Automatic glue / solder paste dispenser  - Page 1
Forum section: electronics / general

author: dimbmw
author_rank: Regular Contributor
timestamp: January 06, 2017, 09:59:05 am
content: HiI would like to have an automatic glue dispenser to be able to accurately and automatically dispense glue when assembling certain things (display glasses, housing covers, etc) - smith likehttp://www.torchsmt.com/Automatic-dispenser-TD3310-pd28192.htmlBut the price quoted for the above td3310 dispenser seems too high (around $5000).I am wondering if there are cheaper alternatives on the market?Given that the CNC routers (like model 3040 for example) - are so cheap on eBay - can be had for around $600 shipped , being in my opinion the same thing almost but with a dremmel instead of the dispenser.Maybe it is easy to DIY ? Does mach3 software support dispensing? Maybe one can just buy a 3040 kit and a solder paste/glue dispenser for under $100 (like thishttp://www.ebay.com/itm/AUTO-GLUE-DISPENSER-SOLDER-PASTE-983A-DIGITAL-DISPLAYLIQUID-CONTROLLER-DROPPER-/181999281731?hash=item2a6000a643:g:GOIAAOSw9mFWKKrY) and mach3 will do the job?Thanks!

author: ar__systems
author_rank: Frequent Contributor
timestamp: January 06, 2017, 12:54:41 pm
content: Forgetaboutit.solder paste dispencers are useless pretty much anyway you look at them. I was thinking about them a year ago. In the end they just don't make any sense at all.First of all they can only do large dots. anything below 0603 pads is a problem. (Unless you are talking about 20K$ machine). Second, they are super slow. May be 10 times slower than a manual printer. And then maintenance. You need clean, fill the paste, I imagine it is not fun.Just get a paste printer. Stencil can be had from China for 25 bucks!

author: Kean
author_rank: Unknown
timestamp: January 06, 2017, 01:57:52 pm
content: OP wasn't talking about solder paste dispensing, but glue dispensing.@dimdmw I think this can be made to work pretty much as you describe. I'd suggest using g-code commands to turn on and off the coolant enable (M8/M9) with a short dwell (G4) between. Should work with Mach3 or grbl.

author: dimbmw
author_rank: Regular Contributor
timestamp: January 06, 2017, 05:45:54 pm
content: Quote from: ar__systems on January 06, 2017, 12:54:41 pmWow - solder paste dispensing was my second hidden agenda as well, you were really reading my mindBut I really need to dispense some glue as wellBy the way, can you give the links to quality and fast $20 China stencils please ? I think I pay a little more.

author: dimbmw
author_rank: Regular Contributor
timestamp: January 06, 2017, 05:49:28 pm
content: Quote from: Kean on January 06, 2017, 01:57:52 pmDo you know if anyone already had DIY-ed it ? I've noticed that when I come up with something and I think it is unique, most of the time it turned out that it has been already done by someone, and there is a wiki about it, and step-by step instructions how to do it

author: cowana
author_rank: Frequent Contributor
timestamp: January 06, 2017, 05:57:45 pm
content: Quote from: ar__systems on January 06, 2017, 12:54:41 pmI'm surprised to read that opinion - I've been using one of the cheap ebay units for years, and rate it very highly!Probably the main thing to state is that I use it for one-off PCBs where a stencil would double the cost of the project - I fully agree that a stencil is vastly faster, and much more suited to any form of production.I haven't had any issues with dot size - I typically use a largish needle for large parts (0603 and up), then switch to a much finer needle for the smaller passives and QFNs/QFPs.I don't bother transferring paste between syringes - I just keep a small stock syringe in the fridge, and when I want to use it, snap on the air-adaptor, discard the first few mm of paste (which may be slightly dry), then attach the needle and get going. When I'm done, the needle goes in the bin, the syringe gets capped at both ends, and goes back in the fridge.

author: ar__systems
author_rank: Frequent Contributor
timestamp: January 06, 2017, 06:18:57 pm
content: Well I was talking about automated paste dispencers, not manual.Elecrow.com makes stencil very cheap.

author: dimbmw
author_rank: Regular Contributor
timestamp: January 06, 2017, 06:28:41 pm
content: Quote from: cowana on January 06, 2017, 05:57:45 pmCould you suggest the model of your cheap ebay unit? Thanks

author: cowana
author_rank: Frequent Contributor
timestamp: January 06, 2017, 10:24:11 pm
content: I've got a DS-982A. They're all pretty similar though - all that's in the box is a timer circuit and solenoid, triggered by a foot pedal.If you wanted to control one via Mach3, that would be a pretty simple job using a relay (or solid state equivalent).

