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PostPosted: Tue Dec 12, 2017 11:10 pm 
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Location: Coalmont BC
Today I tackled the job I hate the most, but possibly the most satisfying if it turns out well.... I turned the stub and rear face of the tank block.... The piece I started with was a 1-1/4 x 3-1/2" piece of 6061-T6 rectangular bar stock.... I roughed out the stub material with my power hacksaw (finished with a hand saw) and then cut a piece 2-3/4" long, ending up with an "L" shaped piece of aluminum.... The small part of the "L" is for the round stub that inserts into the front of the tube, so I had to mount it in the lathe to make that round and the correct diameter, and cut the O-ring groove.... In the same operation, you face the rear surface of the block flat square to the stub.... The trick was mounting it in my lathe....

I have a 4-jaw chuck, with reversible jaws, but with them in the normal orientation one jaw was right out past the chuck face, because the block has to be offset so that the round stub is at one end.... I reversed that jaw, which solved that problem, but then the block has to sit on top of the first ledge on the jaw, and I didn't like the idea of trying to shim the block at the other end, there is incredible load when turning this piece, and it must be very rigidly mounted.... or it could jar loose and come flying out of the lathe, or break something (and maybe me).... I came up with the idea of reversing the opposite jaw as well, so that the block would sit on both of them, but NOT reverse the side jaws, so that they had more clamping area.... it worked perfectly, as you can see below.... Top and bottom jaws reversed, side jaws "normal"....

Image

Before putting the block in the chuck, I laid out and drilled a center hole for the stub, using a 60* center drill.... The by using a 60* center in the tail stock, pressing the block against the two reversed chuck jaws, it was pretty simple to get it centered.... I have never turned such a large, offset block before, and the impact with the tool bit is considerable if you take too big a bite.... so I used the slowest feed rate (0.004") and could only remove 0.005" per pass off the flat surface beside the stub.... I had left the material 1/10" oversize, so that took 20 passes at over 3 min. each.... well over an hour just to machine that flat surface.... Then I had to turn the 1-1/4" square stub that was sticking out to a 1.05" circular one, drill the center air passage (1/8") and cut the O-ring groove.... Between the setup and machining, it took all afternoon, and some of the evening.... I must be the world's ~ s l o w e s t ~ machinist.... ::)

It was pretty nerve-wracking, so I will have a good sleep and tackle the rest of the block tomorrow....

Bob

_________________
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsonal;
Too many! Springers, Pumpers, CO2, but I love my PCPs and developing them!

Life is too short to be wasted worrying about the opinions of others.


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PostPosted: Wed Dec 13, 2017 12:38 am 
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Amazing work Bob! Thanks for sharing! Everything looks superb!

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PostPosted: Thu Dec 14, 2017 1:33 am 
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Location: Coalmont BC
I finished the tank block today.... My 300 bar, 500cc Carbon Fibre tank clears the main tube by just over 1/16" when installed.... Here is the side view, showing the regulator installed....

Image

The notch on the top front is for a barrel band, there are two 6-32 holes drilled and tapped on the front face to attach it.... As you can see, there is a Picatinny rail on the bottom.... The hole there is for the plug for the vertical air passage.... The plug is a low-profile 10-32 SHCS with a # 008 O-ring under the head in the milled 5/16" recess.... There are four 10-32 screws to retain the stub of the tank block in the tube, again drilled at a 45 deg. angle so that the tank block can be removed without removing the barrel.... The stub seals into the tube with a single # 118 O-ring.... The 1/8"-27 NPT tapped hole in the side is for a gauge for the pressure downstream of the regulator.... Below is the rear view....

Image

The method of mounting the regulator is different from common practice.... Instead of using the two (red) O-rings inboard of the threads in a bored hole, the hole in the block is simply drilled deep enough to clear the length of the regulator and tapped 1/2"-14 NPS.... At the top of the hole is a recess milled with a 7/8" end mill to a depth of 0.085" to accept a # 115 O-ring.... This is a snug fit over the regulator, in the groove between the threads and the shoulder on the bonnet, which is 0.900" OD.... When the regulator is tightened into place, that O-ring fits into the groove in the tank block, and seals the regulator outboard of the threads.... This trick, pioneered by Travis, is much easier to machine, and is used on the Flex and Cobra.... Qudos to him and Jim Gaska for coming up with the idea.... The three 5/8" wide grooves milled around the middle of the tank block and the back and sides are only to remove a bit of weight, and pretty it up a bit.... Even so, the block weighs a hefty 8 ozs.... ::)

Bob

_________________
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsonal;
Too many! Springers, Pumpers, CO2, but I love my PCPs and developing them!

Life is too short to be wasted worrying about the opinions of others.


