Evan's WIP Thread

Discussion in 'Gun Building, Modifications & Repairs' started by Evan J Johnston, Jul 21, 2020.

  1. Evan J Johnston

    Evan J Johnston Member

    74
    33
    Libertyville
    Howdy fellas. I've recently successfully completed my first repair, which you can read up on if you wish. I posted quite thoroughly about it in my very first thread.
    Since then, I have been picked up by a team, made quite a few friends at the local fields, and bought 2 new RIFs. I'm about to have a lot of work ahead of me :)
     
  2. Evan J Johnston

    Evan J Johnston Member

    74
    33
    Libertyville
    Starting off the thread, I have a CYMA Platinum M4 QBS w/ 8.5" M-Lok. These RIFs come standard with 13:1 CNC steel gears, full steel piston teeth, double O-ring CH, and a microswitch MOSFET trigger unit, along with some other decent internal goodies. No O-ring on the nozzle, but according to Guges Mk3, that could be nearly or entirely negligible. I believe the more important factor here is fitment to CH tube.
    I already cracked it open for general sorting of common Chinese airsoft manufacturing gremlins. Nasty, thick blue grease with metal and plastic filings all over the place, ZERO airseal, rough surfaces and edges, and an incredibly dirty inner barrel. You can see I'd already wiped some grease off the bevel before I took pictures.
    Edit: I just want to note as I've gotten several inquires on this RIF. I do think these CYMA platinums have many great things about them, but I think they should have gone for a plastic body and kept the price closer to $200USD.
    20200721_222832.jpg
    20200711_100059.jpg 20200711_100055.jpg 20200711_100106.jpg 20200711_023402.jpg
     
    Last edited: Aug 30, 2020
    JHat, link0 and Chow like this.

  3. Evan J Johnston

    Evan J Johnston Member

    74
    33
    Libertyville
    The insulation on the power wire near where the motor inserts was already clipped a bit by the motor. This could be my doing. Doesn't look like any strands of wire got severed. The cutoff lever doesn't appear to accomplish any mechanical work. I can't tell if there's a sensor for it or not. I also just thought of this as I'm typing right now: perhaps the selector plate interacts with the PCB in some way to tell it what to do. And this is where I believe I'm having problems.
    After disassembling EVERYTHING and cleaning the whole thing out, shimming, heat stretching the piston O-ring to create some semblance of an airseal, and downgrading to a Lonex M100 spring (I think stock was m110 or m120), I was having overspin issues. Every 3rd or 4th trigger pull in semi was producing a burst fire of 2-3 shots. I do have some thoughts on how to deal with this, but any other suggestions would be appreciated. I'm using a 7.4V 2500mAh unknown C rating Valken Energy Li-Ion swapped to deans. It lists a peak current output of 35A. And I don't know if this is relevant to the situation but wouldn't that be 259 Watts peak output? I'm going to school for mechanical engineering so forgive me lol.
    20200721_232455.jpg
    I haven't tried my 11.1 yet for obvious reasons. It's also Li-Ion 2500mAh Valken listing "35A Peak" swapped to deans. 388.5 Watts peak output per my simple mind.
    20200721_232652.jpg
    Additionally, after chrono-ing at home and being satisfied that I could potentially get away with using it or otherwise use my avalon, I went to chrono at the field and it was ONLY firing in bursts. Testing it again just now, it rarely fires a single shot. Usually a 4 round burst. That's some pretty preposterous overspin. I suppose this could be due to the spring settling as it was a brand new spring and possibly sitting compressed for some extended period of time.
    Luckily, it has a true quick change spring system. Clocked myself at 2 minutes 15 seconds and I wasn't really trying to go fast, just filming for my buddies.
    Here's a pic from after I finished sorting all the manufacturer blasphemy. These gears are really something. Very similar to SHS CNC steel gears, if not identical.
    20200717_020918.jpg
     