author: packetbob
author_rank: Contributor
timestamp: January 06, 2017, 11:09:50 pm
content: I also have a cheap AliExpress type dispenser that I use for solder paste and echo COWANA's sentiments. I find it great for small one off (or a few) projects where a stencil work be more work to set up.I keep the solder in a syringe and change the needle size as required..Small dots are an issue , letting the paste warm up and using a decent brand of paste seem to help...If you are interested I have an Instructable (shameless plug) on how I setup and use mine:http://www.instructables.com/id/How-to-set-up-repair-adjust-and-use-a-solder-paste/Quote from: cowana on January 06, 2017, 05:57:45 pm

author: dimbmw
author_rank: Regular Contributor
timestamp: January 07, 2017, 12:07:25 am
content: Quote from: cowana on January 06, 2017, 10:24:11 pmI am not familiar with the mach3 yet, is it easy to generate a 3D - path for the nozzle? Can I just export the path from, say, solidworks ?Pedal gives one portion on every click - that is not exactly what I am looking for when it comes to glue - I'd prefer come constant flow when the nozzle travels along the path.

author: Kean
author_rank: Unknown
timestamp: January 07, 2017, 11:59:21 am
content: Quote from: dimbmw on January 07, 2017, 12:07:25 amI have an ebay dispenser I bought probably 8 years ago for around AU$200, and it has served me well for glue and solder paste dispensing. I would have spend many times that initial outlay on syringes and needles, let alone glue and paste. I have had to repair it a couple of times due to split air hoses (internal). My experiences with solder paste dispensing are much like cowana & packetbob, although I make slip on caps for the needles using polymorph plastic. For small in-house runs or PCBs with fine pitch devices (especially 0402s) I will often get a cheap unframed stencil (e.g. from Seeed or PCBway).Regarding control via g-code, it really wouldn't be that hard if you have any programming experience. Basically just a sequence of command to move to an XY coordinate at a specific speed then activate the output signal. Unless you have really complex paths, you might be better off doing the manually, and just getting measurements from Solidworks. I think you'd need SolidCAM to generate g-code.You can configure most dispenser models to either dispense a single shot of a fixed time, or continuous while the "pedal" is actuated. So using either delays, or movements, interleaved with the coolant enable/disable commands would work. You can then tweak the movement speeds or air pressure to more accurately adjust flow.I'd actually suggest looking at using grbl if you have any experience with Arduino. I've helped build several dispensing and testing robots using grbl on an Arduino Mega for 6-axis motion control, and either another Arduino or a Windows app sending the g-code sequences.

author: dimbmw
author_rank: Regular Contributor
timestamp: January 07, 2017, 08:44:20 pm
content: Quote from: Kean on January 07, 2017, 11:59:21 amHi, thanks, I looked at grbl and liked it. Seems pretty easy and cheap to implement (and fun to play with!).Have a couple of questions, if you don't mind:1) It seems though that grbl it only supports 3 steppers. I need 4 as I want to also rotate the item that I want to dispense the glue on.On the other hand I see some kits with 4 drivers available, for example:http://blog.protoneer.co.nz/arduino-cnc-shield/I did not dig deep into it just yet, but I assume the 4th stepper can be added somehow?How did you do 6 axes? What version of the CNC Shield would you recommend?2)Is there any G codes to activate some digital outputs (to switch the dispenser on and off, for example) ? You said i need to use coolant enable/disable for that?3) Is there any limit switches support?4) Is there a (free?) software that can converts the movement path one creates in the software (like for example a 3d- curve in solidworks) into a sequence of G-code to move the dispenser head?Thanks!PS I have programming experience in C and Asm for micro controllers (even though it was long ago). Did not touch arduino yet, but don't think I will have any issues with it.

author: packetbob
author_rank: Contributor
timestamp: January 07, 2017, 09:32:34 pm
content: Some thoughts on issues you may experience usign the pneumatic syringe with a CNC system (but naturally my advice is totally based on never having tried it)The delivery of the paste via the pulse of air tends to vary a bit based on several variables including:Temperature of pasteAmount of paste in the syringeType of pasteI find that I am adjusting the air pulse width on my machine while using it to get the optimal dot size. Not really any issue when doing it manually but perhaps not optimal for a CNC type system. It's not really precise.You may want to use a motor driven design that may give you more accurate and repeatable delivery as it is based on the positive displacement of a mechanical plunger rather than the somewhat more intangible pulse of air..Ymmv.....

