Posted by BillS on January 16, 2017 at 15:32:59:
In Reply to: Gleason 3 Inch, Straight Bevel Gear Generator posted by Inshaajee on January 06, 2017 at 07:20:40:
I had some Gleason spur machines that I think were called 3 inch machines. these used segment arms to set the pitch angle, and each pair of arms covered a small range of pitch angles. The arm had a vernier adjustment to fine tune the arm for a specific pitch angle value.
There were index plates that could be "stacked" to achieve the desired number of teeth to cut.
There is an adjustable stop mechanism on the back of the machine to count the number of teeth/cycles to complete the gear and shut the machine off.
There is a roll cam (behind a door on the left bottom) to control motion of up and down swing to complete the cutting cycle for each tooth space. There is an arm adjustment in the cam follower to control the amount of up/down "roll".
The cutter pairs are rack form, mounted on "Clacker boxes". Two machine adjustments are used to set upper and lower clacker boxes each to 1/2 tooth angle. The space at tooth root is determined by cutter point widths of the two cutters and the tooth angle.
To set cutters, there is a bridge gage and proof block used to bring each cutter position to a "0" setting. This gage allows you to remove, sharpen, and reset the cutters to proper position.
Sharpening cutters is not to be done cavalierly. We used to do this free hand on the corner of a stone mounted on a cylindrical grinder (living dangerously), but that takes some practice. The angle of the cutter finishing edge affects the pressure angle of the tooth.
After sharpening the cutters, remove the bur at the tip without dulling the cutters. Easily done by sliding the cutter top surface on a straight machine way. This avoids a bur affecting the cutter gaging process.
This next procedure describes mounting the cutters in their respective clacker boxes, upper and lower.
Taking the upper cutter first, advance the upper clacker box to its extreme cutting position, beyond imaginary toe of gear. Don't go too far, else you would be in the return and retracted path of the cutter. Mount the upper cutter loosely with its two screws to the upper clacker. Adjusting the cutter requires sliding the cutter left or right in the clacker (left raises the cutter tip, right retracts). Place the bridge gage on the machine reference surfaces so that the gage can be swung back and forth above the tip of the cutter. (When you contact the cutter, lift and place the gage to a position behind the cutting tip to avoid dulling the cutter or unnecessarily rubbing the gage plate.)
Move the cutter in its mounting to bring the tip in contact with the pressure plate that actuates the dial. You want to be able to tighten the cutter in position such that dial is reading "0".
Repeat the above procedure to mount the lower cutter. Move the lower clacker to its advance position and use the same bridge gage to zero the tip of the lower cutter in its tightened position.
Adjusting cutters requires loosening the two cutter mounting screws just enough to allow the cutter to be moved left or right to cause the dial to be zeroed. This takes some practice.
A proof block (found in a box made for it) is made for each machine. The proof block duplicates machine center location to set the bridge gage. If your machine doesn't have a proof block, you can still use a bridge gage, but you will need a way to estimate machine center to set the bridge gage. Once the gage is established, don't change it! This gage should be used each time you remove and reinstall cutters.
There is no ratio of roll or other means of pattern control that Gleason incorporated in later machine designs. The 3" Gleason is a good utility machine to cut gears productively, but is not intended to produce gears of high accuracy.
I know this is probably confusing, especially since I don't have pictures. I'm doing this from memory I had four 3" (or was it 2" machines?) back in the day so maybe someone else could join in the discussion.
Feel free to ask questions. If you want to share pictures with me to clarify your questions, that would be helpful too.
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