“...I prefer a real pistol grip...” - I agree that a real pistol grip would be slicker. Are you suggesting just a pistol grip or a pistol grip with trigger? I don’t think I could use a pistol trigger unless I were using an electric or pneumatically-actuated valve (very short travel). If I use a pistol grip without a pistol trigger, how would I mount the brake lever?
“...a bike handle is much better than a PVC pipe!” - Actually, what I have modeled for the handle is
PVC pipe. Technically, it’s rigid CPVC tube for drinking water, which has the appropriate OD for a bike brake lever. I am trying to keep this as light as possible. I’ll swap it out with aluminum if it doesn’t work.
Other parts of the handle assembly shown in the wire-frame view below include a “Sit-on-Top” strut washer, a 1/4”-20 weld nut, two 25-degree spacers, a long 1/4”-20 cap screw, a 7/8” OD washer, a wedge lock washer, and a rubber handle grip. Items not yet modeled include the bolts, 0.02” shims, and nuts I intend to use to attach the handle assembly to the strut channel.
“Like Ben, I too am rather skeptical about the choice of a plastic ball valve...” - You guys are probably right; so, I replaced the plastic valve with a compact brass one in my model. I was unfairly comparing a 5/8”-port plastic valve to standard-port and full-port metal valves. I didn’t realize 5/8”-port 3/4” NPT metal valves existed, but Specialty Manufacturing does make them.
“How long is the blaster and how much will it weight empty and full?” - Including the laminator and 2” sweeper nozzle, the blaster is 36.5” long. So, it’s more than 2” shorter than the original Monster XL, but about 1.5” longer than the 2002 Monster XL.
If someone wanted to make this concept shorter, they could cut the PC cover and find a smaller reservoir (or use a backpack reservoir). If someone felt my laminator/nozzle setup was excessive, they could have nothing more than a 3/4” NPT drilled cap (or 3D printed nozzle) protruding from the 4” PC cover end cap. This would still allow them to jam in straws sandwiched between two screens.
At the moment, my model weighs 8.27 pounds. That’s about 1.27 pounds lighter than the Monster XL’s dry weight, but I don’t have the pump and other miscellaneous items in there yet. I don’t know how accurate this weight is. For example, the brass valve I downloaded from Specialty Mfg is one solid piece; I assigned it the SG of brass, but the ball and seats are not actually brass. The Travel Agent is not solid in real life like I have it modeled, and I don’t have to use a brake lever as heavy as the one I downloaded.
A full reservoir would add 8.82 pounds of water. I’m thinking a full pressure chamber will not hold more than 1.33 liters, which would be 2.93 pounds. With the large reservoir, it may not be necessary to “fill-pump-fill” in every situation if you are worried about weight.
“Perhaps you should test the forces created and needed beforehand...” - Absolutely; this is a MUST. The valve is the first thing I need to buy & test before buying anything else. There is one on ebay right now; perhaps I should scoop it up.
“...pen and paper still works wonders.” - With my hand-drawing skills, this is pretty much how the concept looks...
“How are you planning to do the reservoir-to-PC connection? - As Ben suggested, I’ll connect it to the other end of the bladder using flexible tubing (I have the unconnected tubing adapter in the model). I’ll probably use self-retracting tubing like McMaster part number 9148T165. I’ll breach the PC cover at the end cap that abuts the reservoir. From there, I’ll use regular flexible tubing to connect to a tee or wye that leads to the reservoir and pump. I have not modeled the tee/wye or check valves yet.
“I recommend having the tubing and pump be as wide as possible” - Both volume and pressure are important. If the diameter is too small, it will take forever to fill the chamber. If the diameter is too large, you cannot build as much pressure. I would like to make a convertible pump (somewhat like this pump
). So, initially, you would pump with the inner and outer pistons. When pumping gets too difficult, you would pump only with the inner (smaller diameter) piston.
“My mountain bike has this fancy ‘short reach’ brake lever.” - A shorter-travel lever would not work in this application because the valve requires a long travel to open fully.