Inverted Roller Build

[Grizzlestomp]

Whenever I start a new build based on a design I haven't done before, I overengineer the blank to allow me to get away with narrow dimensions and crazy ideas without worrying about flex or catastrophic failure.

May have gone a little overboard on this one, 17 Teak and Ipe laminates with 16 carbon fiber stringers between each board. Brick shithouse.

[apeogre]

Mother of god!

[sealark]

Make sure if your boat sinks have the gun secured under a gunnel. It could keep the boat afloat.

[Behslayer]

Legendary start

[willstroo]

Woah.. This thing could be epic, almost like using "navy seal grade" marine ply haha!

Look forward to updates!

[spearVibes]

What areas are you concerned with on your inverted roller design?

[Grizzlestomp]

I'm always concerned with the muzzle, depending on how narrow I shape the dimensions.

Also, I plan on starting one band at the top near the muzzle, running it along the stock, around a roller, then down along the bottom to the pulley (like on the new Alemanni guns). I want to be able to inset that band down into the stock and don't know how narrow the stock will be at that point.

[Grizzlestomp]

Going to try to have a play by play breakdown of the build. I noticed there are a ton of these for traditional build, but far fewer for inverted rollers. Hopefully it might be helpful to some people.

First thing I do is rout oversized mech pockets, fill them with epoxy, then rout the correct sized pocket leaving a nice protective epoxy rim.

I do the same with the pin holes. Drill them at 3/8", fill with epoxy, then drill 3/16" holes through the epoxy. This also helps drill them perfectly straight as the drill bit is less likely to wander in wide guns through the uniform consistency epoxy.

I also over-rout the track a little deeper than I need, fill with a graphite and epoxy mix, and then re-rout at the proper height.

For my rollers and inverted rollers, I rout the mech and track deeper than others. That is because I shape the muzzle risers out of the blank. The track has to be deep enough so that a spear and sharkfin could fit in it and the sharkfin tabs are still below the top of the blank.

[Grizzlestomp]

Next I rout the pockets for the rollers. Same as the rest, I rout the oversized pocket, fill with carbon fiber and epoxy, then rout the exact size pocket I need through the epoxy and carbon fiber to ensure a protective rim.

I also cut 1/4" gaps and insert carbon fiber stringers in the muzzle and over the handle with epoxy. the 1/4" carbon fiber works great as a muzzle riser as there is no risk of splintering and wearing down that there would be if a muzzle riser made out of wood was worn away over time by a wishbone at high tension.

For all of this I use the big Festool router with double edge guides. This setup is fantastic. The double edge guides allow for minute adjustments and have no give to make sure you can make repeated cuts in a straight line using both sides of the blank to keep the cuts true. And you can see what's going on as you do it which is a huge advantage over using a router table.

[willstroo]

Wow.. I cannot wait for more updates..

Very jealous of the tool setup as well. With my builds, its all very ad-hoc, with a lot of, "oh woops.. well i guess that goes there now!" haha!

Looks amazing, more more more they cried!

[Grizzlestomp]

Before and after pics of removing the excess material from the blank, leaving the carbon fiber stringers standing proud for the muzzle risers. Can also see from the side pic that the handle will be as high up as possible with the Neptonics tuna trigger mech.

Also, something I like to do but rarely see done is leave extra wood in the stock so that the top of the back of the gun is flush with the top of the trigger mech. I've found that it doesn't affect the sight picture, makes the loading pad a little less bruising where you'd otherwise have only a very narrow pad because of the super high handle, and adds a little bit of variation to the lines of the gun.

[FreediveCA]

This is going to be a beautiful gun. I'm calling that out now. I can't wait to see the progression.

[Grizzlestomp]

I'm going to make the stock super thick near the handle and heavily tapered to the muzzle. I like the idea of adding mass to the gun without reducing the maneuverability.

Unfortunately, this requires a crazily long line release. Which is probably the reason why the vast majority of spearguns have a narrow stock at the handle and then have a beefy midsection.

Making one out of 1/8" thick marine stainless with a hacksaw, grinder, and some hand tools.

Also, finished my custom rollers out of delrin. I like to use all ceramic bearings, which cost a fortune UNLESS you use the size commonly used for skateboards. Unfortunately, this size doesn't fit in the factory rollers, which is why I make my own. Only downside is they are held with an 8mm pin (instead of the usual 6mm pin).

[apeogre]

You've probably looked at it, but what about the same line retention system as the sea sniper? Would a line release that long slow the release of line?

The roller pockets then filled with epoxy is a great idea. I'm looking forward to seeing the final form. It looks bad ass. Will you use a line riser on the muzzle for the wishbones?

[Grizzlestomp]

Yeah, I debated over using the other type of line release, but want to keep the line nice and tidy on one side of the gun to avoid the risk of any tangles. I'm pretty sure I'll be able to design it so that it doesn't slow anything down, just play with the angles until it releases quickly and doesn't get hung up.

The carbon fiber stringers in some of my previous pictures will be shaped into the muzzle risers. I used the same method in my previous gun, and they work really well. Generally speaking, I like to avoid screw in parts as much as possible, although I'm sure they may work as well (or better) in many cases.