4th axis ?

[sdwilson]

has anyone here succesfully made a machine with 4 or more axis? just wondering about my current comerical router table for possible retrofit.

[CNCAddict]

Hello,
I have heard of people adding a rotary table on it's side for a 4th axis. Is this what you had in mind?

David B.

[rab]

Hi,

I added an 8" rotary table as an A-axis to my router for handling rotary work, it's the 6th axis to be added to this router, but only upto 5 axes operate at any one time. There's a picture at http://www.rainnea.com/cnc_5axis.htm
and a video clip at
http://www.rainnea.com/MOV01123.MPG

Regards,

Rab

[turmite]

Hey rab I love your machine. I want to build a 6 axis some day down the road but mosty because I want to build the machine. Does that make sense? I have a design in mind and was curious if you made your 4th and 5th axis head yourself. If so what are the inch dimensions? I'm not too good on the mm conversions. I gues I am just too lazy to do the math.

turmite

[rab]

The 4th and 5th axis head unit was made from some surplus satelite positioning units of approx 4" diameter. There's some close-up pictures in the photo section here;
http://groups.yahoo.com/group/CNC_Toolkit/
The units are made by Globe Motors and the motor code is 409A582 rated at 12V. A quick Google search will bring up some links.
I removed the brake and tach sensor and replaced them with a US Digital encoder disc and pickup and drive them with Gecko 340 servo controllers. I had to make up some differential transmitter /
receiver circuits for the encoders as they were picking up noise over the cable run. (see http://www.geckodrive.com and
http://www.usdigital.com )
The units have a flange that I machined off and I mounted them at 90 degrees to each other using some 8mm aluminium angle (this bracket should probably be beefed up)
There is an amount of backlash in these units, some more than others, but then they are very cheap. The motor / encoder assembly is quite long and sticks out beyond the unit a bit too much. You also need quite a bit extra clearance to allow the tool to rotate and your work area will be smaller than for an equivalent size 3-axis machine.
If I could find a low weight / low backlash / reasonable cost, etc.
alternative then I `d use that. I used a Sherline CNC-ready rotary unit for the 5th axis on my Taig
mill, but these are too heavy for the router. An alternative set-up
with timing belts and pullies could be constructed. I'm also looking at some parallel kinematics design ideas for tilting the tool angle as an alternative to rotary units.
I can quickly change out the Z-axis on my router from the 4/5 axis
unit to just a simple, but larger router if I'm doing a job that only
requires 3-axes, or indeed a vinyl cutting knife.

Regards,

Rab

[boxwood]

Hi Rab
awesome machine there Rab I am interested in learning more about the cnc_toolkit and have requested entrance to your yahoo group, I have a 4 axis router and assume it can be utilized for this setup, I have never used a 4th axis for anything other than indexing because of programing limitations. I have read some of the post and it seems quite complicated but hopefully with some help and lots of effort I can learn to manipulate it.

[rab]

Don't be put off using your 4th axis, it isn't as complicated as it might first appear and I'll try to help you through any problems,

Rab

[sdwilson]

thanks all for your input. i really want to make my own machine for the garage. and my boss was interested in a 4th and 5th axis head retrofit for are commerical machine(router). i hadnt really thought that far ahead. hey Rab i was wondering how rugged that 8020 aluminum is that i see your using .....like whats the toughest stuff you can cut. i really want a machine that can cut steel(light cuts) just wondering? i was going to weld a frame up out of 3" square tubing. mill style, not gantry. any suggestions would be appericated.

Thanks

this forum Rocks

[turmite]

Hey Rab. Thank you for all you input. I have this idea in my head of building a really small 6 axis with the total footprint not being over about 15"X15"by as high as necessary to get everything to work. Made of machined aluminum with precision ball screws and minature thk profiled ways and bearings. I want a tiny dc motor to use for the spindle and the drive motors will be size 11 steppers. I want to build the machine just for fun mainly but I though it would be a great way to take to the local schools to interest the kids in machine work and cnc in particular. I would primarly use it for cutting wax and maybe soft metal as in gold or silver. Feasible??

turmite

[Klox]

Rab,
I downloaded the video clip. Good stuff!!!!
I like it.....very impressive!

Klox

[rab]

sdwilson

I've cut 12mm aluminium plate with my router, but only taking 0.5mm deep cuts at a time.
I've cut steel on my Taig mill using a cheap wood router, a small end mill and very shallow cuts.
So, what you have in mind may be possible for light cuts.

Rab
http://www.rainnea.com/cnc.htm

[rab]

turmite,

bear in mind that you lose a lot of useable work area when doing full 5-axis cutting, imagine when your tool is horizontal and rotating to approach your workpiece around 360 degrees for a worse case scenario,

Rab