Solder paste/flux manual syringe applicator

[neslekkim]

Robenz, you have the know how and tools to offer great paste dispensers that don't require air compressor. Have you considered it?

Thanks for your confidence in me!  I have not thought about it because I have an air dispenser that works very well. That is a very good idea that I will put some thought into.

I like this setup: http://letsmakerobots.com/content/solder-paste-dispenser
But with your machining skills, I would guess it would be even better?

[robrenz]

Nice, but I am thinking purely mechanical operation.

[neslekkim]

Nice, but I am thinking purely mechanical operation.

yes, but can it be handheld?, with some light and strong materials that would be cool., but I'm not so sure about this idea: https://www.tindie.com/products/Pieco/paste-press/

[zapta]

I like this setup: http://letsmakerobots.com/content/solder-paste-dispenser
But with your machining skills, I would guess it would be even better?

My prototype is based on this one with two changes, it can also pull back and it didn't need the two guiding rods which makes it simpler to construct.

[neslekkim]

I like this setup: http://letsmakerobots.com/content/solder-paste-dispenser
But with your machining skills, I would guess it would be even better?

My prototype is based on this one with two changes, it can also pull back and it didn't need the two guiding rods which makes it simpler to construct.

That one can also pull back, just a small change to the source..

[zapta]

I like this setup: http://letsmakerobots.com/content/solder-paste-dispenser
But with your machining skills, I would guess it would be even better?

My prototype is based on this one with two changes, it can also pull back and it didn't need the two guiding rods which makes it simpler to construct.

That one can also pull back, just a small change to the source..

Are you sure? The nut is not embedded so I think it can only push but not pull. I printed it from the files on Thingiverse.

[neslekkim]

Are you sure? The nut is not embedded so I think it can only push but not pull. I printed it from the files on Thingiverse.

Good call.. Glue the nut in..

[zapta]

Are you sure? The nut is not embedded so I think it can only push but not pull. I printed it from the files on Thingiverse.

Good call.. Glue the nut in..

I don't think the other end of the plunger can pull, it's just flat. The original version was not designed to pull, just to release pressure, that's why it needed the two guides, to prevent it from rotating with the shaft.

[zapta]

Spend some time this weekend to work on the paste dispenser.  A few pictures below. My conclusion so far are that 1) it's workable  2) control and results are much better than pressing the syringe by hand, 3) printing result is not as good as using a stencil, 3) the quality of the paste makes a big difference.

Using a cheap Mechanic paste from ebay. The paste barely sticks to the board. Big mess. I was able to assemble that board but it required massive rework.


Using a good quality ChipQuik T4 paste. It sticks much better and provides good control. This board required significantly less rework.


The mechanical contraption. All blue pieces are 3D printed with PLA on a RepRap printer. The syringe is hold in place using a plate and two M4 screws. The syringe can be rotate around to optimize the orientation when using a bent needle.


The dispenser disassembled. The motor to threaded shaft coupler is also 3D printed and is held in place using two M3 screws and nuts.


Another view


The motor mount


A look into the plunger. The thread is a M4 heat fit insert (mcmaster 94180A353).


The bottom of the motor mount. Same M4 threaded inserts.

[PlainName]

Looks impressive

What happens when the syringe is worn out, specifically the neoprene seal on the end of the custom plunger? Presumably you nick the one off a new syringe?

FWIW, by hand I use a 1ml syringe since it gives the most movement to small amount of paste. I think the  luer lock only shows up on 3ml a bigger, though. But, anyway, maybe a smaller syringe might improve delivery a bit due the the higher 'gearing'.

[neslekkim]

This build looks impressive!.
You printed the plunger so it can pull the rubber piston back?

A look into the plunger. The thread is a M4 heat fit insert (mcmaster 94180A353).

After looking at mcmaster page for that heat fit insert, I wonder, the installation tip for soldering iron, I cannot find any information about that, which soldering iron will it fit?
Or did you use other ways of inserting it?