author: Kean
author_rank: Unknown
timestamp: January 08, 2017, 05:42:00 am
content: Quote from: dimbmw on January 07, 2017, 08:44:20 pmI believe the protoneer 4th axis is a slave axis - i.e. it runs in parallel with one of the other axes. For example some machines will have dual steppers on the X axis. Alternatively it can be jumpered to used the spindle output pins for an A-axis, but this isn't supported as standard so would need some hacking.On an Arduino Mega you have many extra pins available, so it isn't hard to hack the code to add more axes. I've got a hacked 6-axis version of grbl 0.9 that you can look at (shouldn't be hard to re-apply to grbl-Mega 1.1)https://github.com/electrokean/grbl/tree/6-AXISMost of the stepper shields do not make use of the optimised pin allocation used by grbl to get high performance (up to 30kHz) so I have generally built my own shields, especially for the 6-axis Mega (most mega shields are for Marlin which uses completely different, and sub-optimal, pinouts).QuoteYou could use the spindle enable or coolant enable outputs to drive a relay (through a transistor) to trigger the dispenser, or possibly even just an optoisolator. Recent grbl can also do PWM output for spindle speed control. On the Mega you could also hack in additional features if needed, but the Arduino Uno is pretty maxed out in terms of I/O and program memory.QuoteYes, standard grbl supports 3 limit inputs (X/Y/Z), and you can handle more on a Mega.QuoteIf you want to do it in Solidworks, I have no idea. If you can afford Solidworks, then generally you pay for something like SolidCAM.There are plenty of free or open programs that can generate 2.5D g-code, like Inkscape, but more complex 3D paths usually involve paid software. You could potentially export in STEP or STL format into a free program. I'd suggest looking at Fusion 360 also (not free, but low cost).QuoteIf you have some programming background, then most of this is relatively easy. Heaps of help just a google search away. For some similar projects that I've worked on, I was basically an advisor helping the people who did the final implementation. They had very little programming experience, being from other engineering disciplines, but once the basic framework was implemented they just tweaked the timing and paths.Just don't underestimate the time you'll need to get up to speed and get it working reliably. As packetbob mentions, you may need to adjust your dispensing method if you can't get reproducible results due to external factors like temperature. I've found viscosity of solder paste is much more variable than glue, and that really affects dispensing.

author: dimbmw
author_rank: Regular Contributor
timestamp: January 08, 2017, 06:23:25 am
content: Quote from: Kean on January 08, 2017, 05:42:00 amKean, thank you so much for the detailed info, your directions are very helpful. I am ordering a CNC kit now and some other stuff to get started.For the dispenser, I liked this ideahttps://www.tindie.com/products/DanM/dm-dispenser-for-solder-pastes-and-adhesives/By the way, do you know a cheap way to convert a gerber file into a text file with the X,Y coordinates of the centers of SMD pins and their area?Dmitry

author: Kean
author_rank: Unknown
timestamp: January 08, 2017, 07:47:50 am
content: No worries. Yeah, that dispenser actually looks like it could be better than the compressed air ones for your application, but I probably wouldn't want to use it handheld.I've got this one, but haven't yet used it enough for a comparison. It didn't work out of the box though (faulty).https://www.kickstarter.com/projects/3dfacture/fixer-a-professional-3d-print-finish-repair-and-glI've also backed for this one, but it hasn't shipped yet. I do like the feature set, but concerned it may be a bit bulky.https://www.kickstarter.com/projects/2129383335/i-extruder-smart-solder-paste-and-fluids-dispenserFor the gerber files, I don't know if you could do anything automatically without the original design files. I'm pretty sure Eagle can be scripted to generate a coord data file from design files. If you have gerbers of the stencils, they would be better than the copper layers. You could also load the gerbers into various CAD programs (e.g. Altium or CamBam off the top of my head) and manually note the coordinates. I've used CamBam to process gerber and NC drill files like this for aligning things when making test jigs.

author: dimbmw
author_rank: Regular Contributor
timestamp: January 08, 2017, 08:10:09 am
content: Quote from: Kean on January 08, 2017, 07:47:50 amKean, one idea that crossed my mind is this - in the original PCB design files to substitute the components footprints with their alternatives - all through hole - same but remove holes, all SMT - change to the same but add holes in the middle of the pads with the drill bit size proportional to the area of the pad (at least roughly). Then just to forget the Gerber and generate a Echelon drill file. I assume drill file is easier to parse, as it is a text file with just coordinates and a drill bit diameter. Then just dispense the solder paste at these coordinates, with the volume dispensed in proportion to the set drill bit diameters. Not sure if that is easy to implement, but there are not too many footprints on the board - maybe a dozen? So if there is an easy way to substitute the footprints in a completed PCB in some PCB layout software (for example by copying a set of "modified" footprint files over existing ones - then why not? What do you think?PS Both kickstarter design you've mentioned seem to use a stepper do dispense the paste - it proves that it is a good idea!

author: Kean
author_rank: Unknown
timestamp: January 08, 2017, 08:14:55 am
content: Could work, but sounds a bit messy. What PCB CAD are you using?

author: dimbmw
author_rank: Regular Contributor
timestamp: January 08, 2017, 09:09:05 am
content: Quote from: Kean on January 08, 2017, 08:14:55 amPADS...

author: Kean
author_rank: Unknown
timestamp: January 08, 2017, 09:31:09 am
content: Quote from: dimbmw on January 08, 2017, 09:09:05 amI'm so sorry!Just kidding, I have no experience with it.

author: dimbmw
author_rank: Regular Contributor
timestamp: January 08, 2017, 09:37:55 am
content: Quote from: Kean on January 08, 2017, 09:31:09 amActually me neitherI am not the one who designs PCBs, some outsourced guy doesPS just asked him, he said it is easy