Indexer tech info

[cip]

Does anyone know the math formula to calculate the number of degree , revolutions, per inch or travel of the spindle needed for proper turnings.

thanks
mike

[scottcox]

Mike,

You need to view the "width" of your project as the "circumfrence" of your project and use C=pi*d .

I find it easier to see what material I have on hand then design a project around that. Let's say I have a 6"x6" post (kind of crooked). I can get a good clean 5" diameter round blank from it.

Using C=pi*d, then 5" * pi = 15.71". So the "width" of my project would be 15.71 and the length would be along the axis of the indexer, however long.

There is some basic indexer info on the ShopBot Wiki (http://shopbotwiki.com/index.php?title=Indexer) that should help you, but ask again if you have questions about anything.

And please show your work! We need to see more active indexer users here.

Good luck and let us know the results.

-Scott Cox

[myxpykalix]

Mike,
When you ask that re:"proper turnings" depending on the design you are trying to make will determine the degrees, revolutions, ect.

What i mean by that is for example if you are trying to turn a square to a round using a 1/2" endmill your revolutions (per inch of X travel) will be much more than if you were trying to put a spiral on a column as in this example which was only three revolutions:
http://www.youtube.com/watch?v=jSy8PGj2eDU

Then again lets say you want to carve a lampbase with a specific profile, that again would be different.
I believe Scott's example is turning something round. There is programs that will calculate carving a 4 sided piece. I use Millwizard and that will "carve" your piece is 4 sections as opposed to "turning" it like on a lathe.

Although this link is not specifically for the indexer and for a Legacy ornamental mill it does give you a simple formula to follow for understanding "pitch formulas" that might help you with the indexer:
http://legacywoodworking.com/technique.cfm?techniqueID=7

The best thing is for you to figure out what you want to make then ask us how to do it and someone should have the answer.

[cip]

Thanks Jack & Scott
Based on your response I guess my question wasn't clear enough.

What I'm looking for is a basic formula to calculate the revolution per inch for a smooth round dowel.

Having said that, what the problem is the ShopBot control software sets the step over based on the distance to travel and the number of revolutions.

Example:
M5,10,,1.5,,720 would produce a spiral,

while M5,10,,1.5,,180000 would be a much smoother surface like a dowel.

So, whatever the formula is it would have to take into consideration distance to travel and step over desired producing the number of revolutions as a result.

duh, I'm sitting here typing this out and it hits me.

(distance to travel in inches) / (step Over in decimal inches) * 360 = number of degrees of spin.

example: for a 10 inch travel with a .01 step over the formula would be:
10 / .01 * 360 = 360000

code to produce a nice a smooth dowel .75" rad.
M5,10,,.75,,360000.

Of course this would have to altered to fit an individual application but it's a starting point.

thanks for your help

Mike

[myxpykalix]

Isn't it fun when that light goes on over top of your head?
To be honest i don't write much manual code myself so i get confused also. However don't you use the indexer virtual tools for rounding stock? Then you don't have to do it manually thats what the wizards are for.
Go to TI- in the control software
Tools/Indexer/Turn a blank to a finished size

[cip]

Jack:
Yes I use the tools but I also do custom profiles that the tools can't handle, so that's why I need some sort of guide line for manual programming.

thanks again all

Mike

[jim_anders]

http://www.spauldingbryant.com/sbconvert/

[Forum Admin]

Thread is reopened for discussion on the math formula. Some posts were deleted because they were off topic; some were removed because they referred to posts that had been deleted and therefore made no sense.

[donclifton]

On math formula's its pretty simple. If your using degree's find out how many step it takes to turn your indexer one revolution and / that buy 360 and that will give you number per degree. If you using inch you must change the setting every time you change dia of work. If your work is 10 inches around then / your steps it takes to rotate you indexer one revolution one turn by 10.

If your using gecko drive (micro stepping) the formula would be 200 x 10 =2000 x what the gear ratio is of the indexer.
I hope this make sense
Thanks
Donald Clifton