I guess Mcmaster still don't want to ship internationally, I tried last in 2011, but no-go.

[zapta]

What happens when the syringe is worn out, specifically the neoprene seal on the end of the custom plunger? Presumably you nick the one off a new syringe?

Considering the low amount of movement I don't think the syringe will worn that quickly. At one point I cleaned up the syringe and plunger with IPA and then the seal did not fit in because of too high friction so I put a small amount of silicon grease and it went in smoothly (which made me to think that syringes come with a small amount of lubricant).

There are many 10ml syringes available on the internet and they are cheap. One thing you need to make sure is that the one you buy fit the plunger you printed. Below are the ends of two 10ml plungers, the one at the top fits the plunger I printed. You can tell between them by the number of black seal rings you see from the outside, the one at the top has two rings and the one of the bottom has three rings (this is based on a very small sample).

 

Mine look like this one  http://www.cmlsupply.com/dispensing-syringes-10cc-10ml-pack-of-10-with-tip-caps/

The plunger I printed fits into the rubber seal and can both push and pull it. You can see the 3D model here

https://github.com/zapta/misc/blob/master/paste_injector/openscad/plunger.stl

After looking at mcmaster page for that heat fit insert, I wonder, the installation tip for soldering iron, I cannot find any information about that, which soldering iron will it fit?
Or did you use other ways of inserting it?

I guess Mcmaster still don't want to ship internationally, I tried last in 2011, but no-go.

Here is some information about those inserts. Since I am merely a hobbyist, take it with a grain of salt.

This is the M3 set the McMaster sells. The M4 is similar. The insertion tip is at the top and the extraction tip is at the bottom. The tip in the center is of the Weller SP40NUS solder iron they sell for this purpose.



For insertion I just use a Metcal STTC 125 tip that I happen to have (with a MX500 solder station). It worked just as good. This is a fixed temperature setup.



As for finding those inserts, you can search under different names such as 'heatfit threaded inserts' 'ultrasonic threaded inserts' 'heat threaded inserts'  'tapered threaded inserts'. For example

https://www.google.com/search?q=ultrasonic+threaded+inserts&es_sm=119&source=lnms&tbm=isch

There is also that kind of symmetrical inserts that you can find on ebay, for example, http://www.ebay.com/itm/New-20pcs-Brass-Knurl-Nuts-M4-8mm-L-6mm-OD-Metric-Threaded-nuts-insert-round-/221526229763?hash=item3393fe0303  They are good for the 4 motor mount holes but not for the plunger because the sharp edge at the front end causes the long hole inside the plunger to clog. You can try filing one end of these inserts to make them conic, possibly this will avoid clogging the plunger hole.

Also note that all the dimensions in my 3D models were tweaked to match the parts I have and the tolerances of my 3D RepRap printer so you may need to tweak them.



PS: considering that these inserts are so easy to use and useful for 3D parts, I am surprised that they are not more popular with the 3D make community and available from vendors catering to hobbyists.

[zapta]

I did a few experiments with the cheap inserts from ebay and they seem to work. Those inserts are designed for molding, not for heat insertion, but tapering one end with a Dremel disk solves the problem. I was able to insert the taperd insert without clogging the plastic hole past the insert which is required for the plunger.

A stock vs. manually tapered inserts (this is a M3, the paste injector uses M4 but it should be the same):



This is how I held the insert while tapering it with a Dremel disk:

[neslekkim]

ah, good to know, that the shape is important like that.
Found some that sold better ones on ebay, from US, but it seemed like the shipping was kinda expensive ($28-30 for 50-100 pieces).

But anyway, need to get parts printed also.. that can be expensive.

[zapta]

ah, good to know, that the shape is important like that.
Found some that sold better ones on ebay, from US, but it seemed like the shipping was kinda expensive ($28-30 for 50-100 pieces).

But anyway, need to get parts printed also.. that can be expensive.

I can mail you from here the printed parts with the inserts installed. You pay out of pocket mailing cost.

