Here is an example of true indexer work. As you will appreciate, the RPM is not a factor when cutting these shapes. And you cannot do them on a normal lathe. To sand them, they must stand still.

This stuff can be done on indexers or lathes. People want to sandpaper them while they spin. Here speed is an important factor.

What I am interested in at the moment would be the second type of machine. Architectural wood coluns does not interest me at least for the moment.

It will mainly be candle stands, stairways, walking sticks etc not exceeding a lenth of 48".

Gerald now I begin to understand. What I have built is an indexer. What is the difference between a 4-axis mill and an indexer? Using 2" stock at 100 RPM it equates to 600 IPM. This would be too fast if I was Cutting with the point of the cutter but it has been my experience that I get a cleaner cut if cutting with the side of the cutter with the cutting edge coming down into the wood (climbing cut?). It is my interpretation that if I use the point of the cutter then for a 2” piece the max rotation will probably be 50 RPM and a 24” piece will be 6 RPM. Side cutting will probably be limited to 12” and less. What IPM range would you consider the max for side cutting? The only time higher RPM's are desirable are when roughing a multi sided piece to round. This is the code I am using, G0 Y96 A1000, for roughing and G0 Y966 A2000 for finish cut and I am side cutting. Is there a better way? On pieces where you can’t reach horizontal centerline to cut the cutting would be done as close to centerline as the tool will reach. This way the tool is still cutting with the side.
The RPM speeds I have used in other posting are in doubt. If I set F200 then Mach posts feed rate at 200 but posts units/minute of 167. What is my actual RPM?
Sanding solution.
Sanding manually is a PIA. A better solution is a flap sander. Here is a version used on the Legacy that could be modified to MechMate. I see it as mounting on the side of Y car with manual Z and XY plane adjustment.
http://turningaround.org/Pugn2.htm

Art, What does PIA stand for. I hope and pray that you meant "Pakistan International Airlines". Most of the Pakistani test Cricketers still work for this institution (Just having some fun on your account).

Art, As I understand The main difference between a indexer and a wood turner is this.

In a wood turning lathe the force to cut the wood is provided by the RPM and the weight of the stock. You need a powerful motor to provide this circular to motion to the stock. This is why you talk about this 1 Hp motor.

In a indexer the cutting force is mainly provided by the router and not by the RPM of the stock. Due to this the machine has the luxury of turning at a lower RPM.

An indexer is a device which can control the exact rotational position of a workpiece. They can stop and hold with minimal backlash.

Fabrica, you say you want to do the "second" type of work (candle stands, stairways, walking sticks etc.). For that you do not need a stepper motor (or MAch3 or gecko) to turn the wood because you do not need a precise stopping position to cut detail. Therefore you don't need an indexer.

The right production machine for candle stands, stairways, walking sticks etc. is a copy lathe, and the MechMate will be perfect to cut the templates (or masters) to use on the copy lathe.

Copy lathe:

http://www.mechmate.com/Forum/messages/2514/3540.jpg

It might still be interesting to use the CNC as the copy device...

Check those out:

link 1

link 2

link 3

Gerald, How am I to do the flutes on the stock. Paco Thanks for your info. I think the machine that you suggest is what I have in mind. How can I get more info on it. I need to mount this on to the mechmate.

Fabrica,

you though about it, I did and so some other did too, but the links I shared are from a talent fellow Botter that share his trial recently. I suggest you do a search on this forum and maybe post your questions directly to Brian. In fact, he might just be reading this thread HERE too...?!

The concept is quite simple; it's pretty much what Gerald post above but the cutter is driven with the CNC X (or Y) and Z axis. You may want to chuck in a 60 deg. V tool bit for final sharp inside corner detailing...

Thanks Paco for your valuble info. I will get in touch with Brian.

The main reason I mention a copy lathe, is for production. In a country where labour is relatively cheap, a copy lathe will very easily beat a CNC indexer for speed, price and ease of sandpapering.

Of course, a copy lathe can be equipped with CNC motors, but then I will put the "gantry" under, or behind, the workpiece so that the operator has maximum access for sandpapering.

No Gerald What I plan to do is to have this thing mounted on the Mechmate parallel to Y axis.

You already said you would do that for making small quantities of samples, and I am not arguing with you. I am simply pointing out some options for mass production.

Fabrica,

Here are a couple more pictures of another Shopboters lathe\indexer.

http://www.mechmate.com/Forum/messages/2514/3552.jpg

http://www.mechmate.com/Forum/messages/2514/3553.jpg

I also will be doing this to my machine at some point.

