rotary type 4th axis

[mocnc]

ok....here goes....I am at my witts end here......has anyone built or designed or even just seen a rotary type 4th axis? By rotary type 4th axis I mean a way to hold wood stock(square or round) and have it able to turn so that either it can be cut(simular to a lathe) or have the stock rotate so that inlaying/carving can be done. I am looking to inlay pool cues, I would also love to be able to cut some pool cues out using the same method on my cnc. Your help is greatly needed and appreciated. I would love to keep costs down as much as possible. Is this just a dream?? Can it be done?

[MarkWink]

...sure 4th axises happen all the time, although your inlay will require some precise motion.

Do you have a 4th axis control?, and CAM software to generate the code?

Look for a used or cheap new rotary table and remove the hand wheel and couple on a motor.

Rotary stages (photographic type) often have the motor and are very precise.

You can use a stepper with a gearhead on it, although watch the side loading on gear heads, it will need to be built into a fixture so the output shaft doesn't bear much side load.

The mechanicals are cheap.
Good 4th axis CAM OUCH!

[Graham S]

You could use a small wood lathe less motor (ebay) to provide a head stock and tail stock. You then need to couple a stepper motor to it via a reduction drive. The best sort is a harmonic drive as these are backlash free (they turn up on ebay from time to time), they also turn up on ebay from time to time. Otherwise a decent worm drive could be used.

Graham

[airbrush]

also interested in a 4th axis rotary if anyone has more info on this?

[turmite]

Guys there is a vast difference between a 4th axis and a lathe. While the 4th axis is fairly simple to build, the software is a little more complicated, but not to the point of despair! On the other hand, trying to use a 4th axis like a lathe is another matter all together. For a 4th axis to work properly it has to have interpolated moves just like the xyz axis of your machine. The lathe requires constant rotation to be able to cut your stock round. The two functions are not to easy to acheive on the same axis.

Now a way to make the cue with a 4th axis is to use indexing and let the router cut the full length of the part as a 4axis function rather than a lathe function.

Mike

[airbrush]

I'm not interested in a lathe machine, just a 4th axis to move the piece to achieve more complex parts.
For what I want the 4th axis doesnt need to moving at the same time, it can do its rotation then the cuts can be done etc.
Mach 3 has support for up to 6 axis...how hard is it to set it up to cut with a 4th axis?

[turmite]

Airbrush mach software is what I use as well and it is fairly simple to set the software up for the 4th axis. You have to activate the axis in the config page, designate it as a rotary or linear axis and set the units.

I use my 4th axis mostly like you have described which is called indexing.

Mike

[airbrush]

Originally Posted by turmite Airbrush mach software is what I use as well and it is fairly simple to set the software up for the 4th axis. You have to activate the axis in the config page, designate it as a rotary or linear axis and set the units. I use my 4th axis mostly like you have described which is called indexing. Mike

Great, thats good to hear.

So do you think it would be possible to retrofit a rockcliff fixed gantry machine with a rotary onto the table?

Is there a better route to go for adding one, would a different design work better (for example, fixed gantry or moving gantry or does it make a difference?)

What sort of machine setup do you have, did you build it yourself?
Info is much appreciated, thanks.

[andy_ck87028]

Forgive me if I am barking up the wrong tree however I don't think Turmite is describing full 4 axis.

I know I am showing up my lack of real knowledge but please bear with me as I'm sure my point is valid.

Indexing is typically used for cutting gears on a mill. For example, 100 teeth means 100 movements around 360 degrees.

Mach may handle 4 axis but mach takes G code to drive it and if all you are doing is stepping the 4th axis around by 100 steps, then your use of the 4th axis is limiting your other 3 axes to 100 separate planes.

If, instead, you want full 4 axis whereby a complex 3 dimensional shape is needed to be cut, then an indexed 4th axis is not necessarily going to do it.

With such a shape, it is the sophistication of the generated toolpath that mach depends upon.

So, we know that mach can handle 4 axes but for the machine to be a fully fledged 4 axis machine, it has to have quality toolpath and that can only be achieved by quality cam.

So, Turmite was technically correct but I think he is actually describing 3.5 axis.

I think CAM is where the real challenge is for 4 axis and not downstream from it.

Andy

[turmite]

Originally Posted by andy_ck87028 Forgive me if I am barking up the wrong tree however I don't think Turmite is describing full 4 axis. Oh yes I am! I know I am showing up my lack of real knowledge but please bear with me as I'm sure my point is valid. Indexing is typically used for cutting gears on a mill. For example, 100 teeth means 100 movements around 360 degrees. This technique may work for straight gears, but how are you going to cut helix gears? The gear itself has to rotate somehow! Mach may handle 4 axis but mach takes G code to drive it and if all you are doing is stepping the 4th axis around by 100 steps, then your use of the 4th axis is limiting your other 3 axes to 100 separate planes. True.....to some degree. If, instead, you want full 4 axis whereby a complex 3 dimensional shape is needed to be cut, then an indexed 4th axis is not necessarily going to do it. But it can. Just because you don't use the 4th axis in a continous method does not mean that it will not make the work much easier. Just ask me! With such a shape, it is the sophistication of the generated toolpath that mach depends upon. Partly true, but the programmer also has to know how to use the software to accomplish what he needs done. So, we know that mach can handle 4 axes but for the machine to be a fully fledged 4 axis machine, it has to have quality toolpath and that can only be achieved by quality cam. Not true. I personally can hand code a spiral fluted table leg should I need one. To be able to to that, my 4th asxis must be capable of true continous rotation during the necessary moves. Cam is great, but on some items, it is not at all necessary. So, Turmite was technically correct but I think he is actually describing 3.5 axis. No......I was completely correct in my discricption of a full 4th axis, used as a indexer when needed, or capable of full 4th axis work, if needed. I think CAM is where the real challenge is for 4 axis and not downstream from it. Totally true. Andy

.........Mike

[High Seas]

I've been wrong before - but... as I understand it:


1. Rotate the tool about the X Axis on a 3 axis machine and you'll have 4 axis control, X, y, Z, A.

2. Rotate the product about the X axis and you'll have a 4 axis control machine = X, Y, Z, A.

I admit you might be limited to the size of the product based on your X, Y, Z dimensions - but it ought to be 4 axis control regardless.

Loads on the system will be different - High milling lodes better accomplished on the example 1, but foam and light loads (small product) can be done on 2 above.

Did I get that right - or other than size and milling loads why are they Not both 4 axis?

Just want to know -as I thought I was making a 4 axis setup knowing these constraints - but maybe I am unhampered by experience.

[airbrush]

http://www.rainnea.com/cnc_toolkit.htm

the above link would be ideal for me since I already use 3dmax in my every day workplace. It is a plugin for max to generate toolpaths. Software shouldnt be too much of a problem, i'm a 3d artist and use autodesk 3dmax and Maya everyday.
I'm not sure i'm following all of this...why would there be only 100 increments of movement...if a stepper motor is hooked up to the rotary wouldnt it give you more movement than that?