Ray's Juki Rack for Automatic Tool Changer

[Ray Kholodovsky]

Hi Folks,

Seeing as how many of my adapters have reached their customers at this point and are starting to pop up in the wild, I've put together a basic design for a single juki nozzle rack (can be into an array of your preferred size, obviously) for use with my adapter.  

I saw that Genie put together a 3D Printable design, which is awesome, and I've started it printing on my machine, but anyone that's spoken to me knows that I design for production (and use that exact phrase a lot) and I don't see FDM printing as viable because of dimensional issues, rough surfaces, and time spent when making many.

As such, I considered CNC milling the two halves, which when considering the fact that I need a 1.5mm groove in 12mm thick stock, didn't seem like the best idea.  I could get this SLA printed which would work as far as no internal supports and smooth surfaces, but it would be cost prohibitive as a production strategy.  So, laser cutting and stacking it is!

The following pictures, and keep in mind that this is fresh out of CAD that I did in the last hour so, represent a half section of a series of 3mm plates that I intend to laser cut out of acrylic (and could be done out of delrin which might be a better material for this type of 'gliding' application) and stack together.  You are seeing 4 plates in the half section, which would make for a total of 8 plates resulting in a total width (as viewed from the front) of 24mm and the plates will be retained using M3 screws probably 30mm long and nuts.  Now keep in mind this is just a first revision and I haven't tested anything yet.  Maybe the orange plate needs not to follow the top contour and instead be a wall for the collar of the adapter.  Maybe the path in the red plate that the juki nozzle's ring sits in needs some chamfers on the outside to make it easier to guide in, and maybe the path needs to dip towards the end such that the nozzle falls into a shallow groove and thus would be unable to wobble out perhaps due to vibrations.  All things that will be figured out...

I look forward to all your thoughts.

Cheers,

Ray

[Andrew Frazer]

My concern with laser cutting the acyrlic would be that the process leaves the material quite brittle, and its prone to break/crack over time, particually if its got mition over it.

You might be better to go with water jet cutting for the acrylic, but that has other challenges as well.

[Ray Kholodovsky]

Waterjet is certainly an option if doing a run of these. Delrin should not be as brittle and can just as easily be laser cut as well. I have acrylic and a laser cutter in house so that will be a fast way to prototype this. 

[Mark Harris]

Laser cutting isnt what makes acrylic brittle... acrylic is what makes acrylic brittle.

PMMA has only 2% elongation before breaking and really doesn't have much in the way of plastic deformation.

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[Rich Obermeyer]

Ray,

I would think you would want a small notch on the bottom 

for the tool to land into to "register" it's location very accurately 

when not used.  This way when it disconnects from the head it 

falls centered in this small notch.  When the head disconnects 

it always going to stay exactly where you want it for pick up later. 

Other factors may move it if it's sitting there. 

My machine moves back and forth a lot from forces of head 

pick n placing. Now when you say load a tool, you can sure it's 

very close to where you think it is. You don't have a lot slack 

when go back hunting for the tool.

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[Ray Kholodovsky]

Hi Rich, 

I've added a small cavity as you've described and show the nozzle lowered slightly to sit in it. The entire depth of this cavity is currently 0.25mm, so it's extremely minute and I will tune this as necessary.  The reason for this is that there's only so much that the balls can pull the juki up and into the locked position, so we've got to account for the maximum distance that the the nozzle can be affected by gravity and make that no more than the 0.5mm (eyeballing this figure) or so that the balls can pull the nozzle up into position.

Cheers,

[Graeme Bridge]

Why not just price it in aluminium, my guess would be that on 50 of these they would be around $12-18 

[Rich Obermeyer]

I would have to play around with the cad myself to get as close to 

this as you already are.  so take my comments with a grain of salt.

I would have the nozzle released somewhere about 3/4 the way up 

the ramp. Then moving farther simply moves the tool into the 

resting notch which could be vary large (should it be needed).  

Now cut a hole in the top right above the tool large enough so 

the head can go down and get the tool no matter how deep it was.  

Then you can apply a little pressure onto the tool to make sure it 

registers good and not depend on the ball to "pull it in" before 

you pull the tool up and out for use.

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