1st post - please be gentle with me

[snyper]

Hi Everybody
Brief intro - come from the UK, retired and have lived in very rural Thailand for the last 8 years. Missed my hobbies of clay and air rifle shooting as nothing available here. Fed up with catapults, thought the locals bike pump up air rifles pretty useless so decided to make one! Sources and inspiration from Spudfiles also Bill Gilmour, Swan Donovan and M.Simon on Youtube.

Bought a length of steel tubing - - (6 pounds UK money for 120mm) and some bb's the locals use from the nearest hardware shop. BB's were 5/16" (I also bought a smaller tube and was provided with 1/4" bb's later).
Nothing else is really available here so I have to source via web sites such as Ebay, AliExpress, Lazada and Banggood to name a few - Keeping a close eye on delivery charges and 3 to 6 week shipping times!

Have tried to solve one problem at a time before moving on - Namely :
Best valve to fire the QEV and give a decent trigger feel. 1 first valve (2way 3port) was manual and difficult to get a crisp, fast release without jerking the rifle. (See mark 1 photo). So moved on to AirTac 12volt solenoid release - excellent.
Lousy trial groups! This was using the first barrel - so I bought the smaller sise - 1/4" - and tried again - only using 120psi but pleased with power - slightly better but still bad grouping with a few flyers.
Did some reading up and discovered smooth bores will never be that good but you can improve certain things.
Polished the bore of the 1/4" barrel using a dremel with a long flexy drive and fine wet and dry until mirror finish - tested and a bit better. Realised bb's were a little loose and thought about using patches like the old muzzle loaders. Then - and I dont really remember why but I checked the tube size by using twist drills!!!!!! 1/4" loose - 6.5mm perfect!!!!!!! Checked the 5/16" barrel - loose - 8mm drill perfect!!!!!!!!!!!!
Next problem getting those sizes in Thailand - having to source from China by the kilo - shipping costs 8 times more than the bb's but hey ho!!!! (Having got the correct sizes now the bb's will not run down barrel until you move your finger off the barrel end - they are creating a perfect vacuum which is great!)
Not finished all tests and tweeks but a vast improved

Ok - Current spec as follows:
QEV - Cheap Chinese job 1/4" fittings barrel 3/8"
Air Chamber - alloy moisture trap for pcp hand pump 1/8" thread but drilled out hole. Can easily put in candle wax to reduce volume. (Changing to smaller barrel should mean I can reduce the chamber volume to get more shots).
Barrels - 8mm and 6.5mm with threaded fittings fastened with epoxy. Length 60mm and covered with plastic electric conduit.
AirTac - 2 position 3port 12volt solenoid - with body turned through 180degrees to convert from NC to NO.
3000 MaH nicad rechargeable battery
Trigger Switch - 12volt push button
Air tank - .5 litre airsoft style tank and regulator - rated up to 2,500 psi.
Pistol Grip - piece of hardwood, shaped and laquered
Telescopic sight - Bushnell 3 to 9 X 40.
Rifle action frame (for QEV and Solenoid etc) Scrap metal from roof building!
Silencer - plastic plumbing scrap with cotton wool packing - untested as yet but rifle has a real muzzle bark at the moment!
Various copper fittings and adaptors - see photos.

Air sources - 2,400psi capability stirrup type pcp hand pump.
Small 120psi compressor.

Future developments -
20 bb tubular bolt action magazine - ala M.Simon design on Youtube. (muzzle loading is a pain!)
Making a Airbow barrel and arrows.
Developing some shot shells - again Youtube is great for ideas.

Immediate problems - Because of the pressure limitations of the QEV and Solenoid - I want to keep the pressure down to 200ps. But I would like to pressurise the tank to say 5 to 600 psi to give me more shots before a recharge - I did try one 300psi regulator at about 2000 psi but it blew the gauge to bits and split my solenoid sealls !!!!!!!!!!!!!!!!!!!!! am just limiting my tank to 200psi now! I think there is an adjustable regulator in the US but about 100$ !!!!!!!!!! way too much - any other ideas please?

Still awaiting bipod to delivered and led torch with remote switch for shooting at night.
Total cost estimate under 150 quid - careful buying and watching out for hidden delivery charges!

Photos -
1st one shows the original solenoid with a rubber band to hold it Normally open.
Last photo is the nearly completed tool but without the battery fitted - slides into the rear of the frame above the regul;ator. Also I have a cover and butt stock for the air bottle.
Thanks for wading through it all - hope it was worth it LOL!

