Turning a square blank round

[cstorer]

I have recently set up an indexer off the end of the table on my PRS Alpha router. My student and I have tried creating a tool path on Aspire 3.5 to turn a square piece of wood into a cylinder but the router always runs off to the right of the wood. I am unsure of this because of our indexer setup, software, program setup etc. I am asking for someone to help me by giving me a step by step process on how to perform this task. Can post pictures of the table setup if needed. Any help or guidance would be appreciated.
-Thanks Carl Storer

[myxpykalix]

I'm not sure how to do it in aspire but, it sounds like you may have some settings incorrect.
Sometimes it can be a bit confusing but just think of it like you are setting something up on your table.
It sounds like you are setting your x,y point in your program say in the center and starting it at the end with the unexpected move "out of bounds".

If you have any pictures or dxfs or screenshots or whatever to let us see what is going on that will help define what your problem is. This isn't anything most of us haven't seen dozens of times so someone will have an answer.:eek:

[Brady Watson]

Where are you telling the machine 0,0,0 is in relation to the indexer? Is the indexer parallel with the X or Y?

You want Z0 to be at the center of the lathe spindle, If indexer is parallel to the Y axis, you want X0 to be the center of the lathe spindle in X. Y0 can be at the tailstock or headstock depending on how you have it setup.

-B

[rb99]

Is it the toolpath or is it deflection as in the Z axis and bit flexing?

[cstorer]

Thanks for the reply Jack. What program do you use to turn a square blank round? I would be happy to use any program that you are comfortable with if you could provide direction. Carl

[jdervin]

I'm not Jack, but...

...for something as simple as turning a square into a cylinder, the [TI] command from within the ShopBot control software is pretty much all you need.

Just remember to take Brady's advice on putting 0,0,0 in the center of the piece.

[jdervin]

Also, I might add that it helps me to measure the diagonals of the square and treat them as the "diameter" of my square. (After all, when the part is rotating, the corners represent the furthest point of material from the center.)

There's a better way to word all this, I'm sure...

[myxpykalix]

Carl I have a self written app to do my turnings and spirals but regardless the basic functions are the same.

One thing that might help you figure some things initially is to take for example a 5"x5" square that you want to turn down to a 4"x4" round

First make an X on the end of the blank and find the center.
Take a compass and make a 4" circle
then take a ruler and measure from the tip of the square end to the outside of the circle. This tells you how deep your bit is going to be cutting when the the material is at the diamond shape (square tip up).

Because most programs having a Z zero set to the CENTER of the material, I don't think take into account that extra material when turning. I would start out with small passes on my roughing pass.

Once you know what the depth from the square tip to the top of the round is you can start out by turning the square up 90 degrees to its tip and clip off the square corners.
Then use your rounding toolpath in your program.

The above directions is not necessary to get a round file but it is a good exercise to make you see what is going to happen when you start to try to round your first square. It is going to dig into your square and bite way more then it should if you say, for example, you want it to take a .25 roughing cut it will be cutting probably .75" which is too much.

Here is a good tutorial to help give you more info done by Randall Newcomb that probably says, in more detail what i was trying to explain above:
http://www.humblesticks.com/cnc-rotary-tutorial.html

Again i'd remind you to post some pictures or files that someone can look at and see where you may have some wrong settings.

[rcnewcomb]

Scroll down to Exercise 3: Square Peg, Round Hole on this page: ->Link (http://www.222artisans.com/Rotary/RotaryYaxis.html)

[myxpykalix]

I could have saved myself some time and effort had I just posted that link:eek:
It says it much better....:D

I had this basic issue come up that i had forgotten about and was cutting into the material as the Z was traveling down to start a new cut and the B was turning. What i had to do was input a home Z higher point for my roughing pass then input a lower Z for my finishing pass or it would waste a lot of time going up and down at the end of each pass during the finishing cut.

[cstorer]

Jack,

Can you tell me what all of my values need to be set to when setting up the indexer? Should I have X,Y,Z,,A,and B settings. What exactly should my software settings be set to? Here are some screen shots of my settings