Indexing jig

How many holes?

I have a small old dumbbell weight that I thought could be used as part of a basic indexing jig on my mill. I’ve not worked out exactly how I’d use it but I’ve been wondering what would be the most useful number of holes to drill on the periphery of the weight once machined? It’s not very large so likely no more than about 36 holes? Maybe even less. Any suggestions?

36 sounds good to me … but 24 is probably adequate

Unless to are particularly fond of 5, 7, etc.

MichaelG.

With the 36 holes (10 degree spacing), you might be able to come up with a vernier plunger/indexing pin to achieve one degree resolution.

Have a look at the standard 5C spin indexer for inspiration.

When you are in the supermarket, have you ever reflected on how the 'ten items or less' checkout is misusing the English language?

Edited By DC31k on 27/08/2023 13:26:22

If you skim off the periphery to make a wider section can you get two rows in? Or a row on each face too. Sometimes it is better to be simple with only 8 holes to make it less likely to miscount.

What Baz says two rows 36 & 40 that is what got used most when I had the Unimat that came with 4 plates. The 5C indexer with it's 36 holes is good but sometimes being able to do 5 or 10 is useful but I've not got round to making a second plate

I've seen dimples next to holes with different colour infill to help locate common combinations

That might be a good 3D printing job - different coloured, different arc length masks for the unused holes (so for 6 divisions in a 36 plate, each single mask from the blue set of six would cover five holes). It would give you a little flexibility of clocking over a dimple in a fixed position. Simple solution might be 35 individual hole bungs.

Not particularly until you mentioned it Michael, now I’m not so sure!

I will give the project a bit more thought and maybe machine the “blank” to see what can be done with it.

127 is a useful (but prime) number. Useful for english to metric conversions. But difficult to make from scratch and somewhat huge.

Tim