FWB 65 servicing

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Thirdwheel
Plinker
Plinker
Posts:50
Joined:Thu Sep 19, 2013 8:15 pm
FWB 65 servicing

Post by Thirdwheel » Thu Oct 31, 2013 8:13 pm

Hi all
Feinwerkbau 65 service (think it is an early one)
As I’ve put a new piston ring, piston buffer, safety bumper and barrel seal in today I thought I would write it up for others to see how I did it and to have it saved somewhere, so when I have to do it again I do not have to reinvent the wheel.
I’ve not had the gun long and was happy with my purchase and it seemed to work well but it had a heavy spring, crumbly looking white barrel seal and safety bumper and it dieseled a bit as it had been oiled – now a FWB should run dry as the piston, piston ring and cylinder are moly coated. The previous owner said he had put a stronger spring in it so it was not standard.
Tools and materials:-
Phillips screw drivers
Selection of quality flat bladed screwdrivers
Jeweller’s screwdriver set
Small snipe nosed pliers
Scriber
3mm allen screw driver shortened on the short side and a ball drive on the long side.
Sash Cramp
Wooden blocks to use with sash cramp to compress and release spring
Dowel rod with sawn groove to hold squares of “J” cloths
“J” cloths
Scissors
Low strength loctite
Acetone
Moly powder
Plastic pippete
Moly gun grease
Note book
Pencil
Torch
Soft rags
Piston bumper, safety buffer, piston ring, barrel seal and main spring.
A word about screw drivers, most of the ones for sale are cheap rubbish and most of my good ones have seen better days – No problem with the flat blade ones as I can sort them out on the grindstone. Phillips drivers cannot be recovered and get thrown in the bin as soon as they wear and before they “cam out” on an important job and ruin a screw. Now please forgive me if I’m telling you how to suck eggs but do you know there are two different types of cross point and many sizes of each type.
Type one : Philips head – a cross head screw used mainly in engineering and is the type used on the
Feinwerkbau. The Driver has a plain cross drive with clear grooves.
Type two: Posi drive – a cross head screw used primarily on wood screw BUT the system is creeping into all areas of construction. You can tell if it is a Posi head by looking at the head and if the four drive slots are bisected with a scribe cross it is a posi drive. The driver has a cross but in the grooves there are four pointed tangs that point at the scribed crosses on the head of the screw.
The problem is both systems will drive each other but not perfectly as the angles inside the slots are different and one has a more pointed relief at the bottom of the slot (posi). Use the right driver in the right screw and you will mess up less screws.
The trick is to choose the right driver of the right size, again there is a problem as different sized do overlap a bit and it can make you mess of the head. For smaller sizes of screw heads I have gone over to using replaceable bits in a magnetic screwdriver holder – when the bit is past it’s best it goes in the bin. Quality replacements do not cost an arm and a leg and if you are using ferrous screws they stick to the tip magnetically, which is a real plus sometimes. As with all screw driving match the bit to the head and push down more than turn until the screw cracks free, this is to stop “camming out” messing up the head, and a whole new ball game starting.
Method I used to service the FWB 65
• Make a wooden block with a cut out to fit on the back of the cylinder, this has a slot cut in it 18mm wide and 15mm deep and the face that abuts the cylinder cap is cut at 5 degrees – have a look and you will see why. This block along with a small piece of 10mm ply holds the gun in the sash cramp when removing the spring and replacing it.
• Take off the grips
• Loosen but not remove the two Philips screws in front of the trigger guard and the two 3mm allen screws inside the handle.
• Now remove both Phillips screws – the longer one must go back nearest the trigger guard and the allen screws, put the frame and trigger system to one side.
• With a cloth clean up any mess you find.
• Remove the screw that is the pivot for the cocking lever, it is staked to stop it coming undone but it will come out, unhook the cocking arm from the cylinder.
• On top of the gun at the rear in front of the sights there is a screw – crack this undone but do not do more than this.
• Put gun in sash cramp with special block holding the cylinder cap and the ply on the other end and on the barrel. Take up tension remove previously loosened screw, back off the cramp and the rear cap along with the spring will emerge from the gun.
