in seal less force is needed, however runout of nozzle I have not tested ...

https://youtu.be/Kw6WZqhsMWk 

Mike

[3d.m...@gmail.com]

How about using the quick change holders from Betz Tecknik: https://www.betztechnik.ca/store/p32/Quick_change_Juki_nozzle_holders-_NEMA8%2F_11_hollow_shaft.html.  

[greg.hj...@gmail.com]

I have the PNP head from Betz and I really like it.  Has anyone made a quick change holder (for the PNP table) for these? 

[chende...@gmail.com]

I didn't knew about Betz, looks promising. Thanks.

[Mike Menci]

Greg 

See details under video text to GitHub 

https://youtu.be/KRR3bC9j_3s

Mike

On 29 Nov 2020, at 21.26, chende...@gmail.com <chende...@gmail.com> wrote:

I didn't knew about Betz, looks promising. Thanks.

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[chende...@gmail.com]

The holder looks good, but I need to change it in order to make it shorter. The one from the video is quite long. I have at least 40 nozzle tips on the machine, it will take too much space.

[mike....@gmail.com]

This is the only Juki nozle changer that I know, that has force, which can compress the Nozzle holder spring
It is not done by Z axis but with X or Y motion, which has more force due to travel of nozle on slope!

[chende...@gmail.com]

Yes, I noticed the force comes from xy motion due to the slope of the top part of the holder.

I just need to modify it a bit, with a shorter travel distance, so that the holder takes less space. I will probably build it from metal also, not 3d printed.

After all it seems this is the combination I'm looking for. I think I will order 4 holders.

[mike....@gmail.com]

Without nozzle holder spring- station like here could be option for 40 nozzles ;  https://www.youtube.com/watch?v=xCwV6Qziv-Y

[chende...@gmail.com]

Yes, I saw that one few days ago. It looks ok but I have something against magnetic holders, that one from the video looks magnetic to me considering how the tip jumps up a bit when is loaded. 

[mike....@gmail.com]

Correct - I dont like magnet as well - but the pro nozzle banks look like this:

https://www.smtlinemachine.com/sale-11344260-change-station-yamaha-nozzle-6-5kg-weight-ce-certification-for-ys12-ys24.html

[chende...@gmail.com]

I don't think the station from the video and the one from the pictures (smtlinemachine.com) is compatible with the spring type holder from Betz.

If I'm not mistaking, the slider of the station is only there to capture nozzle tips. I don't think it is designed to push the spring with a sloped edge, I do not see any slope there.

But I see it on the 1.png image you attached. That should to the trick.

[Sandra Carroll]

I know I don’t post much but wanted to throw in something.

On the nozzle holder in question.  The tension of the balls appears to come from the clear sleeve over the balls.

Would it be possible to replace that with something a bit more flexible to allow for easier insert/removal while keeping the balls snug enough to retain the nozzle?

 

Sandra

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[mike....@gmail.com]

Sandra we were missing you :-)) 

Betz uses spring = https://www.betztechnik.ca/store/p32/Quick_change_Juki_nozzle_holders-_NEMA8%2F_11_hollow_shaft.html

China low cost are with plastic sleeve - correct!

Mike

[chende...@gmail.com]

Hi Sandra,

Thank you. I was thinking at this but I discarded this idea because I don't know how stable that material would be. Current sleeve is too tight, requires high force to detach. If I lower that force by replacing material, it must be sufficiently low so the nozzle tip could be removed without spring getting elongated. Also it must be sufficiently high so that the nozzle tip does not vibrate or fall due to head accelerations, up to 5G on my machine. It looks like a fine threshold to me and I don't know how stable is that threshold over time, over a larger temperature swing, etc.

There is another issue, the current shafts have some eccentricity error (I was expecting this) and I would like to replace it with something better machined. I plan to go as low as 0201 if I can and I need good nozzles for that.

[ma...@makr.zone]

To make it more compact (on the edge of the machine): one x/y-wedge could be shared by all the nozzle tips and the individual tips then parked into slots 90° to the side(s) of a longer "non-wedge" track (the less often used tips parked further in).

For those not yet dead set for Juki: also have a look at Samsung CP40 nozzle tips. They are much simpler (because the spring is in the holder), sturdier, easier to load/unload, much more compact to store, no leak problems reported (unlike for Jukis), also less expensive, I would presume. They are the ones used on the Liteplacer. But the Liteplacer steel holder is way too unforgiving, IMHO. Better make one from plastic/3D printed, something more forgiving and less abrasive. Like this one made by Richard Klingler:

https://youtu.be/qcL0MLGex4M

https://www.liteplacer.com/shop20/index.php?route=product/product&product_id=63

_Mark

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[Sandra Carroll]

I was wondering if surgical tubing would work for this.  It’s strong, resists tearing,  chemically safe and has more give.

 

I have the same head but have not made much progress on my machine.   I also have a DIY Laser Engraver in progress and found that the area I have cannot accommodate both machines.

So I’m at a standstill until I decide what to do.  

 

I too need to go down to 0201s and will look to ordering the nozzles from Betz

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[greg.hj...@gmail.com]

I like Mark's idea on the sideways track since it seems like it would take up less space on the table.  Would OpenPNP need more 'moves' in its nozzle change sequence though?  

Greg

[bert shivaan]

Well maybe the extra moves can be incorporated in a script? You can now run actuators between moves.

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[Mike Menci]

I measeured the run-out / used Seal as holder

Video link

https://youtu.be/BsT1WkRWPh0

Mike