Jul
7
Rotary Axis CNC Stepper Motor Retrofit for a Taig Milling Machine
By karlw
After using my CNC machines to create 3 dimensional art for an art show I wanted to add a fourth rotational axis to ease in the production of 3 dimensional objects and parts. I decided to add the 4th rotary axis to my Taig CNC Milling machine since I had just upgraded to a 5 axis’ controller and had a matching stepper motor. A rotary table used in conjunction with a mill allows a machinist to produce virtually any part he can design. The only limits are size, not complexity.
Using a 4th axis rotary table greatly reduces the amount of time and complexity that it takes to shape an object. Without a rotary table you must devise a registration system and are forced to reposition the object several times during the milling process. The precision that a rotary table provides also ensure uniformity and high quality in components.
I could have bought a cnc ready sherline rotary table but I decided that I’d rather get a table locally and build a stepper motor mount for it myself since half the fun is in the build. I decided to go with the Soba 4-inch rotary table (part# B2424) from Busy Bee tools down the highway in Mississauga. While I was there I also picked up the matching 4-jaw, 3 1/4-inch chuck (part# B2710) and Tailstock (part# B2424).
I wanted to design a mount that would let me return the table to its original state if desired. I used a CAD program to design the mount so that it could be dropped into place and secured with 4 set screws around the existing shaft collar.
The mount is 2-1/4 x 3 x 3 inches and constructed with 1/4-inch thick aluminum. All 4 of the parts were milled on my Taig milling machine with the new controller and stepper motors. I’m always amazed at the amount of precision and accuracy of that taig mill! The rotary shaft is 10mm in diameter so I ended up drilling out two 3/8-inch shaft collars to 10mm. The shaft collars are used to take up the extra space since I wanted to leave the shaft at its original length. I used a 3/8-inch flex coupler drilled to 10mm, a rubber spider and 1/4-inch shaft flex coupler from Princess Auto to mate the rotary shaft to the stepper motor.
Rotary axis with 4-jaw chuck attached.
Stayed tuned for my next blog post where I’ll show the rotary axis in action attached to the Taig mill.
Karl P. Williams
Subscribe to RSS Feed
Follow us on Twitter
Our Mailing Lists
Visit Kwartzlab TV
Beautiful finish, Karl. Do you anticipate any backlash with the rubber spider and flex couplers? Just take that up in software?
Great job.
DW
Thanks Darin! The flex couplers with the spider fit tight and add very little backlash, if any. It’s the same system I used for my router table. I still haven’t wired it to the controller yet but when I do I’ll test it out. The worm gear and rotary table gear seem to be very precise as well. The smallest turns in opposite directions on the worm gear gets an immediate response to the table.
Hey, you mention you found a few of your parts at Princess Auto. How are the prices and selection there for that sort of thing? I’m planning my own CNC machine and making up a parts list for McMaster-Carr, and some of the prices are a little steep. It would be great to have a less expensive, local source.
Hi Jeff,
Princess Auto has a good selection of shaft couplers in many different sizes and their prices are much cheaper than McMaster-Carr. The also have a variety of bearings, bearing mounts, threaded rod and hardened steel rods. When I built my cnc router table from scratch I used the princess auto bearings and mounts, rods and the shaft couplers between the threaded rods and the stepper motors.
http://www.princessauto.com/power-transmission/driveline/bearings/components/list-all
Excellent! That will shave a bit of money off the price. I’ve scavenged quite a bit of the parts I need, but some pieces are still hard to come by…
Hey, if you guys find cheap thrust bearings with a 1/4″ I.D., please let me know. It’s a whole world of cheap *radial* bearings, thanks to inline skates and harddrives, but scarce on thrust bearings. Really could use those on the screws for my mill instead of the hacky plastic margarine tub lid I’ve been using.
And c’mon, McMaster Carr! How about some love for Canadians in the cross-border shipping dept? Digikey figured it out.
Thx
DW
Hey Darin,
I was looking for a thrust bearing last week and ended up salvaging one from some old parts in my basement. I agree that it would be nice to find a cheap local source.