New easy to use paste/adhesive dispenser design, CNC/3D printer compatible - Page 1
Forum section: electronics / general

author: dmmt40
author_rank: Regular Contributor
timestamp: April 14, 2016, 04:54:12 pm
content: Hello, I’m very excited to reveal a new design for a dispenser that I’ve been working on for the last year. No need for compressed air, super easy to start using, can be hooked up to a 3D printer and it can also double as a vacuum pick up tool!Here’s a video that I made, make sure to watch to the end: (sorry if the editing is bad, there’s a lot to cover)If I had to say what the biggest advantage of this dispenser is, I would say convenience/ease of use, what's the point of getting something if you never touch it after 2 or 3 tries because it's a pain to actually use it? quick refills, small size, USB powered, simple UI, syringe design, all add up to remove the hassle of setting up and using the machine.I actually have some experience in this field, originally I designed the system for work back in 2014, to be used in an industrial environment (for adhesives), as you know time is critical and any new operator has to be able to pick it up and start using it right away. You actually have to assume people DON’T want to use it in the first place, if you had to sit there dispensing for 3-4 hours every day you’d also be annoyed by even the smallest problems.Anyway, after many months of getting it "consumer" ready I've finally finished it, took much longer than I thought but I'm very happy with it. I’ll start selling it on ebay or tindie or something similar (other ideas?) in the next couple of weeks. This is a great little tool if you’re looking to get into SMD prototyping, or if you do it already and just want to make your life easier.It will include the following:-Controller and stepper motor.-2 empty syringes with caps and pistons, there's clear or amber color for UV sensitive adhesives.-10 luer tips, I can recommend a couple depending on your application.I will also have external switches ready to use: Pedal, finger switch and proximity sensor, as shown in the video. These are optional and you can always make your own of course.Here’s some comparisons:VS stenciling:-Faster setup and cleaning time, plus you can use the vacuum pick up mode to place the components. When you consider everything it’s probably faster for one-off prototypes of small and medium sized boards.-Much less messy and wasteful.-Stencils add extra cost and/or time to each PCB order.By the way even if you already use stencils and are very happy with them you can still use this dispenser to apply exactly the right amount of paste for each squeegee pass or even just for the pick up mode, of course there’s already vacuum picking machines from china, but they’re big, cumbersome, noisy and not that cheap (the good ones at least).VS a compressed air dispenser:-Much smaller footprint, just 9x7cm saves space in your bench.-No compressor.-Pedal or any other external switch is optional so you don’t have to run extra wires on the floor and table if you don’t want to.-Much more flexible triggering options.-LCD with numeric control for a better user experience, instead of pressure gages and dials.- Maximum dispensing speed is lower but in practical terms it's not bad at all, too fast is not desirable either since you'll quickly loose consistency in drop size.-Dry pastes with play doh-like consistency can't be dispensed or it gets difficult, if you really want to reduce the viscosity there's a couple of ways to do it, but you should be using quality paste regardless of dispensing method.-Internal memory stores settings for up to 15 different types of fluids.-You can hack it! If you have a very weird application you can connect to the ICSP header and reprogram the micro with custom firmware but it’s so flexible that it’s not even necessary, but yes it’s possible.-Has vacuum pick up mode! no need to buy a separate machine, yet more money and space saved in the bench.If you have questions, suggestions, want some tips, know the history behind it or anything please ask, but most importantly tell me if you’d be interested in buying one of these. The size of my first batch will greatly determine the BOM cost and therefore final sale price, if a lot of people show interest I can commit to buy a larger volume of parts, I can say for certain that it's going to be cheaper than buying a dispenser plus a vacuum pickup from ebay.Cheers, Dan

author: dmmt40
author_rank: Regular Contributor
timestamp: April 15, 2016, 09:59:03 pm
content: Ok just wanted to add a little more information, yesterday someone asked me for dimensions and weight because they wanted to implement it in their desktop pick and place machine.Total weight (motor+ empty syringe): 145gTotal length with tip: 177mmSyringe length with tip: 140mmSyringe outside diameter: 1inPersonally I think this would be the perfect accessory if you already own a pnp machine, for two reasons:- They are very accurate, more than enough for paste dispensing.- You already have a jig to line up the board with your machine coordinates.Also I’ve just uploaded another video where you can see my 3D printer dispensing a reasonably sized board 14x8.5cm, this could easily be done with a proper pnp:And finally here’s a sample of the g-code I wrote for that: (remember the fan output is connected to the dispenser)G1 Z3(lift the tip 3mm)G1 X-.75 Y6.24(go to pad1 position)G1 Z0(lower tip)M106 S255(turn fan on, starts dispensing)G4 P350(wait 0.35s, this is the actual dispense time)M106 S0(fan off, stop)G4 P300(wait 0.3s, gives the dispenser time to suck back to prevent oozing)Repeat for next pad, same code just different XY coordinatesG1 Z3G1 X3 Y6.24etc.I wrote the code by hand but I don’t think it would be particularly difficult to make a small script that reads the paste gerber file and gives you the complete gcode, that’s another project I’ll finish in the coming weeks.Also I plan to do a little video tutorial on how to easily line up your 3D printer with your physical board, it’s actually not as hard as you might think.

