Home-Made Rotary Table

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Dallas
Posts: 23
Joined: Fri Mar 27, 2015 5:25 pm

Home-Made Rotary Table

Post by Dallas » Mon Feb 08, 2016 10:20 pm

Hi folks. I wanted to use my Shapeoko 3 to cut some fairings to attach to my triathlon bike to make the wheels more aero. (You can buy entry level aero wheels, of course... for about the price of a Shapeoko 3. :o ) Bottom line: I needed to machine a part about 25" in diameter -- just a little too big for a standard Shapeoko 3.

I did some quick number crunching and realized that if I made a rotary table and hung it off the front of the Shapeoko, I could machine the part I wanted if. The outer edge of the rotary table needs to just squeeze between the y-axis extrusions. Here's a CAD drawing in Onshape. Onshape accounts are free and I made this file public.

https://cad.onshape.com/documents/5da85 ... c089b9781e
Presentation4.png
Presentation4.png (86.29 KiB) Viewed 1504 times
The final unit isn't exactly like the CAD drawing (I changed non-critical dimensions based on the materials I had on hand). Bottom line, the unit works.

Some "unusual" supplies that you'll need that you can't pick up in a big box hardware store:

Lazy susan turntable
http://www.amazon.com/gp/product/B0045D ... ge_o02_s00

Two MXL belts
http://www.amazon.com/gp/product/B00CMI ... ge_o08_s00
http://www.amazon.com/gp/product/B00CMI ... ge_o02_s00

An MXL pulley
http://www.amazon.com/gp/product/B00QUN ... ge_o09_s00

1/4"-20 cross dowel (<-- I got mine at Home Depot but you'll have to hunt for it)
http://www.amazon.com/Cross-Dowels-Barr ... l+1%2F4%22

A NEMA 23 stepper motor (I got mine from SparkFun)

Dallas
Posts: 23
Joined: Fri Mar 27, 2015 5:25 pm

Re: Home-Made Rotary Table

Post by Dallas » Mon Feb 08, 2016 10:35 pm

Assembly Instructions

My Shapeoko sits on a torsion box table and I wanted to bolt my rotary table to the front of the torsion box. I cut some angle iron and drill holes to attach it to some 3/4" MDF. I counter sunk those holes because I didn't want the bolt heads protruding on the top surface of the rotary table. I made sure to offset the holes in the angle iron so the protruding bolts didn't interfere with the lag screws to mount the table to the torsion box.

Because I wanted to make my rotary table handle sizes other than exactly 25" I added a sliding & locking mechanism. There is a sliding table, a locking wedge, and two MDF guides. One of the MDF guides has V-grooves cut into it on a 1" spacing. There is a bullet catch on the edge of the sliding table (opposite the wedge) to engage the grooves.
Attachments
SlideTableParts.JPG
SlideTableParts.JPG (90.98 KiB) Viewed 1500 times
Base.JPG
Base.JPG (96.04 KiB) Viewed 1500 times

Dallas
Posts: 23
Joined: Fri Mar 27, 2015 5:25 pm

Re: Home-Made Rotary Table

Post by Dallas » Mon Feb 08, 2016 10:41 pm

Assembly Continued

Here's a close up of the bullet catch.

And a close up of the wedge.

I drilled a LONG 1/4" hole in the sliding table. (That's 1/2" MDF, by the way. Not much margin for error to accommodate a wandering drill bit. 8-) ) Then I drilled a hole through the board for a cross-dowel nut. I ran a 1/4-20 threaded rod through the hole, threaded it through the cross-dowel, connected with the wedge, and captured it between two sets of jam-nuts. Then I put a knob on the threaded rod. By turning the knob, I slide the wedge forward and back. Sliding it back wedges the sliding table against the guides, locking it in place.
Attachments
BulletCatch.JPG
BulletCatch.JPG (97.05 KiB) Viewed 1499 times
Wedge.JPG
Wedge.JPG (64.64 KiB) Viewed 1499 times
Crossdowel.JPG
Crossdowel.JPG (103.77 KiB) Viewed 1499 times

Dallas
Posts: 23
Joined: Fri Mar 27, 2015 5:25 pm

Re: Home-Made Rotary Table

Post by Dallas » Mon Feb 08, 2016 10:47 pm

Assembly Cont.

I used business cards to shim the sliding table and the guides. I wanted a little slop.

Finally I attached strap iron (with permanent shims -- cut up business cards) to capture the sliding table.
Attachments
SlideTableShimmed.JPG
SlideTableShimmed.JPG (88.25 KiB) Viewed 1497 times
StrapIronShims.JPG
StrapIronShims.JPG (94.23 KiB) Viewed 1497 times
StrapIrons.JPG
StrapIrons.JPG (106.49 KiB) Viewed 1497 times

Dallas
Posts: 23
Joined: Fri Mar 27, 2015 5:25 pm

Re: Home-Made Rotary Table

Post by Dallas » Mon Feb 08, 2016 10:48 pm

This is a photo of the parts for the sliding table... (Should have put it earlier)...
Attachments
SlideTableParts.JPG
SlideTableParts.JPG (90.98 KiB) Viewed 1497 times

Dallas
Posts: 23
Joined: Fri Mar 27, 2015 5:25 pm

Re: Home-Made Rotary Table

Post by Dallas » Mon Feb 08, 2016 10:56 pm

Assembly Cont

Time for the lazy susan. I found a better than average quality lazy susan that I though would fit my needs. It's got some slop. It's probably OK for woodworking. Maybe not so good for metal working or high tolerances. Problem is, there's no easy way to add teeth.

