Need chart for a Excel Rotary table.

I have a 10" Excel rotary table and need a chart for it. It is 10", 90 to 1 turn, and 40 division dial. No dividing plates with this model.

If the charts for your table are anything like the ones going the rounds for "Other Makes" being sold,you might be as well off without them and try pot luck,or buy a Lotto Ticket.. The errors in these charts have to be seen to be believed.

Dont ever try cutting gears using them !!

Might be OK for planting spuds.

When you say a chart, what do you want it to tell you, especially as it doesn't have any plates? Obviously one turn is 4 degrees, and one division a tenth of a degree. As it has a 90 tooth wheel, any tables for a 90 tooth wheel will apply such as those for the Myford DH, of which I have a copy somewhere. That would help you if you had the plates. But actually it's easy to work out without the tables.

I had no charts with my rotary table (good price, second hand, a long time ago). I have no wish of any charts, especially after reading of the errors here and elsewhere.

Calculating, from basics, is easy enough (for me) for the few settings I am likely to need at any one time. It most certainly is not rocket science.

Plenty of accurate charts are available via google.

Charts are for plates though, they give you the number of holes and which row etc.

I made a very big tactical error. The dial has 48 divisions instead of 40. My bad.

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Then ... Assuming that it does really have a wormwheel ratio of 1:90

90 x 48 = 4320

4320 ÷ 360 = 12

so 12 divisions on the dial gives 1° of table rotation.

Which seems fairly practical.

MichaelG.

There is a spreadsheet (and a chart) on the HV6 thread, showing the calcs for my 90:1 HV6 after i found the maker's chart to be dubious.

After some calculations, and with the help of the Chart, you could start making up your own Division Plates, if you can't find any for sale anywhere. With each new plate, you should be able to make the others that you might need. In any case it would be useful experience.

With regard to the comment "Don't use it for gear cutting"

I do, and have, (probably more than any other use) almost from when I first bought it. (DP20, Mod 1, Mod 1.25, Mod 1.5 so far), as well as graduating plates, and milling radii.

It was cutting a 13T gear that highlighted the errors in the Vertex HV6 chart. And, if i was to repair my smash up, I HAD to find a way of correcting things!

Someone gave the very useful tip to make up a peg, to act as a stop, and reference point for the fingers, (obviously move it around as the fingers are repositioned).

Good luck

Howard

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I may be wrong, Howard, but I think Larry's comment was refering to the dodgy charts [them], rather than the rotary table [it].

MichaelG.

No offence taken! Sorry if I misunderstood the comment.

But if the charts are inaccurate they are useless for spacing holes, gear teeth or anything else. As I found out to my cost. It wasted three days of my time, and material to discover that it was not my counting at fault, but the ****** chart supplied with the RT. (* errors or omissions) A day or more on the PC with EXCEL resulted in a spreadsheet and chart which appears to be accurate.

Am beginning to wonder if I could produce one or more Division Plates to fill in the gaps / extend the range.

All that I need is the courage to do it!

Possibly, amending the Ratio formula in the spreadsheet, would enable a chart to be produced for Rotary tables / Dividing Heads with different ratios, such as 40:1 which seems to be a popular one.

P S At 10", that's a big RT.

Howard

Edited By Howard Lewis on 07/04/2018 14:57:57

Does one need a chart as long as the method is known and understood?

But I'm still puzzled why the the OP needs a chart when he doesn't have the plates!

Edited By John Haine on 07/04/2018 16:08:52

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Howard,

You may be interested in the way I tackled this, many years ago:

... the following is copied from my post on the third page of **LINK**

http://www.model-engineer.co.uk/forums/postings.asp?th=117379&p=1

It doesn't produce tables, or fancy graphics, but it does give the 'first solution' for any number of divisions.

** warning: some modification would probably be required for other dialects of BASIC **

MichaelG.

