FAS604 Rear Sight

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Tank
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FAS604 Rear Sight

Post by Tank » Wed Nov 13, 2013 9:56 pm

So. Bob, being the sort of person he is, loaned out one of his pistols, a FAS604. Without going into all of the details, the rear sight was badly damaged. As you can see from this first picture the rear sight blade is a pressed steel item and you can see the windage adjusting bracket is bent out of square.

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So, after making enquiries as to the availability of this blade as a spare, I decided to set to and make a replacement. And in the immortal words of my Uncle Paul - "we will need a bit 'o stuff". The plan is, we are going to take a two foot length of bright drawn steel bar and turn it into a little tiny piece of bright something. For this, we need a saw:

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I like this saw, it makes my life just that little easier :D
I made a couple of "spares":

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Next, into the Mill and a sharp cutter:

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So, this is where we are. I have a good blank copy in solid steel and I am quite happy with it. However, the adjusting screw was also destroyed and this is a 3mm left hand threaded screw. It has the usual knurled end to facilitate adjustment and is retained by an external "C" clip on the other side so it will require a machined groove. But that adventure will have to wait until next week as I will first need both a Tap and Die in 3mm Left Hand thread. :shock:

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Last edited by Tank on Thu Nov 14, 2013 11:48 am, edited 2 times in total.
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Re: FAS604 Rear Sight

Post by micken » Wed Nov 13, 2013 11:04 pm

Very impressed with this Graham, I'll try to get some photos posted this weekend of my two 604 sights from earlier failed pressed steel affeir and later "block and blade" arrangement.

Big kudos to you.

Mick

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Re: FAS604 Rear Sight

Post by Leonardj » Thu Nov 14, 2013 6:31 pm

Very nice work, Graham.
Tiny little pieces like that are often much more of a challenge than the larger bits.

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Re: FAS604 Rear Sight

Post by Tank » Thu Nov 14, 2013 6:58 pm

Thanks for the kind words guys.
You are right Leonard, a small deviation is magnified out of all proportion when you are making such a small piece. The early guns came with this type of rear sight and the later guns came with a two piece sight, the rear blade is held onto the adjustable windage block by two small screws. I can see of course the reason for this as a complex job such as this - making it from one piece - would be far too expensive on a production gun. You wouldn't think so though as FAS are not shy when it copmes to charging. They want 130 Euros for the rear sight :shock:

I only charge a hundred :mrgreen:

Suddenly, buying the machinery to do the job yourself starts to look like a viable alternative. Wonder if I could sell a couple to FAS?
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Re: FAS604 Rear Sight

Post by Tank » Sat Nov 16, 2013 2:49 pm

So, having a bit of time to myself this morning, I set about the rear sight blade unit again.
In the beginning, having thought about this, I decided to use a piece of steel that was quite hard. No two steels are the same, we have for instance EN1B which is leaded steel, I like to use this when turning as it gives a lovely finish and tends not to destroy HSS tooling, then there is EN3b which is Bright Drawn steel and this stuff is harder but mills well. What I used, although Mild Steel, was tough and hard, more like 303 stainless but machined well. I could not of course use stainless as the finished article needs to be Blued.
And this is the point when this decision was to bite me in the Ass!
It was in the back of my mind of course, but I now needed to drill and tap this stuff a depth of 14mm with a 3mm Left hand Tap. :shock:
First of all, I needed a Tap and Die set so I sent off to RDG tools for these, Tap and Die sets aren't cheap so I opted for the "economy" range. I wonder where they came from?:

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I then checked the square on the Drill Press. Although the left to right was spot on I was not happy with the front to back deviation, I have owned this press for a long time now, we have done a lot together but I think this accuracy was asking too much of it:

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So it was time to get creative. There was nothing else for it really and fortunately I have quite a selection of Drill Chucks:

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The mill has a runout I can cope with, it is minute, and as Leonard has observed any magnitude of error will become very obvious on such a small part such as this, can you imagine trying to get a sight picture and the sight slopes off to the left or right? It would drive me potty!
Anyhow, a hole was successfully bored and it was around about then that the "Tapping Machine" that I had promised myself I would one day build became a very desirable item. A four jaw chuck for the lathe would have been useful alternative too (it's on the "list" of tooling-to-buy)! Not to worry, I started the thread off and going carefully with plenty of cutting fluid the job was a success. Not for the faint hearted though, Left hand Tapping just feels so wrong!
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Re: FAS604 Rear Sight

Post by micken » Sun Nov 17, 2013 7:13 pm

Here we go photos of the various things I've posted about.

