Tuesday, January 27, 2009

Derrick's on a Trigger Frenzy! Part 1

Derrick here today. Some projects just beget other projects. While working on the wide-bladed brass trigger for the Crosman 2250 last week, I came up with a different trigger idea that I had to work out. As per my usual, I started working without a real plan--and as usual, it's got to have some match gun style.

First, I wanted some better pivot pins for this soon-to-be trigger. Found a piece of hardened 1/8" drill rod and marked off several intervals of 0.410". Might as well make a couple extra.

Used a carbide v-shaped bit to groove each 0.410" section. I didn't bother to cut all the way though. The hardened 1/8" drill rod is incredibly tough stuff. While that's just great for wear resistance and reduction of friction, it's lousy for cutting. I essentially "scored" the rod with the cutting tool. The drill rod then went into a vise and each section was snapped off. Was like breaking a glass rod. Not shown: I then turned on the grinder and ground each pin down to 0.393"---The final length needed for Crosman sized replacement pins.

The soon-to-be trigger blade: I wanted the face of the trigger grooved--just like in the movies! Mounted a piece of 1/2" wide brass in a Taig milling vise. Then bolted that to the horizontal milling attachment for the Taig lathe. (The Taig is all modular. It's pretty ingenious that way) It almost fell apart when I realized (incorrectly at the time) that I didn't have a small enough milling cutter. I ended up making the cut by using the tip of a center drill. My thought was that a center drill is so rigid, and this was soft brass, the tip wouldn't deflect. It worked. Two hours later, I realized there were 10+ suitable cutters in the Dremel kit. Sigh.

I cleaned the grooves up by hand with a needle file and set this aside.

I wanted the trigger blade to be rotational on it's long axis. A 2" long piece of 3/16" brass rod was chucked, faced, spotted and drilled through. I think I used a number 33 drill. The hole just allows clearance for a M3 x 0.5 bolt. I'll cut the brass to length a bit later.

Quack! It's a little aluminum duck! Cut away all the parts that don't look duckish.

Didn't show the first part of this plan: Took the world-renowned Crosman 22XX trigger, transferred the pivot and sear contact locations to this piece of scrap aluminum bar stock. Used a high precision fat tipped Sharpie. Color: Uh, green.

Excel Jeweler's saw. Think "micro coping saw" and you've got it. A great, inexpensive tool for fine precise cuts. Note: Fine precise cuts not shown here.

The Excel people are probably sending someone to repo my saw...

I'll knock it down closer to size on the grinder then go to it with a small file. I wanted some extra material here to work with. The big marker ensured it.

Does this help visualize my dream? The aluminum piece is the trigger pivot and sear contact. Call it a rocker arm.

Sunday, January 25, 2009

Sunday Ramble and Miscellany

I'm tidying up some loose ends with this post. Beyond what you see below I have a Daisy/Milbro 230 rifle and three Crosman 101's in partial process. Not sure how/when I'll have any of them done...as these things go. I'm also working on some other parts, etc. I also have a Gamo 220 that I need to de-Gamo-ify. I bought some Maccari springs and seals to see if I could tame it. I also am learning how to resolder Benjamin barrels that have come unstuck. We'll see if that bears any but humiliating fruit for the blog. Oh yeah, there's a Sheridan C that has an ugly chunk out of the pump arm. Not even sure what's to be done about that.

A Crosman 760 that has a completely jammed barrel and broken parts, an early 1377 pistol that is in pieces and some other 1377 parts left from the carbine conversion and a 2250(?) barrel

Just ugly and worn.

Recutting the 1377 bolt for a larger o-ring.

Less Ugly? Basically just a way to use up some parts and make space. Hey, it shoots!

Some 80/20 aluminum extrusion I got at the scrap yard.

At one end of my shop.

A post that duplicates the mounting of my spotting scope.

Now I can sight guns in, inside the house...and not have to keep walking back and forth to see where the pellets are landing on the target. It stows out of the way when not in use.

Thursday, January 22, 2009

Derrick Lightens His Webley Tempest Trigger

A few weeks ago, I bought a .177 cal Webley Tempest pistol from world-renowned airgunner, Wayne Burns. Thanks Wayne! When I shot the gun, I thought the trigger pull was in the 12+ pound range. (Not Wayne's fault!) It was like a Glock with the "New York" trigger. When I told Nick how high it was, he said I must have the target model! Both Webley Tempest and the similar Hurricane air pistols (same base guns, different sights) share the same trigger mechanism. Until recently, I'd owned a Hurricane for about two decades and that trigger was just as heavy.

Nick and I pondered the trigger situation. Then, Nick forwarded this link: http://www.rimfirecentral.com/forums/showthread.php?t=219638
Seems like I'm not the only one who thinks the trigger pull weight is absurdly high.

The trigger is retained with, yep, small roll pins. What a great way to start! More required reading: Nick disassembled a Webley Hurricane on a previous blog post. Pay attention to the way he numbered the roll pins for disassembly. Handy! http://anotherairgunblog.blogspot.com/2008/05/disassembling-webley-hurricane.html
Note: Worry not. There is exactly zero danger that the mainspring will come blasting out of the gun by removing the roll pins.

Grip panels off. Unscrew the flathead holding the safety lever and pull it off the stud. The safety spring then comes right off.

Knock out the roll pins in the order Nick has them marked in blog post #31. Not necessary in the least to push them completely out of the frame. I pushed them out from left side to right.