[neslekkim]

ah, good to know, that the shape is important like that.
Found some that sold better ones on ebay, from US, but it seemed like the shipping was kinda expensive ($28-30 for 50-100 pieces).

But anyway, need to get parts printed also.. that can be expensive.

I can mail you from here the printed parts with the inserts installed. You pay out of pocket mailing cost.

Sent you an pm

[0xdeadbeef]

Side note: someone is already trying to sell a stepper driven dispenser on eBay:
http://www.ebay.de/itm/Syringe-Solder-Paste-Dispenser-5V-DC-USB-powered-Lotpaste-Regler-dispenser-/271979673060?hash=item3f534075e4
Looks a bit cobbled together though.

[zapta]

Side note: someone is already trying to sell a stepper driven dispenser on eBay:
http://www.ebay.de/itm/Syringe-Solder-Paste-Dispenser-5V-DC-USB-powered-Lotpaste-Regler-dispenser-/271979673060?hash=item3f534075e4
Looks a bit cobbled together though.

I think it's by this guy. His email address is in the video description.

[KL27x]

http://www.ebay.com/itm/New-Digital-Precision-Solder-Paste-Auto-Dispenser-controller-CNC-/221866155560?hash=item33a840de28
There's this one, too. If I am remembering, right, it is the first that I ever saw, using this sort of design with the stepper motor. The designer put it on a blog/webpage and sold some of his extra proto board order. He used a PICAXE, IIRC. That must have been at least 3-4 years ago.

It's hard to see the one in the video link, but maybe it's the same board, even.

[zapta]

http://www.ebay.com/itm/New-Digital-Precision-Solder-Paste-Auto-Dispenser-controller-CNC-/221866155560?hash=item33a840de28
There's this one, too. If I am remembering, right, it is the first that I ever saw, using this sort of design with the stepper motor. The designer put it on a blog/webpage and sold some of his extra proto board order. He used a PICAXE, IIRC. That must have been at least 3-4 years ago.

It's hard to see the one in the video link, but maybe it's the same board, even.

This is Geir's design which is the inspiration for my design. Main difference are not having the two anti rotation guides and allowing the motor also to pull the plunger.

https://www.tindie.com/products/Dead_Bug_Prototypes/solder-paste-controller/

http://www.thingiverse.com/thing:384680

And then there is the Pieco. Didn't work well for me and kept oozing badly (no easy way to relive the pressure).

https://www.tindie.com/products/Pieco/paste-press/

[zapta]

[https://www.youtube.com/watch?v=lurK1yjgyEU][/img]

What motor are you using?

I am using 28BYJ-48 which is cheap, easy to mount and works but kind on the bulky side.

[mike_58]

Here is a larger stepper used as dispenser for solder paste.

[mike_58]

Hello,

The motor itself is not the key to solder dispenser, in order to have sufficient power you need a gearbox which (if selected properly) will give you the required torque & force to move the solder paste trough the needle.  There is no code for motor I use, but it has a build-in gear box with all metal gears with gear ratio 1 turn on piston is about 25 short clicks on controller command-Press.

I hope this will help you.
BR
Mike

[zapta]

Hello,

The motor itself is not the key to solder dispenser, in order to have sufficient power you need a gearbox which (if selected properly) will give you the required torque & force to move the solder paste trough the needle.  There is no code for motor I use, but it has a build-in gear box with all metal gears with gear ratio 1 turn on piston is about 25 short clicks on controller command-Press.

I hope this will help you.
BR
Mike

Thanks Mike. Can you share with us where you source that geared motor?  I am using this one, it requires 512 half steps per threaded shaft revolution (which has a 0.7mm pitch).

http://robocraft.ru/files/datasheet/28BYJ-48.pdf

Also, do you generate an individual drop per pad, as the pneumatic devices do, or just a very slow flow that you apply to one pad after the other? Mine does the latter.

[mike_58]

Larger motor with the same controller PCB test:

Mike