Review: Delta 16" VS Lathe 46-756 (Long)

Searched Google and found no references to this product, so I became the guinea pig in response to an offer I couldn't refuse. Presented here are my personal observations and conclusions in case others desire more information about this lathe in the future.

I had been looking at larger lathes, but the prices were pretty steep for the heavy duty Poolwoods, Stubbys, Oneways, etc. I had been lusting over. The Teknatool Nova DVR was more in the price range I could afford, but that incessant beeping and custom motor components, while quite possibly superior, kind of put me off. Will there be parts available in 20 years? Who knows. But since I adhere to the KISS principles of mechanical design, ease of repair and conventional off-the-shelf components are what I lean towards. And that mostly describes the Delta 46-756 16" Steel Bed Lathe. While the VFD design offends the Luddite in my soul, my practical geek side appreciates the solid advantages to be gleaned from such abstract gee-wiz technology. Such is life - the struggle between compromise - and more compromise.

A local dealer was itching to move this last store display lathe, and I took the bait. After an hour of lugging 450 lbs of steel around town, it was set up in the shop/garage; destined to replace the venerable Jet Mini I had been using to spin 9" chunks of found wood.

The Jet has been an excellent machine for the money, and has performed every task it has been asked to do with no complaints. I have used it as a 10" disc sander, a ring press, as well as primarily turning items at the limit of it's swing. It has never seen a pen blank.

The Delta, however, promised easy solutions to the shortcomings of the Jet's simple design. Slower speeds, greater swing, and more bulk were primary criteria for a replacement. The ability to utilize existing chucks/accessories was also required.

Specs: (measured) Swing: 16" Swing-over base: 11.5" Bed Length: 58 1/8" Usable bed length: 40" (Mfg Claimed: 42") (less head/tail stock) Bed Rail Flatness: < .006 Bed Rail Deviation: < .014" diagonally over 36" (limit of straightedge) Toolrest Post Diameter: 1" H/T Morse Taper: #2 Spindle Thread: 1.25" x 8 TPI Indexing: 24 positive stops Faceplate Runout: .0015" Bearings: 6207LB - Mfg: NTN Deep Groove Ball Bearings, Non-Contact Seals OD: 72mm - ID: 17mm 9,800 Max recommended RPM/greased Drive: Flat Ribbed Poly-V Belt - Mfg: Tokurope (who?) Country of Manufacture: Frame/Bed: Taiwan Motor: USA VFD: China*

Motor: Marathon, 2 HP, 230 Volt, 3 Phase, 1725 RPM NEMA 56CZ-80 Open Frame, Mfg in USA VFD: Delta Custom/Plotech Design - Mfg in China* Speed: Infinitely adjustable range of 0-3000 RPM Display: Red 4 digit LED displays predicted RPM/10 Only 3 digits are used for the numeric display, the leading digit displays "F" constantly... ? 4 additional tiny red LEDs for FWD/REV/RUN/STOP Controls: Membrane switches for RUN/STOP/FWD/REV PC mount potentiometer for speed control 2 position slide switch for Accel/Decel rate Two additional unidentified membrane switches RJ Serial Port-Protocol Unknown Power Switcher: Mitsubishi IGBT Hybrid Module CM20MD1L-12MH 20 amp, 600 Vces, Six-IGBT three phase bridge

• = probable ? = unsure if this is normal, or indicative of a "Fault" condition.

While some might be confused by the 230v three phase motor, rest assured that the lathe comes equipped with a standard NEMA 6-20P connector and operates on standard 220v single phase residential power. The secret to both this and the electronically variable speed lies in the Variable Frequency Drive (VFD) controller. This is basically a device which converts standard 220VAC to DC, and using a microcontroller and an IGBT bridge module, supplies precisely timed pulses to the three legs of the motor to achieve rotation in either direction, variable speed, and high torque/low speed capabilities. There are no start capacitors, brushes, or contactors in the motor itself - just magnets, windings, and bearings/housings.

In addition to variable speed which ranges from 0 to 3000 RPM and reversible rotation, there is a programmed gradual start-up and power assisted decel feature adjustable by a two position slide switch that allows changing the acceleration/deceleration of the motor to "Fast" or "Slow".

Realize that hitting a price point means that compromises are made in manufacturing any mechanism/device. One of these is the VFD. While power is adequate so far, and speed/load variations seem trivial, there are a few oddities.

The VFD is fan cooled, as in computer fan; right out there with all those shavings and dust. While its location does negate being struck by a tossed work piece and most shavings, it is still exposed.

Delta apparently chose to partially design their own VFD controller, with the assistance of Plotech, a Chinese design house, rather than using an off-the-shelf commercial controller. Custom ASICs and software are evident in the 911703 controller. And although it is field programmable and contains several odd unidentified buttons on the controller face, the manual is annoyingly silent concerning the controller and its features. And it truly contains the worst Start and Stop buttons ever seen on a piece of woodworking equipment. Tiny, un intuitive, and impossible to hit in an emergency. It would have served them/us well to allow the connection of a user supplied pod of auxiliary heavy duty SPST switches through the barrier strips on the controller PCB. In this instance, the Oneway's user controls stand vastly superior - but at a premium. There is no warning when switching to reverse rotation, and the tiniest LED direction indicators on earth are pretty useless from a normal turning stance. And why is the RPM LED display prefaced with an "F"? Why not display an "F" or "R" to indicate rotation direction? Or is this lathe in a perpetual "Fault" condition? The manual will never tell...