The trigger and sear are buffed (bench grinder fitted with a 6" stitched wheel). Lots of polishing compound on the wheel. A small container of water near the buffing wheel keeps the part cool. All the mating faces are polished until they look like mirrors.

Trigger and sear after buffing. The allen set screw behind the trigger blade gives the spring something to bear against. Screwing it in increases trigger pull weight. Backing it out lowers. The trigger spring is so stiff (and so long) that the set screw only really gives you the option of "too high" and "really too high" in it's adjustment range. The spring is 0.145" diameter and 0.616" long--"free length" in spring speak.

The trigger shoe is from Crosman It's for their 2300 custom shop guns. It fits quite well. Crosman part number 2300-012. About $9 if I recall. It's not always available for after market sale. Beeman used to sell a really nice steel trigger shoe from Flaig Ace. Beeman's old part number was #7761.

I looked around at all my springs, but couldn't find anything small enough in diameter to replace the stock trigger spring. A trip to several local hardware stores also came up dry. It's possible that Webley used a metric sized spring. If that's the case, it's probably a 3.75mm OD and it crushed very, very slightly when I put a caliper on it. I found several good options in a few seconds online, but didn't want to order and wait. I chose instead to cut 2 coils off the spring to lower the preload. Alternately, it might have also been possible to change to a shorter set screw in the trigger itself that bears against the spring. Either way, the spring will then exert less force against the sear.

Pick your poison. Just cut the spring shorter. Reassemble in the reverse order. I lubricated all the contact surfaces with Castrol MP grease. Use whatever bearing/chassis grease you have around. And, yes, a moly grease is fine for this as well.

The return spring for the sear goes in this way. This is the only part that might cause some head scratching during reassembly.

There's a relief cut on the trigger guard for the long leg of the return spring.

Gun is lying right side up. Long leg of spring is on top and towards the front of the gun.

The short leg at the rear of the return spring fits in notch cut in the sear. Notch is there at the top.

Once the guard is pinned back into place, only the safety lever needs to be reinstalled.

Have I mentioned yet that these Webleys have single-stage triggers? Well, there you go. The trigger pull weight can be fine-tuned using the set screw at the rear of the blade with a 1/16" allen wrench. By adjusting the set screw to preload the trigger spring, my pull weight was variable from a high of about 4 lbs 2 oz down to 2 lbs 8 oz. Mine is currently adjusted to about 2 lbs 12 oz. Pretty good considering it was in the 8 pound range before the job. It's still not "match grade", but perfectly acceptable for a fun plinker.

Side note: IF the set screw is backed out of the trigger blade more than approximately 0.120" from flush, the gun will fail to cock. The protruding set screw will contact a shelf inside the rear of the trigger guard and the sear will not hold the piston back. Turning the set screw in a few turns will immediately fix the problem.

Warning to Americans: I failed to match up the thread size on the set screw. It's not metric--and it doesn't match up with SAE. It's probably a BA #4. You are hosed if you drop this under a work bench outside of the UK.

Monday, January 19, 2009

A Sight Aperture for a Beeman (Williams) Sport Aperture Sight

I made the mistake of getting a copy of the Brownells catalog recently... So as I was reading through it the other night I noticed that they sold apertures for the Williams range of sights. I have a Beeman Sport Aperture sight on my trusty FWB 124 that has a somewhat dinky aperture with much too large of a hole (.093"). The Beeman sight is made by Williams. I wish I had the "deluxe" version with adjusting knobs, but that's a subject for another day. Anyway, I noticed that the thread size was 7/32"-40 for the thread on the aperture disc. So I quickly looked to see how much a die in that size would cost...$74.95!!! I wasn't about to engage in single point threading a tap to make a die, or threading the aperture disc so the project lost its luster. (My but I'm wordy today) I did find a source for a cheaper die, by the way.

Today I had a few moments to spare so I decided to sort through all of my taps and dies, taking any of the non standard sizes and sorting them in a new drawer unit. Imagine my happiness when I discovered that at some time I had acquired a 7/32"-40 die! Thus am I able to bring you the project below:

The Beeman Sport Aperture Sight (non-deluxe version).

That's a big aperture in that there disc.

The threads looked awfully short, I wonder if the previous owner had knocked a few off at some point?

Turning down the shank on some 3/4" steel.

Drilling #21 (.159")

Drilling #55 (.052") I might make one with an even smaller aperture but figured that this would be a good place to start.

Yawn, yet another picture of me using a die.

I did a straight knurl.

Chamfering the edges.

And cut off from the stock.

Boring out the front.

Just a bit too shiny? I then put it back in the lathe and used a steel brush against that face while it revolved.

I used some Oxpho blue on it. It looks shinier than it is because of the flash.

Much better. I really need to clean that grime off the rifle.

Sunday, January 18, 2009

A Cocking Handle for My RWS (Diana) Model 45, Part 2

Just the shim to make.

Drilling some solid to make tubing...

Turning to fit the brake.

Reaming to the size of the barrel.

Left a shoulder to bear against the end of the brake, the last one had a disturbing tendency to swallow the shim and get all out of place. See, I'm learning! Next one will actually integrate the transition between the two...

Slotting.

The brake was cold blued with Dicropan T-4, the shim with Oxpho blue.

The shim slips over the front sight grooves.

All together.