author: chickenHeadKnob
author_rank: Super Contributor
timestamp: April 16, 2016, 08:13:42 am
content: Quote from: dmmt40 on April 14, 2016, 04:54:12 pmHello Dan,Yes I am interested, count me in for 1 unit. I noticed at around 6:40 in your first video you show the syringe clamp/adapter for the cnc attachment. I am somewhat concerned that this is not rigid or repeatable enough for heavy duty use, mostly because those syringes look flexible. My questions are:1. ICSP, this implies Atmel-AVR, correct? which processor?2. Those white plastic parts, are they 3D printed? will the production units use the same?3. The syringes appear to be limited life consumables, are spares cheap and easy to buy? from where(part number?)Over all I like your design, good engineering!

author: dmmt40
author_rank: Regular Contributor
timestamp: April 16, 2016, 04:06:09 pm
content: Hello chickenHead thanks for your interest, let me answer your questionsQuoteThe adapter is something I 3D printed for my specific setup, since every 3D printer is different you'd have to design your own, and you can make it as rigid as you want but really there's nothing to it, it's literally just a 1 inch inside diameter cylinder where you slide the syringe and that's it.Now, you're probably wondering if they're rigid because I squeezed the sides to get the piston down right? don't worry this is actually the method recommended by the manufacturer!When you buy a case of these syringes they actually come with a little manual and it's all explained, I can scan it if you want. But trust me they're very solid and very well made, after all they're designed to withstand up to 100psi of pressure!QuoteYes it's actually a PIC, nothing fancy just a16F series I'll release the schematics later on.QuoteExcept for the piston, yes they're 3D printed, and they have to be 3D printed since this is the only way to get this particular shape, I've also tested SLS printed parts and I can say they perform exactly the same as regular3D printed parts, looks prettier but it would cost $10 more, some people wouldn't mind paying extra for that and others wouldwe'll see.QuoteIf you ask the manufacturer they'll obviously tell you that are consumables, I guess they don't want to be held responsible if someone's using it with compressed air and it blows up on their face, but I can tell you after more than a year working with them in the industry they CAN be reused, specially in this scenario because it's mechanical dispensing and there's much less force acting on the syringe/piston. To give you an idea, we've dispensed nearly a liter of adhesive using a single syringe and piston before changing it... so yeah they're pretty good.These are the best in the industry, don't know if you can buy them as an individual, I get them trough the company I work and they only sell them in bulk, but don't worry I'll be selling these as well.

author: lasersbee
author_rank: Newbie
timestamp: May 08, 2016, 01:06:30 pm
content: Quote from: dmmt40 on April 14, 2016, 04:54:12 pmHey Dan,Nice neat design...Where do I get a hold of your dispenser with a few spare cylinders ??BTW how much are they... I can't seem to see any prices...Jerry

author: dmmt40
author_rank: Regular Contributor
timestamp: May 08, 2016, 09:56:14 pm
content: Hello guys, sorry if I haven't updated in a while I've been very busy with other work.I already have all the parts: motors, pcbs, electronics, etc I'm just waiting on the barrels to arrive, which should be later this week, in the mean time I'm assembling and testing the first units.QuoteI'll be selling the dispenser on Tindie, with everything you see in the picture, price to be confirmed but it will be very reasonable. I will update here once my store is onlineAs for the syringes themselves, I get them through work (we use them all the time) they're for industrial use and you have to call them directly, get a quote etc and only sell them in bulk maybe that's the reason why so many hobby dispensers out there don't use them, unless you've worked before or have experience with them you'd never know they even existed.No problem though, I will also be selling these. Can't tell you exactly how much but they're not that expensive.But anyway, like I pointed out in the video these barrels can be reused many many times! so don't even worry about it just yet

author: lasersbee
author_rank: Newbie
timestamp: May 11, 2016, 10:58:17 am
content: Quote from: dmmt40 on May 08, 2016, 09:56:14 pmThanks for the update. Please link us to your Tindie sales store when it is up and ready.Jerry

author: mike_58
author_rank: Regular Contributor
timestamp: June 01, 2016, 07:50:19 am
content: HelloIn compare to this one:https://www.tindie.com/products/marjan_mike/solder-paste-dispenser-v3-retired-see-v4-/is a bit different approach but let user decide what they want.