Good Luck,
Tom

Thanks Tom for your info.

Fabrica
Where are you with your laser deal?

I have received the optics the gun is on the way.

Roughing out
 

Here is a 18" pedistal that I am roughing out. I have to rough it up between each layer glued up because I only have 20" between the rails and not enough Z depth. I am rebuilding the Z with 10" of travel and using a lead screw because of the laterial impact forces involved.

Art, do you use much y-travel when you rough out? Could you do the roughing with the y-car nearly fixed in one position? (say 6" or 4" off TDC). I have an idea for a simple "stabiliser" for roughing out . . . . . .

Tdc
 

Normally I cut about 1" off top dead center. This one is being cut so far off TDC because I don't have enough Z travel to get higher.

Then this stabiliser rod should work:

I'll have to move this over a bit more but I think it will work well here. The last bed rail will have to move too I think. Any other opinions/thoughts/ideas on this 4th axis?

Just as a way to clear this up in my head... is it mandatory to have x,y,and z axis + the a axis (rotational) or can you build an indexer with x or y and z and a? I am asking because sometimes in theatre (our machine is being built so we can build scenery and props more easily) there is a requirement for the type of things an indexer would be great for and we don't need production level speed, but I purchased the G540 which will only drive 4 motors. If I run an indexer parallel to my y axis and use one of the x motors (and disable the other) I would have enough motors for my needs. Also, do Mach3 and the vectric software packages handle indexers to anybody here's knowledge? It looks like people are modifying their gcode directly, but that seems like it would be a rough approach to something like a spiral cut spindle.

Thanks for any input, I probably won't try to set up our MechMate as an indexer for quite sometime but I'm sure that when we find out we could use it we won't have much time to implement the system.

Brian,
Since you are using the G540, your options are pretty few. With the prewired configuration of the G540 you are allowed x, y, z and a. x and a will be the x axis gantry motors, y - the cross car, z - being z. Mach will slave a to x in your setup.

For you to add an indexer in the future my suggestion would be to purchase a second BOB, like the PMDX 122 and add a second parallel card to your PC and then an extra driver.

Cost for the aforementioned will be about:

-88$ for the PMDX
-20$ for the Parallel Card
-147$ for a high current Gecko Driver (you will need at least a 4.5A output to do the job well at your voltage)
-250$ stepper motor to do the job

(also, if you happen to find a indexer unit like mine on Ebay, it could be servo driven with encoder feedback to the amplifier with the same setup but purchase the appropriate Gecko DC servo amplifier card.) It's not TRUE closed loop feedback, but the servo reacts to step/direction control the same as a stepper)

Mach 3 will easily address the indexer and second parallel card. Don't be concerned about Mach 3.

The biggest challenge you will have when your ready to jump to true 4th axis cutting will be the CAM software package.
I am a recent "expert" :D on purchasing a 4th axis package and entry level is about $2500 for the most affordable and usable package from RHINO CAM or Visual Mill (Same vendor) The price quickly goes up by thousands from here.

You can do simulated 4th axis in the 300$ range and is about as accurate depending on what level of column, prop skull/statue etc. your trying to achieve. Vectric has a very good 3d carve program that does 4-face machining in the indexed mode and will cut in 90 degree rotations. Very affordable, very easy, very quick to learn.

Your welcome to give me a ring on the phone if you want to discuss in detail.

Sean

Brian, I think the reason that the indexer people need so many axes is because they alternate between cutting with the tip of the cutting bit (better detail?), or the side of the bit (smoother finish?). If they were only using one strategy, then there would be an idle axis.

Indexer
 

At http://turningaround.org/MechMate/Mechmate.htm you will see my indexer. I am updating site and if you have any questions please ask and I will add to site/reply. A indexer can run with as few as 4 motors representing X, Y, Z and A. A fifth motor, B, can be added as a slave to the X. I have it on very good athority that X and B can electronicaly be slaved on the controler by Campbell shown on my site. I will be confirming this within the week and will post results. The problem is that if Mach has a slave axis on Reference All the slave will also try and go to a limit switch. I don't need a limit switch to true the gantry on the slave side so if I electronicly slave the motors Mach doesen't know that the slave exists. As to software 90% of the stuff I do can be done with the wizard listed on my site. Best $75 I have spent. I am beta testing the new version which is even better.

Indexer software
 

Also there is a write up and examples of some examples of work done with Rich'e wizard.

Art,
The writeup on the wizards looks great. Cant wait to get a machine and indexer running.