    Last edited: Jul 22, 2020
  4. Evan J Johnston

    Evan J Johnston Member

    74
    33
    Libertyville
    I'm looking for 1.1 joules on this thing, ~350FPS on .20g BB. I am almost exactly on point with that right now, but I will chrono again shortly to see if anything changed. I was having issues with the piston O-ring returning to original size. I attempted to stretch it 3 separate times, the final time, I quickly threw it in the fridge while still wrapped around the cylinder in hopes this might set the shape more permanently. I used a heat gun and was very careful not to melt it, so perhaps not enough heat? Regardless, my options I'm aware of for reducing overspin without changing gears:
    • AB MOSFET
    This one is pretty obvious but I'd like to spend as little money as possible on this fix. It's also just a shame to have gotten a RIF that came stock with a microswitch just to replace it right away. I would at least want to wait for the switch to fail first before buying something expensive to replace it.​
    • Heavier Piston
    The more I think about it, the more this seems to be the most feasible option, but has obvious downsides.​
    • High Torque Motor
    I remember reading somewhere that a high torque motor speeds up and slows down much quicker than a high speed motor, and so can prevent overspin. If this were significant enough, this would be a perfect solution for me as this gun will most likely never be used on full auto. All of my local venues are semi-auto only except for one does full-auto fridays and another has a specific arena where they allow full auto presumably because it is larger. I'm not versed on the technical specs of motors yet. Working on that this week. Understanding these characteristics and then knowing the exact specs on the stock motor could help guide me to something more suitable. It seems similar to the motor in my VFC Avalon mk18 which isn't especially torquey. I think it has neo magnets, but nothing crazy strong. I have no idea of the TPA or RPM.​
    • Stronger Spring
    I feel this is pretty much not an option. It is my understanding that to make this work at the proper muzzle velocity I would either have to ruin my airseal, undervolume, use .20g BBs, or some combination of these. Perhaps the accuracy loss could be negligible for indoor CQB play, which is the intended use for this gun, but I'd also like it to be competitive outdoors as well.​
    • Weaker battery
    I'm a little uncertain about this option as I feel my current battery isn't all that powerful. Voltage is voltage, Amperage is Amperage, no? A li-po vs li-ion shouldn't make a difference. For comparison, a 1000mAh 30C li-po is 30A continuous output. If it was 7.4V, that would be 222 Watts continuous. Isn't that pretty moderate? Is my current 7.4 @ 35A PEAK really too much for this setup?​
    • Convert to mechanical switch
    This is undesirable but I would take this over a stiffer spring or taking the dremel to anything. I imagine using a COL in its traditional fashion would reduce overspin significantly, but to be sure I supposed I must figure out how the current system determines when to cut power and how long power is supplied per trigger pull.​
    • Short stroke sector gear
    This I saw recommended somewhere which I cannot recall, but it is a little vague to me as to how this would be effective. I Imagine reducing the weight on the sector gear could help it slow down quicker, but I feel like there's another component to this potential solution that might negate the aforementioned effect.​

    I think for that final solution, and just in general, I need to study the cut-off/fire selection mechanism in this gun first to truly understand how to go about this most effectively. There is a chance I just end up with a new MOSFET trigger system.
     
    Last edited: Jul 22, 2020
  5. Evan J Johnston

    Evan J Johnston Member

    74
    33
    Libertyville
    I know I'm always super long-winded. I like to get all my thoughts out on paper before I go to work. I'm more or less using the forum as my own personal log. After I do a bit of research, observation, and testing, I will come back and edit these posts to be more concise.
    Anyone that reads all of this before I make major edits: bless your curious mind and may the odds forever be in your favor.
     
    Last edited: Aug 27, 2020
  6. aotsukisho

    aotsukisho Active Member

    425
    245
    This is usually a fix no matter how bad the overspin is. Active braking is also destructive to your motor brushes/comms, will consume more battery on each shot, and heat up the battery/motor/wires more.

    However, as your gearbox already has its own ETU, you will need to replace the entire thing. You do not want to be piggybacking MOSFET controllers.

    This will do little to help overspin, as the problem is occurring when the sector and piston are disconnected.

    I use >=16t motors for this reason, the more winds a motor armature has the stronger the magnetic field and thus stronger the torque and braking effects are. This is the first thing I would try, get a 22t neo motor and see what happens.

    I have a yet-unfinished article about motors if you are interested, there are no photos yet but most of the theory is there.
    https://docs.google.com/document/d/1nLFCnwCfKcBs6AK8YB4Ax2R0kTGSdlkhRb8BFN5XZzI/edit?usp=sharing

    This is a more feasible option than heavier piston. You do not want to compromise your airseal, you will probably want to short stroke your sector gear first as a method to both reduce FPS and increase the time window that the sector is free-wheeling and can be stopped without compressing the spring.

