Hacking the Crosman Vigilante



Author Topic: Hacking the Crosman Vigilante  (Read 14085 times - 4 votes) 
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Offline George Schmermund

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Re: Hacking the Crosman Vigilante
« Reply #260 on: November 22, 2017, 10:28:31 PM »
I spent some more time machining the 6 shot clips today and the new reamer is working perfectly. With the new fixturing in the mill the precision of the drilling and reaming has been improved. The improved clip alignment with the forcing cone has now increased the muzzle velocity to run fairly steady between 350 and 375 fps @ ~ 80บ F with rapid cycling. This isn't really great performance in the overall scheme of things, but it's an improvement. I'm going to order some longer barrels from Crosman and see where things get to before hacking the powerplant.

« Last Edit: November 22, 2017, 10:30:04 PM by George Schmermund »
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Offline Rob M

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Re: Hacking the Crosman Vigilante
« Reply #261 on: November 23, 2017, 01:08:12 AM »
looking very nice.. at some point , the barrel length will outweigh the available gas.. But when that is , who knows.. I'm guessing a 14 inch barrel would be a great starting point , and even the 10.3 incher would in theory get  you over 400 fps.
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Offline George Schmermund

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Re: Hacking the Crosman Vigilante
« Reply #262 on: December 06, 2017, 10:53:26 PM »
Now that I've started the Vigilante .22 cal project it's obvious that I'll need to get more gas into the valve section. At the moment it seems reasonable to increase the volume of the valve and to enlarge the transfer ports. It all looks pretty straight forward with some simple machining.

The volume of the valve can be increased about 20% initially by machining some grooves into the inside wall of the valve body. The wall thickness is nominally 0.100" thick. By cutting some grooves into the inner wall and leaving some space between the groves I should be able to leave small sections of full wall thickness that will act as sort of inverse barrel hoops to deal with the pressure.

The photos show the setup to measure the inside wall uniformity and also the wall thickness. I'm using a Starrett back plunger dial indicator arrangement for the lathe measurement. It's virtues are that it's an easy measurement and it can reach further into the valve cylinder than the typical test indicator. It also gives me reliable axial alignment for setting up the grove cutting tool.
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Offline Rob M

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Re: Hacking the Crosman Vigilante
« Reply #263 on: December 06, 2017, 11:11:27 PM »
very nice setup ! looking forward to the gains produced !
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Offline WhatUPSbox?

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Re: Hacking the Crosman Vigilante
« Reply #264 on: December 07, 2017, 02:35:33 AM »
The full thickness section barrel hoops will not help with the axial strength of the valve wall if you thin it too much in the grooves. May be worth running some quick numbers to make sure you have sufficient margin.
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Offline George Schmermund

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Re: Hacking the Crosman Vigilante
« Reply #265 on: December 08, 2017, 04:00:27 PM »
Assuming that the valve casting material is ZAMAK 3 (a safe bet) and using Barlow's Formula, the burst strength of the valve walls when thinned to .035" should be in excess of 3000 PSI near room temp. This would be without any internal hoops. I don't plan on the working pressure getting above 1000 PSI.

The longitudinal forces at 1000 PSI have a safety factor of at least 10 under worst case conditions.
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Offline George Schmermund

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Re: Hacking the Crosman Vigilante
« Reply #266 on: December 10, 2017, 07:42:51 PM »
Up until now I've been using split ball bore gages to measure the effects of muzzle treatments and general small hole dimensions. The down side of these instruments is that they require a transfer measurement to get the numbers. This method will allow for only one static measurement at a time. This makes probing the bore at more than one place slow and tedious. Also, the radius of each 1/2 ball is generally too large to get a measurement down to the bottom of the grooves in the rifling so you're left with only the bore diameter at the lands.

I've just acquired a dial type bore gage that uses a different technique. It's a vintage Federal Products instrument that makes dynamic measurements as you continuously probe around in the private parts of a bore. It will reach in 2 1/2" and reads directly to 0.0001" It can easily be interpolated to 1/2 of a tenth. There are 12 probes that come with the set and each probe has a range of 0.008". The full range on this set is from 0.122" to 0.250". This will cover the barrel bore diameters of interest to me now. The use of setting rings is a big help in setting and calibrating the probes, but a good micrometer can also be used, thought it does make for an awkward measurement.

