Mark’s PushPullFeeders (Tobys too): anybody reconstructed it with a Push-Version instead Pull?

[Pete]

I just printed one of Mark’s PushPullFeeders (actually Toby Dickenson’s fork) and took a closer look at the assembled unit. It looks like it might meet my requirements and it is working flawless in my (manual) tests. 

Nice feeder!!! (btw: thanks for your contribution Mark and Toby)
Unfortunately, I have a problem: the heads of my PNP are all inside a fixed housing (the housing doesn’t raise or lower). So I have no way to engage the U-shaped lever from above  (and then pull) like it is planned with the original version. I might try it sideway, but the housing is a perfect fit for all whats inside and right now I do not see any easy possibility to mount anything to the housing.
I’m sure others have run into this problem too. Has anyone ever modified this feeder so that it works in push mode and not just pull mode? That would make live a lot easier for most users, as just pushing against a lever would be easier to realize than fiddling a U-shaped pull-construct into the lever.

[Toby Dickenson]

Hi,

Do I understand your problem correctly that you cant do Z actuator
movements? But you can do X and Y?

If so, your actuator could be a hoop which engages from the side of
the feeder (rather than from above) then pulls and pushes. Does that
work?

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[Mike Menci]

Motify the lever to have a wedge type of extention that you drive on-to and push - with spring return ??? 

[Pete]

I've been racking my brain all week trying to come up with different options, but I can't seem to find a workable solution. The idea with the wedge extension wasn't bad, but it's not feasible because I can't mount the pressure point as low as it needs to be.
As I have to change rotation direction (push instead pull), I think I’ll have to work with two gears: the first will be the bearing of the current lever—the round bearing just gets teeth all around it. The existing (pull) lever arm at the top can be eliminated. To the right of it, there will be a second gear with an upward-facing lever. When you push against it, the direction of rotation is reversed by the two gears, and the feeder works as it should.
See the rough drawing attached. What do you think—is this feasible, or am I missing/overlooking something?

Thx!

[Pete]

thats right, I cannot move the head in z-direction (as there is a fixed housing around the nozzles). 
I had looked into feeding a ring or something similar in from the side and then pulling the lever, but that creates a problem with narrow feeders. There just isn't enough space, and besides, I end up with various other mechanical issues due to the design. That way will not work here.

Currently the above mentioned gear solution seems to be the best.

[jdlv]

Hi,

in a similar situation I made a moving hook using a small SG90 servo. It's quite fast and it works.

You can see it in action here :

https://groups.google.com/g/openpnp/c/7hVaXU_Ih8g/m/1wTGs8_nAQAJ

joël

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[Toby Dickenson]

On Sat, 9 May 2026 at 00:30, Pete <displ...@gmail.com> wrote:
>
> I had looked into feeding a ring or something similar in from the side and then pulling the lever, but that creates a problem with narrow feeders. There just isn't enough space, and besides, I end up with various other mechanical issues due to the design. That way will not work here.

You might be right, but does this geometry work? This replaces the lever handle with a peg 4mm diameter. There is a 5mm gap between the peg and the next feeder, assuming a puller ring might have thickness 3mm and allowing 1mm clearance either side.

Code here:

https://github.com/tobydickenson/PushPullFeeder/commits/lever_peg/