Hey Sputnik Jig Owners

[Clockwork]

I just got a used Sputnik and am really excited but have a few questions. It doesn't look like one can fine-tune the BB shell center (side to side). It came with a spacer for 68 and 73mm shells which will be fine for lugless shells, but centering a lugged shell seems like it won't work. Am I missing something?

Thanks, Joel

[ToddFarr]

Joel,
Sorry to thread jack, I'm just curious because I'm still learning about what's important in a jig. Are you saying you need the adjustment because the lugged shell can be slightly oversized to begin with? So when you build a lugged frame are you measuring the width and then dividing that by 2 to find your center?
Thanks
-Todd.

[Clockwork]

Joel,
Sorry to thread jack, I'm just curious because I'm still learning about what's important in a jig. Are you saying you need the adjustment because the lugged shell can be slightly oversized to begin with? So when you build a lugged frame are you measuring the width and then dividing that by 2 to find your center?
Thanks
-Todd.

The problem I see is that all BB shells are different widths, so if you're indexing off the right side, the center will be in a different place every time. This isn't such a big deal if you BB shell center is defined, but lugged BB shells have a defined center.

I've already got an idea for a simple part I can make and I have enough metal to do it so I'll start tonight and take pics.

-Joel

[Eric Estlund]

In practice it hasn't been an issue for me.

[Andrew R Stewart]

Not an answer to your question but some jigs allow the BB shell to be located along a shaft, not determined by the shell's edge but with cones held with set screws or split collars.

In looking at the jig in photos it seems that it would be easy to replace the BB post with a shaft and cones. Or you could face the business side of the shell to the correct dimension before building. Andy.

[prolix21]

Or you could face the business side of the shell to the correct dimension before building.

Any concerns about possible heat distortion during the building process if you face it first?

[Clockwork]

I'm going to give this a shot. The adjuster has a nice slip-fit over the post so the set-screw shouldn't through things off too much.

[dbohemian]

The problem I see is that all BB shells are different widths, so if you're indexing off the right side, the center will be in a different place every time. This isn't such a big deal if you BB shell center is defined, but lugged BB shells have a defined center.

I've already got an idea for a simple part I can make and I have enough metal to do it so I'll start tonight and take pics.

-Joel

I am with Eric on this. Non issue. If you BB shell is very wide than you can chuck it up in your lathe with and internally expanding collet and face down the edge facing the fixture. I blue print all my BB's anyways and leave just a bit for final facing.

Seems complicated to try and modify the fixture as opposed to just making your shells correct and honestly has a 10th of a mil ever made a big difference anyhow?