    I've skirmished with both a stock ARP9 (3/4 cylinder, 125mm barrel, overvolumed) and an AEG with the ARP9 gearbox (3/4 cylinder, 455mm barrel, undervolumed) and had no noticeable loss of accuracy.

    Not a good idea, and I dislike the 'voltage is voltage' argument because it is an oversimplified view. It completely ignores factors like internal resistance, heat dissipation, age-based degradation, and the like. You can measure your open-circuit battery voltage being the same between cells, but under load the voltage will sag differently.

    Easiest way to size your battery is to measure current draw using a battery that has no problems delivering far more power than is actually necessary. Gate mentions that they test the Warfet using a car battery, that battery's CCA is essentially its ampere burst rating. An inline ammeter is very useful, and while it may not be fast enough on the readings to capture true peak current draw and minimum voltage it will quickly and painlessly give you a ballpark figure to work off of.

    You do not want to limit your battery as a way of controlling other parameters.

    I'm not familiar with how your specific microswitch trigger unit works, but usually those have a switch on both the trigger and the cutoff lever. Changing an electronic cutoff sensor to a mechanical cutoff with additional points of failure is not something I would do.

    Grinding off teeth on the sector gear will reduce the distance the piston is pulled back, thus reducing the force applied by the spring. It will also increase the time window between piston release and pickup, thus giving the geartrain more time to slow down before the sector reengages.

    It is a destructive modification, but it's the route I would go if you are still overspinning after changing motor and do not want to get an ETU with active braking. You need to grind off the pickup-side teeth as to not alter tappet plate timing.
     
    JHat and Evan J Johnston like this.
  7. Evan J Johnston

    Evan J Johnston Member

    74
    33
    Libertyville
    All done with class for 2 weeks!
    Got a ZCI High Torque motor 22TPA. The armature has a little vertical play to it. I think I've seen worse in some YouTube videos, though. The stock motor has zero play in the armature, though.
    Anyway, So I'm just really not liking a lot of the stuff going on with this gearbox. Some of the bearing bushing fit way too loose, literally just dropping out of their slots, the inside of the shell is pretty rough with casting marks, and the microswitch mosfet is just weird.
    It seems that it uses the gearbox shell as part of the circuit or just ground, but perhaps the metal plate on the selector plate acts as a switching mechanism. That doesn't explain the presence of the cut-off lever, though. There appears to be some sort of a sensor for the COL, but trying to play around with it produced unreliable results. Not only that, but eventually the mosfet just started getting super hot in one particular spot with just the battery plugged in. No motor, switch off. A couple times it was firing the motor on its own, but didn't do it consistently and I continued fiddling with it. None of the other components got concerningly hot, just the one spot on the mosfet. Motor got warm of course but it wasn't alarming by any means. To me this seems as though the ETU is the problem. Sad to see given how great this RIF seems on paper.
     
    Last edited: Aug 27, 2020
  8. aotsukisho

    aotsukisho Active Member

    425
    245
    If it bothers you, you can bend the endbell tabs to remove the armature and add shims although if you don't pop the pinion you can only do so behind the armature which may push the winds out of alignment with the magnets, depending on which side needs shimming

    Bushings should always be glued in anyway with JB Weld or something similar.

    I am also unsure of operation just by looking at that photo of the PCB, if it does not work properly with the gearbox closed then I would suggest getting a replacement ETU or retrofitting in a normal trigger assembly with external MOSFET, if possible.

    Shorts are usually not caused by touching the PCB and getting it oily, that usually manifests itself down the line long-term by becoming a place where corrosion starts...but any commercial PCB worth its salt has corrosion resistance in terms of epoxy coating or gold plated contacts. That being said, I have seen corroding gold plated contacts on cheaply made electronics so you might want to clean the pcb with alcohol if you think you left oil etc on it.

