Better nozzle with auto change?

[Spikee]

If I had a cnc lathe than I would also change the current mechanism and use a hollow shaft stepper , a good rotating air coupler and a custom adapter for these nozzles.
The place where I bought my cnc mill they are also doing the last testing on a new cnc lathe they developed. If all goes well I will get one of those somewhere around January.
At least if it is <5K euro.

Just a upward motion and "stopping" the nozzle in the z axis would be all that is needed for auto changing.

[mrandt]

If I had a cnc lathe [...] If all goes well I will get one of those somewhere around January.

Wow, you just sparked my interest for another machine

What brand are you looking at? Do they have a website yet?

On the other hand, would you be willing to make and sell a few couplers to the community once you have your machine working?

You could put me on the list

[mrandt]

I inquired about having custom Juki nozzle couplers made in China.

I want the coupler to connect to the following stepper available from RobotDigg:
http://www.robotdigg.com/upload/attach/ ... e68b01.jpg

The suggested stepper has 8mm outer diameter on top end of shaft and also an M5 inner thread - so you can either directly connect a rotary coupler (like Misumi RTCN6-M5) or your own construction with either thread, press-fit or glued connection.

The customized coupler will have an M8 inner thread so it will nicely mate the outer thread on front end of shaft of the stepper motor.

Also, I asked for a total length of 40mm which is shorter than the ones sold on eBay.

The connector will have ball lock for Juki nozzles like the one that Karl used for his auto tool changer:
https://vimeo.com/144454866

If I were to buy 10 of those couplers, they would cost me USD 69,00 each + shipping + tax / customs.

I am also looking for a good deal on Juki nozzles.

Anyone in Europe interested in a bulk order? I would also ship elsewhere, but I guess overseas shipping cost might kill the deal then.

[mrandt]

More details on the set - it will contain:

1x coupler as per the specifications from previous post with 40mm total lentgh and M8 thread - here is a picture (mockup):

liteplacer_juki_coupler_mockup.jpg (46.87 KiB) Viewed 18266 times

9x Juki compatible nozzle (not original parts from Japan but good quality from China) sizes 500 through 508:

juki_nozzle_set.jpg (36.26 KiB) Viewed 18266 times

This set will work for most common SMT components, but the nozzle coupler will enable you to also obtain and use other Juki compatible nozzles.

Juki nozzle portfolio also contains grippers for large parts and connectors, molded tips for LEDs or MELFs and other special nozzles - find a catologue here:
http://avipre.com/products/smt&tht/juki ... Rev-C3.pdf

I will import the holders and nozzles from China could offer the complete set in Europe for EUR 200 flat + shipping to your location.

This will be a fully legal import, which means I will pay tax and import duties and send you a proper commercial invoice along with the parts.

I would need to take at least 5 orders to make the deal happen - please shoot me a private message if you are interested.

[kerel]

I would like one set. Do you also ordering stepper for it? Can you provide EU VAT Invoice?
Shipping would be within EU.
Can you please PM me as I'm not allowed to initiate PM's due to fresh registration.

[gtrplaya101]

I want a set! Sign me up!

[Pixopax]

To pick up the idea with the hollow pushrod inside the nozzle holder:

If you still want to order a holder in china, consider making it shorter.
Then we glue or press an acryl or polycarbonate tube on it, with M8 thread in it.

Then we can detect the pressing of the nozzle optically.

Just a quick sketch:

juki2.png (34.81 KiB) Viewed 18060 times

If I had one of these holders I could make a sample, I have a lathe.

[JuKu]

Seems like the A axis need a redesign anyway. (http://liteplacer.com/phpBB/viewtopic.p ... 1&start=10). The top bearing could go lower, so there is room on the tube above. Mount the up pushing spring there. Put another collar on the shaft below the bearing so, that a bit after the switch has triggered, it prevents the shaft from going up any further, giving a nozzle change mechanism something to push against to.

