Angled Hopup "pad": replacement for nub

[Reckless]

I like both designs

I'm definately up for getting my hands on some once they become available

[Azathoth]

I have a suggestion. Instead of CNC'ing something that small. Why not make the process easier by making the entire arm of the hopup unit?

You will have far more space to work with some designs.

What would be excellent is a system where their is another spring or tensional device on the hopup arm that allows the arm to shift slightly as the BB passes past it like a fly wheel). Then that way the dial on the hopup unit that we can adjust backspin via spring stiffness on the hopup arm AND the dial we have on the hopup units that we use traditionally.

Are you on Airsoftmechanics?

[krap101]

I considered making an entire hopup arm, but that would restrict me to only one kind of hopup, whereas nubs are basically universal. Once I figure this stuff out, I may try that, but the m4 hopup arm is quite weird, and I'm not that great at replicating real parts yet. (It's easier to just make something new). Right now, I'm constrained by the window cut into the barrel, because that is quite small, and I want this to be a drop in upgrade, so cutting the barrel isn't an option :P

And yes, I also have a thread on ASM.

[Azathoth]

I'm going to move my posting to the ASM thread (same subject line?). But I still strong believe that working on the hopup arm is a better path to go for the reasons I stated

[krap101]

Once I test my "dropin", I'll work on getting some of the more common hopup arms, and design around them. This will be more stable, and will be more consistent, but developing the entire arm will take awhile, and I might as well test out the theory first.

[ScooterVauto]

If you need more testers feel free to pm me, I have a TM VSR it shoots a constant
470 FPS (its my Laylax Poster child )
I have a DMR platform at a constant 380 as well
Good luck on your project.

[krap101]

Originally Posted by ScooterVauto

If you need more testers feel free to pm me, I have a TM VSR it shoots a constant
470 FPS (its my Laylax Poster child )
I have a DMR platform at a constant 380 as well
Good luck on your project.

Currently I'm going to leave testing up to a few of my friends here at UofI. Once I leave the "alpha" testing phase, I'll try to mail some out to get tested. Right now it's in the proof of concept phase, where I'm trying to get some opinions from the community. Currently I have a few designs coming up. The first one is the angled plate, next is flat plate, third is an angled-coned concave, and finally, I'm considering doing something with nylon brushes to replace the bucking altogether.

[ScooterVauto]

Thinking outside the Preverbial "hopup box"
well done, This is how cool stuff enters the universe

I do agree with Azaoth, Once you have your design, I would also reccommend doing complete hopup arms.
M4/ak/mp5 etc.
then also brand names so for eg.
I would be looking for a Modify version for my DMR m4 and a SystemA version for my other M4
then again for my AKs etc..

I hope to see your product on shelf soon.
Be well
SV

[krap101]

Azathoth had an idea of adding "flywheels", so I added rollers, and I think this will work quite well. I think this is what he wanted.


I think if I am to add bearings to this design, it would increase cost by quite a bit (relatively), but I suppose it would be good for slippage>>consistency.

Added two more "rollers". I think this would work very well, but I'm concerned with the little empty areas between the rollers. This could be either solved by using many tiny rollers or design some sort of belt system... but this is seemingly increasing too quickly in complexity for me :P. I suppose people would want the rollers to be made out of delrin :P
[img width=850 height=419]http://farm6.static.flickr.com/5185/5688473843_26f2e39b30_b.jpg[/img]

Added a belt. I expect rubber bands should work


Yeah, after seeing the ptw hopup, I would need to get rid of the bucking for this to work correctly. Looks like I'm going to have to test the concave vs flat plate designs now.


Edit:

I'm hoping to have "alpha" and "beta" testing done by the end of the summer, and will try sending a few out for testing. Depending on performance (compared to stock and SCS/PCS) I'm expecting the price to be around $5ish for the flat/angled plate and $10ish for the concave nub (concave nub will take 2-3x longer to cut). I'll design a second set that will fit into the vsr-10/bar-10 series SR's and we'll decide from there what to do next.