_________________________________

For anyone with 'BASIC' nostalgia:

Here's how I did it on the Commodore 64, in 1993

DIVIDING.BAS

100 PRINT CHR$(147)
110 PRINT "RATIO = ";
120 INPUT RATIO
130 PRINT "DIVISIONS = ";
140 INPUT DIVN
150 HOLES%=0
160 HOLES%=HOLES%+1
170 MAX=RATIO*HOLES%
180 LOT=MAX/DIVN
190 IF LOT=INT(LOT) GOTO 210
200 GOTO 160
210 TURNS=RATIO/DIVN
220 T%=INT(TURNS)
230 PLUS=LOT-(T%*HOLES%)
240 PRINT CHR$(147)
250 PRINT RATIO;":1 ";DIVN;"DIV"
260 PRINT T%;"+";PLUS;"/";HOLES%

Yes indeed,I was refering to the charts,sorry if I caused any misunderstanding. The tables sometimes have their own problems ! How do I know ? Dont even ask !

Michael

Thank You.

Unfortunately, I disposed of any machine using BASIC, a few years ago, but the logic remains the same.

Have just spent the last couple of hours copying the table of possible divisions with a 90:1 ratio device, onto my PC from Harold Hall's book on Dividing, Workshop Practice Series No 37. (Might come in handy one day)

To my immense joy, it does not call for any other than the three plates that I already have, and covers from Divisions 20 to 360, but obviously there are gaps.

No doubt with extra plates, some, if not all, of the gaps could be filled, if required. Maybe, one day, I'll get round to making another couple of plates, to fill more of the gaps, but don't hold your breath!

Possibly some of the errors found result from misreading poorly handwritten written characters. Whatever the cause, the errors cause a lot of folk a lot of anger, frustration and waste. Not to mention time spent making calculations to correct the errors!

At least, after some calculations, the OP has the means to produce one some plates for his large Rotary Table.

Mark,

If you want to know the number of holes on the plates supplied with the HV6, (which is also 90:1) please PM me, and i will supply the details for each of the three plates, (and the extra two that MAY, one day, be made to supplement) They can be made in an enlarged form to fit your Excel, and you will then be in business.

Howard

How would I mount the plates? It did not come with any and I have never heard of this being mentioned before this. I thought the ones that had plates were made that way. You Guys make figuring this stuff out look really easy, sort of like watching a welding video.

Edited By mark costello 1 on 07/04/2018 20:45:37

To be honest, Mark ... you could do a lot without any plates.

The combination of a 90 gear and 48 graduations on the dial will give you a wide choice of divisions [excepting those that involve the awkward prime numbers like 7, 11, 13, etc.]

Pick a few numbers you might want to use, and I will try to demonstrate.

MichaelG.

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P.S. Adding a stepper motor to your table might actually be simpler than mounting plates.

Eurika, I see says the blind man. I did the maths and was getting 4 graduations on the dial was .333. Getting 4 divisions to a degree makes every graduation worth 1/4 degree,makes sense now.

Well done, Mark ... it sticks in the mind better when you've worked it out for yourself.

Sooner or later you will also want to know what numbers of equi-spaced holes, or gear teeth, you can conveniently index:

I mentioned 4320 yesterday ... Pop that into this calculator, and select 'Verbose Mode' **LINK**

http://www.mathwarehouse.com/arithmetic/factorization-calculator.php?

MichaelG.

And one division is 5', rather less awkward than 6' - if your drawings are specified in degrees and minutes, of course.

Neil

On the HV6-type RT removing the winding handle reveals 3 screw holes that hold the plate mechanism. The mechanics are quite simple - you add a sort of clock pointer to the existing handle that allows you to index a peg into holes drilled in a dividing plate. All it does is help you keep count when keeping count isn't bleeding obvious. Like cutting a gear with say, 27 teeth, you have to repeatedly do things like 'turn the handle completely 4 times and then go past 7 extra index holes'  to get the right angle. The tables tell you which plate and set of holes are needed to achieve a given tooth count; the clock pointer follows the position of the extra indexing so you don't forget where the new start point is.

Easier to do than describe but I make mistakes galore. Instead I built a stepper-motor controlled by an Arduino to do the maths and the winding. It's just as easy to set up, you don't need any tables or thinking, and it never gets bored and loses the plot like I do.

Dave

PS Speaking of losing the plot, I typed this post while waiting for my meal to cook.  Just discovered I forgot to put it in the oven.  Back to square one...

Edited By SillyOldDuffer on 08/04/2018 19:16:56