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PostPosted: Thu Dec 21, 2017 7:49 pm 
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A couple of days ago I got a start on one of the valves.... got it roughed out, made some parts for the inside, and then spent a day finishing off the design.... Today I finished the first valve.... Here is the inside roughed out.... The valve is 5/8" ID with a 5/16" throat and a 1/8" stem....

Image

The spring retainer end cap is a vented wheel that fits into a recess in the front of the valve and is retained by an circlip.... The area for the wheel is 3/4" ID.... I made the 3/8" thick and machined out the inside, leaving a 1/8" vented web.... That was my solution to the difficulty of holding a 1/8" thick part for machining....

Image

Here is a front view of the completed valve.... The two long 6-32 screws are the front mounting bolts for the receiver.... They penetrate the valve BEHIND the valve seat, straddling the throat, which allows me to use larger screws than an MRod valve and yet have a larger ID....

Image

The O-ring is located behind the recess for the wheel, where the valve wall is full thickness.... The gauge is tapped directly into the left side of the valve, behind the O-ring, so no need to drag it across a large hole in the tube.... Here is the back view, showing the huge 0.257" port, which is on a 30 deg. angle towards the 5/16" throat for improved flow....

Image

The four valve mounting bolts are 10-32 x 1/4" SHCSs set down with the heads in shear.... They are in staggered pairs, the top and bottom pair in a similar location to an MRod valve, but the ones on the sides are 1/4" further forward.... I had to do that to make sure there was enough tube material for proper strength on the RH screw, which sits ahead of the cocking slot for the hammer.... The slot ends exactly at the back edge of the valve body....

The reason for no photos of the inside is that this valve is my own home-made version of the ART/SS valve.... Since I was privy to the development of it, I was able to design and make my own version.... but out of respect for Travis, I am not divulging the details until he gets his patent in place.... My sincere thanks to Lloyd and Travis for their help while I was making the very intricate guts for these valves.... I made several versions before I managed to get any parts that were even usable, they are, to say the least, challenging.... and well worth their price, IMO....

Bob

_________________
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsonal;
Too many! Springers, Pumpers, CO2, but I love my PCPs and developing them!

Life is too short to be wasted worrying about the opinions of others.


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PostPosted: Fri Dec 22, 2017 10:10 pm 
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Today I drilled all the holes for the valve in the long (unregulated) tube.... Here is the right side....

Image

You can see the cocking slot for the hammer, and now you can see why I moved the side valve mounting holes forward, to give lots of material between it and the front of the slot.... here is the left side....

Image

You can see the large hole for the gauge on the side.... I installed the valve, hammer, SSG assembly and trigger group today and tested everything.... With the hammer set for 1" of travel I still have 0.22" between the front of the hammer and the back of the valve, and about 1/16" between the cocking handle and the front of the slot.... This allows for 0.20" of maximum lift and still have a 0.020" gap for the SSG.... The valves have an internal travel of about 0.24", so with the stem protruding 0.20" the hammer will hit the back of the valve before anything else hits and gets damaged.... I also made the second valve body today....

Image

The one in the foreground is for the shorter regulated tube.... Since there is a gauge downstream of the regulator in the tank block, there is no hole in the side of the valve for a gauge like there is in the valve for the unregulated tube in the back.... The valve in the front is also larger in diameter because the regulated tube is 0.095" wall instead of 0.120" wall....

Bob

_________________
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsonal;
Too many! Springers, Pumpers, CO2, but I love my PCPs and developing them!

Life is too short to be wasted worrying about the opinions of others.


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PostPosted: Fri Dec 22, 2017 11:11 pm 
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Amazing work! Looking forward to seeing how they perform for you!

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PostPosted: Sat Dec 23, 2017 2:22 am 
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Location: Winnipeg, Canada
Hi Bob.

What is your valve material?

I agree- a very interesting project. Am staying tuned :mrgreen:

-D.S.

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-S.R.V.

Guess I've got that old travellin bone,
and I feel I've got to move..."
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PostPosted: Sat Dec 23, 2017 11:36 am 
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Location: Coalmont BC
The valves are made from 2024-T351 aluminum.... it is not only stronger than 6061-T6, it machines more easily, with a superior finish as well.... a case of you get what you pay for.... The tank block (in fact all my rectangular stock) is 6061, many of the sizes I couldn't get in 2024.... Both tubes are 2024-T3 as well....

Bob

_________________
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsonal;
Too many! Springers, Pumpers, CO2, but I love my PCPs and developing them!

Life is too short to be wasted worrying about the opinions of others.