    Electronics malfunctions are normally caused by shorts caused by uninsulated contact points touching the gearbox shell and connecting two parts in the circuit that should not be. Another common malfunction type is when a component, normally SMD (surface mounted) is knocked off mechanically while being manipulated, usually visible by seeing a component outline and solder pads with evidence of soldering on it but nothing between them. The hardest to spot common malfunction is caused by cold or cracked solder joints, where the solder is not making good contact with the component it's supposed to be connected to. During operation, the PCB can be flexed slightly or components poked gently with an insulated object (chopstick, etc) and if circuit behavior changes consistently then you might have a bad joint. Difficult to do with optical type sensors as those are blinded/confused by ambient light when the gearbox is open, but might be something worth trying.

    Regarding the localized heating, make sure that there was no switches or sensors being tripped or partially engaged. Hot for humans and hot for components are on a different scale - plenty of MOSFET semiconductors are within parameter even beyond 50°C where human skin starts to burn at around 45°C. However, heating up when no input to the circuit is being made usually means poor design or component failure. An ammeter will help diagnosing shorts, as the battery will be draining more than a few mA which is normal idle consumption by a computerized MOSFET unit.
     
    Evan J Johnston likes this.
  9. Evan J Johnston

    Evan J Johnston Member

    74
    33
    Libertyville
    I know very little about electronics but here are some pictures of the mosfet and its components with comments about my concerns, etc.
    evan0.jpg
    Suspected a potential fault with the board shorting on the COL. This is the position it sits when in full auto.
    evan7.jpg
    Here you can see what i thought was hot glue caught between the capacitor (yeah?). Turns out its grease. Pretty sticky, though. don't think this was my doing but who knows.
    evan8.jpg evan2.jpg evan1.jpg
    Here are some photos of a component apparently labeled D12 (diode?) with the COL in place as it would be positioned when in Semi-auto. I was suspecting this to be a COL sensor. I know of "LED" so I assumed this could be an optical sensor. In the first two here you can also see a conductor material around the hole where the board mounts with a single uninsulated screw to the GB just as a standard trigger switch would be.
    evan9.jpg
    Back of the board. You can see the "auxiliary" board is just mounted into a slot on the "main" board. Correct me if there are better terms to use here or if I'm just totally wrong lol. Some identification number is shown. Let me know if you need further clarification on the text. Also note, the screw holding the microswitch to the board pokes through and does in fact make contact with the gearbox shell.
    evan5.jpg evan6.jpg
    Photos of the "auxiliary" board
    A. evan3.jpg B. evan4.jpg
    Overview of the board (A) plus close-up on the status LEDs (B). One glows red (B left) and one glows yellow (B right). Further testing and research needed to discern their functions.
     
    Last edited: Aug 27, 2020
    Chow likes this.
  10. aotsukisho

    aotsukisho Active Member

    425
    245
    upload_2020-8-10_15-10-17.png
    D12 looks to be a SMD 3010 or 1608 90-degree photodiode or LED, both emitter and receptor are available in that package. What I'm guessing is D10 on the opposite side might be a SMD 3215 or 1608 photodiode. If D12 is an LED and D10 is a photodiode/sensor IC then that would explain how it manages to sense the COL.

    upload_2020-8-10_15-34-56.png
    This is a poor quality solder joint, the surface finish is rough and as you can see there's a pit where the capacitor lead was when the soldering was done. The capacitor body was hung off the edge of the pcb when the leads were soldered, then bent into the current position after the solder was cool. Insufficient heat or surface prep treatment/flux usage means the solder can't 'wet' the metal and adhere to it properly.

    upload_2020-8-10_15-45-38.png
    This is also worrisome, I think most of this pcb was soldered manually which makes QC extremely difficult. I'd be surprised if both of those LEDs in the middle work properly with how poor the joint is.
     
    Evan J Johnston likes this.
  11. aotsukisho

    aotsukisho Active Member

    425
    245
    Whoops my post took too long to put together lol

    Possibility, although you'd have to mount the ETU and COL in the gearbox to test continuity.

    Yes it is likely an optical sensor. The conductor material you're talking about are test pads for QA testing, the ETU is mounted in a jig and power is applied, voltage is measured on those pads to ensure they are within parameter and the ETU 'works'

    Not far off with terminology, formally the primary board is called the 'motherboard' and all auxiliary ones attached are 'daughterboard(s)'. The silkscreened text is likely coded manufacture-related information (factory line, date, batch, hardware revision, etc).

