Ok all, lets get into the the trigger area of the build.
Both pillow blocks are used in this process, for those with a jig your jig is at heart a set of pillow blocks with some holes and plates with holes that mount to the top of the blocks. Once sandwiched in the blocks I use 2- 1/4" bolts and mount them through the blocks and the lowers front and rear takedown pin holes.
Again square up! same process as in part one, the only difference is you are running against the back pillow block. Clamp your work firmly to the table and re-check your squaring. As before when you re-check if it is not square loosen the clamps and re-square it must be squared!
In the picture above note that a couple of scrap pieces of aluminum are being used to hold the work off the table. Even those using jigs and a drill press this is important, mill or drill you will drill through the bottom of the trigger area when you add the trigger slot. Also note the clamp on the rear area this is also important be it a mill or drill. you will remove metal in between the rear take down pin holes. once every thing is tight and secured the 1/4" bolt in the rear must be removed (a bolt will ruin an aluminum cutting end mills day don't forget this).
Note that my 1/4" drill stock is chucked up again, this is to find centers and zero the DRO's. As in part one everything is related to the center of the front takedown pin holes. They are 1/4" so for the x-axis move your table so the drill stock is past the front bolt, lower the head and crank it back until the stock just touches the 1/4" bolt and zero the x-axis DRO. OMG now we do math
this is not the center, the drill stock is 1/4" and the bolt is 1/4" and the outside edges are touching, raise the head and move back .250" so half the distance of both equals .250 or 1/4" not so hard right, zero your x-axis DRO again you are sitting at the center of the front takedown holes.
For the Y-axis it is a little more difficult but not much. move the x-axis until you are near the center of the trigger area. move the y-axis beyond either side of the blocks and lower the head. move it back until it just touches the side of the block and zero the y-axis DRO. raise the head and move beyond the block on the opposite side, lower the head and again move it until it just touches the block. yeesh math again, note the value displayed on the y-axis DRO and divide it in half. Raise the head and move the y-axis until it reaches the divided number and zero the y-axis again. you now have the center line of the lower and the middle of the front pins as zero's and are ready for the next step.
What is going to be needed? 1/2" drill bit, 3/8" drill bit and a 1/8" drill bit..... yup no mills just yet, well if you wanted to you could. End mills aren't the cheapest of things, so removing a lot of metal with a drill bit is just plain old cheaper in the long run.
OK note the series of small holes in the lower that's the 1/8" bit don't have to go real deep just a pilot hole to help ensure the bigger bit gets off to a true start without walking around. the holes are located at the following locations x-axis 3.540, 4.065, 4.590, 5.115, 5.608, 6.072 and 6.514 all of these are on centerline except for the one at 5.608 it is .031 off center to the drivers side. the first 4 holes are drilled with 1/2" bit. once chucked and well tightened lower the head until the tip of the bit touches the surface of the lower and zero the Z-axis, move off of the work area and lower the head until the z-axis until the DRO reaches 1.240 and set your depth stop. Yeah I know it's supposed to be 1.250 total depth here trust me I will get to that later. drill the first 4 holes lots of cutting fluid and slower speed maybe about 500-600RPM max. change bits to the 3/8" bit and rest your z-axis as before and again set your stop for 1.240 and drill the fifth hole. The remaining 2 holes are shallower and your depth stop should be set to .615 to .620 and again I know the spec is .630. If you forgot to remove the bolt from your back take down holes....congratulations you just found it with your drill bit
Things should now look like this.
Mill or Drill the next steps will require 2 end mills. 1- 7/16" inch and 1- 5/16" The 7/16" will make the correct radius in the corners and the 5/16" will complete the trigger slot. When choosing the 7/16" mill it is best if the cutting edges are more than 1.250" it will make for a nicer finish. The 5/16" needs to be able to go through the now empty trigger area and cut the trigger slot so make sure the OAL is long enough to reach remembering some of the OAL will be lost in the collet on a mill or chuck on a drill.
In part 3 we'll cover the milling procedure and final steps.
