08/17/2014 MEGA Rev03

The InTurn™ 4th axis specs and features

‘Mega Duty’   ‘Tail Stock II’

‘InTurn ULTRA’ and ‘InTurn ULTRA-T’  


The following are brief descriptions of the machines and general specifications.

e-mail Steve@thecubestudio.com for detailed spec sheets, photos or model comparison chart.


The InTurn™ Mega:

About to have its second birthday, this model is mature and well tested. Some upgrades have been incorporated based on feedback and in-house experience.

This is an industrial grade machine. Spindle bearings are SKF Explorer series. The massive aluminum frame draws heat away from the bearings for a 100% duty cycle. Run this machine hard 7 days a week 24 hours a day. If you can break it we will fix it  . . free.

With a custom made 1144 steel spindle and industry standard D1/A2 mounting flange, this machine can handle any work that a Bridgeport type machine would normally do. ANY servo motor up to 3HP can be used  The motor mounting plates are all custom cut to mount your motor.

The Mega has two speed ranges via moving the 5mm pitch GT style timing belt between ‘direct drive’ and ‘back gear’ The standard 12:1 low range ratio provides high torque for extremely heavy or accurate work. High range pushes the dynamically balanced rotating assembly smoothly and quietly up to 4,000 RPM for use with the included 5C collet capability built into the hollow spindle as a standard feature. A balanced collet draw tube is included.

The InTurn™ Ultra:

This is the brute strength version of a 4th axis. The spindle is the heart of any machine tool and the Ultra has a very big heart.

The massive forged alloy steel spindle is cut from a single 90lb 4140 alloy steel forging.

The spindle features an industry standard D-6 Camloc AND A2-6 mounting flange.

The hollow shaft accommodates:

      Large stock pass thru.

      A standard 16C collet in the spindle nose (Draw tube is included)

      The pull tube of a POWER CHUCK.

Pick from column A or column T.

A pair of double sealed SKF Explorer series deep groove ball bearings. These relatively new bearing series are made to ABEC3 and outlast even SKF’s standard bearings many times over.

If you need to off center drill, bore, shave, knurl, hammer, punch on a work piece or hold a could hundred bound chunk of steel cantilevered a few feet out from the chuck . . i.e things that would quickly destroy a 4th axis . . . no problem . . just choose from column T for massive tapered roller bearings.

Static loading on the front bearing on the Ultra-T is 10 times that of a deep groove ball bearing.

To accommodate the 10 + HP that can flow thru this machine and support the heavy hydraulic actuator required by a power chuck, the main drive pulley is 8MM (Mega is 5mm) and made from steel. The belts are the limiting factor on power and the 8mm belts have several times the power capacity of the 5mm belts. To maximize the power handling, as well as smooth quiet running, only the newer GT series curvilinear tooth belts are used. 


For normal work, any 4th axis tail stock can be used with the InTurn™. However, to take advantage of and even enhance the unique capabilities of the InTurn™, the custom Tail Stock was developed. It features a custom designed hollow steel spindle with 5C collet capability. The Tail Stick spindle rotates on double sealed ball bearings so rotating centers are not needed. Any stub on the work piece can be held in a 5C collet by the tail stock and rotate on the tail Stock bearings up to 4,000 RPM.

Stock can also pass thru the tail stock spindles so that machining can take place on the end  . .or even the middle of a shaft . . . .with both ends of the shaft supported.

Need to hold instead of rotate? No problem. The Tail Stock has an internal spindle damper/lock that is both manually adjustable and pneumatically actuated.  Getting some chatter 18” away from the chuck? No problem with the InTurn™ tail stock, just dial in some damping at the tail stock and the chatter settles down. Need to lock the far end of a part solidly enough to drill a series of holes off center? Long trunnion table flexing a little? Again, no problem. Torsional issues are handled by the InTurn™. The pneumatic cylinder will take over and put a hard lock on the spindle. Upon release, the Tail Stock returns to the manually set  drag. Got a taste for fancy? A digitally controlled pressure regulator can take the place of the manual drag adjuster and have the 200psi rated air cylinder do both the drag and hard locking.