Eventually, I selected MLX belting as a solution because the teeth looked symmetrical. It looked like one belt would engage another belt. I bought an MLS belt that was ever so slightly bigger than the 300 mm OD of the lazy susan. I measured carefully and cut a spacer ring out of 1/4" hardboard to use as an adapter. I epoxied the spacer to the lazy susan and the belt to the spacer.

Once done, I found the center line of the sliding table and drilling a 1/8" hole on the center line. I kept the waste from the spacer and cut it down to fit inside the ID of the lazy susan CAREFULLY marking the center of the disc. I drilled an 1/8" hole in the disk and then used it (with shims) to mount the lazy susan on the center line of the sliding table.
Attachments
LazySusanParts.JPG
LazySusanParts.JPG (89.13 KiB) Viewed 1495 times
LazySusanGearCloseUp.JPG
LazySusanGearCloseUp.JPG (75.58 KiB) Viewed 1495 times
LazySusanMounting.JPG
LazySusanMounting.JPG (86.83 KiB) Viewed 1495 times

Dallas
Posts: 23
Joined: Fri Mar 27, 2015 5:25 pm

Re: Home-Made Rotary Table

Post by Dallas » Mon Feb 08, 2016 11:09 pm

Assembly cont.

With the lazy susan in position, I drilled holes corresponding to the inner race into the sliding board. (By the way, the holes as purchased don't go all the way through the races. You'll need to drill them through. No damage is done to the lazy susan that I noticed when I drilled the holes through.)

Since the inner and outer races of the lazy susan are the same height, I needed to add spacers. Spacers under the inner race and spacers over the outer race. My CAD file shows washers (which would work) but I ended up using 1/4" nylon stand offs.

Screw the lazy susan down to the sliding table. Make sure your screws don't go through the sliding table into the 3/4" MDF base below (or it won't slide very well no matter how loose the wedge is. :lol: )
Attachments
LazySusanandNylonSpacers.JPG
LazySusanandNylonSpacers.JPG (96.62 KiB) Viewed 1492 times

Dallas
Posts: 23
Joined: Fri Mar 27, 2015 5:25 pm

Re: Home-Made Rotary Table

Post by Dallas » Mon Feb 08, 2016 11:18 pm

Assembly cont.

The workpiece needs to be attached to the outer race of the lazy susan somehow. I decided to have a permanent piece and a waste board attached to it. The permanent piece needs to have holes cut in it that matches the locations of the screws for the inner race. The assembly order is: Flip the lazy susan upside down and attach it to the "top" piece via the holes in the outer race. Then flip it right side up and attach the assembly to the sliding table via the holes in the inner race.

Because I used 1/4" nylon stand offs, my drive belt was going to be 1/4" off the surface of the sliding table. I took some left over hardboard and created shims to glue under the drive belt at strategic locations.

The next step is to mount the NEMA 23. Here's some parts I used. I wanted to be able to slide the motor to adjust the belt tension.
Attachments
StepperMotorMount.JPG
StepperMotorMount.JPG (114.84 KiB) Viewed 1489 times
BeltGuides.JPG
BeltGuides.JPG (108.15 KiB) Viewed 1489 times
TopRotary.JPG
TopRotary.JPG (73.1 KiB) Viewed 1489 times

Dallas
Posts: 23
Joined: Fri Mar 27, 2015 5:25 pm

Re: Home-Made Rotary Table

Post by Dallas » Mon Feb 08, 2016 11:28 pm

Assembly Cont.

Here's a shot of the final rotary table as well as a spare photo or two.

I disconnected the X-axis stepper motor on the grbl board (or whatever it is). It's the plug farthest to the right as you are looking at the front of the Shapeoko. I slide the router over the center line of the sliding table and blocked the x axis from moving side to side by clamping some 12" Dewalt hand clamps on either side of the Z-axis assembly. Then I wired and plugged in my rotary table stepper motor into the freed-up X-axis pin connector on the board.

I attached a wasteboard of 1/4" hardboard to the upper table of the lazy susan. I drilled a hole in the center of the wasteboard and used a 1/8" drill bit to align the center of the wasteboard to that 1/8" hole on the center line of the sliding table. This is the center reference of my workpiece.

When I mounted the rotary table assembly to the torsion box that holds my Shapeoko, I mounted it so the bottom of the 1/4" waste board was about 1/8" off the waste board of the Shapeoko. Then I put a piece of thick felt under the rotary table waste board. The felt prevents the wasteboard from deflecting while machining and it wipes the bottom of the rotary table clean.

Y and Z work as normal. Any movement in the X-axis is interpreted as a rotary motion. So I design my parts as long rectilinear elements, and machine them as normal.
Attachments
RotaryAssemblyFinal.JPG
RotaryAssemblyFinal.JPG (100.92 KiB) Viewed 1481 times
IMG_2675.JPG
IMG_2675.JPG (85.72 KiB) Viewed 1481 times
MountedStepper.JPG
MountedStepper.JPG (99.56 KiB) Viewed 1481 times

AnonymousPerson
Posts: 758
Joined: Sun Apr 26, 2015 1:16 pm
Location: 3753 Cruithne

Re: Home-Made Rotary Table

Post by AnonymousPerson » Tue Feb 09, 2016 5:18 pm

That looks pretty well done. Any video of it in operation? :)

Also, which software do you use for gcode generation?
Shapeoko 3 #516

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