Walter Rotary Table

[pete]

Hi Ted,
I've been giving this some thought off and on since you first posted your R/T questions. There's certainly not much information around about that brand of R/T. I'd guess it was a fairly high end piece of equipment and very well made, and the odds of finding the exact dividing plates are about at the lottery lucky level.

120-1 also seems to be a fairly rare dividing ratio.Have you pulled the handwheel and dial off yours to see if the casting behind those parts has been drilled and tapped so dividing plates can be used, or at least your R/T was originally designed to use them? If not, you might need to set up your R/T casting and use X,Y calculations to get the mounting holes drilled and tapped in the correct locations.

Without lucking out and finding the correct plates for a 120-1 ratio table, then it looks like you may need to go thru the mind numbing task of building your own. I've got a book recommendation for you. "Workshop Techniques" written by George H. Thomas. ISBN 1 85761 106 3 It's about 40 bucks including shipping, and sold thru Tee Publishing or Hemingway Kits, both are in the U.K. The Ebay sellers over here usually want about $70-$80.

Half of the book deals with building a 60-1 dividing head from castings. But it gives more than enough information and how to do the calculations along with a lot of excellent tips about building the plates and the sector fingers that it would be more than worthwhile for yours. Even doing a proper job drilling the holes in those plates is a lot more complicated than the average person would think to do it right. If you've got to build your own? Then that $40 will seem like nothing in comparison to the time involved. Personally I wouldn't attempt that job without the book.

Pete

[shootnride]

Hi Pete,
First off, thanks very much for taking the time to respond to my post. Yes, I have removed the handle and outer vernier dial and it does appear that the unit could easily use dividing plates. There are four tapped holes on the inner stationary dial. I hate to seem so ignorant about this whole subject, but I have never used a dividing head or RT with dividing capability. Actually, I'm fairly recently retired, always wanted to learn machining, and at 65 am now beginning my self-taught machinist apprenticeship.

I found a used copy of the book you recommended on Amazon for $81.00 but haven't checked the websites you recommended yet. I'l be doing that later this evening. I agree with you about having a resource like that before tackling a project like making my own plates. I was originally thinking that it would be much easier to just buy plates that could be adapted to my RT with a little machining, but after digesting the information from you and folks on this forum, I think I need to do a lot more homework before jumping into this. I do have the capability to make my own plates but was looking for an easy way out

Thanks again for your help. I'll let you know how I progress.

Ted

[pete]

Hi Ted,
Well IMHO, your miles from being ignorant. You've obviously done enough research to come up with some clear and concise questions. So we now know your table was originally designed to use the dividing plates, so that's one step already done for you.

LOL, I'd do the same for trying to come up with the easiest solution. But those Ebay sellers are a total ripoff. A new book is 40 bucks. 2 weeks tops for delivery. That book will save you far more than it's cost just in frustration.

As I mentioned, the book is not an exact match for your situation, but all the required info can be worked out by using it..........................along with some questions on this forum also while your working out just how to do it.

Pete

[mklotz]

If you go to my page and download the DIVHEAD archive you'll find it contains a program called DPLATES. This program will tell you which hole plates you need to make all divisions up to some user-specified maximum.

Here's a sample output from that program...

============================================


REQUIRED DIVIDING HEAD HOLE PLATES

DH worm gear ratio [40] ? 120
Maximum number of divisions needed [50] ?

Hole plates required for all divisions up to 50
4,5,9,11,13,17,19,23,29,31,37,41,43,47,49,

============================================

Note that it will yield a minimum hole drilling solution. You can, if you wish, combine some of these hole circles into a single circle. For instance the 4 and 5 hole circle could be combined into a single 20 hole circle in this example.

Once you have your hole plates, you may want to investigate the DIVHEAD program also included in that archive. It will, given number of divisions required, tell you turns and holes required for that job.

[shootnride]

Hi Marv,
Thanks very much for the link to your Home Shop Freeware site. There's so much good stuff on there that I got side-tracked and almost forgot what I was looking for. I did download the dividing head program and finally got everything working on my computer except the DIVHEAD OUT program. But, I can still figure out the number of turns and holes required with the other information. Also, I did quite a bit of research today on this subject and found that my Machinery's Handbook has a chart for a 60:1 ratio which works fine for my 120:1 by just using a multiple of two for all of the incremental values. This has been an educational experience so far and has shaken loose some rust.

Ted

[mklotz]

Hi Marv,
Thanks very much for the link to your Home Shop Freeware site. There's so much good stuff on there that I got side-tracked and almost forgot what I was looking for. I did download the dividing head program and finally got everything working on my computer except the DIVHEAD OUT program. But, I can still figure out the number of turns and holes required with the other information. Also, I did quite a bit of research today on this subject and found that my Machinery's Handbook has a chart for a 60:1 ratio which works fine for my 120:1 by just using a multiple of two for all of the incremental values. This has been an educational experience so far and has shaken loose some rust.

There is no DIVHEAD.OUT program. You probably meant DIVHEADT.OUT, the output file for the DIVHEADT program. It will reside in whatever folder you run the DIVHEADT program from. It's an ASCII text file readable with any text editor.

[shootnride]

Hi Marv,
I used Windows Notebook and the DIVHEADT.OUT file did open. However, I have not been able to get it to generate a table for anything other than a 40:1 ratio. Will it generate a table for other ratios ?

Thanks,

Ted

[shootnride]

You need to know the gear ratio of the rotary table. The plates need to be drilled and spaced for that ratio, or an even multiple of the table ratio. My .02 worth. Steve

Hi Steve,
Since I've been studying this indexing subject and getting feedback from people like you, I'm beginning to get an understanding of the basics. You are absolutely correct about the hole spacing of the plates needing to correspond to the gear ratio of the rotary table.

Thanks for your input,
Ted

[mklotz]

Hi Marv,
I used Windows Notebook and the DIVHEADT.OUT file did open. However, I have not been able to get it to generate a table for anything other than a 40:1 ratio. Will it generate a table for other ratios ?

Did you read the TXT file of instructions that accompanies the programs?

DIVHEADT uses the same data file as DIVHEAD. (This data file is named DIVHEAD.DAT.) The very first entry in this file is the table ratio. Change it to whatever ratio you want.

[shootnride]

Hi Marv,

Yes, I did read the text file, but apparently didn't understand what I was reading. I'm kind of a dinosaur in the computer world so some times the terminology just doesn't quite make sense to me. However, I did change the ratio in the DAT file and as you said, it generates the table I was looking for.

Thanks for your help,

Ted

[mklotz]

You need to know the gear ratio of the rotary table. The plates need to be drilled and spaced for that ratio, or an even multiple of the table ratio. My .02 worth. Steve

Hi Steve,
Since I've been studying this indexing subject and getting feedback from people like you, I'm beginning to get an understanding of the basics. You are absolutely correct about the hole spacing of the plates needing to correspond to the gear ratio of the rotary table.

Thanks for your input,
Ted

Steve's statement is, to my mind, somewhat confusing.

The spacing of the holes within the hole circle doesn't depend on the table ratio at all. A 13 hole circle needs 13 holes spaced at intervals of 360/13 degrees. When you need to turn the table crank by n/13 of a revolution, the 13 hole circle from any plate will work.

Which hole circles you need is influenced by the table ratio. The DPLATES program I mentioned above will answer that question for you.

[shootnride]

Marv,

I think your mind works on a whole different level than mine (probably many levels above mine). In your last sentence, "Which hole circles you need is influenced by the table ratio." is exactly what I extracted from Steve's reply.

Thanks,
Ted