SM change gears - Imperial 1120 for metric gears

8

88hillman

Member
@Brent H how does the banjo fit over the oiler on the quick change input shaft? When I was considering making the banjo in the first place I assumed it needed to pivot around the input shaft, but the oiler on there complicates things. Just pull the oiler out and install in the banjo so you actually oil THROUGH the banjo?

1710389917250.png
 
Brent H

Brent H

Ultra Member
IMG_6350.jpeg The banjo has the oiler fitted to it and the other oiler is removed. The banjo pivots on the flange of the gear box. A bolt hole needs to be drilled and taped into the gear box to allow the banjo to be secured after the backlash is established on the drive gears.

You will see a raised area on the banjo for the oiler cup. I believe there is also a relief slot in the banjo so that the oil passage is not blocked when the various gears change the rotation of the banjo.

My USB drive is having issues and we are going to try and transfer all my files over to another drive - fingers crossed here as my drive has a load of info …..
 
8

88hillman

Member
Thanks for the info @Brent H ! That makes complete sense. My 1120 does have a tapped hole in front of the input gear boss in what seems like the correct location to secure the banjo.

A friend of mine let me know that he has a 3D printer now so he's able to print for me. That could either be indexing plates for a dividing head or the gears themselves. I believe I've got enough information to develop a drawing for the banjo that should work, even if it's not a match to an original. That's probably where I'll focus for the time being and get some drawings/models sent to my friend for the following gears to test everything:

16DP 14.5PA
- 68T idler (wide)
- 48T (with hub)

24DP 14.5PA (or Mod1 20PA)
- 127T
- 80T
- 50T

This is seems like the fastest way to get up and running. I'll still need to make the standoff/shaft for the banjo to mount the intermediate gears.
 
8

88hillman

Member
This morning I looked again to see if it was possible to pivot the 83T idler gear to the back of the lathe rather than swap it out for a 68T and move the idler axle to a new hole. The headstock drain is in the way. It would be necessary to remove the standoff pipe and put a pipe plug directly into the headstock. The new intermediate gears would also likely foul the door, even the 48T that would remain on the lathe full time.
20240316_064141.jpg
 
8

88hillman

Member
I placed an order for a set of steal mini lathe gears. The set of 27 gears includes all the change gears I need except the 127T. Since they are all Module 1 20PA it will be easy to get different ones in the future too. That leaves the 48T and 68T 16DP 14.5PA gears to find since they need to match the existing gears.
 
Susquatch

Susquatch

Ultra Member
Administrator
Moderator
Premium Member
88hillman said:
That leaves the 48T and 68T 16DP 14.5PA gears to find since they need to match the existing gears.
Click to expand...

Or, you could just change everything...... And be done with it.

Or just cut those particular gears.
 
Brent H

Brent H

Ultra Member
@88hillman I was able to salvage my USB and transfer data over to a jump drive. The forum does not support uploading a DWG file - If you PM me your email I can send you what info I have. I have the banjo and gear layout - did not dimension it yet as the project stopped when I got the metric lathe, however, should be easy enough to do. I believe I was working out what mods to the lathe were required?? I think the idler pin requires a move up on the plate for the smaller 68 tooth gear.

Gear Layout.jpg

Metric gear banjo.jpg
 
YYCHM

YYCHM

(Craig)
Premium Member
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