diy cnc rotary table free sample

About 3 years ago I bought a cheap rotary table that I converted by taking off the handle and replacing with stepper motor. I used thrust bearings and whatever I could think of to minimize the backlash but it was a big FAIL. The internal worm gear mechanism was so sloppy that backlash was measured in degrees. Its been sitting on the shelf collecting dust. Since then I found out about Harmonic Drives and what high end CNC/Robotic systems use for rotational axis. A new harmonic drive is big $$$$ so eBay to the rescue. The gear head I used is planetary but made by Harmonic Drive Systems so it is very precise. It’s simple and just the right size for my small cnc. Since the stepper motor, gecko drive and gearhead was bought off eBay, it wasn’t that expensive. Under $150. I had upgraded my mini lathe to a bigger 5″ 3 jaw chuck. The 3″ chuck wasn’t being used anymore so I put it on the gearhead.

Years ago, before I learned CNC, I owned a Phase II 8″ horizontal/vertical rotary table that I purchased from Kap Pullen’s Getmachinetools.com store. He has them at a good price, BTW, and he’s a darned nice fellow to deal with as well as being a frequent HSM contributor. Anyway, its a nice little table, but I hadn’t done a whole lot with it for quite a while after purchasing it. As is so often the case, one day, a project landed on my doorstep and I was glad to have it.

Before I could get started, however, I had to make some accessories for it. Basically, I needed some T-Nuts to fit the table, as well as a little fixture that makes it easy to hold a plate up off the table through a hole in the center so you can machine it. The latter, what I call a “plate machining fixture”, was inspired by something similar I saw the Widgitmaster of CNCZone fame using to make Dremel clamps for his mini-router:

I turned the round spigot using the 4-jaw on the lathe. I’m making the fixture out of MIC-6 aluminum plate, which is pre-ground very flat on the sides. This is a 5 inch by 3 inch piece. I’ve clamped it to the rotab using my T-nuts and the regular mill clamps and step blocks. It is sitting on parallels to make sure I don’t cut into the table. You can also see how I’ve clamped the rotary table to the mill table using a big cast iron V-block I have. You can never have to many blocks with precision faces hanging around!

Having a 4-jaw chuck on your rotary table is mighty handy! Because it’s a 4-jaw, you can dial in the workpiece by adjusting the jaws until it is perfectly concentric with the table’s axis of rotation. The best way is to make an adapter plate that attaches to the back of the chuck in the same way that your lathe does so you can exchange lathe tooling with the rotab. Here is an example:

For the example, the chuck is threaded onto the adaptor plate, and then the holes in the adapter plate’s flange are used to bolt down to T-nuts on the table.

In my case, I bought a 4-jaw from Shars brand new, and simply drilled some through-holes in the chuck to mount to the table directly without an adapter plate:

First, you want to make sure your part is properly centered on the table. To do that, I clamp the table down on the mill table (no special place is needed), put my Indicol indicator holder on the mill spindle, and find some round feature on the part to indicate on. For example, on the plate milling fixture above, indicate on the round boss, or on the center hole. Spin the table and bump the part in until spinning the table doesn’t move the indicator.

Second, locate the center of rotation directly under the mill spindle. You can simply use the X and Y table handwheels to do this. Use that Indicol to indicate off of a circular feature you want centered under the spindle. Turn the indicol around on the spindle and adjust the handwheels until the indicator stays put relative to the spindle position. A Blake Coaxial indicator will make this last even simpler.

When you’re rounding partially by cranking a part around on the rotary table, it’s really easy to go a little too far and screw things up. The answer is to drill the end points to make the exact stopping point on the rotab a lot less sensitive:

Centering with a Blake indicator is really fast, but what if you don’t have a Blake, or worse, what if your mill is too small to accomodate one? Here is a nice solution I found on a German site. This fellow has made an ER collect fixture for his rotary table, and has taken care that when installed on the table, the axis of the collet is aligned with the table’s axis. He can then place a dowel or other straight pin in the collet and line up until it will go into a similarly sized collet on the spindle. Nice trick! It’s similar to how Widgitmaster showed me to align a drill chuck on a QCTP to the lathe centerline with a dowel pin held in the lathe chuck.

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I am wondering how it would work to mount a stepper motor or servo motor on the rotary table. What all would I need in order to make a laptop computer operate the rotary table?Sherline makes a very small rotary table that is just what I am looking for but it is tiny. I need something bigger and stronger. The sherline looks like you can program a certain number of divisions and then every time you hit the button it moves to the next location.

Step 1: measure the amount of force it takes to turn the wheel, so you know what size stepper you need. Put some load on the table, like a heavy vise and pull the edge of table with 50+lbs of force (1/4 horsepower, scale up as needed) to simulate machining forces (although in your immediate app, you probably won"t be machining and moving at the same time). Give yourself a safety factor. A double ended shaft is recommended, so you can mount a handwheel on back end for manual operation. For a small table like the sherline, most NEMA-23 motors should work. For a larger one, you may need higher torque NEMA-23, NEMA-34, or geared steppers.