The InTurn™ Tail Stock slides on its own track which is supported by heavy steel blocks that are bolted to the mill table. The rail and tailstock can be moved leaving the blocks in place on the table. This maintains the Tail Stock alignment and also provides some handy fixturing attachments. As with all Tail Stocks, the InTurn™ Tail Stock has a lead screw to advance the spindle toward the chuck. The InTurn™ Tail Stock slides along its rail dragging the leadscrew with it. The leadscrew support can be locked to the slide at any point and the leadscrew used to advance the leadscrew. Unlike a traditional tail stock, The InTturn™ Tail Stock can advance a drill bit 6”, 12” 18” into a work piece all at  once without resetting, and can even do it automatically if the leadscrew is powered.

The InTurn™ Tail Stock can also retract the spindle away from the chuck. It is no longer impossible to machine long thin or small diameter, or ultra flexible materials. The InTurn™ Tail Stock, but virtue of its lead screw and 5C collet, can impart tension on a workpiece. Task: cut a deep, continuous radial cam slot into 1/2” diameter Delrin with a pitch that steadily decreases over the 12” length. Doable? Yes and without a follow rest. Putting some tension on that little stick of Delrin and it behaves like a 1” bar of aluminum.

With a power chuck and a powered Tail stock, well . . the possiblies are endless.


Replacing the InTurn™ Tail Stock is the new Tail Stock II. It has all of the capabilities of the previous model and one vey major advantage. It addresses the single negative aspect of using the InTurn™ Tail Stock on a mill; namely having to take down the chuck in order to set up the Tail Stock on the table.

The new Tail Stock II is specifically engineered to work WITH a mill table chuck in place. All controls and locks as well as the pneumatic cylinder were moved up high on the frame so that the Tail Stock II ‘head’ can simply be clamped in the vice!. The Tail Stock II rides on a flat steel rail that is arranged to sit at the exact level of the vise bed so that the rail can be put on by simply opening the vice jaws wide enough. The Tail Stock II head has no protrusions that prevent it from sliding right thru the vice on its own rail!

So if you need a tail stock for a quickie job, you don’t have to decide if it is worth the effort to take down the vice,  set up the tail stock, dial in the tail stock, make the 10 minute cut, then take down the tail stock track and put the vice back up and dial in the vice all over again. The 10 minute cut took 45 minutes!

No more! Same scenario you just grab the tail stock head, clamp it in the vice and GO!. Piece is longer than the vice? Not a problem. The Tail Stock II rail mounting blocks can be left on the mill table as they are specifically designed to straddle the vice. Grab the Tail Stock head and mounting rail. 4 bolts hold the rail to the blocks. (If very precise alignment of the tail stock is needed, the fail can be doweled to the block after the initial alignment)

The ROI on the Tail Stock II is incredibly fast due to the explicit focus on making it fast and convenient to use. Potentially saving 30 minutes on each setup or better yet, paying for itself in one incident where a tail stock was called for but not used because it was such a PIA to take the chuck down, or ‘there was not enough time’ due to a rush job. Could you ruin an expensive part and damage an expensive chuck by not using a tail stock?




Frames are constructed from thick 7000 series  Aluminum plate, boxed in with heavy structural cover plates.

The aluminum material serves two purposes;

   1) Less mass for table servos to move – retuning not needed.

   2) Aluminum efficiently pulls heat away from the bearings

Bearing pockets are line-bored in the same fixture for perfect alignment.

Full belt covers are integrated into the top and side with a formed 0.1” thick cover for the motor drive belts.

Mounted on optional ‘outrigger’ plate, the 4th axis overhangs the mill table and only takes up about 4” of table space.


Spindles are balanced to run at 4,000 RPM.

The 4th axis have combined D1 and A2 industry standard mounting flanges.

