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jcolley
01-10-2005, 08:33 PM
Just curious if anyone has built or considered cutom building a 5-Axis machine. I am currently in the part collecting stage of building my own 3-axis machine, but would like to be able to machine smallish, circular, extremely complex shapes (i.e. turbine and compressor wheels).

I sort of have an idea of how I would like to lay it out, but would appreciate any feedback.

-The usual X and Y movements provided by THK LM guides.

-A cradle assembly which moves on the XY and carries a rocking pivot on which is mounted a rotary table.

-Z axis on fat THK KM Guides.

Any thoughts?

Jim

JFettig
01-10-2005, 09:23 PM
http://www.rainnea.com/cnc_5axisMill.htm

take a look at that.

About the Z axis, I suggest that it gets built just as rigid as X and Y.

Other than the funds, the only thing stoping me from building a 5 axis machine is: how on earth do I program it without spending $15,000 on mastercam or similar

It woudl be possible to make a mini mill like mine into a 5 axis machine, put a rotary table on the xy table and a rotary table behind the head, The way to do this would be to mill dovetails into a thin peice and fix it to the back of the rotary table and attach the front part of the head to the front side of the rotary table. The head comes apart into 2 peices, the back peice(dovetailed peice) is close to 3" thick I think.

machines with more than 3 axes intrest me quite a bit, programming them is another story.

Jon

jcolley
01-10-2005, 10:15 PM
Jon,

I had thought about this also. It seemed at first that it would be simpler to do as you mentioned by placing a rotary axis on the head.

But following the thread on building a spindle (http://www.cnczone.com/forums/showthread.php?t=7004), I sort of had the thought of going the 3 phase/VFD route and using pulleys to determine spindle speed range. I think this might make for an overly cumbersome head assembly to throw a rotary table into. Realistically though, your arrangement might just simplify programming over what I am thinking.

I have a simple SW rendering of my plan, take a look in my gallery for the pic. It basically has two pillars which are mounted to a XY platform. The pillars support the cradle with large diameter bearings, allowing the cradle to pivot about 60 degrees forward and aft. A rotary table with about an 8" chuck would sit in the cradle. I plan on a beefy Z axis as well.

Jim

JFettig
01-10-2005, 11:07 PM
That is another way to do it too, one thing is that you may want to lessen the depth of it, so that you can go without a chuck on it, you may also want to go a full 90 degrees with it too.

A design like that will take a large amount of travel on the Y axis.
About using a rotary head, do you mean like not having enough room on it? I think thats a possible problem, but its also fixable. I really dont see a big problem with it, although I dont know much about the 3 phase/VFD route.
I am currently using a variable speed ~1.5hp DC motor with a fixed size pully to conroll my spindle.

The other thing I have taken into consideration when seting up a 4/5th axis up like that is what would you do if you wanted to mill a long peice of stock? it would stick very far out of the chuck/fixture.

Jon

jcolley
01-11-2005, 08:49 PM
I thought about that as well since I'm sure that I would eventually want to machine something that wasn't round (what are the odds, right?).

I think with my layout, if I were to make a mill table which bolts directly to the top of the cradle and spans the distance across the rotary head, it would still allow my XYZ as well as the rocking axis.

Combined with a large enough X travel, I should be able to use most of the distance of the cradle lengthwise for milling.

Thanks for your input Jfettig, I wish more would join in.

As far as the software side of it, I would be willing to plunk down a decent amount of money for a good CAM setup, if I could pull of the machine for less than an arm and both legs. I plan to use EMC for the machine control as it will support up to 6 axes. I can use the last axis to drive the VFD and control spindle speed as well.

My gears are turning so fast I can't even draw in SW fast enough to keep up. I have more napkins laying around...my wife keeps throwing them away :/

Jim

RotarySMP
01-12-2005, 03:03 PM
Turbine blisks really need to be vaccuum cast as the super alloys are a real ***** to machine. You can do your turbine blisk in wax on a four axis machine.

Compressors are readily available in a huge range of sizes, at pretty low prices.

Regards,
Mark

jcolley
01-12-2005, 08:09 PM
I sort of planned on eventually going to a method of casting them, but I plan to prototype a few different designs first.

Axial compressors on a small scale are also hard to come by, only a few people I know are working at developing them, so this is another planned use.

All of this stuff, is still hypothetical at this point thought, since I need a mill to even start building :)