KeithB
Resident Half Fast Machinist
One of our customers wanted us to make some brackets for mounting one end of a hydraulic cylinder. The small quantity involved (about 100 or so pieces) makes production methods such as die casting in one shot or extruding and machining impractical. The only way to make this small quantity is by machining the part from a solid billet.The basic part is 1" x 1" x 2.5". Our customer wanted us to make them out of 1" x 1" stock. While that would use the least amount of material it would mean the the cutters that would cut the material away to make the ears would be spending a lot of time entering and leaving the cut. It would simply not be cost and time effective. My way to make the part is as follows:
1. Cut a 1" x 3" bar into pieces 12" long. This gives me 12 pieces from a 12' bar.
2. Drill the 20 mounting holes for 10 pieces spaced on 1.2" centers. Center drill holes along the edge of the piece on 1.2" centers offset by .6" from the mounting holes. These will be used as a guide when cutting the pieces off in the cutoff saw.
3. Flip the piece over and cut away all the material to generate the profile. Note that the root of the ears have a .12" radius and not a sharp corner. A special 1/2" diameter end mill with .12" radius corner was used for the finish passes.
4. Cut the individual pieces apart.
5. Mount the pieces in a fixture and mill the profile of the base.
6. Mount the pieces in a different fixture and mill the profile of one ear and drill a hole in one ear. Flip the piece 180 and do the other ear.
To make this piece I had to write 8 CNC program, make a special set of vise jaws, and two fixtures, one with several parts. If we make more of these we will be set. I will note that the base milling fixture required handling two 5-40 screws to mount the part. When I made the ear milling/drilling fixture I opted to make a fork clamp and screw that is held captive so no fiddling with little bitty screws.
The basic part. Looks a lot like a bracket for a bathroom stall wall. We checked. Nothing off-the-shelf available.
A screen shot of how I see a gang of parts.
A screen shot showing the parts in the billet. The dashed lines show where they will be cut apart.
Had to make a set of 12" long vise jaws to hold the foot long billet properly.
Here is a shot of the bottom of the 12" bars showing the bolt holes and cutoff center drill spots along edge.
Here is a shot of a bar mounted face up. You can see the profile and the mounting holes along either side.
Here is a corner radius end mill used to finish sides and bottom of ears with proper root radius.
Here is bar getting cut into individual pieces. Note saw blade lined up over center drill spot.
1. Cut a 1" x 3" bar into pieces 12" long. This gives me 12 pieces from a 12' bar.
2. Drill the 20 mounting holes for 10 pieces spaced on 1.2" centers. Center drill holes along the edge of the piece on 1.2" centers offset by .6" from the mounting holes. These will be used as a guide when cutting the pieces off in the cutoff saw.
3. Flip the piece over and cut away all the material to generate the profile. Note that the root of the ears have a .12" radius and not a sharp corner. A special 1/2" diameter end mill with .12" radius corner was used for the finish passes.
4. Cut the individual pieces apart.
5. Mount the pieces in a fixture and mill the profile of the base.
6. Mount the pieces in a different fixture and mill the profile of one ear and drill a hole in one ear. Flip the piece 180 and do the other ear.
To make this piece I had to write 8 CNC program, make a special set of vise jaws, and two fixtures, one with several parts. If we make more of these we will be set. I will note that the base milling fixture required handling two 5-40 screws to mount the part. When I made the ear milling/drilling fixture I opted to make a fork clamp and screw that is held captive so no fiddling with little bitty screws.
The basic part. Looks a lot like a bracket for a bathroom stall wall. We checked. Nothing off-the-shelf available.
A screen shot of how I see a gang of parts.
A screen shot showing the parts in the billet. The dashed lines show where they will be cut apart.
Had to make a set of 12" long vise jaws to hold the foot long billet properly.
Here is a shot of the bottom of the 12" bars showing the bolt holes and cutoff center drill spots along edge.
Here is a shot of a bar mounted face up. You can see the profile and the mounting holes along either side.
Here is a corner radius end mill used to finish sides and bottom of ears with proper root radius.
Here is bar getting cut into individual pieces. Note saw blade lined up over center drill spot.