Dividing Plate Numbers

OK, let's check this... if turning the crank 1 time equal 18 degrees then the ratio is 20:1 not 18:1

Just to double check, count how many full crank turns it takes to make your table turn one complete turn (360 degrees). This number would be the ratio to one.

I don't know what the ratio of my Phase II 10" rotary table is, but my diving head is 40:1 which is pretty much standard. I don't really use my rotary table all that much.

Ted
 
Here's a page out of a 1967 high school text book. It tells how to use the plates and the sector arms to get the right angle for your task.
 

Attachments

  • Sector Arms.pdf
    818.9 KB · Views: 34
Hi Ted,
I just saw your message now, but I now have to run out the door to pick my son up at school. So, until I have a chance to read your post and reply, for nor I will quickly post this picture that I took earlier today. I had the pointer on the dial set to zero before I did my one rotation of the handwheel. After one full rotation, the pointer was set at 5. The dial has 4 sets of 0-90 for each quarter of the dial. Regardless, it would still be 5 out of 360, right? Gotta go now20181009_124616.jpg before I get in trouble for being late in picking up my kid
I appreciate your feedback and correction of any of my mistakes.
Susan
 
Hi Ted,
I just saw your message now, but I now have to run out the door to pick my son up at school. So, until I have a chance to read your post and reply, for nor I will quickly post this picture that I took earlier today. I had the pointer on the dial set to zero before I did my one rotation of the handwheel. After one full rotation, the pointer was set at 5. The dial has 4 sets of 0-90 for each quarter of the dial. Regardless, it would still be 5 out of 360, right? Gotta go nowView attachment 277293 before I get in trouble for being late in picking up my kid
I appreciate your feedback and correction of any of my mistakes.
Susan

OK, looks like your is a 72:1 then. (360/5=72) So, make sure you use look up tables for 72:1 ratios.

The post by Hawkeye is very good, but looks like it's for a 40:1 ratio so the math won't be the same for yours, but the example is great!

Ted
 
The math is the same. Just substitute the number of turns your dividing head uses for the 60.
 
Special thanks to Ted and Hawkeye for clarifying my foggy wrong calculations. I will print out Hawkeye's high school textbook page, keeping in mind the ratio difference. Hopefully I will eventually really understand how to use dividing plates correctly, especially since I'd like to make some spur gears, to start off with. I have a special project i'd like to try out that involves lots of gears.
 
The math is the same. Just substitute the number of turns your dividing head uses for the 60.

60? Yes, the formulas are the same, replace the "40s" with "72". That's what I meant by the math is different. Thanks for the clarification.

I did a quick search for a look up table for plates with 72:1 and didn't come up with anything. Lots of 40:1 and 90:1, but no 72:1. If you search more you may be able to find one. There are on-line calculators where you specify the ratio and desired divisions and those might end up being your best bet. For simple divisions, i.e. ones involving full turns of the crank, you can use the formulas in the post by Hawkeye.

Ted
 
I just noticed my slip in the last post. Guess I was thinking about my rotary table. I built it around a 60-tooth gear I found at the scrappers.
 
Thank you guys. I can use your anseers as a future reference when I finally start using the dividing plates
 
Back
Top