You don’t often need to make a second more accurate plate unless your first is made by drilling randomly while drunk. The process improves accuracy by the factor of the worm but that applies when making the job too so probably going to be accurate enough. Presumably you did 6 turns and 9 holes on a 21 hole plate.
If you want the trouble of mounting and using your 14 hole plate you now do 6 turns and 6 holes – you have reduced your number of plate holes from 21 to 14 so 2/3 the number so the final rotation is 2/3 of 9 ie 6.
happy counting.

useful link
https://www.cgtk.co.uk/metalwork/calculators/dividing

If you have a Rotary Table with a 90:1 ratio, you should not need to make a new plate or any extra holes.

The corrected chart (The one supplied with my Vertex HV6 showed inaccuracies and omissions) shows that 14 divisions can be obtained.

14 divisions are obtained by using the 21 hole circle on the B Plate,  rotating by 6 turns and 9 holes for each division.

Howard

On 16 June 2025 at 18:38 larry phelan 1 Said:

Just an update to the above, I have just done another “Test Run ” to check where I went wrong. I was expecting to get 14 holes right away, but of course it does not work that way, you still have to make 6 full turns plus so many holes. This time round, I followed Bazyle,s advice but copped on that I needed 6 Spaces, not 6 holes !

The result was Success !!!

So, thank you both, once again.

In computer coding, this is called a fencepost error. (6 rails, 7 posts)

I suspect it depends on how some visualize or even count certain things. But I do the same and count the spaces instead of holes and then use the next hole after that last space. For whatever reason and how my own thinking processes work, that seems more mistake proof than using the holes. Dividing using full or partial rotations and those division plates isn’t quite as intuitive as it seems without doing a bit of practice first.

I think it’s also worth understanding and depending on how your first generation plates were produced such as using a really good cnc or not. A second generation of plates may or may not be more accurate, or even worth the effort unless its for a plate with different hole counts than the OEM plates already have and the division number required isn’t possible with those.

There’s also inevitable inaccuracies in the worms and worm wheels. And simply because of how there manufactured. My Vertex are only single pointed for the worms, and milled wheel teeth. Much better accuracy would result with high precision form grinding and possibly lapping to reduce and average out further errors after that. Costs for the finished product would be multiple times higher though. Drilled plate holes are also subject to the same issues as any drilled hole has for it’s exact location. Mathematically, a second generation of plates would be more accurate by the gear ratio, but that doesn’t factor in anything else that’s involved. So far I’ve not needed any better accuracy than what I already have, but not everyone is the same.