[coach]

Alright, I wasn't really going to post but I think you're going a little too far with possible 'practical' and usable designs. The nubs are so small that the thought of flywheels, rollers and belts in my hopup system, screams at me one more thing to fail.

I mean no offense and props for the efforts and ideas. I just don't see these designs as being a reliable upgrade from things like the SCS. The whole idea of slowly introducing spin seems a bit absurd. The fraction of time that it spends under the nub it so small that I honestly can't see it making a noticeable or reliable difference. Please do try to prove me wrong. I'll be the first to say you told me so.

[MadMax]

One inventor to another: I get the feeling that this democratic design process is going to find out that reality and public opinion are not going to meet.

Few if any airsofters are hop up designers who have tried their ideas out in materials so our input (mine included) is going to have limited if any bearing on what will actually work. I have some limited experience in prototyping in elastomers, but that's about it. I've never cast a hop up and compared it to other designs so it's pretty hard to provide any learned opinion on your CAD models efficacy in apply spin.

Making and comparing design revisions in a test gun is going to yield far more practical input on your design. I find that in early product design I apply the axiom: "get physical fast". It is very easy to fall in love with early design concepts that seem so perfect as a thought experiment. Once you make something in materials the impact of some of the simplifications you made in your thought experiences becomes more clear and you'll smack yourself upside the head: "What was I thinking?!". Iteration in materials gives understanding far faster than coffee table discussion with those who have never worked in the materials you plan to.

As a comment on your component designs outside of backspin considerations, it does appear that you are designing rubber parts with features that may be too small to practically mould. I find when I CAD small features that it is helpful to pull out a pair of calipers and look at the size of the features that you are modeling. SolidWorks is a great modeling program, but the ability to look at something at a huge scale on a big 24" screen can make impractically small features look feasible. Other features like undercuts can be difficult to demould from your tooling. You may have to post cure parts for quite some time for them to have sufficient strength to be demoulded if you have many small or thin features which wrap around tooling. I think that mould release agent may help with this, but I find that they often get slightly adsorbed into the surface of cast rubber parts. While this ok with many applications, your product quite necessarily needs to apply friction to a pellet. A thin film of demoulding compound adsorbed into your part surface could be problematic.

I also note that some of your designs include thin sections that terminate in a sharp edge. This can present a manufacturing problem where you can't consistently exclude bubbles. Thin sharp terminations can trap bubbles which results in bad parts. Venting and injection points are going to have to be placed to assure flow across these stagnation areas. These tooling features will result in stubs which will have to be cut off.

[krap101]

Originally Posted by MadMax

One inventor to another: I get the feeling that this democratic design process is going to find out that reality and public opinion are not going to meet.

Few if any airsofters are hop up designers who have tried their ideas out in materials so our input (mine included) is going to have limited if any bearing on what will actually work. I have some limited experience in prototyping in elastomers, but that's about it. I've never cast a hop up and compared it to other designs so it's pretty hard to provide any learned opinion on your CAD models efficacy in apply spin.

Making and comparing design revisions in a test gun is going to yield far more practical input on your design. I find that in early product design I apply the axiom: "get physical fast". It is very easy to fall in love with early design concepts that seem so perfect as a thought experiment. Once you make something in materials the impact of some of the simplifications you made in your thought experiences becomes more clear and you'll smack yourself upside the head: "What was I thinking?!". Iteration in materials gives understanding far faster than coffee table discussion with those who have never worked in the materials you plan to.

As a comment on your component designs outside of backspin considerations, it does appear that you are designing rubber parts with features that may be too small to practically mould. I find when I CAD small features that it is helpful to pull out a pair of calipers and look at the size of the features that you are modeling. SolidWorks is a great modeling program, but the ability to look at something at a huge scale on a big 24" screen can make impractically small features look feasible. Other features like undercuts can be difficult to demould from your tooling. You may have to post cure parts for quite some time for them to have sufficient strength to be demoulded if you have many small or thin features which wrap around tooling. I think that mould release agent may help with this, but I find that they often get slightly adsorbed into the surface of cast rubber parts. While this ok with many applications, your product quite necessarily needs to apply friction to a pellet. A thin film of demoulding compound adsorbed into your part surface could be problematic.