Disclaimer: I dont' have the mechanism, I have no idea how hard push it needs.

[Pixopax]

I consider this nozzle changer as a high-end option, I am sure the standard needle system will do for most people. But I often have small and very large parts to place.
So it would be a nice-to-have thing.

Most people put these holders on hollow-shaft-steppers. I am not sure how much force it produces while changing, but the spring looks strong.
Since motor bearings are not made for this load, we should consider using your idea and press or screw the thing to a 8mm hollow shaft.
That would make it sturdier, as the changing mechanics put much load on the system.

If we would do it really right, we should take small angular contact ball bearings, like the 30/8 2RS.
But there is no readymade holder for that bearing. Not a problem for me, but most people do not have the machines to make them.
So if malte does not currently have plans to make this holder, I will order one, and modify my system to use it, with a clear part for optical height detection, and angular bearings for the load.

[mrandt]

holder [...], consider making it shorter. Then we glue or press an acryl or polycarbonate tube on it, with M8 thread in it. Then we can detect the pressing of the nozzle optically.

At least with the Juki nozzles an available couplers / holders the design will not work - or I did not understand it correctly

Find below a CAD drawing of a Juki 502 nozzle - once in "normal" state and once with spring compressed:

juki_502_default.png (10.35 KiB) Viewed 17862 times

juki_502_compressed.png (7.35 KiB) Viewed 17862 times

As you can see, the inner shaft only protrudes slightly when spring is fully compressed. To measure this optically, the sensor would need to be in the holder itself.

Otherwise we could put some "extension" into the holder which moves upwards through the coupler and any hollow shaft attached to it so it can be detected furthert upwards. It must not obstruct the flow of air though and would either need to be heavy enough or also have a spring to move it back to neutral position when the nozzle does not touch anything.

If this does not work, we can still go back to Karl's approach of putting a small contact into the holder and detecting electrically when the nozzle touches a surface.

Most people put these holders on hollow-shaft-steppers. I am not sure how much force it produces while changing, but the spring looks strong.
Since motor bearings are not made for this load, we should consider using your idea and press or screw the thing to a 8mm hollow shaft.

The couplers I am testing have a ball lock mechanism to hold the nozzles in place. Actually quite similar to the connectors used for compressed air on compressors or pneumatic tools. You have to push up the outer ring upwards to insert or release a nozzle.

Karl achieved this upward motion by using an angled plastic holder, which converts a sideways motion of the head in X or Y direction into a upwards momentum on the nozzle coupler's outer ring which slides onto the angled surface.

I agree that in this mechanism the shaft bearing will suffer sideways load. I am not sure though if this load is exessive as stepper bearings are often able to sustain relatively large loads.

However, we could also move the Z-axis to release / load the nozzle; we would need to "teach" LitePlacer software the right movements to load / unload a nozzle then.

If we would do it really right, we should take small angular contact ball bearings, like the 30/8 2RS.
But there is no readymade holder for that bearing. Not a problem for me, but most people do not have the machines to make them.
So if malte does not currently have plans to make this holder, I will order one, and modify my system to use it, with a clear part for optical height detection, and angular bearings for the load.

I am currently testing four sample couplers. If you want to experiment, I could send you one of those. The ball lock is not perfect yet but I guess it would be good enough for a start and would certainly allow you to modify and experiment with different ways of mounting.

My plan is to mate the coupler to a NEMA11 stepper with M8 threaded shaft. I believe this stepper's bearings can take sufficient load to change a nozzle and produce enough torque to rotate the parts and overcome any friction from vacuum coupling.

Biggest problem so far - besides manufacturing tolerances in China - is the precision of the threads. The coupler and nozzle tip have some runout, they are not exactly centrical. I might go back to a cylindrical shaft and set screws which would allow to compensate this a bit.

Press on fit might be even better; but as I already mentioned the tolerances are a problem and press-on would require even better tolerances.