[farcticox1]

Looks great

[keks2033]

great job. But I would advise you to make a QEV valve from plumbing, it is not difficult and it withstands great pressure. My piston valve withstands and operates at 100 atm and it is homemade [youtube][/youtube] On the video in the valve 45 atm, it turns out 3 shots

[snyper]

Don't think the limiting factor is the QEV ( have heard of people putting 500psi through that model) - its the pressure the solenoid seals will take - good trigger is paramount - mine using a spring behind the trigger blade is effectively 2 stage now.

[snyper]

Sorry just noticed a typo!!!! I converted the Airtac Solenoid from NC (normally closed) to NO (normally open) by dis-assemblingthe unit and turning the body round by 180 degrees - not turn the piston or end caps etc round. NO keeps the QEV pressurised then and fires via the solenoid which releases the pressure when triggered.

[snyper]

Sorry - noticed a typo!!!!!!!!! Airtac Solenoid comes supplied as NC (normally closed) - you need to swing just the solenoid through 180 degrees to convert to NO (normally open) so it fires the QEV when triggered.

[jackssmirkingrevenge]

Great build! My one immediate criticism would be the support of the main bottle here because a drop from the right height and that connection is going to snap dangerously. That being said you've titled the image as "trial assembly" so I guess it's not finished!

Higher pressure is definitely the way to go for small bores if you want decent power, there is no substitute. Ditch the solenoid and go for manual actuation. One option is to have a hammer valve as a pilot, this fellow on youtube managed to make one cycle full auto and if you search around the forum there are a few semi automatic examples. If you're keen on having an electronic component, you could use a solenoid to actuate a hammer valve as our man wyz had done, here's a similar thread on the forum.

Did some reading up and discovered smooth bores will never be that good but you can improve certain things.

Well they're good enough for some of the best guns on the modern battlefield, the question is having the right kind of projectile!

thought the locals bike pump up air rifles pretty useless so decided to make one!

Shame you're not in the Philippines

[keks2033]

The piston valve is very convenient to work in semi-automatic and automatic mode, I tried both options and they are definitely cheaper and simpler than yours.
[youtube][/youtube] here I tested the valve at 50 atm, it worked well and at 70, only very loudly. [youtube][/youtube] here 17 atm in the balloon
And this is an attempt to make an electric shock.
[youtube][/youtube]

I hope I helped you.

[snyper]

Firstly thank you to Keks 2033 and Jacksmirkingrevenge for constructive input!
I never had any preconceived plan for this project it has been 'plot an bash' and is just gradually evolving.
In the photo of the trial assembly its not actually bolted together LOl! - Have changed a few things and will post a photo when reassembled. The frame is steel at the moment and a bit heavy - in a later version I plan to change to alloy section, lengthen it to support the air bottle as well.
Think I'll have to go to an alloy door and window firm for offcuts! - Big problem here is I don't speak the lingo and only have very limited tools - namely Chinese type Dremel copy, electric drill and angle grinder + cheap hand tools - so this often controls the design
I like the valve idea and think later on I could make one. Would that just trigger the QEV? Would I need to fill the chamber then as Swan Donovan has done?
Short term will just involve getting working ok what I have already done. Want to try to see what levels of accuracy I can now get with the polished barrels and correctly sized bb's.
Had a great result yesterday - some Neodymium magnets turned up from China - 9 weeks delivery!!!!! 12mm x 2mm with an 8mm hole. With a bit of easing fit perfectly into the QEV brass adaptor - see photo. I will put in a small washer with a slightly smaller hole to stop the bb's (8mm and 6.5) dropping into the QEV. Cost 3.8$ for 10 so not broken the bank .
Waiting for some 1/4" 90 degree brass fittings (previous ones crap!) and will then reassemble and post more photos.
ps. Sorry about photo quality - only have cheapo phone LOL!

[jackssmirkingrevenge]

I never had any preconceived plan for this project it has been 'plot an bash' and is just gradually evolving.

Nowt wrong with that

Big problem here is I don't speak the lingo and only have very limited tools - namely Chinese type Dremel copy, electric drill and angle grinder + cheap hand tools - so this often controls the design

If you look through the body of work amassed so far by our Resident Ruski, it's evident that lack of resources can be compensated for with a bit of ingenuity.

One thing to look into is epoxy casting, it's no substitute for proper machining as I would go on to find out but it does give one the ability to create high-strength parts with a minimum of financial outlay.

[farcticox1]

I never had any preconceived plan for this project it has been 'plot an bash' and is just gradually evolving.
only have very limited tools - namely Chinese type Dremel copy, electric drill and angle grinder + cheap hand tools - so this often controls the design

Sounds like me I did invest in a small drill press.