machining tips for an aluminum breech

[QVTom]

Fred, it seems that you are off to a great start.  Each part  you design and make will get a bit nicer, more sophisticated and speedier.  Soon you will be planning your moves several operations in advance! ( maybe you already are )
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Making your own parts sure beats the heck out of "hello world" 

Don't forget to post your efforts.

Tom

[fredfunk]

Just fired my first shot through the new breech!
Cycles smooth and shot seems to have full power! I still need to machine the faces for a nice shiny look but it is functionally complete. Im not sure if it shoots any better and it certainly looks worse, but I am slowly replacing all the plastic parts with wood and metal...

Thanks everyone
Fred

[fredfunk]

I have not even cleaned up my 1377 breech but I am already anticipating my next project... I just ordered a 10rd marauder magazine as I am planning to design/fabricate a multishot breech for my discovery. I do not have a marauder handy so this will be much more difficult than just duplicating the 1377 breech... should be fun
Fred

[Pete]

Prob a bit late to this party...
but what I have done on a 2240 breech...
I run a 3/4" end mill along on a 45* angle
it gave a radius very close to what I required..
You need a mill that you can set the head angle on..

[QVTom]

Very nice Fred!

[Rescue35]

You need a mill that you can set the head angle on..

Or a way to secure the breach at 45º on the table.

I get your point though Pete. Its better to remove as much material with a standard endmill before going to the expensive and lees efficient ballmill. On larger breaches I have step milled them which involves plenty of math and several tool changes before going to the ballmill.

[fredfunk]

DSC_0123 by freddyfunkalicious, on Flickr

DSC_0122 by freddyfunkalicious, on Flickr

DSC_0119 by freddyfunkalicious, on Flickr

DSC_0118 by freddyfunkalicious, on Flickr

DSC_0117 by freddyfunkalicious, on Flickr

DSC_0116 by freddyfunkalicious, on Flickr

DSC_0115 by freddyfunkalicious, on Flickr

[fredfunk]

DSC_0124 by freddyfunkalicious, on Flickr

[fredfunk]

Here's the pics of the final product!

[Rescue35]

Looking good. Keep it up.

[lloyd-ss]

The fit of the breech to the tube looks perfect.  Nice job.
Lloyd

[fredfunk]

Thanks Lloyd... I followed bobs suggestion and only cut in one direction!

[ZipSnipe]

Looks great Fred,  I think I would just file all your edges and sand/polish the outside and your set!!!

P.S.  One of the best things I did when I got into metal working was that I bought one of those old machinist toolboxes filled with tools. And the original owner of the box, I could tell was one of those clever machinist's, had cool lil homemade tools in it.  I think I paid about $125 for it but it was a great deal  .....  so keep your eye out for one of those

[jct842]

About 6-7 years ago I bought a micro-mill from harbor.  I was pretty disappointed that I could not get a large ball mill to work in it for making a breech.  I did similar to rocco in post 18 with a long bar in my lathe.  I had originally bought a milling attachment for the 7x12 but found it not very useful and got the mill.  I remounted the mill attachment to hold the breech as in rocco's picture but with a milling attachment you can raise and lower the breech to center the hollow.  I have a 3/4" bar in it now and am limited on length of breech to around 5" but have a plan to increase it an inch or so.  It is really satisfying to make a gun pretty much from scratch out side of barrel and screws, all other parts can be made at home in my shop out of stock from a metal supply house.  I have used the crosman 2260 triggers, with the 3 screw mod they are pretty good and saved me a lot of time.   john