Muzzle Brake for a Crosman 600 -- Part 2 Final

Picking up where I left off...I need to enlarge a tiny portion of the radius cut at the breech end to clear the bulk tube sleeve.  To do that, I need to first center on the radius to get an even cut.  Put the muzzle brake in a 5C collet and then into a square collet block.
















That funky steel block thingy with rods on the left is a surface gauge.

Might've been a bit more accurate to have set this on a surface plate, but the mill table is plenty flat.  Brought the indicator down until it just touched the left-side top edge of the radius.



















Slid the block over and compared with the right side.  Rotated the piece in the collet until the left and right sides indicated the same way.  This centered the radius to the top of the block.  Plenty of other ways to do this, but this worked well.


 

A 4-flute 7/8" endmill.

Block went into an insert vise.  Insert vise went into the milling vise.  Not shown:  Used a chucked 7/16 reamer in the mill head to center the work on the X-Y axis(--when the reamer would enter the hole in the muzzle brake, it was lined up)

Brought the work away from the cutter without moving it side-to-side.  The amount the tool overlaps the piece represents how long the step needs to be to clear the sleeve.

With the depth set, the radius was deepened then I cut each side out by 0.008".

Flipped the work in the collet and aligned again using the surface gauge.  This is the muzzle end of things.  More protrusion this time so I can add some slots.  Did some layout that proved to be a waste of time.

Fortunately, I didn't start at the muzzle.  Made the first slot with a 1/4" ball mill.  Cut in several passes until I'd cut through and into the bore.

When I got to final depth, I turned on the spindle depth readout and set it to zero.

About then, I realized that I might want to add a front sight to the muzzle brake in the near future to increase the pistol's sight radius.  Did some quick math and changed the location and spacing of the slots.

All the slots were cut until reaching zero on the readout.

Some clean up polishing removed the clamping marks.

Neat.  Round holes at the bottom of each cross slot.

Was going to add set screws to the brake, but realized that it doesn't really need to be removable.  Epoxy will be fine.  The painter's tape is to ensure there will be a gap between the bottom of the brake and the gas tube after the glue dries.  Essentially, it ensures that the barrel remains free-floated.

These non-regulation sized Gamo targets are good for something.

Removed the now one piece barrel/brake unit and pulled off the tape.

I like the way the radius hugs the gas tube.

Gave it a quick shot of black Krylon and let it dry inside.

Just enough room at the muzzle if I ever want to add a front sight.

Thanks for reading.  Please check back soon.

Muzzle Brake for a Crosman 600 -- Part 1

Been telling myself that I'd finish this Crosman 600 for way too long now.  I fit a longer barrel to the gun several years ago then later switched from 12 gram CO2 cartridges to bulk-fill with an extended gas tube from Bryan and Associates.  So, now, the problem here is rather obvious--the barrel is too short.  Could've made a new barrel, but I've already been down that road.  A muzzle brake that extends to the end of the gas tube seems like a reasonable solution.















A piece of 5/8" aluminum rod.

Suppose I'm technically making a "shroud" since it's going to cover the entire exposed length of barrel.

Faced off one end and spotted with a center drill.

Progressively drilled about three-quarters of the way through until I had a 7/16" hole to fit over the barrel.

A slight chamfer to remove the sharp edges.

Flipped the piece, faced and center drilled.

Drilled 17/64" to ensure the .22 cal pellet will clear with room to spare.

Countersunk the muzzle.

A couple of edge finders.

Want to find the center of the workpiece.  Set the work on parallels in the milling vise and found the edge. The contact tip is 0.200" diameter, so the edge is 0.100" from the center of the indicator.  As I want to center on a 5/8" diameter piece, I need to move the milling table half of 5/8" PLUS the 0.100" the center of the indicator is from the edge.  (5/8)/2 + .100

Cranked in 0.4125" of travel and I was on center.

Used a 7/8" ball mill to radius the bottom of the muzzle brake shroud to match the gas tube.

Wasn't sure how much metal to leave in the web, so I checked the gap between the barrel and gas tube with a feeler gauge.  Want to free float the shroud, so the web needs to be slightly thinner than the feeler gauge stack.

A couple more passes and...

it'll clear with several thou to spare.

Test fit.

Looks promising.

Need to make a small relief cut in the shroud to clear the flange at the rear of the bulk tube. I should be further along soon.  Check back in a couple days.

New Muzzle Brake on the FWB 124--Final

A little scotchbrite on the brake gave it a good enough finish for now.  I was going to blue it, but after looking at the various airguns, I decided to install it on the old two-tone FWB 124 as is.  If it ends up finding a permanent home here, I'll run it down to Akron Plating and let them give it a coat of hard chrome to better match the compression tube.   















It's hard to take a decent pic of rifles that are over 40" long and have them show up well on the blog.

The brake matches the hard chrome fairly well.  I've given it a coat of wax to prevent corrosion.

The trim size works well with the slenderness of the stock.

The setscrews are dead flush when tightened.

Think I may be overhauling the Sterling next time around.  I've got several other project guns here including both a Rochester and old Benjamin pumper in many pieces.  Also, just picked up an unfinished walnut stock inlet for a Crosman 160.  There's lots of possibilities.  Nick should be back with a project soon.

Check back.

A New Muzzle Brake--Part 2

Happy 2012 from Another Airgun Blog!

















Still working on the muzzle brake.  I flipped the brake around and milled the back end square.

Off on a quick tool tangent:  Turned an indicator holder from a piece of 5/16" key stock. It fits in a spare tool post holder.
















This is mounted to the headstock in one of the various t-nut channels, either on top, or on the back. 

After adjusting the runout, I got out the compound crosslide.  (It's on the right)

I'm sure we've shown this before, but the compound mounts to the top of the crosslide and allows the cutter to travel at an angle respective to the work.

With a steady rest mounted to help prevent deflection, many light passes cut the taper.

Then back to the mill for a couple mounting screws.  A couple pieces cut from a target protect the workpiece.  Spotting for the hole here. 

Through drilling.

Tapping M4 x 0.7mm. 

Snugged a handle around the body of the tap.  The tap itself is barely held in the Jacob's chuck for alignment. 

Mentioned about a month ago about needing some new countersinks.  Over the course of a couple weeks, I replaced everything I had and then some.  I've found that gun shows are often excellent hunting grounds for machine tools at low prices.  Now, when I need a countersink, I feel like Rodney Dangerfield in the pro shop in Caddy Shack.  Hey!  I'll take one of these, two of those...

Used a 90 degree single flute cutter to chamfer the edge of the hole. 

Still need to finalize what to put this on and make sure it fits then get a finish on it.

More soon.