Broaching Drivers

[prrf3c]

After the discussion about working on Drivers in the Pennsy Power 3 thread, I decided to post some pictures of the process that I used to broach the drivers for my 1.6 PRR F3c loco. Some of this is a repeat from the other thread except that I added pictures....and everyone loves pictures. ;D

Pic 1:
I bored the centers of the wheels on the lathe, then I made pin that had a nice sliding fit into the wheels. I mounted this pin on to my milling table. The pin has a hole in the middle so I used a T-nut and bolt to mount it onto the table. I indexed the spindle of the mill to the center of the pin and then offset the spindle the correct distance in the X axis for the crank pin hole. I placed each driver onto the pin and rotated it until the spindle lined up with the centerline of the crank pin boss.

[prrf3c]

I clamped the driver down on parallels so that I don't drill into the table. Then I drilled and reamed the crank pin holes.

[prrf3c]

I now that I have all the axle holes and crank pin holes exactly the same, I made a fixture that referenced both the axle and crankpin holes and locates the broach in the correct location.

[prrf3c]

The next step is to broach the wheels. I took liamlocomotive's (Andy's) advice and broached a matching set of wheels with the wheels back to back.

Here is a picture of the front set of drivers

[prrf3c]

Just as a final test to make sure that the keyway was in line with the axle hole and crankpin hole, I placed the maching set of drivers front to back, (I broached them back to back) placed the pins in, and then placed the key in the keyway slot.

[pkastagehand]

What a lovely, clear explanation and almost self explanatory pictures. These kinds of explanations with photos are so interesting and helpful for those of us who haven't done this before.

Thanks!!!!

[prrf3c]

pkastagehand said:

What a lovely, clear explanation and almost self explanatory pictures. These kinds of explanations with photos are so interesting and helpful for those of us who haven't done this before.

Thanks!!!!

I'm glad that you like it! This is not the only way to broach drivers, it just seemed to work the best for me.

[liamlocomotive]

Looks good to me, too, Brian.

I'm working on getting some pics of my freight car wheels during the finishing operations posted. Hopefully, I can get them scanned in the next day or so and posted.

Andy

[pockets]

Brian, you have answered questions I haden't even thought to ask, yet. Thank you.

Greg

[Bill Holland]

Thank you for posting those pics, I've only read about doing it that way, never seen pictures of it being done, thanks.

[prrf3c]

I'm glad everyone like the pics and thanks for all the kind words. If anyone has any questions, just shoot away.

I'm in the process of getting the tires ready to shrink onto the drivers. Maybe next week I'll have a step by step pictures of shrinking the tires on.

Andy, can wait to see some progress on those car wheels!

Brian

[liamlocomotive]

Hi Brian,

The wheels are done. All 40 of them. 32 of them are 4.25" and 8 are 5" for 2 motor cars for friends. That will give me a caboose and 3 more cars. The pics are in the camera at the moment. Hopefully, I can get them transferred to a floppy tonight or tomorrow so I can share them.

I still need to make 14 4.5" and 4 5.25" wheels for a future project. I haven't decided whether to do them in 1.5" scale or 1.6". Sizes will vary accordingly....

Andy

[GoldenSpike53]

Hey, Brian, great photos, and a well-done job.

Just as a means of letting everyone know that there are more than one way of skinning a cat, or cutting a keyway that is correctly aligned with the crank pin hole, I will try to explain something that Chad Goedeke, who is in a model engineering group here in the Sacramento area, showed me for doing this job.

He makes a jig composed of a flat rectangular plate with the axle hole and keyway cut in it, then adds a piece of round stock for the axle and a key attached for the keyway. At the other end of the plate, he has a hole cut out for the crank pin hole, which he uses to locate and cut the crank pin hole. This method also makes sure that the crank pin hole is exactly aligned to the keyway on each wheel, but does so with almost exactly the opposite approach as does Brian's method.

It's interesting to see the varying methods used by different machinists to accomplish the same task.

Dale Dennis

[patyoung]

Brian,

I will bookmark this message if I ever need to see how to broach something!

Regards,

Pat Y.

[prrf3c]

goldenspike53 said:

Hey, Brian, great photos, and a well-done job.

Just as a means of letting everyone know that there are more than one way of skinning a cat, or cutting a keyway that is correctly aligned with the crank pin hole, I will try to explain something that Chad Goedeke, who is in a model engineering group here in the Sacramento area, showed me for doing this job.

He makes a jig composed of a flat rectangular plate with the axle hole and keyway cut in it, then adds a piece of round stock for the axle and a key attached for the keyway. At the other end of the plate, he has a hole cut out for the crank pin hole, which he uses to locate and cut the crank pin hole. This method also makes sure that the crank pin hole is exactly aligned to the keyway on each wheel, but does so with almost exactly the opposite approach as does Brian's method.

It's interesting to see the varying methods used by different machinists to accomplish the same task.

Dale Dennis

Good Point Dale,

The method that you mentioned is how I was originally going to do this job. The only reason that I did it the way that I did was because I had a fear that the crank pin hole would not come out in the center of the crank pin boss. If I didn't broach the key way right on the centerline, then when I went to use the fixture to drill the crank pin hole. The hole would be off to one side of the boss. This would only effect the looks not the function, and you'll probably never notice it but I was just being picky.

Thanks,
Brian