Warning for PhaseII rotary table owners (incorrect dividing plate info)

Not knowing the specifics of your rotary table, but using mine as an example. Mine is 1:90 ratio. Number of turns = 90 divided by number of holes desired

90 / 8 = 11.25 The whole number of 11 is the number of complete revolutions of the hand crank. Drop the 11 and change the decimal remainder to a fraction. .25 = 1/4 multiply the "4" in 1/4 by any number that will match up with a circle of holes in the plates you have.... in my case both the 28 hole circle and the 44 hole circles will work so... 4 multiplied by 7 gives 28, and the 1 multiplied by 7 gives you 7 so 11 complete turns and seven holes on a 28 hole circle. If you multiply the 4 by 11, you get the 44 hole circle, and 1 x 11 = 11 so it would be 11 holes on the 44 hole circle. I don't know if there would be any difference in using the 28 hole circle or the 44 hole circle.... shrug Ken

....mine goes to eleven.

Just use a calculator, like a TI-30 and enter the number of holes and the gear ratio as a fraction. It automatially converts that fraction to lowest common denominator.

Example: 90 turns for the gear ratio. 8 divisions.

enter 90 / 8 = 11 1/4

Example: 90 turns for the gear ratio. 11 divisions.

enter 90 / 8 = 8 2/11

You then need to find a plate that the fraction can divide into. In the first case, any hole pattern divisible by 4. (28, 44, 56 etc.) In the second cae, any hole pattern divisble by 11. (33, 44, 77 etc.)

The point being that the calculator with fractins does all the work for you.

Pete

First, Ken's description of the process I thought is very complete and understandable. The only point I would disagree on is using a calculator. I teach my students to do these calculations by simple division. Then there is no need to convert, for example 11.250 to 11 and 1/4. Just my philosophy.

On the other hand, geez Louise, Pete. Have we gotten so lazy that we can't do simple division without a calculator? If so it is a sad day indeed.

Just my .02 of course.

Errol Groff Instructor, Machine Tool Department H.H. Ellis Tech

613 Upper Maple Street Danielson, CT 06239

860 774 8511 x1811

It is the only place I know of where you can still use division with "Remainders" in the answer.

Paul K. Dickman

Geez Louise! Errol, Have you gotten so lazy you can't even read a post and understand it before you have to resort to name calling and flames, without any understanding of what the post was about?

IF you had read it, the point was that:

1. There are calculators that do do fractions, and _display_ fractions. What's this junk about 11.250 vs 11 1/4 ?
2. Even though one description might be complete, restating it another way might make it more obvious to someone else besides you. Do you only explain something only one way for your students, and if they don't see it exactly the same way as you, right away, do you call them lazy or stupid?
3. I tried to re-describe it in terms of fractions, and pointed out that there are cheap and readily available tools for working with fractions.

Even though I certainly do know how to do fractions, and have even played with them for recreation! not everything in the world should always be done the long way by hand every time. I was tought to use fractions, and to do it by hand. I only get paid for what I produce, not for how much time I take to do it. Sometimes I have to teach an employee to be more "lazy". To find the quickest way to get a job done, and the next job started.

Hope you are having a better day today. Relax, mellow out, it is the Fourth of July!

Pete

Pete:

I did read the post (I am assuming you are referring to your post of 3 June) and understood it quite well. Any comment I made certainly intended no insult or flame, if you took it in that manner I apologize.

Perhaps my comments were colored by the fact that I do teach young people and haven't yet wound down from a stressful school year.

What's this junk about 11.250 vs 11 1/4 ? Well, you would probably be stunned and depressed at how many people would have no idea how to convert a fraction to a decimal let alone go the other way. That is why I have my students do it "the old fashion" short division way.

I often explain things several ways to my students and if I can't find a way to get them to see the light I will ask my fellow instructor to have a go at it. I am very aware that not everyone grasps things when they are explained one way but that another way might make sense.

I can honestly say that in seventeen years of instructing I have never called a student lazy or stupid. Even when they are. Few are stupid although they go out of their way to convince of that but way too many are lazy as a yellow dog on an August afternoon.

I really thought that I was having a fine day yesterday.

And a happy fourth to all!

Errol