Also, the speed control potentiometer is a small PCB mounted control that is a bit cheesy, and should be more rugged. But it does work. And when the speed pot dies as the warranty expires, perhaps I'll box up a custom version with better switches and controls. And if it gives up the magic black smoke, one could install another controller (and/or motor) without too much grief.

Another compromise was the choice of an open frame motor. One factor influencing this selection could be motor cooling. At low RPM, the internal fans generate little to no airflow, and a TEFC motor might run hotter than one that can utilize ambient airflow to assist in cooling at low speeds. Perhaps it was chosen because it was the cheapest motor available. It could be a combination of both factors. While there is little possibility for explosion, due to the absence of a contactor and capacitors in the three-phase motor, the design leaves the windings exposed to environmental contaminates, primarily dust. My personal choice would have been a TEFC motor using an independent auxiliary fan rather than motor shaft driven fans. I would have stepped the speed down under stop conditions, and revved it back up when the lathe was running. Mostly trivial to implement, but that's my take. I would most assuredly suck any dust out regularly (NOT with high pressure air), as fire could conceivably result from a buildup of wood dust in the motor windings. I'm just not accustomed to seeing open frame motors on WW equipment.

With that said, however, the motor is smooth and powerful enough, even at low speeds (a shortcoming of conventional 120v Motor/VFD designs), and doesn't run particularly hot - although it does get pretty warm during extended low speed operation. One additional observation is that the engineers who design these things must suffer from high frequency hearing loss, as the non-dampened, harmonic rich impulses fed to the motor by the controller result in an audible high frequency whine which emanates from the motor windings. Some can't hear it, I find it annoying. While LC filtering could have been used to reduce this, the size and cost would be substantial and EM Feedback controller sensing is problematic as well. High-pressure impregnation of the motor windings might help, however, and dampening the motor temporarily with sound deadener reduced it noticeably. It might not be a problem for me in a few more years... as I get older... and older...

Well, enough of this EE gobbledygook, how does it all work? Pretty well, so far - especially considering what I paid - 1/3 the cost of a 16" Oneway, and 2/3 the cost of a Nova DVR 3000.

The steel bed is stiff enough, but it does make odd sounds at certain frequencies. Same with the legs - the welded clamshell box design contains resonant cavities that should be filled with sand to dampen audible vibrations - and that capability was designed into the unit.

The steel screw levelers caused a sympathetic vibration in our concrete floor at 1030 RPM, and after some experimentation, I found that decoupling the stand from the floor with HD rubber pads eliminated most, if not all, of the resonance. I will probably turn some HDPE feet to place under the levelers.

The tool rest, headstock and tailstock do not lock as securely as the Jet mini, and this is apparently caused by the same steel clamp on the bottom of all three assemblies. Careful adjustment of the clamp U-bolts improved the situation, but a thicker clamp plate would probably help more. I've not experienced any tool rest base movement in use, but the tailstock/headstock can slip unless they're really torqued down.

Reverse/Slow Speed is useful when sanding for eliminating those torn fibres you can't get any other way, just make sure the spindle is very secure as it could unscrew itself in a hurry - about 12 turns, which at 800 RPM happens in about .9 seconds. I personally wouldn't actually turn in reverse, not without the proper handed threads, and I'm a lefty. The faceplate has a setscrew, but I have noticed that none of the high dollar faceplates have a grub screw - not even the 1 1/4" x 8 TPI Oneways. Listening Bill N?

The variable speed is great, and the really slow speeds allow application of finishes devoid of runs and pooling. Although I have not yet tested this, I would watch for motor overheating while waiting

The headstock and tailstock are open castings, ribbed and well finished, but not as solid as an encased casting. It's no Poolwood. The toolrest seems a little soft, but no worse than the Jet Mini. The handwheel is curiously small, but well machined and smooth. The tailstock has a self-ejecting MT2 center with an applied rule. Balance of the tailstock handwheel is good. Supplied cast 4" faceplate runout is acceptable. Head/Tail center points meet nearly dead-on. Welding is good, but some slag splash remains. The headstock slides the length of the bed, useful for bowls and hollowing, but I personally can't envision practically using an outboard toolrest to exceed the 16" swing limitation. Paint is good, but chipped here and there due to store display status. There are built in flanges for mounting a 12" wide, 52" long shelf. You may install 4x4s in the stand bases to widen the stance. You may adjust the height with 4" x ?" hardwood/plywood lumber, although you will have to replace the 3/8" carriage bolts with suitably longer hardware. It is ~2" too short for me, and I'm 5' 9". And lastly, Two Guys can move the thing, unlike some lathes.

I've constructed a vacuum chuck using a shopmade rotary bearing milled from HDPE and fitted with deep race sealed bearings. It fits both the Delta and the Jet. Also built a 16" sanding rig for ring segments.

In conclusion, nothing jumps out and screams CRAP as with some products - built to a price point, perhaps, but what isn't. Long term usage should reveal more information, but that's it for now. I believe that, nits aside and based on the cost and my somewhat limited turning experience, the Delta 16" Lathe was a good buy overall.