    The screw going through the pcb and trigger switch likely does not cause any kind of electrical problem. It looks like it threads into the switch body and acts as a mechanical brace when it pokes into the hole in the pcb.
     
    Evan J Johnston likes this.
  12. Evan J Johnston

    Evan J Johnston Member

    74
    33
    Libertyville
    So, the CYMA is going on the backburner for a bit. I SS'd 2 teeth and I didn't first count the teeth. The sector only had 12 teeth for the piston to start, so now it has 10. Note that the piston had a full rack. Probably could have eliminated PME concerns just by removing piston teeth. It seems obvious now that the overspin issue was a result of a bad ETU. Learning to run thorough checks on absolutely every aspect of a gearbox, etc. before doing anything.
    I figure I might as well use this as an opportunity to do my first DSG build since this will be my indoor gun anyway so large compression volume is not needed. Won't be using any heavier than .25g BBs. This will be a pretty moderate DSG build for semi only. Just looking for efficiency all around. Quick cycle time, pre-cocking preferred but not important, proper matching of gearing to motor. Any threads out there to explain this in depth? The stock ratio is 13:1. @aotsukisho I read your google article on motors. Thank you for that. Is there any more you might add to the "Armature" section? I'm not interested in fully rebuilding a motor (yet) so armature turns and the wire used are my biggest concerns in a motor at the moment unless you think there's something else that would be an easy change to fit my application.
    For a DSG I don't think I can consider the stock ETU to be reliable even if cleaning it up and resoldering some of the components might get it working without overheating, but I will still do this to have as a spare unit. Off the top of my head I'm considering a gate warfet for precocking or an ASCU gen 5. At this rate, I figure AB will be fine since I would likely shred through COLs and I'm convinced the stock motor is actually decent. Still have the ZCI High Torque if it dies early. Let me know if anyone knows of any other budget MOSFET options easily available to the US.
    My largest concern will be compression:barrel volume as I believe this has a 270mm probably 6.05 or 6.08 diameter barrel. Definitely going to invest in some decent bore gauges at some point. Might just get a new outer barrel and start cutting stuff up.
     
    Last edited: Aug 28, 2020
    Chow likes this.
  13. Calidoo

    Calidoo Member

    58
    15
    Elko
    Wow man, came across this thread and gotta say its pretty cool. So I take it your not in love with cymas platinum series? And also how many guns have you worked on? Assuming your a somewhat new tech, are you sure your ready for a dsg build? After my 5th custom build i was confident that i was totally ready for a dsg, and while it worked.....I had many frustrated times lol. Though Seeing that your learning pretty fast makes my think that your capable. For saying a couple months ago that you did your first repair and got into teching id say your quite a knowledge sponge. Though I'm sure being into mechanical engineering helps a bit, as it did with me
     