Step 2: physically mount motor to rotary table. On some tables, the shaft is supported on one end by a piece that bolts on. This provides convenient mounting. You may be able to machine a plate that has the original mounting holes, a bore for the bearing, and 4 holes for standoffs that match the stepper motor mounting holes. You will need a flex coupling. Bear in mind that the position of the shaft determines how well the gears mate and how much backlash there is. You may want slots for the mounting holes so you can slide the plate.

Step 5: PC interface. If your laptop has a parallel port, all you need to do is connect ground, step, and direction. The latter two can be connected to D0 and D1 on the parallel port. You will configure the software to tell it what pins you used. Parallel ports are going the way of dodo birds. USB->Parallel adapters are not suitable. USB is a bit trickier, though there are some stepper controllers available: here is one: http://www.usbcnc.com/index_products.html. I have seen a cheaper one designed by someone here or on CNCzone that looked halfway decent but can"t find it at the moment. About EU$69, USB, PIC based, 3 axis, no source code, windoze software included. Looked adequate for what you are doing but not for my purposes:

EMC is free but requires you reboot the computer to run real time linux. TurboCNC is $60, requires you to reboot to dos. There is some more expensive stuff out there. If you have a USB or RS-232 controller that speaks g-code, then you can probably just open a terminal emulator to the controller and type g-codes. "G01 0.0", "G01 15.0", "G01 30.0". If you have any programming ability, you can just write a trivial program to do this. Bear in mind that Windoze, as well as normal non-real time linux, Mac OS X, and other desktop operating systems are lousy at real time applications. Thus, an external CNC controller can work better.

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From the May issue of Modern Machine Shop Magazine " A CNC retrofit provides improved reliability and functionality compared to an older machine’s original control, and this is helpful in a number of ways. For example, a more intuitive control interface can help speed setups and minimize the chance for programming and/or setup mistakes, which could possibly damage or scrap a high-value work piece. Similarly, shops are also more confident in quoting work for large, expensive parts knowing the new control won’t hiccup partway through an operation and cause the part to be damaged. Shops also are better-positioned to take in “hot” jobs that require fast turnaround due to the retrofitted machine’s improved"... click here to see the complete article in PDF.

CENTROID Boss series II retrofit customer testimonial"The quality and workmanship of the CENTROID equipment was outstanding and very professional. CENTROID was able to custom tailor the control to allow us to continue to use our rotary milling arrangement as before and even expanded our capability. The short story is that we ended up with a four axis CNC mill for less than half the cost of the three axis Haas. This includes the work that was done by our staff."

With this extension, your CNC milling machine gets the 4th axis. That allows you, for example, to mill round parts or create engravings on rounded surfaces.

This rotary axis is made to order for us by a German precision mechanic. In this price segment, this rotation axis for CNC milling machines is unrivalled in Europe!

There are many rotary tables on the market. If possible, they have to be inexpensive. You can get a lot of them! Usefulness? That is where the wheat is separated from the chaff. For example, there are many CNC turntables with the cheapest belt transmission. The disadvantages are obvious: slippage due to the belt. If not in the belt drive itself, then on the load or idle side of the belt. Perhaps useful for engraving work. For milling, however, usually not or limited in the choice of material (aluminium 3D milling not possible).

That means you can use the CNC router for 3D 360° machining in almost all materials. Even round engravings on Plexiglas are possible without any problems with this CNC accessory. That means for our CNC machine users: Round surface milling of plastic parts, wooden parts, aluminium parts or round parts made of brass, as well as engravings of all kinds.

G94 is used to perform simultaneous milling. The relay is pulsed at the beginning of the step so that the CNC mill goes to the next block. The Servo Control then executes the L steps without waiting for start commands. Normally, the L count on the G94 is set to 1 and that step is followed by a step that is run simultaneous with a CNC mill.

You will need to take the rotary table apart (2 screws at the bottom) and remove the worm gear/handle. Drill the piece, top and bottom (very easy to drill and tap) about 10.5 mm from the edge...

I am using this 4" rotary table to convert into a 4th axis for my SX2 CNC Mill. [url]http://www.ebay.com/itm/4-ROTARY-TABLE-NEW-3-28-12-PIC-5794-/231628103620?pt=LH_DefaultDomain_0&hash=item35ee1c5fc4[/url]

I had a manual Sherline Rotary Table (#3700) that I wanted to convert to CNC. This design is for a frame to secure a Stepper Motor to the Rotary Table"s Worm gear"s shaft, as well as a spider coupler to transmit the rotary forces from the stepper...

I had this rotary meec tool laying around and I was building the diy dremel cnc by Nikodem Bartnik. I didnt want to buy a dremel because I had this one laying around and it was unused so I designed a mount for it.

Water plasma table for me DIY cnc You can see this table in this video : http://www.youtube.com/watch?v=Cg4g8d4JUjQ without water. ...The milling table from picture is here : Milling table for me DIY CNC milling machine

A SolidWorks model from the book "Build Your Own CNC" by Patrick Hood -Daniel and James Floyd Kelly during my spare time and practice using solidworks.

This is the Fusion 360 Design of the CNC-Machine I"m currently building. Maybe this is of interest to someone else, too. ...I"m also happy about some feedback, since I"m not sure the Y- or Z-Axis designs are really stable enough.