Besides the dynamic reading capability, I like the radius difference between the larger and longer fixed anvil and the smaller radius of the moving ball anvil. The ball can get down into the bottom of the grooves and the longer fixed anvil can straddle the grooves while staying on the faces of the lands. This allows accurate step height measurements of the rifling.

The photos show the basic arrangement of the instrument.
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Offline George Schmermund

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Re: Hacking the Crosman Vigilante
« Reply #267 on: December 13, 2017, 10:11:49 PM »
The project to expand the volume of the valve by removing material from the ID of the valve body seemed pretty straight forward. The calculations indicate that the remaining wall thickness was safe at typical operating pressures. The problem with the approach of removing material is that I can't put the material back in if need be. After studying the situation through the lens of a few extra beers the solution came to me in the form of another one of my visions.

I'll make an adjustable volume by adding an appendage to the side of the valve body that can be exchanged for different sizes as needed. There's quite a bit of room between the pistol frame halves to accommodate these extra volumes. Starting with a piece of 1/4" 12L14 steel rod, I'll bore out a blind hole to some yet to be determined ID. The open end can then be threaded to 1/4"- 40. The valve wall can be threaded to match. Loctite red can them be used to seal the threads. Using the same threading arrangement will allow the change of appendage volumes without having to do any more machining on the valve body.

The photo shows the basic tooling needed to accomplish the task.

 
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Offline Rob M

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Re: Hacking the Crosman Vigilante
« Reply #268 on: December 13, 2017, 11:10:24 PM »
excellent idea and that will add a lot of volume if needed.. I'm sure just the extra 1/4 rod and the base valve volume should get you into the 400s/.. I don't recall the barrel length as it sits, but if still at 7 inches 10 would be great
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Offline George Schmermund

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Re: Hacking the Crosman Vigilante
« Reply #269 on: December 16, 2017, 10:24:45 PM »
It turns out that I can put 3 of the volume enhancing stubs onto the valve body to increase the flexibility of tuning the powerplant. They can be installed at 90บ to each other and there's plenty of room to make the valve bristle with ports to add pressure gauges or other measurement devices. The pistol frame will still be easy to assemble and disassemble without the constraints of trying to fit everything inside. I'll try using Loctite Blue for starters and see how it holds up. I want to be able to take the threaded joints apart to re-machine the stubs for different measurements. Pressure wise the 12L14 won't be a problem, but this ZAMAK 3 is like machining cheese. We'll see what gives first. Hopefully neither one.

The photos show where things are now.
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Offline Rob M

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Re: Hacking the Crosman Vigilante
« Reply #270 on: December 16, 2017, 11:27:36 PM »
makes sense , good thing you used a super fine pitch
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Offline George Schmermund

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Re: Hacking the Crosman Vigilante
« Reply #271 on: December 17, 2017, 09:54:17 PM »
Now that the .22 cal Vigilante is looking more viable and the valve volume can be increased easily, I wanted to try and seal the breech end of the barrel better than just the clip being pressed against the bare metal. Today's exercise was to see if an o-ring grove could be trepanned into the face of the barrel. I looked into the ready available trepannig tools and they were all dedicated to a narrow width selection and they weren't cheap.

The solution at hand was to mount the Dermel into the tool holder again and use any of the available bits that I had. The selection of these bits out there from many sources makes this rotary tool exceptionally versatile and limited mostly by one's imagination. Anyhow, the test was done on a piece of 12L14 steel and the results were very promising.

The photos show what the method looked like. This is all preliminary, but it looks like an o-ring seal can be easily add to the breech of this .22 upgrade.
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Offline Rob M

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Re: Hacking the Crosman Vigilante
« Reply #272 on: December 17, 2017, 10:29:30 PM »
perfect ! I wonder if this will lead to a measurable gain
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Offline George Schmermund

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Re: Hacking the Crosman Vigilante
« Reply #273 on: December 19, 2017, 10:45:55 PM »
There's no denying that I'm caught up in the world of CO2 as the powerplant for making carbine mods, but the world of PCPs is hard to ignore. They're surely the wave of the future for a large segment of airgunning. I've read quite a bit about various attributes of this newer (?) species and have watched several YouTube videos where the proud owners are extolling their new gun's virtues. It's  inevitable that I'll end up there sometime in the future. For now it seems that time is on my side as I watch the price of entry sliding downhill fairly quickly.

Many of the videos make a point of showing that their PCP gun comes with a pressure gage built in. Realizing that my carbine's lack of a pressure gage is like driving around in a car with whitewall tires, I decided to get my builds into the 21st century by following suit.