author: dmmt40
author_rank: Regular Contributor
timestamp: June 01, 2016, 04:19:38 pm
content: Just a quick update…First batch is ready!10 units fully assembled and testedWith their respective barrels.But, I’m not ready to sell yet, I still have to set up the store and all the documentation, so that means cleaning up the schematic, writing the user manual and some tips, take pictures etc, just a couple more days. I will probably put a separate post for that.By the way I’ve finally decided on a name, it will be theDM dispenser, sort of an acronym for “dispenser for makers” but also my nameQuotehello mike, yeah I saw your design a couple of weeks ago, personally I think both designs are different enough that they won’t compete against each other, yours is around half the cost of what I’ll be selling mine and is very purposed designed for solder dispensing.Mine is more complex in terms of software, hardware, number of parts, etc and price inevitably goes up but it also allows advanced users to use it in some interesting applications.Either way I think is great that there are more options out there for people that are getting into SMD prototyping or adhesive dispensing.

author: mike_58
author_rank: Regular Contributor
timestamp: June 02, 2016, 03:58:56 am
content: Just two short questions;- how much power/torque do you get from your stepper motor on direct shaft to plunger ?- and how do you get the air out of syringe at the point when you press into the syringe new paste and start inserting your plunger into the large syringe?and for CNC Printer a motor and shaft are needed only - controller is usually existing - (you can use extruder controller -stepper driver and programme it to run your stepper in more simple form:

author: dmmt40
author_rank: Regular Contributor
timestamp: June 02, 2016, 05:17:50 am
content: QuoteNo problem,- The motor torque... I actually don't have a way to measure it accuratelybut I don't think is as much as the geared motor in your video. Having said that, the reason I can get away with using a direct drive solution is in great part to the syringe design, it's tapered on the end which reduces the pressure needed to push the paste.- And how air gets out? During the filling procedure when you squeeze (very firmly) the syringe on the sides a tiny gap is created between the piston and the wall allowing air to escape through the top. This happens because the piston is rigid, compare that with a medical syringe where the plunger is made of rubber and it's very flexible.The paste or adhesive doesn't go through because the gap is very very small, and of course when you stop squeezing it goes back to normal. As I mentioned before, this not something I invented! this is actually what the manufacturer recommends as a standard filling procedure so the syringe was obviously designed with this in mind.Dan

author: mike_58
author_rank: Regular Contributor
timestamp: June 02, 2016, 05:53:36 am
content: Classical dispensers use min 3 bar (apx 45 Psi) for their operation - 4 to 6 would be normal. If you want to test your device attach a hose to the syringe luer-lock end and connect the bar meter to the hose. Run the motor and read the pressure on the gauge, at one point the motor will stop-this is max pressure what your motor/assembly can handle.

author: mike_58
author_rank: Regular Contributor
timestamp: June 02, 2016, 07:02:22 am
content: something like this:

author: dmmt40
author_rank: Regular Contributor
timestamp: June 02, 2016, 03:30:54 pm
content: Interesting... I'll definitely give it a go, I have a pressure gauge but don't have the hose or fittings so it'll have to wait until I get those.

author: mike_58
author_rank: Regular Contributor
timestamp: June 05, 2016, 07:47:07 am
content: - And how air gets out? During the filling procedure when you squeeze (very firmly) the syringe on the sides a tiny gap is created between the piston and the wall allowing air to escape through the top. This happens because the piston is rigid, compare that with a medical syringe where the plunger is made of rubber and it's very flexible.The paste or adhesive doesn't go through because the gap is very very small, and of course when you stop squeezing it goes back to normal. As I mentioned before, this not something I invented! this is actually what the manufacturer recommends as a standard filling procedure so the syringe was obviously designed with this in mind.DanThis manufacturer video explains function of your piston "as air driven dispenser piston" in different way;

author: dmmt40
author_rank: Regular Contributor
timestamp: June 05, 2016, 05:25:20 pm
content: No no no, you're confusedyou linked to a flexible piston, which you're right is meant to be used with compressed air systems, but that's not the one I'm using!I use the standard white pistons:When you buy a case of these they actually come with a little booklet with filling instructions, let me show you:I quote:QuoteSo there you go, I'm not doing anything out of the ordinary with these syringes, we've used them at work for nearly two years now and never had a problem filling them like this.By the way guys, I've already set up the Tindie store, I'm just waiting for it to get approved, I'll link to it once it's online.

author: mike_58
author_rank: Regular Contributor
timestamp: June 06, 2016, 01:52:05 am
content: OK - noted