Both pillow blocks are used in this process, for those with a jig your jig is at heart a set of pillow blocks with some holes and plates with holes that mount to the top of the blocks. Once sandwiched in the blocks I use 2- 1/4" bolts and mount them through the blocks and the lowers front and rear takedown pin holes.
Again square up! same process as in part one, the only difference is you are running against the back pillow block. Clamp your work firmly to the table and re-check your squaring. As before when you re-check if it is not square loosen the clamps and re-square it must be squared!
In the picture above note that a couple of scrap pieces of aluminum are being used to hold the work off the table. Even those using jigs and a drill press this is important, mill or drill you will drill through the bottom of the trigger area when you add the trigger slot. Also note the clamp on the rear area this is also important be it a mill or drill. you will remove metal in between the rear take down pin holes. once every thing is tight and secured the 1/4" bolt in the rear must be removed (a bolt will ruin an aluminum cutting end mills day don't forget this).
Note that my 1/4" drill stock is chucked up again, this is to find centers and zero the DRO's. As in part one everything is related to the center of the front takedown pin holes. They are 1/4" so for the x-axis move your table so the drill stock is past the front bolt, lower the head and crank it back until the stock just touches the 1/4" bolt and zero the x-axis DRO. OMG now we do math
this is not the center, the drill stock is 1/4" and the bolt is 1/4" and the outside edges are touching, raise the head and move back .250" so half the distance of both equals .250 or 1/4" not so hard right, zero your x-axis DRO again you are sitting at the center of the front takedown holes. For the Y-axis it is a little more difficult but not much. move the x-axis until you are near the center of the trigger area. move the y-axis beyond either side of the blocks and lower the head. move it back until it just touches the side of the block and zero the y-axis DRO. raise the head and move beyond the block on the opposite side, lower the head and again move it until it just touches the block. yeesh math again, note the value displayed on the y-axis DRO and divide it in half. Raise the head and move the y-axis until it reaches the divided number and zero the y-axis again. you now have the center line of the lower and the middle of the front pins as zero's and are ready for the next step.
What is going to be needed? 1/2" drill bit, 3/8" drill bit and a 1/8" drill bit..... yup no mills just yet, well if you wanted to you could. End mills aren't the cheapest of things, so removing a lot of metal with a drill bit is just plain old cheaper in the long run.
OK note the series of small holes in the lower that's the 1/8" bit don't have to go real deep just a pilot hole to help ensure the bigger bit gets off to a true start without walking around. the holes are located at the following locations x-axis 3.540, 4.065, 4.590, 5.115, 5.608, 6.072 and 6.514 all of these are on centerline except for the one at 5.608 it is .031 off center to the drivers side. the first 4 holes are drilled with 1/2" bit. once chucked and well tightened lower the head until the tip of the bit touches the surface of the lower and zero the Z-axis, move off of the work area and lower the head until the z-axis until the DRO reaches 1.240 and set your depth stop. Yeah I know it's supposed to be 1.250 total depth here trust me I will get to that later. drill the first 4 holes lots of cutting fluid and slower speed maybe about 500-600RPM max. change bits to the 3/8" bit and rest your z-axis as before and again set your stop for 1.240 and drill the fifth hole. The remaining 2 holes are shallower and your depth stop should be set to .615 to .620 and again I know the spec is .630. If you forgot to remove the bolt from your back take down holes....congratulations you just found it with your drill bit
Things should now look like this.
Mill or Drill the next steps will require 2 end mills. 1- 7/16" inch and 1- 5/16" The 7/16" will make the correct radius in the corners and the 5/16" will complete the trigger slot. When choosing the 7/16" mill it is best if the cutting edges are more than 1.250" it will make for a nicer finish. The 5/16" needs to be able to go through the now empty trigger area and cut the trigger slot so make sure the OAL is long enough to reach remembering some of the OAL will be lost in the collet on a mill or chuck on a drill.
In part 3 we'll cover the milling procedure and final steps.