• Clean up any greasy mess.
• The piston will not come out until the rear slider is removed, this is removed by taking off two “E” clips – beware they are small; I used a jeweller’s screw driver for the rear one and a fine pair of snipe pliers for the front one. Note there will be small shims between the “E” clips and the sledge fitting they may be of different thicknesses so put them down so you know where they go back. Push out the pin and remove sledge noting what way round it fits.
• The piston can now be removed but if you do you will need to remove the cylinder as well because you will not be able to put it back as the piston ring will stop you. If all you want to do is replace the safety bumper leave the piston in and you a but of jiggery pokery you should be able to turn the cylinder 180 degrees at bring it to the top and you can dig it out with a scriber or any other instrument of torture you like. I wanted to replace the bumper and piston ring and re moly the cylinder so I pressed on.
• To remove the cylinder you need to unhook the rear most spring, and the rearmost pin by removing an “E” clip. As above jiggery pokery and out the cylinder comes.
• Removed barrel seal, safety bumper, piston bumper and piston ring – it was well worn and was no longer parallel in cross section. Degreased using first white spirit then acetone. Use the dowel with a saw cut and cut “J” cloths to clean inside the barrel.
• Fit new piston ring.
• Mix up a solution of moly powder and acetone and dribble it over the inside of the cylinder and outside of the piston and allow to dry then buff off with a bit of “J” cloth.
• Polish the ends of your spring using fine wet and dry so it can slip easily as springs turn when they are compressed and released. Mine was a genuine Feinwerkbau spring and was quite rough.
• Push in new barrel seal, safety bumper and piston bumper – I used a vice for this one.
• Compress piston ring with fingers and fit piston to cylinder with the gap in the ring on the opposite side to the cut out on the cylinder.
• With some jiggery pokery refit cylinder and piston – some of the mechanism must be lifted out of the way – you do not need to use any force.
• Make sure cylinder is round the right way with the hole for the cocking arm in the right place.
• Put the rear pin, Spring and “E” clip back in place.
• Lightly grease and replace rear sledge, pin, shims and “E” clips.
• Put a little moly grease on the ends of the spring and I really mean a little and lightly coat the rest of the spring (again very light as it must not fling off and end up on the cylinder wall , in the research I've done it seems FWB put it in dry but I could not bring myself to do this so the ammount I used was minimal).
• Replace spring into piston then end cap.
• Compress and relocate screw.
• Hook cocking arm into cylinder.
• Grease cocking lever pivot, put a little low strength Loctite on threads, and screw home.
• Replace frame making sure longer Phillips screw goes to the rear. Do not tighten fully any of the four fixings yet as to should align the sliding system first. Just snug them up and fire a couple of pellets – that should shock them into alignment. Now finally tighten them.
• I put a little gun oil on the outside of the cylinder and I do mean a little but none goes inside the cylinder.
• Replace grips and enjoy.
This all took about 3 hours but next time it will only probably take an hour or so. Hope this helps, the spring is quiet strong and I need to hold the barrel while I cock it – I must be weak as I see on you tube people just holding the grip and working the lever – perhaps the spring is shorter for the early FWB 65?! I bought the parts direct from Germany using ebay took about 10 days to arrive.
Hope this is some help
George

zooma
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Joined:Sat Nov 10, 2012 9:12 pm

Re: FWB 65 servicing

Post by zooma » Thu Nov 07, 2013 7:52 am

Hi George - thanks for taking the time to write your very informative thread about servicing the Feinwerkbau Model 65 and it will also provide a good guide for the Model 80 and Model 90 as well.

There seems to be more and more of these popular pistols in use and of course they are all getting older ( like the rest of us) every day and most will be in need of some attention sooner or later so your guide is timeless and will become a good reference guide for the future.
Feinwerkbau P40 Tricolour wanted.........still !
http://www.bobsairguns .com - proud to host the RMTC site since April 2011.

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