  14. Evan J Johnston

    Evan J Johnston Member

    74
    33
    Libertyville
    Thank you!
    It's pretty decent except for the fit and finish of the receivers. The paint is fine but anodizing has a more realistic feel to it. The receiver material is likely zinc alloy (pot metal) instead of the beloved aluminum alloy used in some higher end M4s like VFC and Maple Armouries. There are others but I don't know exactly which. The CYMA's rail is anodized aluminum though, and feels spectacular in the hand. The main drawback appears to be the trigger unit MOSFET. As aotsukisho pointed out, the quality of the soldering is just terrible and it seems like a very rushed component.
    Everything else is pretty great for a tech though and it seems like that's exactly the demographic this gun should be geared towards. True quick change spring can be done in 2 minutes. I believe I timed myself on removal and reinstallation at like 2 minutes 16 seconds and I wasn't really even trying to go fast with it. The motor seems pretty decent although I don't know the specs on it. Definitely neo magnets, though. Piston head and cylinder head are mushroom shaped to absorb impact and eliminate some noise. Piston head also has a rubber padding to it. I don't recommend full metal tooth pistons as there is a lot that can go wrong there without proper shimming and maintenance to prevent jams and damage to the teeth. For a standard AEG, 5-7 metal teeth on the release end is still overkill, but since this one has 13:1 gears and only 12 teeth on the sector, 5-7 would have been perfect for reliability and saved weight compared to the full metal rack and would help prevent premature engagement.
    Overall I'd say the retail price for these guns is too high given the immediate problems they have with the ETU. In my opinion, this thing would be perfect if it instead came with a polymer body, traditional trigger switch, and standard MOSFET and everything else as-is and drop the price closer to $200. I recently ordered a Maple Armouries Marauder which retails at $180USD. 13:1 gears, ZCI high torque motor, many other ZCI internals, and a basic Jefftron MOSFET. Very promising if you ask me. This is more or less what the CYMA Platinums should be competing with IMO.
    I will do a review on the RIF as soon as I get it. There is a caveat to the Maple RIFs, though. Maple Airsoft Supplies is a small company in Canada possibly run by just one dude. He is so over-stacked with orders. I pre-ordered mine in early July or late June, his latest shipment supposedly came in around mid-to-late July. He printed the shipping labels for my order and my buddy's order (both Marauders) on August 12th and they still haven't been received by UPS. My hopes are that his business will continue to grow and shakes up the market a bit. Also note, all the prices on the MAS website are listed in CAD. Last I checked there was only one internal review of the Maple Blackout which is the aluminum body version. It's all the same internally except it has like one extra ZCI upgrade part.. Want to say it's compression/airseal related. Needless to say I will be posting a review as soon as it comes in. This will likely be my first YouTube video posted under my Midwest Tech alias.
    I'm also on Instagram as @Midwest.Tech if you're interested in following me. Its much easier to make quick summary posts on IG. Also good for attracting business. At the moment, I do not charge for my work as I don't believe I've had enough experience yet to justify that, but I am confident in the work that I do. Diagnoses on the more illusive issues are the things that I don't think I can really learn without just cracking stuff open and making observations. So in my book, doing work for free is the right way to get that experience quickly.
     