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PostPosted: Sat Dec 23, 2017 10:14 pm 
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Location: Coalmont BC
Last day in the shop before Christmas.... I tidied up all the loose ends.... no photos because there was nothing new, just a second batch of what I have already made.... I built all the internals for my second ART/SS valve (my version), and drilled the holes in the short (regulated) tube to mount the valve.... Other than cut that tube to length (after I get the regulator for my 500 cc CF tank) and drill the 4 holes to retain the tank block, both "lowers" are now pretty much finished.... I am waiting for some 70D O-rings, once they arrive I will be able to assemble and pressure test them.... Oh, I forgot I still have to lap the valve seats and make sure the poppet face is square....

I finalized the design for the receivers today.... The material I bought wasn't tall enough to allow for slope in the scope dovetail, but fortunately I have enough 1 x 1.5" aluminum bar stock for the two receivers.... The scope rail will be angled 20 MOA to put the scope pretty much on optical center with a POA of 100 yards.... These are both single-shot guns, and I wanted to make both receivers identical and yet set one up for 6mm and the other for .257.... I plan to use an "L" shaped insert in the loading area, sized for each caliber, that will bolt into place.... The left hand wall of the receiver will be full height to increase rigidity, the bullet will load from the right, like on my Monocoque.... at least that's the plan at the moment....

I want to wish all my friends here on the Forums all the best for a Merry Christmas and a Happy New Year.... 8)

Bob

_________________
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsonal;
Too many! Springers, Pumpers, CO2, but I love my PCPs and developing them!

Life is too short to be wasted worrying about the opinions of others.


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PostPosted: Sat Dec 23, 2017 10:47 pm 
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Merry Christmas Bob! Thanks again for another great year of sharing your projects!

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PostPosted: Wed Feb 07, 2018 6:41 pm 
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Location: Coalmont BC
I have been cleaning up some leftover projects for the last month while I have been waiting for some 1.2 mm CS O-rings to arrive for the poppet in my version of the ART/SS valve.... They finally got here and I made a new poppet which worked out great.... The smaller O-rings allowed a shallower groove, which I moved further down the poppet towards the seat and now it seals great and seems to function fine, even at 4200 psi.... It is holding air pretty well, losing less than 100 psi per day, which is good enough for now, and often slow leaks like this improve with time, as they are often the poppet on the seat.... Anyways, assuming it is good enough for now, the next order of business is to make the uppers, and then ream the chambers and mount the barrels.... After that I can shoot these guns for the first time, as I cast some bullets last week as well....

I started on the receivers yesterday, cut them to length (actually 1" over) and machined the concave bottom to fit against the tube on both receivers, which will be interchangeable on the lowers.... Today I laid out and center-drilled both ends of the bore for the barrel and bolt, high enough above the top of the tube to allow for the 20 mm OD barrel sleeve, plus 0.20" to allow for the thickness of a piece of 1-1/4" ABS pipe which I will be using for the foregrip on the unregulated .257 cal.... That plastic pipe is 0.150" wall, so it will just nicely clear the Carbon Fibre barrel sleeve.... It will be captured between a recess on the bottom of the receiver and the tube, like I did with the foregrip on the Monocoque.... Anyways, the C/L of the bore is 0.60" above the top of the main tube.... Once the locations were center-drilled, I mounted the receiver between centers on my lathe, and then held the back in my 4-jaw chuck.... Having it sit on a 60 deg. center inside the spindle bore allows easy centering of the jaws, you just tighten them progressively on the four side of the receiver until it is secure.... Using a live center (ie one that spins on a bearing) in the tailstock, I machined a 1" long collar on the front of the receivers (which is why I left them 1" too long).... The collars will ride in my steady-rest to support the receivers on center while I drill them full length....

I first drilled a 1/4" pilot hole from front to back, using a foot long 1/4" drill bit, stopping just before I hit the 60 deg. center in the headstock.... I then used a long 1/2" drill to increase the diameter to the finished size, removed the receiver from the lathe (so the 60 deg. center wasn't in the way, and drilled through the last 1/2" at the back.... The hole was straight and true, and parallel to the top of the tube in both planes, which is what I wanted.... A piece of 1/2" CRS slides perfectly through the receiver, full length, so I know that the bolt and the barrel will be aligned and parallel.... I them mounted the receiver back in the lathe between centers, re-checked the steady-rest position, and then drilled the front of the receiver out to 25/32" to accept the 20 mm CF barrel sleeve.... The sleeve is about 0.004" larger than the drill size, but it just starts into the hole, so all it will need is a bit of sanding to be a perfect slide fit.... Here is what it looks like at the moment.... I only have one drilled at the present time, the other one will be done tomorrow, all going well....

Image

The plan is to cut off the collar, it was only there to allow me to support the front of the receiver in my steady-rest.... I don't need it for support, as the barrel sleeve goes 2.5" into the receiver, which is over 3 diameters.... It will be located by two sets of 3 setscrews at 120 deg. so the assembly should be 100% rigid when complete....

