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PostPosted: Sun Jul 04, 2021 7:07 pm 
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Joined: Sat May 15, 2021 7:32 pm
Posts: 17
Location: Thornhill, Ontario
https://imgur.com/gallery/imTj9na

Spent 3 hours heating the old sight block with a blowtorch and hitting it with a hammer. Stained the wood, paracorded the stock, it's a lot more comfortable to shoot now.

Hardening the sear didn't work, looks like I really am going to have to cast a new one. Building an arc furnace to melt steel for it. Going to be doing lost PLA casting.

Tore it down, cleaned all the rust out, oiled the gaskets, smoothed down the burrs, polished it all up.

Next steps:

Replacing the sear once the furnace is done

Replacing the spring for one I already bought

Touching up the bare spot on the top with some Birchwood Casey super blue

Adding some 3d printed rear sight onto the rail

Depending on the FPS I get with the new spring, maybe chopping the barrel

Thanks for checking out the post guys!


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PostPosted: Mon Jul 05, 2021 7:31 am 
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Joined: Wed Sep 07, 2016 11:04 am
Posts: 1879
Casting the sear? Isn't it just flat steel cut to shape?

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I have some airguns.


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PostPosted: Mon Jul 05, 2021 2:46 pm 
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Joined: Wed May 12, 2021 8:34 am
Posts: 494
Location: Just north of Toronto
chloroform wrote:
. Building an arc furnace to melt steel for it.


Wow, I feel happy when I file a shim to the right size or polish a trigger part...

Clearly you have a different level of commitment to this hobby!

I shall happily peer over your shoulder as you craft this.


Sent from my SM-G973W using Tapatalk


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PostPosted: Mon Jul 05, 2021 3:32 pm 
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Joined: Mon May 26, 2014 1:08 am
Posts: 820
Location: Thunder Bay
The sear is a difficult part(s) to fabricate. Stoning the original part would be the recommended procedure. If the original part is too messed up for whatever reason, I would purchase a new OEM part. Note that if you try to fabricate new sear parts, they must be made from hardenable steel, hardened and tempered to the correct level of Rockwell hardness. If you were unsuccessful attempting to harden the original sear (over the years, I've owned five different B3s, all had correctly hardened sears -it seems you're just unlucky!) it may be easier to simply buy a new original sear.
I currently have three B3s. Two in .177, one in .22. A proper sear engagement in a B3 is critical since a failing sear can easily remove the end of your finger/thumb when loading a pellet.
B3s are very basic in terms of engineering and quality control. The sear and trigger mechanisms are primitive and don't respond well to tuning except on a very basic level. The biggest improvement you can make is to replace the flimsy plastic spring guide with one made of metal. If you don't have a metal lathe, a spring guide from a Crosman B18 (Phantom) will work with minimal fitting. Google is your friend.
B3s are fun guns. They're cheap, fun and shockingly accurate when tuned correctly. I hope you enjoy yours as much as I enjoy mine.

_________________
Theory is when you know how something works, but it doesn't.
Practice is when something works, but you don't know why.
In my shop, Theory and Practice are combined!
Nothing works and I don't know why.

Two lathes and too many projects


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PostPosted: Mon Jul 05, 2021 10:34 pm 
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Joined: Sat May 15, 2021 7:32 pm
Posts: 17
Location: Thornhill, Ontario
ricksplace wrote:
The sear is a difficult part(s) to fabricate. Stoning the original part would be the recommended procedure. If the original part is too messed up for whatever reason, I would purchase a new OEM part. Note that if you try to fabricate new sear parts, they must be made from hardenable steel, hardened and tempered to the correct level of Rockwell hardness. If you were unsuccessful attempting to harden the original sear (over the years, I've owned five different B3s, all had correctly hardened sears -it seems you're just unlucky!) it may be easier to simply buy a new original sear.
I currently have three B3s. Two in .177, one in .22. A proper sear engagement in a B3 is critical since a failing sear can easily remove the end of your finger/thumb when loading a pellet.
B3s are very basic in terms of engineering and quality control. The sear and trigger mechanisms are primitive and don't respond well to tuning except on a very basic level. The biggest improvement you can make is to replace the flimsy plastic spring guide with one made of metal. If you don't have a metal lathe, a spring guide from a Crosman B18 (Phantom) will work with minimal fitting. Google is your friend.
B3s are fun guns. They're cheap, fun and shockingly accurate when tuned correctly. I hope you enjoy yours as much as I enjoy mine.


That's some good advice! Thanks for your reply.

I haven't been able to find replacement oem parts, though I would just replace the sear with an oem part if I could. I'd really rather keep my fingers, I've already drawn up the sear in fusion360 in order to CNC it or build a furnace and cast it. Haven't decided yet.

Sometimes I think maybe the hardening process failed, and I just made it worse. I remember it was very soft and I could take a file to it easily, and after hardening it I just couldn't file it down. So that's not very likely. Considering how hard it is, I'm surprised it still got rounded down.

Not sure what you mean about the spring guide, mine doesn't have one. Mine just has a divet in the trigger, and a nipple on the main tube in order to hold it in place.


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PostPosted: Mon Jul 05, 2021 10:37 pm 
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Joined: Sat May 15, 2021 7:32 pm
Posts: 17
Location: Thornhill, Ontario
jckstrthmghty wrote:
Casting the sear? Isn't it just flat steel cut to shape?


Nope! The trigger is cut and stamped, but the sear is cast, and seems to be pot metal.


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PostPosted: Mon Jul 05, 2021 10:40 pm 
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Joined: Sat May 15, 2021 7:32 pm
Posts: 17
Location: Thornhill, Ontario
Rob27 wrote:
chloroform wrote:
. Building an arc furnace to melt steel for it.


Wow, I feel happy when I file a shim to the right size or polish a trigger part...

Clearly you have a different level of commitment to this hobby!

I shall happily peer over your shoulder as you craft this.


Sent from my SM-G973W using Tapatalk


Thanks for your support! Don't let what I'm doing discourage you from being proud of your work, I'm putting a lot of effort into this one part but I'm leaving everything else kind of rough because I lack the skills to make it look good.

The seemingly small work, polishing, fitting, etc, always takes the longest and requires the most patience. Those are very good skills to have.


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