  15. Evan J Johnston

    Evan J Johnston Member

    74
    33
    Libertyville
    I've fixed up my VFC Avalon MK18, two other VFC Avalons, one containing a Gate Titan that was having airseal issues due to burs on the tappet plate digging into the gearbox shell. Pretty interesting to see and felt good to catch that and make it a quick, free fix. It also needed shimming as the retailer that did the Titan install did not re-shim and the sector was contacting the titan. Very upsetting to see that given the price he paid. The other was 100% standard but had a cracked body. Fixed with JB weld and sanded flush. Body was still a bit warped though so I couldn't get it back to original shape without fear of more cracking. Did my best though and I felt it came out quite well. Sanded flush so it won't be noticeable if he does a paint job. Also did a clean and re-grease on that one. He painted the lower without taking out the GB though so there was paint in the grease. I've cleaned and re-greased every gun that's come in. Idk if that's a standard thing for a tech to do whether accepting payment or not, but kind of a necessity IMO. I like to start fresh. I've been messing with the CYMA and I'm confident it would have worked fine if not for the ETU. I might have messed something up there but all I did was clean, shim, and re-grease. I did find grease on the ETU that was not the standard blue CYMA smurf goo. Perhaps that was the issue.
    Regardless, I need the experience of building a DSG and this seems like a perfect opportunity. At the moment, I also have a teammate's ARES Amoeba on my desk that he got used and had low muzzle energy, non-functional on 7.4V battery, but works on 11.1V. Found a component on the ETU had been broken open. There was a screw missing from the ETU that I found caught at the back of the spring guide and chewed up the back of the piston a good bit. Seems the gun was opened up before by some inattentive individual. I also have his Dytac AK in for a health check/cleaning/regreasing. He decided he wanted to add a MOSFET so we're awaiting parts on that. It's actually quite a piece. Most of the internals appear to be from CYMA. 8mm bearings, ported PH. Decent stuff, I recommend them. Not as good as an E&L from what I've seen, though. I convinced him he should get a MOSFET for it, though since he only has 11.1V batteries and a basic MOSFET is cheaper than a battery. I also have another teammate's Classic Army MK18 that is not getting electrical power. I suspect the ETU is dead. Its another microswitch MOSFET unit. I'm actually about to open that up right now since the other 2 are awaiting parts. Also have a teammate's Echo 1 M4 awaiting shipment of Polarstar Kythera. Another teammate has several old AEGs that are weak or non-functioning. A G36, a JG Bar-10, a UMP, and possibly a few others that will come to me soon. That's gonna be a fun couple weeks. One of my first airsoft guns when I was a kid was an Echo 1 g36, so I'm considering buying his if its JG or Echo 1. I got rid of all my old stuff when I graduated from High School. Another teammate has a UMP that I haven't gotten any details on but I am certainly hoping to get that on my desk. What version GB is in those?
    I suppose I should start a tech log separate from this personal WIP thread. I've worked with MAXX Model hop units as well as the Prowin in my CYMA. Flathopped standard packing with Modify Ryosoku flat nub in that one. I like to use maple leaf super macaron's otherwise, especially in the MAXX units. Still haven't dialed in the proper nub for those, though. I was planning on picking up some ML Omega nubs as I figure they would work better than a standard nub and hopefully not require any modification. Maple leaf has so many great options now that it seems pretty unnecessary to do custom flathops and r-hops anymore. Haven't done an r-hop yet, though, so I suppose I should do that to further my experience and understanding.
    No, lol. But I have been doing my research and I'm confident in my overall technical understanding that I think I can get it right without too many failures. To my understanding, tappet plate needs to be cut down to allow for quick return and piston needs swiss cheese to prevent PME, although the aluminum PH is also a concern here. I think I'm gonna go for a seigetek 9t DSG. Is there a target piston weight you know of that should be good for 13:1 9t? Obviously spring is a major factor as well but I'm not too concerned about this as that seems relatively straight forward. Start strong (m170?) and cut coils to reach target muzzle energy (1.1j). Then of course proper shimming which I think I've got dialed in now. I am concerned about having bearings over solid bushings, though. Guessing I should replace those for a DSG even if its a moderate DSG build. I'm not keen on sorbo pads, though, but many people claim this to be a necessity for a DSG build. Would like to save as much air volume as possible. Are there 10 tooth DSG options?
    I've definitely had my nose in the books so to speak. I spent a good 3 months or more watching and re-watching Negative Airsoft's YouTube videos and watching and reading other V2 gearbox guides and related stuff before opening my Avalon. Common issues, internal reviews, etc. Negative has a lot of tech work under his belt on so many different platforms. Guides by TheAirsoftTech on YouTube aren't bad, either, but I definitely have some disagreements with some of the stuff he's done, but most of his tutorials are 3-5 years old and I'm sure he's learned a lot since then. I watched sureshotmidget14 on YT as well. He's honestly a turd of a human in my eyes but he does have a good bit of experience building DSGs.
    I've also had a lot of different jobs and hobbies that helped a lot to further my general mechanical understanding and I think I've always been pretty mechanically inclined. Worked on my 2004 Subaru WRX A LOT and having gone through so much trouble with rusty bolts and suspension and whatnot really contributed to my confidence and appreciation for working on airsoft guns. Its just physically easier. By a long shot. Also worked in a machine shop for a bit so that gave me some understanding of different materials (both plastics and metals) and how they are made and what needs to be done in order for a machined product to be suitable for use. Stuff like deburring and I got to use a grinding wheel a lot. Stuff I always wanted to do but the tools are expensive. It is all these things that actually got me to realize that I should just go back to school so I've been clearing up some grades at my local community college and plan to transfer this Spring. UW-Milwaukee engineering program seems pretty solid and I'm excited to meet people with similar interests and continue learning. Calculus kicked my *** in the past, but I'm in it for the long haul. Taking it again at the moment. Luckily, I have the first couple chapters down pat at this point:rolleyes:, but I do need to brush up on my algebra.
    Thanks for checking out my thread and sorry for the massive wall of text. Short explanations are not my strong suit :)
     
    Last edited: Aug 28, 2020
  16. Calidoo

    Calidoo Member

    58
    15
    Elko
    I just spent the last 20 min writing a reply and my phone died
     
    Evan J Johnston likes this.
  17. Evan J Johnston

    Evan J Johnston Member

    74
    33
    Libertyville
    technology be like that sometimes XD
     
  18. Beetlebz

    Beetlebz Well-Known Member

    1,964
    34
    New Milford
    Those micro switch triggers in general seem to be more trouble than they're worth. Never owned one. Are they made to a standard or is the fitment of each one proprietary?
     
