[SiliconeSword]

I'm building my own MTW and am currently finished save for buying a handguard, making/buying the outer barrel, and making the hop chamber.

After spending years of my life designing software to create this extremely high tech design, I'd like to share it with y'all and see what you have to say.

All jokes aside, I thought of this last night in the shower and thought it may be good.
The way it works is by having a very smooth and perfectly centered hole above the hop patch, where an SS-nub will sit.
Above the SS-nub would be a bearing ball that is a tight fit in the hole, that could be pressing on a flat or indent in the nub, or even bonded to it.
A little above the ball on the side there would be a screw coming in at a 90° angle to the other hole, which would have a medium diameter high threads per inch screw with a tapered tip.
When screwed inwards, it would use the taper to push the ball and nub downwards, applying hop.

If you have a different design for an M4 style platform that you'd like to share, I'm all ears, and likewise with any improvements or things you would

 

[whalesmash]

My only issue with a single point of contact (especially a round one) between the nub and downward pressure source is the potential for the nub to see-saw back and forth as the BB passes underneath. Depending on how you secure your SS nub, it might not be an issue. As far as using the tapered screw, this method has been done in the OG tippman M4. A TLDR, I wouldn't really recommend it, but if you build it well, it doesn't have any drawbacks. Unfortunately it doesn't exactly do anything better than a normal TDC either, and it's a more complicated method of achieving the same end.

I'm assuming you want this adjustment out of the side so you have access to it without having to break open the rifle?

 

[SiliconeSword]

I will likely remedy this by making the nub taller if I have enough space, but I can make a .0001 or better clearance so there's really no wobble.

Yeah, I'm looking to avoid breaking open or drilling holes in the rifle to preserve it's looks and function, as well as easy use.

 

[whalesmash]

If you have that level of precision, perhaps consider adding vertical channels to the chamber and guide rails of sorts to the nub. At that point, the "sloppiest" area would be the angled contact point between your horizonal screw and vertical pressure pin. The only challenge at that point would just be getting the vertical spacing correct such that there is enough adjustment between hop on/off. I think your approach is fine. At the moment, not much else in terms of alternative designs comes to mind unless you want to scavenge the gearset off of a stock lonex style hop up unit.

 

[Frohst]

I'm assuming from this and your other posts you have access to proper machining tools (lucky).

Design as presented should work, and provided you make your threads nice, shouldn't really back out.
Issues are no definitive restoring force so your hop will take a few shots to 'settle in' whenever you back off the hop.
You won't have much adjustment range but since your making your parts to actual tolerances and not the backside of a barn tolerances most airsoft parts come with, should be fine. I'm assuming your using actual hardened steel threads... And not cast pot metal.

Little things I'd do for quality of life (thumb screw for the drive screw, notching/engraving measurements, etc)

But. Being the SVU user I am... I'd say just look at that hop design and copy.

Nub/carrier is square with guide rails to go up and down. This carrier has a threaded portion in the vertical to a nut on top.
Twisting the nut drives the carrier up/down.
Nut is indexed with a spring & ball bearing to give something like 20 clicks per revolution.

I don't know if you could fit it and be able to turn the nut up top as easily on m4 vs ak esq platforms. But your machining your own stuff so doesn't really matter. Make that top nut a bevel gear or similar to allow you to operate the mechanism from the side.

Sure one design is probably a good 5x as much machine work...

 

[SiliconeSword]

I may do a nub shaped like this in order to keep the bearing ball centered, and keep the nub aligned and unable to twist and get misaligned.

Issue with this is idk if my grandfather or I have a mill bit small enough for this project to do this, as the diameter of the chamber will likely be quite small.

My material choices are brass, 303 stainless, normal steel, leaded steel, Delrin, Nylon, PVC, various aluminums, O1 tool steel, and some sort of weird micarta type thing, but I'll likely use Delrin because it's cheap and easy to machine.
I may do the stainless one, but I'll probably at least do a practice with Delrin to iron out any issues.

I think that the simpler the thing is the better, which can be seen in about every chamber out there since an AA chamber for the VSR-10 with mine, Masada's, or the chap with the CNC arms arms is arguably the best chamber out there, because it's simple.

The SVU chamber definitely looks interesting and may be another good option, but I'd likely need to slide my chamber out of my gun every single time.
Not the biggest issue being an AR style platform, but it'd still be a needless pain in the ass. I could maybe mill a huge flat depending on final dimensions so I could have a small wrench that goes in through the ejection port, but again, I'll have to see what seems better when I have everything together and measured up. Another possibly good choice though.

While I do machine my own stuff, I've got "limited machinery", a South Bend lathe, a huge lathe with low RPM that I hate to use, a factory lathe that was only for one operation and is now a lathe with a 3/4 inch max stock diameter and difficult homemade controls, and a Bridgeport mill that I'm still getting the hang of using. I've got my highly experienced grandfather to help me out, but having machines with limited RPM and only manual controls is definitely limiting in what I can do.