Anyone made their own crosman metal breach ?

[Shed tuner]

I've got a 16mm bar that'll do nicely.. means I can do it all without repositioning the work in the clamp too, as the travel in the mill is only around 70mm, whereas with your approach I could do the whole lathe bed length... can also fine tune the radius with cutter seating depth.

Just need to build a workpiece clamp on the toolpost, but that's not too big a deal... time to dig out the mig...

[hmangphilly]

I've got a 16mm bar that'll do nicely.. means I can do it all without repositioning the work in the clamp too, as the travel in the mill is only around 70mm, whereas with your approach I could do the whole lathe bed length... can also fine tune the radius with cutter seating depth.

Just need to build a workpiece clamp on the toolpost, but that's not too big a deal... time to dig out the mig...

How were you originally thinking of holding the workpiece jon ?

[--ped--]

you don't need to use a ball nosed endmill you can just mill slot like a falcon uses

[Shed tuner]

How were you originally thinking of holding the workpiece jon ?

I have a right angle milling adapter that sits atop the slide instead of the toolpost (with about 70mm vertical travel via it's own slide), which has a small machine vice mounted on it, facing the chuck.

I can modify an old crude tool holder to clamp the workpiece, so it can approach horizontally rather than longtitudinally...

[Shed tuner]

you don't need to use a ball nosed endmill you can just mill slot like a falcon uses

was thinking of the need for the transfer port seal to be close.. but then again, easy anough to make a new bespoke transfer port.

I'm actaully rather glad I started this thread - lots of interesting things to think about - thanks all for the ideas and input

[--ped--]

tp seals in the barrel so it won't make a difference really but if you did it like a falcon it would be a bit more work to get the clearance right

[--ped--]

this is one of my favourite breech's i've made

and the middle one is one a friend made for me in the style of a crosmods but to take a .20 rapid mag using a winerack barrel all the other parts i made or adapted

he also made this -all brass bar the springs stem and hammer

[Shed tuner]

Funny you shoudl post that first one.. the prototype I've just started on will be very similar...

[Shed tuner]

So I used this (purists look away now):


To make this, starting with a few passes with a regular end mill, then switching to the round nose. Taking around 0.1mm off for each pass, it was fine.


fits on this:



Now to turn it around, and do the other end. Will probably take me longer setting it up with the DTI than the actual milling, but hey... I'm not going into production on these, that's for sure !

[Shed tuner]

OK, flipped it round, and with a lot on fine tuning, got the two grooves to line up...


Fits fine:


It's about 40mm longer than the std plastic one, which seems about right. I can always trim down at the barrel end if needed. It's surprisingly weighty, but these guns are all way too light anyways, so no bad thing


Next is to drill the barrel and bolt holes... offset or co-encentric... will have a measure.

[--ped--]

coming on
i prefer to bore for the barrel and probe first then i can set the block in the mill using the bore to set it up so the top can be milled flat to the barrel and then once the top is done flip to do the underneath

[Shed tuner]

coming on
i prefer to bore for the barrel and probe first then i can set the block in the mill using the bore to set it up so the top can be milled flat to the barrel and then once the top is done flip to do the underneath

that was my original plan (to bore first)... but when this test looked like it was going to work I just went with it In the three jaw chuck, I'm thinking to put one jaw down the middle of the groove, offsetting the barrel / probe about 2mm, which will enable me to use a barrel a mill or two larger

[evert]

I've been busy today too, and went with the boring bar method, used an old 16mm steel bar and center drilled it in the end so it could be stabilized by a live center. Used the milling attachment to hold the breech, and aligned it with the already drilled center holes.
Had to mount the boring bit at two locations on the bar to get the entire track milled out, and adjusted it manually to the same depth. That took some measuring! After a bit of sanding with some 180 grit paper wrapped around a 20mm steel tube it worked out really well

[Shed tuner]

I've been busy today too, and went with the boring bar method, used an old 16mm steel bar and center drilled it in the end so it could be stabilized by a live center. Used the milling attachment to hold the breech, and aligned it with the already drilled center holes.
Had to mount the boring bit at two locations on the bar to get the entire track milled out, and adjusted it manually to the same depth. That took some measuring! After a bit of sanding with some 180 grit paper wrapped around a 20mm steel tube it worked out really well

cool... you using Aluminium ? As you say, milling the track in two parts is a real PITA... so much easier if you can do it in one...

[evert]

cool... you using Aluminium ? As you say, milling the track in two parts is a real PITA... so much easier if you can do it in one...

Yes, a bar I bought off "3baj". I didnt mill the track as deep as you, hardly deep enough to cover the transfer port. But this is because I want some extra space for larger barrels. But it still sits very nice on the tube, we'll se how it turns out.

Now comes the placing of the holes and the loading port..... I've left a few mm's extra at each end, and will start with milling the loading port and locating the breech mounting screw hole, so I can trim the rear end to length after those critical dimensions are established.