Bob

_________________
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsonal;
Too many! Springers, Pumpers, CO2, but I love my PCPs and developing them!

Life is too short to be wasted worrying about the opinions of others.


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PostPosted: Thu Feb 08, 2018 7:22 pm 
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I drilled the other receiver today, and then drilled and countersunk all the mounting holes and drilled through for the transfer port....

Image

The small recess on the bottom just behind the transfer port is to clear the upper valve mounting screw, which is just proud of the tube.... The receivers, like the tubes, are drilled on the same pattern, so the uppers will be interchangeable on the lowers.... Although I intend to build the .257 on the long, unregulated tube with the thick wall (4200 psi MSWP) and the 6 mm on the regulated bottle version with the short tube (thinner wall with 3200 psi MSWP).... the interchangeability will allow me to test the other way around, and change my mind should I decide to....

Bob

_________________
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsonal;
Too many! Springers, Pumpers, CO2, but I love my PCPs and developing them!

Life is too short to be wasted worrying about the opinions of others.


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PostPosted: Fri Feb 09, 2018 8:05 pm 
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Today I milled out the loading port area in the two receivers.... Instead of milling it straight across, I left the left-hand side of the receiver intact from the boreline over, so that I don't lose so much rigidity.... These guns are single-shot, so no need to cut it away more than that.... I did this on my Monocoque and it works well, but of course you must load the bullet from the right side.... Drilling a 1/2" hole straight through the receiver to assure the alignment of the bolt and barrel means that when you machine the loading port you don't have a tray to guide the bullet into the bore.... so that is made from a separate piece of 1/2" diameter steel.... I drilled one for 6 mm and the other for .257 before milling them to shape.... You can see one of the inserts sitting on top of the receiver in the foreground.... along with a flat-head 4-40 screw which holds it in place.... The back receiver already has one installed....

Image

With the loading tray in place, the right side is level with the centerline of the bore.... and the left side is vertical, tangent to the left side of the bore.... You don't need to look at what you are doing to load, just place the bullet on the right hand lip of the tray, and roll it to the left and close the bolt....

Bob

_________________
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsonal;
Too many! Springers, Pumpers, CO2, but I love my PCPs and developing them!

Life is too short to be wasted worrying about the opinions of others.


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PostPosted: Sun Feb 11, 2018 9:06 pm 
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Location: Coalmont BC
I got lots more done on the receivers today.... This reduced the weight of them quite a bit.... and vastly improves the appearance....

Image

The top and upper edges are now milled down, leaving raised areas where the dovetails for the scope mounts will be.... I also bevelled the top corners as well.... When I machine the dovetails I will be angling them down 20-25 MOA at the front to put the barrel on POA at 100 yards with the scope still optically centered....

Bob

_________________
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsonal;
Too many! Springers, Pumpers, CO2, but I love my PCPs and developing them!

Life is too short to be wasted worrying about the opinions of others.


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PostPosted: Tue Feb 13, 2018 9:32 pm 
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Location: Coalmont BC
I worked on the receivers more today.... I drilled and tapped the six holes for the set-screws that will secure the barrel.... The original plan was for 10-32 screws at 120 deg. to each other.... but I was unable to get them of the proper length here in town, but I was able to get 5 mm x 0.8 mm Metric setscrews that are 10 mm long.... You can enlarge 10-32 threads to M5 by simply running the tap through them, as they are the same pitch (within less than 1%) and the Metric screws are 0.008" larger than the 10-32s.... I dislike mixing SAE and Metric fasteners on a project, but the alternative would have been to wait weeks to get the 10-32s.... I justified it by the fact that the barrels are 14 mm and the CF sleeve is 20 mm OD.... so at least everything to do with the barrels is Metric.... ::)

Image

I had one other little glitch when setting up to drill the lower holes for the setscrews.... In order for the receiver to clear the carriage on my lathe (I was using my milling attachment to drill and tap the holes accurately) I could not drill them 30 deg. below the horizontal, I had to use 35 deg.... This is of no practical importance, but means that the angle from the top to each side screw is 125 deg. and the angle between the bottom screws is 110 deg.... instead of them all being 120 deg....

I also set up and milled the slots for the bolt handle today.... The front receiver is finished, but dinner hit the table before I got the vertical part of the rear slot done.... I'll do that tomorrow before I set up to fly-cut the recess in the front bottom of the receivers to locate the plastic pipe of the forestock....

Bob

_________________
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsonal;
Too many! Springers, Pumpers, CO2, but I love my PCPs and developing them!

Life is too short to be wasted worrying about the opinions of others.


Top
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