Old School machining question

[Veselin Kolev]

This question is directed to the machinists... back when CNC wasn't so big.

Why can Volstro rotary mill heads only cut in a counterclockwise direction? The one I have been using cuts perfect counterclockwise, and cuts terribly clockwise, and not because of climb/conventional cutting differences. There is even an arrow to tell you that, but you can still cut clockwise. How come?

[mechanicalbrain]

i wonder if it has to do with either the motor or the drive train. im not fmiliar with the system so i cant talk in depth on it without being more familiar. ill look it up on google.

[team222badbrad]

Maybe it has something to do with the way the belts are set up?

[Conor Ryan]

Originally Posted by team222badbrad

Maybe it has something to do with the way the belts are set up?

no it couldn't really be the belts, unless they have rather unique grooves. Take for example, last year's CIM motor, ever run it in reverse? If you did you'd notice there was a rather large change in RPMs. This is caused by the motor brushes most the time. What happens is that the brushes are pushed into an offset position and peak performance doesn't occur when the current is simply reversed.

My one solution to improve performance besides getting a new motor, is to possibly add another gear somewhere to reverse the direction of the spin with out changing the current input into the motor.
------edit------
I guess I kind of worded it wrong earlier, to make my point a little clearer:
1.) Nothing is wrong with the Mill at all, its the motor
2.) The problem with motor is quite simple, first I'd reconmend reading this to understand how a motor works, or you'd probably have no clue what i'm talking about.
3.) What is happening is that the brush is being pushed offset by the direction of the current and by being pushed offset its no long running at the optimised speed. Read this for a more detailed explaination.

[team222badbrad]

I know about the motor speed problems.

I was just thinking that the belts may have some sort of tensioner that might create a shake or bouncing effect in the spindle when run in the opposite direction.

[Veselin Kolev]

This has nothing to do with the mill itself, the mill works fine in both directions. The rotary mill head is something you put on the spindle itself, by clamping it to the quill. It has a standard R8 taper to recieve power from the mill, and it has two levers, cutter offset distance and rotation. This tool is a different approach to rotary table work.

[mechanicalbrain]

Ive been following this thread because i myself have wondered about it. now it kind of makes sense.

[techtiger1]

Originally Posted by mechanicalbrain

Ive been following this thread because i myself have wondered about it. now it kind of makes sense.

Well I read Through this post now twice and I am seeing what you are talking about. I haven't been in machining for that long as some of you here but it seems to me that there might be nothing to do with the mill or the head it might be the cutter you are using. Most cutters will cut horribly back wards not sure if this is the problem but it seems to be it might be worth checking out. Very interested in hearing the solution to this problem keep us posted please.

Drew

[Tristan Lall]

First of all, it seems that some people are wondering what this thing is; here are a few pictures, as well as the opportunity to buy one, if you're so inclined.*

Now, I don't personally have experience with this thing, but is it possible that some components inside are axially loaded, and that loading is dependent on the direction of rotation? (For example, helical gearing transmits an axial load to the shaft, and its direction depends on the direction of rotation of the driving gear.) That axial load could conceivably cause the behaviour described (by forcing the cutter into the workpiece in one direction, and upward into a thrust bearing in the other direction).

*I have no relation to the seller!

[Veselin Kolev]

Thats exactly the one I'm using. I was using a brand new .250" end mill on it as well. Sadly the company has gone out of buisness, but it is useful anyway. As long as you rotate the head the right way.