  19. aotsukisho

    aotsukisho Active Member

    425
    245
    I don't think you're supposed to use standard nubs with ML due to the extended contact patch, I would use ML nubs for that reason

    Unless you are able to measure and maintain a higher at-rest spring preload force using a cut heavier spring than a full lighter spring (difficult to plan around due to unclear spring constant ratings not to mention multistage spring designs) I would avoid doing this. DSGs with their half-length compression stroke rely more on spring preload for piston return speed. Siegetek makes a metal spring spacer for this very reason, and I believe SHS makes heavy plastic ones.

    I just use bushings as they are just less of a failure point, but others have used high quality bearings with no problems. As for 10 tooth DSG options, there aren't any as I believe Riot said that a 9t DSGs the tappet return window is small and requires extra timing care. I extrapolate that to mean that 10t is probably not feasible especially at 10:1 4s type build speeds

    I like Ryan's videos and how he explains things but I do agree that some of his techniques are well-intended but come from fundamentally flawed understanding of an obscure concept, and sometimes explain theory of a mechanical component but not in-depth enough to start troubleshooting when things go wrong. His latest vid on helical gears is a great example:

    Helical-cut gears have several advantages, the ones applicable to airsoft are the fact that they can transmit power more smoothly and quieter due to the teeth engaging gradually rather than abruptly like flat face gears (ie. most if not all automotive transmissions are helical gears for forward speeds and straight cut gears for reverse). They also tend to last longer compared to flat cut gears of similar material hardness, due to gradual engagement and ideally spreading load over multiple teeth rather than fully on each flat tooth.

    There is no discussion on the detriments of helical gears, including but not limited to axial thrust force (angled teeth will push gears up/down under load - better to use bushings), lower mechanical efficiency (larger sliding surface, requires proper lubrication maintenance), and the fact that it negatively affects battery life and ROF due to the mechanical efficiency particularly if you use those sets with helical pinion/bevel mating surface as well.

    But I digress, overall his videos are very informative and helpful. I watch some of the older ASTkilo vids but that's mostly for help with old guns I work on.

    This helps a lot, especially with 'fixing' products with bad QC. I've hand-milled a lot of stuff in my early years using dremel bits chucked up in a drill press. Power tools are probably more affordable than you realize, for me it was more of an issue finding space to dedicate to having them. There is always the issue of drill presses not being designed for lateral load that milling puts on the rotating assembly, but a $150 drill press is not going to last forever by any stretch and I'm sure you can find replacement bearings/chucks to keep it going should you wish

    Best of luck for your educational endeavors. I initially declared an engineering major as well but later changed due to how cutthroat and impersonal the program was and enjoyed computer science at a different school much better. I can sympathize with the math difficulties as I had my share of beatings as well, I actually finished all EE math dept prereqs (up to Calc IV) before transferring and found that CS only requires Calc II and Linear Alg lol

    F

    Microswitch is an umbrella term, so they are naturally made to a different standard and the gearbox is often designed around one specific form factor. ETUs may use very tiny microswitches that are soldered to a PCB with varying amounts of mechanical support, like the G&G G2 ETU or Evan's own CYMA ETU (photos in the second post in the thread). Others use larger more robust switches that look to be commonly based on the Cherry Miniature E Series like my LCT PKP gearbox or an older Ares G36K I'm working on. They do introduce the need to debounce signals when used with active braking type MOSFET controllers but when used in a low-current application then they can surpass a million actuations before failure. Genuine Cherry switches are rated at 6 million operations at full rated electrical load (up to 25A). However, they are not user-serviceable so if you have a traditional setup and the contacts are pitted due to inductive arcing, the switch will have to be replaced rather than resurfaced.

    Something interesting is that due to different spec switches in the same form factor, you can swap in switches with different plunger operating force and point - how 'heavy' the switch spring is, and how far you have to push before it switches - to affect how the AEG trigger 'break' feels. Not something able to be done easily with a simple knife switch. This concept is straight from keyboard enthusiasts, with the whole Cherry MX color preferences - choosing actuation force and type of switching feedback to suit personal preference.
     
    Evan J Johnston likes this.