Look what the metric system has made me do!

A friend came in with a bandsaw blade tracking device. The bearings on it were originally imperial (3/4") but they are getting hard to find in Australia, so he asked if I could copy the imperial tracking spigot and make it so he could run 20mm bore bearings instead.
Why not I said...

[@Kryn-ie1vs]

As per usual, excellent work and a handy tip ,re depth of circlip groove.

[@occasionalmachinist]

Thanks. Circlips are one of those parts that are really easy to not get to work properly.

[@JB-ol4vz]

Always a very nice job. As a hobby man, why not make the square and then bore to a press fit for the shaft? Cheers from Sweden 🇸🇪

[@occasionalmachinist]

LIke sleeving, that would be another way to do it. My concern with that is strength - the original part has a radius at the base to smooth out the stresses a bit. A straight shaft pressed into a hole would be prone to pulling out (the square part is only around 7mm think) and probably stress that area highly.

[@624Dudley]

Quite a good outcome 👍

[@occasionalmachinist]

We've taken it down to final size and it fits the bearings well, so 👍👍!

[@zoltannagy1813]

Nice result.

[@occasionalmachinist]

Thanks

[@graedonmunro1793]

nice vid, cheers

[@occasionalmachinist]

Thanks

[@marley589]

Could the original be turned to 5/8" diameter and a 20mm tube pressed on?

[@occasionalmachinist]

In theory it could, but you would need to accurately bore the tube and turn the spigot, fit the sleeve well enough that it would not spin or come off then turn the OD accurately. That's 3 times more precision work than in making a new one.

[@tates11]

Drill + ream + groove a piece of 20mm rod 16mm and push on. The concentricity and position aren't important. Make this first then turn the original part to suit the bore.

[@occasionalmachinist]

@@tates11 You could try doing it that way, but I think you are over simplifying how it could be done.
For example, if you groove the sleeve first and your fit is not right, will you end up crushing the groove?
The spigot needs to be perpendicular to the axis of the pivot, otherwise thereis a risk of the blade not tracking properly. Sleeving would mean that a method would be needed to ensure that.
There are considerations either way.

[@tates11]

As the spigot and tube are relatively long and not subjected to any significant relative forces I would use a slip fit and loctite. The geometric precision would come from clocking the original spigot in the 4 jaw chuck and reducing the diameter to a slip fit.