With the grinding head mostly machined, I now need to fasten the motor mount to the head. I was going to use a shoulder bolt but opted for a brass bushing.
Here you can see a 1/2" bolt which is a good slip fit into the bushing I made. The bushing is a couple thousandths longer than the distance of the motor swivel and the recess in the grinding head. when assembled and tightened, the bushing is captured by the bolt and the swivel rotates on the brass bushing easily but with no detectable end play. The swivel only has .001" clearance all the way around its circumference. this assembly is very precision and has no play anywhere. This is why it was important to be precise on sizes and everything had to be very concentric to have no binding. The assembly works great.
The swivel is mounted in this photo and works extremely well.
The motor plat mounts and covers the bolt. There will be 4 holes in this plate for the motor to bolt to. Next is the split cotters to lock the motor in position.
This is the print for the brass split cotters. I chose to use two for security although one probably would do the job.
The split cotters are in place and work perfectly. If you look at t he print there is a spring pocket in one half of the cotter. I put a spring in between the two halves so when loosened they separate and release the motor swivel.
I tapped the one side of the head and the other side is clearanced for a 5/16" bolt. The top and bottom bolts are tightened just enough to give a nice sliding head with no slop. the center bolt will be tightened to lock the head in place. this takes a maximum of a quarter turn because the other two hold it so close. I will make a special bolt with a handle for the center bolt later on. The heavy steel washer are close fit and prevent the bolt from digging into the aluminum.
The grinding head is mounted to the 2" column. Everything came out perfect so far.
I made a brass pointer that will be somewhat adjustable for indicating the position of the motor tilt. I will not fasten this until the complete grinder is assembled so it will read zero with the motor and grinding wheel mounted. ( It will also get polished to a nice shine.
The anti back lash lead screw nut is mounted on the head. It is as close as possible to the column to make the elevating easier. ( it has to work harder the farther out it is.)
The next step here will be to make the upper and lower lead screw brackets. One at the top of the column and one at the lowest travel point on the column. Once they are mounted the head will not be able to rotate . The whole column assembly will rotate to change the angle. The head will retain its position because the acme lead screw will prevent it from rotating. I found this worked very well when I built the Bonelle grinder. The precision nut keeps the head from having any play in the rotational axis.
The reason for the massive size of the head is because the 48 frame motor weighs 13 pounds and I wanted a lot of rigidity in this machine.
I was thinking of painting the head with black wrinkle finish, but first I am going to polish the aluminum to a mirror finish and see if I like that better. The head is complete to where it is time to polish it
Here you can see a 1/2" bolt which is a good slip fit into the bushing I made. The bushing is a couple thousandths longer than the distance of the motor swivel and the recess in the grinding head. when assembled and tightened, the bushing is captured by the bolt and the swivel rotates on the brass bushing easily but with no detectable end play. The swivel only has .001" clearance all the way around its circumference. this assembly is very precision and has no play anywhere. This is why it was important to be precise on sizes and everything had to be very concentric to have no binding. The assembly works great.
The swivel is mounted in this photo and works extremely well.
The motor plat mounts and covers the bolt. There will be 4 holes in this plate for the motor to bolt to. Next is the split cotters to lock the motor in position.
This is the print for the brass split cotters. I chose to use two for security although one probably would do the job.
The split cotters are in place and work perfectly. If you look at t he print there is a spring pocket in one half of the cotter. I put a spring in between the two halves so when loosened they separate and release the motor swivel.
I tapped the one side of the head and the other side is clearanced for a 5/16" bolt. The top and bottom bolts are tightened just enough to give a nice sliding head with no slop. the center bolt will be tightened to lock the head in place. this takes a maximum of a quarter turn because the other two hold it so close. I will make a special bolt with a handle for the center bolt later on. The heavy steel washer are close fit and prevent the bolt from digging into the aluminum.
The grinding head is mounted to the 2" column. Everything came out perfect so far.
I made a brass pointer that will be somewhat adjustable for indicating the position of the motor tilt. I will not fasten this until the complete grinder is assembled so it will read zero with the motor and grinding wheel mounted. ( It will also get polished to a nice shine.
The anti back lash lead screw nut is mounted on the head. It is as close as possible to the column to make the elevating easier. ( it has to work harder the farther out it is.)
The next step here will be to make the upper and lower lead screw brackets. One at the top of the column and one at the lowest travel point on the column. Once they are mounted the head will not be able to rotate . The whole column assembly will rotate to change the angle. The head will retain its position because the acme lead screw will prevent it from rotating. I found this worked very well when I built the Bonelle grinder. The precision nut keeps the head from having any play in the rotational axis.
The reason for the massive size of the head is because the 48 frame motor weighs 13 pounds and I wanted a lot of rigidity in this machine.
I was thinking of painting the head with black wrinkle finish, but first I am going to polish the aluminum to a mirror finish and see if I like that better. The head is complete to where it is time to polish it
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