Broken bent steel rear sight blade and tapped windage block.

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What the newer sight looks like.

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Here's one to show the sight assembly undercarriage, the elevation screw has been removed and the sight flipped up.

Graham, since my older 604 has the sight stripped if you want me to post you the windage bolt for copying then pm me your address.

Cheers,

Mick

Image

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Re: FAS604 Rear Sight

Post by Tank » Sat Dec 07, 2013 4:28 pm

Well, I set to today and began the windage screw.

I can report I made a complete hash of the job and made it too small so it practically falls through the new rear sight threaded hole.

Must-Pay-Closer-Attention-to-The-Dimensions. No bloody good having all this digital measuring kit and not use it! Well, tomorrow is another day.
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Re: FAS604 Rear Sight

Post by Tank » Tue Dec 10, 2013 9:01 pm

Having a little time (couple of hours :oops: ) to spend in the workshop this evening I decided to start again with the windage screw.
I would be the first to admit that the actual lathe tools I have to hand are not the best in the world but the tips are new. I had to make a tool for the "E" clip groove which worked well and it has worked out well overall. Next up I need it in the Mill on the Indexing Head for the detents and a slitting saw to create a slot for a screwdriver so you can actually use it to adjust something.

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Re: FAS604 Rear Sight

Post by micken » Tue Dec 10, 2013 10:02 pm

Really good going there Graham, I've got an old Rolex Oyster that I'll be sending over next. :dance:
I'm well impressed with the fine tooling and detailed work you are doing.

Hope it all works as well as it looks.

Mick

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Re: FAS604 Rear Sight

Post by Jim caffery » Tue Dec 10, 2013 10:46 pm

Bugger me, some real nice workmanship there graham, I was wondering if you could have a look at a fwb80 and the baikal I have, i will send you a pm soon. Got to say though I am very impressed with the photos.
Jim

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Re: FAS604 Rear Sight

Post by zooma » Thu Dec 12, 2013 11:08 pm

Good effort Graham - well done!
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Re: FAS604 Rear Sight

Post by Tank » Sat Dec 21, 2013 7:45 pm

And so it continues. I took the simpler, faster way to cut a screw slot in the Windage screw today, a 1.2mm slotting cutter. It is also the more dangerous option because if you start to get ambitious with the depth of cut you just broke a cutter!

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The final machining operation was the drilling of a series of holes around the inside face of the screw that bears against a ball bearing detent. This is where the versatility of the little Taig Lathe comes into it's own. By putting the screw in a chuck in the tailstock and then adjusting the offset the tailstock became a horizontal indexing head. Much simpler and far faster than setting it all up in the Rotary Table on the Mill.

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And this is the finished item, it is not perfect because I had not counted on the fact I couldn't actually see what I was doing - the screw head was down inside the chuck:

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Now the final step. I decided to use Potassium Nitrate (saltpetre) in a Stainless Steel vessel and bring it to a molten state over the flame of a Butane stove. Why? Because I hadn't tried this method before and frankly, my advice is don't! It is extremely dangerous. Just a single drop of water was enough to cause a violent eruption. A very hot flame and dunking into oil will produce a similar finish. This was the Pot:

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I did a few pieces I had been working on at the same time and they came out well:

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Re: FAS604 Rear Sight

Post by micken » Sat Dec 21, 2013 8:32 pm

I'm just loving this thread, it's great to see this developing and seeing how you make choices about which tools and processes you'll use.
Very inspiring.

Cheers, Mick

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Re: FAS604 Rear Sight

Post by Tank » Sat Dec 21, 2013 9:06 pm

micken wrote:I'm just loving this thread, it's great to see this developing and seeing how you make choices about which tools and processes you'll use.
Very inspiring.

Cheers, Mick
Pleased to see it is of some interest Mick. Ninety percent of "engineering" is problem solving (the other ten percent is math, at which my skills are lacking :oops: ) and the simplest of solutions are the most elegant, in my opinion. To work on these guns you don't need thousands of pounds worth of kit and simple machinery will accomplish most of the tasks. Oh, I know, great to have but simple hand tools will often suffice. It is amazing what you can accomplish with a file and a hacksaw. Throw in a basic drill press and you have it made :D
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Re: FAS604 Rear Sight

Post by zooma » Sun Dec 22, 2013 8:59 am

Great effort - your intuitive engineering exploits are an inspiration to us all :clap:
Feinwerkbau P40 Tricolour wanted.........still !
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