Dividing Plate Advice

[john dakinParticipant @johndakin59277]

I need to make some dividing plates for my indexing attachment and need some advice on the best way to go about it for best accuracy, i have cad designed templates and have a precision pillar drill and i also have a die sinker/pantograph machine, would it be best to use the die sinker to drill the holes

[john dakinParticipant @johndakin59277]

[Thor 🇳🇴Participant @thor]

Hi John,

I don't know what kind of pillar drill you have, but mine has a table that can be rotated and the arm carrying the table can be rotated on the column. When I made a dividing plate I glued the paper template to the work and clamped it to the centre of the table. Moved the arm slightly so the centre drill lined up with one of the circles on the template. Then just rotate the table until the drill lines up with each mark, lock the table and drill.

Regards

Thor

[Sub MandrelParticipant @submandrel]

Hi John,

Don't forget that, unless you use direct dividing, any errors will be reduced by the worm wheel ratio. So even if they are 10 thou out, the end result will be an imperceptible 0.00025" error.

Neil

[Jens Eirik Skogstad 1Participant @jenseirikskogstad1]

Posted by Thor on 19/02/2013 05:53:39:

Hi John,

When I made a dividing plate I glued the paper template to the work and clamped it to the centre of the table. Moved the arm slightly so the centre drill lined up with one of the circles on the template. Then just rotate the table until the drill lines up with each mark, lock the table and drill.

Regards

Thor

This method Thor recommend can lead to inaccurate distance between holes. Recommended to use indexing head table. The other method: use gear wheel as "indexing plate".

Edited By Jens Eirik Skogstad on 19/02/2013 21:36:05

[BazyleParticipant @bazyle]

Using the die sinker you might be thinking of using a big CAD drawing and using the reduction to improve accuracy. However in practical terms you only get a 2 or 3 to 1 ratio before the end circle is rather small so it isn't gaining much. Dipends on how accurately you can drop the pointer onto the paper. You could do a practice test of that in a linear row of holes. Then fit a pin into any two holes and measure the separation with a micrometer to see what your error is.

Can you be more specific aboutthe 'attachment'?

I think you would be best served by taking the spindle off the Die Sinker and mounting it on your lathe cross slide. The GA and Deckel single bolt hole makes that very easy, to give you a very controllable drill. Then you can mount your plate in the chuck or faceplate for convenience. Then you can start with direct indexing using any change gears you happen to have. Also depending on the lathe a worm lashed up to work on the bull wheel or a change gear gives you a lot of possibilities.

If you have a chinese lathe they mostly seem to come with a 127&100 pair for metric screwcutting conversion. Using one on the mandrel + a worm and the other as the index gives you 12700 division points which is probably close enough to make temporary plates with which to make final plates.

[Thor 🇳🇴Participant @thor]

Hi Jens Eirik,

I agree that the method I described may not be the most accurate, if your workshop is better equipped there are better methods. If the dividing plate will be used in a dividing head with worm and wheel a small error in the dividing plate will be greatly reduced, as mentioned by Neil. You can use the "inaccurate" dividing plate to make a more accurate one if you have a dividing head with worm and wheel, that was what I did eventually.

Thor

[john dakinParticipant @johndakin59277]

Thanks to every one for your very good replies, my skill level is intermediate, and the tools i have at my disposal are 60-1 dividing head with various plates ranging up to 366 divisions, 360 degree indexing table, small lathe and my pantograph with various reduction sizes, im very gratefull for your replies and will give some o them a try, i am trying to make watchmakers dividing plates so as you know they need to be very accurate.

[john dakinParticipant @johndakin59277]

I also have a very good Ajax precision pillar drill

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