Since some of my valves are getting modified with stubs I decided to add a gage and see how it looks. I really enjoy the steampunk trends that are out there now and the Vigilante carbines are headed in that direction.

The photos shows a crude proof of concept, but it works.


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Offline Rob M

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Re: Hacking the Crosman Vigilante
« Reply #274 on: December 19, 2017, 11:15:16 PM »
that looks great..actually opens the door to later HPA experiments.
 
« Last Edit: December 19, 2017, 11:20:36 PM by Rob M »
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Offline George Schmermund

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Re: Hacking the Crosman Vigilante
« Reply #275 on: December 20, 2017, 10:49:13 PM »
Now that the valve section of the Vigilante powerplant can be probed intimately with stubs it will be a good time to install an electronic pressure transducer directly into the valve's volume. Interesting experiments can now be arranged so that the accelerometer on the hammer can be used again to trigger a timed sequence of the valve opening and closing while still another pressure transducer can measure the muzzle pressure/time information. A transducer can also be installed into the side of the barrel just after the forcing cone to look directly at the pressure as the pellet is released from the clip.

I've been buying up some real sleepers on eBay in the micro-transducer realm along with the electronic amplifiers and conditioners needed to interface them to readouts. Several  simultaneous measurements can now be made in real time. The treasure trove of what's available on eBay for doing testing and measurements is truly staggering. It seem that the more exotic and esoteric the instruments are the more cheaply they can be acquired.

I'm now 1 year into this airgun fantasy and never though it could be this rewarding. I'd have probably lost interest by now if those of you following this expedition hadn't been so supportive and patient along the way. I've learned a lot. Thank you all!

Now for another beer!


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Offline WhatUPSbox?

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Re: Hacking the Crosman Vigilante
« Reply #276 on: December 21, 2017, 01:33:24 PM »
George,  I'm looking forward to when you can tie the entire timeline together. Would a photo diode or even just a broken wire at the muzzle establish pellet exit?
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Offline George Schmermund

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Re: Hacking the Crosman Vigilante
« Reply #277 on: December 21, 2017, 11:47:47 PM »
The collection of transducers that have fallen from the sky, with the help of eBay, have greatly enhanced the measurement capability of my test bench. My favorites for pressure are the Endevco 8530B series instruments. These are miniature devices that are threaded for 10 -32 holes and have assorted pressure ranges. A close runner-up is the Kistler 601B series piezoelectric instruments.

For transit time initiation signals there's not much that can compete with the Endevco mini accelerometers like the 2250A Isotron previously described. As far as muzzle exit signals go there are a variety of methods to trigger when a pellet exits. I've found the trip wire method to be tedious and less than reproducible for these measurements. The photo diode is a good method for getting timing signals and has the benefit of being none contact. The short coming of both of these methods is that they only provide an on/off signal. This signal is OK on many levels, but provides no other information.

My choice at the moment for exit timing is still the same as described in earlier posts using a Bruel & Kjaer force transducer. With this type of device set in position at point blank range at the muzzle the signal provides both timing and impulse energy information. This is a two-fer and saves the need for an extra channel to collect data.

This is my thinking at the moment, but it can easily be changed when new capabilities arise.
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Offline George Schmermund

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Re: Hacking the Crosman Vigilante
« Reply #278 on: December 24, 2017, 09:11:23 PM »
The extra valve volume project got some attention today. I read in some Vigilante posts that the disassembly and reassembly of the valve can be a vexing problem. I've improvised a method that simplifies the exercise and reduces the number of required expletives to a minimum. I use tongue and groove pliers with the fixed jaw clamped in a vise. The clamped jaw has some washers of the appropriate size stacked on it to allow the valve stem to extend past the front face of the valve when the spring is compressed. The moveable jaw is used to compress the valve spring with the help of a 22LR case. The primer end of the case has been drilled out so that it can be slipped over the valve stem and protect the the stem and seal while the circle clip is being installed.

Since the clip manipulation is usually a two hand job, The pliers handles can be kept compressed using some rubber bands or an o-ring. The pressure gage and extra volume stub will be installed after reassembly.

The photos show the usual arrangement for executing the "clip ring maneuver".


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Offline Rob M

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Re: Hacking the Crosman Vigilante
« Reply #279 on: December 24, 2017, 09:20:04 PM »
the third hand in the shop that's never there, nice rig
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