rotery table

Hello all I'm needing a wee bit of help setting up my rotary table,need to cut 125 divisions. my table turns 90 degrees per turn of the crank , how do I calculate it and what index plate should I use. My chart only goes to 100 divisions . Thanks for your help. Farmer Dave

Hi

A lot will depend on what indexing plates you have available, ideally you want one with 25 holes.

90/125 =18/25, so each division works out at 18 holes on a 25 plate.

Phil

90 degrees per turn of the crank sounds a lot. Normal dividing heads are usually 40 to 1 giving a 9 degree movement or or ten turns for 90 degrees.

Just looked at the chart for my 90:1 Hofmann rotary table and there is no 25 hole circle plate with it.

So you might need to make that first. I am assuming you will have a 20 hole circle available as I do.

90/25 = 18/5 = 36/10 = 72/20 which gives 3 full turns and 12 holes on the 20 circle.

Then use that plate to do your 125 divisions as above.

Phil

90:1 which is quite common on rotary tables 4deg per turn

Edited By JasonB on 29/10/2015 20:04:34

Sounds wrong, I suspect 90 is a typo and the OP means 9 degrees per turn (40:1 ratio).

Which gives (25*40)=1000 holes per rotation

1000/125=8 holes =per division

Or with a 50-hole plate, 16 holes per division.

Neil

Jason its not 4 degrees per turn but 4 turns for 360 degrees.

Unusual to find rotary table or dividing head with 4:1 gears (well 1:4 really).

I feel a misunderstanding might be afoot here.

Ian P

Its a rotary table many of which run a 90:1 gear which gives 4 degrees per turn.

40:1 - 9deg per turn is more commonly found on a dividing head but the OP is asking about a rotary table. I've never seen a rotary table with 40:1

The OPs typo is that he put 90deg/turn not 90:1

Edited By JasonB on 29/10/2015 20:20:10

There are lots of online calculators online. Need to download them though. Don't work on my iPad.

If I knew how to add a spreadsheet to this page, I would show you how to work out divisions available using a system of factors.

Phil

Hi Guys Sorry for the confusion/mistake on my part ,my table is indeed 90:1 gearing. thanks for all the replies.

25 hole plate

Index every 18 holes

... I think.

MichaelG.

What if he doesn't have a 25 hole plate though ?

Phil

.

Make one

or improvise

MichaelG.

I'm just having a light hearted dig really, did you see my original posts at the top of the page.

Phil

No 25 hole plate is a glaring error on the B&S style plates.

Once done everyone copied them and this was at a time when 125 and 250 division were ripe on inperial hand wheels.

Myford list doing a 125 division with their dividing head and to use 12/25 but they don't list a 25 hole on any of the 4 plates.

When we make the Myford plates No's 1 and 2 are direct copies but No. 3 has 127 holes extra and No. 4 has 50 holes extra.

Our B&S style plates have 25, 63 and 127 holes extra, one on each of the 3 plates.

Hi

If my calculations are right then 125 divisions can be obtained as follows:-

For a 40:1 table then an index plate with either 15 or 20 holes can be used

15 hole plate    Index at 24 holes or 1 complete rev plus 9 holes

20 hole plate    Index at 32 holes or 1 complete rev plus 12 holes.

For a 90:1 table the same index plates can be used

15 hole plate    Index at 54 holes or 3 complete revs plus 9 holes

20 hole plate    Index at 72 holes or 3 complete revs plus 12 holes

The divisions will not be cut/marked sequentially but after 125 sequences the full set should be cut/marked.

Cheers

Martin

Edited By Martin W on 30/10/2015 01:00:03

Edited By Martin W on 30/10/2015 01:01:02

.

I must have seen but not Noticed ... I had pretty much dismissed everything written in answer to the original [wrong] question as being idle speculation.

You were obviously correct, and may be psychic.

MichaelG.

Martin, on the charts 72 holes on a 20 plate is for cutting 25 divisions, surely if you keep going round the same all you are doing is recutting the same 25 divisions

Jason

Just checked and you are correct and the error could apply to all the values I came up with. Evidently posting too late at night and not thoroughly checking my calculations . Thanks for pointing it out and readers please ignore my post above re division ratios.

Cheers

Martin