Spindles are hollow to pass long stock and take standard 5C or 16C collets Draw tube is included.

Final nose tapers are finished after assembly and bearing preload. Runout at the tapers is less than .0003”


Two speed ranges are provided via a quick change belt move;

   1) The double reduction ‘back gear’ setting provides high torque and holding power.

   2) Direct Drive’ provides high speed turning for small diameter or aluminum and brass materials


Modern GT profile curvilinear tooth pulleys are all custom made for the machines.

Motor shaft extension and pulley are made from a single piece of steel and provided mounting for a separate high speed direct drive pulley.

The countershaft spindle is one piece with teeth cut into the shaft.

Pulleys are specially machined to eliminate the tiny backlash built into the curvilinear profile to provide highly accurate indexing and rotary machining.


Custom made articulated pneumatic caliper provided over 100 ft-lbs of holding torque on 90psi shop air.

Cylinder rated for 200PSI leaving a great deal of added capacity, although so far no operations have needed more than 90psi.

DOT approved hardened and ground steel vehicle disk brake rotor is mounted on a thick steel collar and balanced.

       Note, the Tail Stock II has a combined spindle damper/lock provided by an internal band brake.

CNC controlled solenoid operated pneumatic valve controls the spindle lock. The valve and a CNC compatible relay are included.


*The 4th axis included a non-contact photo-interrupter type sensor for fhoming the machine.

            The high quality industrial sensor is internal and comes pre-adjusted and pre-wired.


There have been no problems with international shipping of the device. InTurn™ 4th axis have been shipped to USA, South America, Canada, The Netherlands, UK, Europe, Russia, Pakistan ad India. Cost varies widely depending on the global situation and changes day to day.


Never a problem. Both Domestic and International buyers can get shipping cost estimates by going to UPS.com or USPS.com and entering the following origin info and your destination info:

Items ship from Sherman, Texas Zip 75090. Pickup is not needed. Put whatever insurance on it that you like. Box sive is approx. a 12” x 18” x 12” and weight is approx. 35lbs

Note: The Ultra will be considerably heavier than the Mega. Shipping weight is not know at this writing.


InTurn™ MEGA Duty 4th axis US$ 2,950

InTurn™ ULTRA Duty 4th axis

 Sealed Ball bearing model        US$ 3,795 (introductory price)

InTurn™ Ultra-T

Tapered Roller Bearing model  US$ 4,995 (Introductory price)

InTurn™ Tail Stock II                US$1,495



Typically these machines are sold out and not available from stock. Produced in batches, the start of a run is announced first to a waiting list, and later to the general public thru various channels.

At announcement and ordering period opens and remains open for a couple of weeks or until the batch is sold out whichever occurs first. Once materials and parts are purchased for the production run, no further orders are accepted and a new waiting list is started.

Shipments typically start 30 to 45 days after the order period closes. Buyer who order an InTurn™ 4th axis and a Tail Strock II may receive them at different times due to batching of the machine types.


High Precision: standard spindle bearings are SKF Explorer Series ABEC3 single deep groove sealed ball bearings.

            The frame now meets install standards for ABEC7 Angular Contact pairs with separate seals.

            This option must be quoted after specs are set, but typically would be

US$500 – US$800

Outrigger Mounting Plate:  Minimum 1” thick surface ground steel plate for cantilevered mounting.

           US$ 95

Rear Mounted Motor:    Motor hole cover plate, standoffs and motor mounting sub plate

            This option if for motors over 7” long that might interfere with mounting large chucks of faceplates.

            The motor is mounted behind the 4th axis on sturdy ¾” dia steel standoffs and separate mounting plate.

            US$ 150

InTurn™ motor controller system (for use with MACH3/MACH4 CNC software):

US $499 (a link to the intro video is on theInTurn.com home page)

Trunnion table:

            US$ 500. (cost varies with the size of the table that is ordered)





            Machines are made in batches. Customer spec and minimum deposit (50%) are required.

            Please contact steve@thecubestudio.com for availability and schedule.