Slipjoint Liner Mill Relief Fixture
I thought I'd post some pic's of a fixture I finished up yesterday for mill relieving the liners on slipjoints. The ideal way to do this would be with a rotary table, but since I didn't have $200 to $300 to spend on one right now. I though I would see if I could put together a fixture out of what I had available in my shop.
I'd like to say up front this is not my idea, but my version of a fixture Tony Bose has posted on his site. Here is a link to the tutorial on Tony's website. http://boseknives.com/liner-milling/
Here are pics of the fixture with a liner in it.
The base is 5" x 4.5" x 1.25" The large holes in the base are not needed for the fixture. The large holes were already in the piece of scrap I had available to work with.
The rotating arm is a piece of 8.5" x 2.5" x 3/8" steel.
I surface ground both pieces. Probably not necessary, but I wanted to make sure both pieces were flat to help ensure consistent results when milling the relief in the liners.
The hold down bolts, set screw and shoulder bolt are all 5/16"-18.
I drilled undersized and reamed to 3/32", a hole in the center of the base and then drilled and reamed a 3/32" hole in the rotating arm.
The set screw hole is stepped and offset in the base. I first cross drilled a #21 (.159") hole in the base which intersects with the 3/32" hole I already drilled. This hole is for the 5/32" brass rod that secures the 3/32" pin when the fixture is in use.
I then drilled and tapped the first 1.5" of the #21 hole for 5/16"-18.
On the setscrew I drilled a #25 (.1495") hole in the center a 1/2" deep and pressed in a piece of 5/32" (.1563") brass rod using my 1/2 ton arbor press. I had to sand down the part of the brass rod that was pressed into the setscrew, as the #25 hole was almost .007 undersized. A #23 (.154") drill bit would have worked better, but all I had was a #25.
The 3/32" pin which holds the base, rotating arm and liner together is a 3/32" harden drill rod that I got from McMaster Carr their item number 3009A116. I had a piece of 3/8" brass rod that I drilled a #43 hole into and then pressed in the drill rod.
Here is picture of the base chucked up in the milling vice, it is sitting on two 5/8" parallels. You can see now why I offset the setscrew hole in order to allow access while held in the vice.
Here are pics of all the pieces put together ready to mill a liner. After tightening the set screw I tapped down the 3/32" pin just to ensure the pin was fully seated.
Pic of the liner after milling still in the fixture. and a pic of the set of liners milled.
These liners are brass templates for the stainless steel ones I plan to use on the finished knife.
I was a little apprehensive when I first used it that the end mill would grap the piece and spin the arm around. To try and help ensure I didn't get hurt, if this happened. I setup a long hold down bolt in one of the slots on my milling table act as a stop in case this happened. You can just barley see it in the second to last picture to the right of the end mill bit. when milling the opposite liner I had to move the stop to the other side of the milling table.
Overall I'm happy with how it it worked. The setup was rigid and milled pretty smoothly. I will continue to be very cautious when using this fixture and utilize the stops, just in case.
Jim
I'd like to say up front this is not my idea, but my version of a fixture Tony Bose has posted on his site. Here is a link to the tutorial on Tony's website. http://boseknives.com/liner-milling/
Here are pics of the fixture with a liner in it.
The base is 5" x 4.5" x 1.25" The large holes in the base are not needed for the fixture. The large holes were already in the piece of scrap I had available to work with.
The rotating arm is a piece of 8.5" x 2.5" x 3/8" steel.
I surface ground both pieces. Probably not necessary, but I wanted to make sure both pieces were flat to help ensure consistent results when milling the relief in the liners.
The hold down bolts, set screw and shoulder bolt are all 5/16"-18.
I drilled undersized and reamed to 3/32", a hole in the center of the base and then drilled and reamed a 3/32" hole in the rotating arm.
The set screw hole is stepped and offset in the base. I first cross drilled a #21 (.159") hole in the base which intersects with the 3/32" hole I already drilled. This hole is for the 5/32" brass rod that secures the 3/32" pin when the fixture is in use.
I then drilled and tapped the first 1.5" of the #21 hole for 5/16"-18.
On the setscrew I drilled a #25 (.1495") hole in the center a 1/2" deep and pressed in a piece of 5/32" (.1563") brass rod using my 1/2 ton arbor press. I had to sand down the part of the brass rod that was pressed into the setscrew, as the #25 hole was almost .007 undersized. A #23 (.154") drill bit would have worked better, but all I had was a #25.
The 3/32" pin which holds the base, rotating arm and liner together is a 3/32" harden drill rod that I got from McMaster Carr their item number 3009A116. I had a piece of 3/8" brass rod that I drilled a #43 hole into and then pressed in the drill rod.
Here is picture of the base chucked up in the milling vice, it is sitting on two 5/8" parallels. You can see now why I offset the setscrew hole in order to allow access while held in the vice.
Here are pics of all the pieces put together ready to mill a liner. After tightening the set screw I tapped down the 3/32" pin just to ensure the pin was fully seated.
Pic of the liner after milling still in the fixture. and a pic of the set of liners milled.
These liners are brass templates for the stainless steel ones I plan to use on the finished knife.
I was a little apprehensive when I first used it that the end mill would grap the piece and spin the arm around. To try and help ensure I didn't get hurt, if this happened. I setup a long hold down bolt in one of the slots on my milling table act as a stop in case this happened. You can just barley see it in the second to last picture to the right of the end mill bit. when milling the opposite liner I had to move the stop to the other side of the milling table.
Overall I'm happy with how it it worked. The setup was rigid and milled pretty smoothly. I will continue to be very cautious when using this fixture and utilize the stops, just in case.
Jim