I also note that some of your designs include thin sections that terminate in a sharp edge. This can present a manufacturing problem where you can't consistently exclude bubbles. Thin sharp terminations can trap bubbles which results in bad parts. Venting and injection points are going to have to be placed to assure flow across these stagnation areas. These tooling features will result in stubs which will have to be cut off.

I'm having trouble keeping straight what I post where, so forgive me if I forgot to post it here.

The plan currently is to use a cnc to machine the parts out of polycarbonate. I will be mostly using square end endmills, but for the concave portion of the second design, (the extended concave) I'll be using a ball-end endmill. The diameter of the bit will either be a 1/32 or a 3/64, and I do understand how small this will be. I cut two parts out that I cad'd very quickly, and the walls of the nub were extremely thin.

I agree I won't be able to tell much until I start making physical parts, but as I have 4 finals next week, I won't be able to spend much more time/effort making them for another week or so. What I can do is try to iron out as many of the problems as possible, and having a couple hundred of people do it with me can't hurt.

@coachster,

I kept all the pictures in there so the progression of the design could be seen, and I assumed you skimmed the thread (I would have) and went straight to the pictures. I scrapped the flywheel/roller idea around 2 days, ago, as it would have to replace the bucking.

The idea about slowly introducing spin stems off the idea of rolling. In dynamics, if the object is rolling, the point of contact is at rest, otherwise it is slipping. By introducing spin more slowly, we can more consistently add the same amount of spin. I believe slip against the nub is around the fourth largest cause of inconsistency (along with bb quality, compression and sidespin). This is why the g-hop has excelled in accuracy, along with the ptw hopup.

[krap101]

Anyways, today I made my first nubs. I'll take apart my hopup tonight and see if it fits. I know that most people wanted the extended concave nub, but I decided that the natural progression was to go from the extruded (where each 2d cross-section is identical) and become more complex. A few problems I encountered were that since the nubs are so small, on the final pass, the nub gets "kicked" off the tape, and leaves a little ledge, but changing the feed rate made this better, and I believe getting a stronger tape and using a smaller bit (a 1/32 rather than a 3/64) should solve this issue.

Sorry for the crappy pics... all I have right now is my phone, and the lighting isn't the best. The one on the top angles downward, and the one on the bottom slopes downward and becomes flat.


I am thinking of starting alpha trials. If I were to do something like one angled nub and one flat nub for 5$ shipped, would anybody be interested? Otherwise, I'll do testing "internally" (with a few of my friends) and sell them for 5 a piece + shipping. I decided it would be better to get these two nubs out first then work on the concave nub later, as I can use things I learn now for the concave nub, but that wouldn't work the other way around. Tell me what you guys think

flat nub



angled nub



My roommate had a camera. The one on the left is the angled nub and on the right is the flat nub. On the angled nub, I plan to use a smaller bit and then make the left part a bit thicker. I'm working on getting rid of that downward sloped part on the angled nub, and I believe it will be solved when I use a smaller bit and changing the design a little bit.

[krap101]

I think, aside from the flaw in the angled nubs, that I will keep the design more or less the same for here on out (until I begin the concave nub of course). I'm adding a 1/32" thick 30A duro pad of neoprene underneath the nub to increase contact area. When the neoprene compresses, it will increase contact area, and also reduce wear on the bucking. I wasn't able to go out today to test the nub without the pad, so I will start sending out test nubs this week once I get the pads done. The pack will include 4, angled with/without the pad, and flat with/without the pad. I'll try and have them tape the performance I can decide what to do next.

Thanks guys!

[Skladfin]

i wanna try this