my thoughts (fwiw)

by ydna-zds

You would make good use of a 440 but it would leave a lot of room to desire something with more features. For reference we have a 770 at my dayjob, with power drawbar and some other accessories, and it's a very useful toolroom machine. (it's a couple years old, from when they were using Mach3) however it has some issues which would make me consider something else if we were looking for another one. We paid about $9k shipped for it.

Stuff I don't like, aka "I wish they hadn't done this..."
- Stepper motors that are slow, and easy to miss steps, or the screw coupling slips (same effect). This is especially noticeable with Z-motion where there's a relatively high load.
- The worst toolchanger of any CNC that I've ever used. It uses 3/4" diameter straight-shank holders which are physically jammed against the R8 collet's "nose" when the drawbar locks. The tools can spin, pull out, and their accuracy is not very good even forgiving the other issues. It's the janiest system ever made.
- The machines are built, assembled, wired, tested, packaged in china. Tormach pretty much distributes them. I guess the guys in wisconsin "designed" it, whatever that means. This isn't a problem per-se, but to me it just adds tormach to the list of companies trying to obfuscate the origins of their parts since they know people don't like it. But whatever.
- The 4th axis rotary hardware is very poor. It's literally just a rotary table with a stepper adapted where the hand crank used to be. It's not meant to be driven with a motor so the design has no way to be lubricated in a manner that doesn't allow all the oil to simply drain out the bottom after 30 seconds. It's chinese trash. I know this may not apply to you right now, but it's still notable.
- Lack of hardwired controls. Using the mouse and keyboard is okay if you're cautious, but nothing beats an industrial control with actual buttons and knobs.
- (older machine with Mach3 only?) The control is generic and therefore not specific to the machine itself. The axes will happily overtravel themselves if you command them to do so, and there are lots of G-code translation quirks that allow it. I guess this is common for any machine using mach3 since the control doesn't know what type of machine it's running. I assume this is different with pathpilot but I don't know for sure.

Some good stuff:
+ The PC-based interface is easy to use. I haven't used the pathpilot system but I don't really see how they could go wrong with that. The machine comes with a cute analog jogwheel which is much more intuitive than an axis jog button. It would still be nice to have dedicated control buttons but at least the remaining control functions are easy to operate.
+ Two-speed belt drive does its job.
+ Spindle power and RPM is good for what you pay. It's especially good for steel cutting where you're running slower speeds.
+ Accessible input power (20-A @ 120-VAC single phase). I've found the spindle inverter is the bottleneck item taking current. Lower speeds need much less current for the whole machine. But running full spindle speed at full rapid will indeed draw 20 amps for a short period of time.
+ Lots of hard-lined lube lines.
+ The machine uses dovetail gibs which are pretty damn beefy compared to most mills of comparable size. Actually this is one thing that really shines on tormachs. They're hard to adjust, though, since you don't have the hand-feedback as with a manual mill/lathe.
+ Despite being right off the boat from lala-land, the electronics are well-made. The wiring is clean and it would be easy to work on, if needed. Upgrading to 4th axis only requires powering and connecting the new stepper drive. (exactly the same procedure as any modern industrial CNC). This point isn't a huge deal, but I've seen some "domestic" companies that build fucking ratsnests for their electronics, like ingersoll-rand, which pisses me off to no end.
+ Generally speaking, the accessories are comparatively cheap. Lots of them are just off-the-boat items, but at least you don't spend a lot for em.

All in all, every machine has its faults but if I had to do it again, after knowing what I know now, I don't think I would have suggested our 770 back when we bought it. I would have found a way to get something with actual feedback on the axes (servos) and ANYTHING that didn't use an R8 taper. I'm sure it was super cheap (easy) for them to use the converted R8 but I simply do not understand why they didn't use LITERALLY ANYTHING ELSE, like an erickson quickchange which is standard on a ton of other machines, or something actually industrial like an ISO or CAT/BT taper. Hell, my first CNC was a 1970's bridgeport hauled out of the junkyard (with a modernized control and servos) but even that crap-o-matic mill used an erickson 30-taper and easily beats our tormach for accuracy after toolchanges. Ironically it's a significantly faster machine too....if it weren't for its size and crappy CVT spindle speed control, it's a much better CNC in the end...I just wish it had a variable speed motor.

Full disclosure, in case somebody wants to yell at me about it: You can indeed buy a BT30 spindle cartridge for the 1100, but it still doesn't work with the tormach toolchanger. It's also not compatible with the smaller 770 and 440...ugggh

I guess my point is that the 440 cost savings may be very appealing but I wouldn't want you to be backed into a corner with tormach being a seemingly de-facto machine, because they're really just another chinese mill in a sea of chinese mills. It's not a bad choice, but not an extremely great choice either. For reference I know a guy that recently bought a Skyfire mini-VMC with accessories for $18k shipped (BT-30 taper, 3 horsepower spindle, 4th axis, servo equipped, full enclosure, dedicated control, everything). A tormach 770 or 1100 is similar pricerange but doesn't compare in any metric other than being cheaper.


Posted on Aug 4, 2017, 8:35 PM

Respond to this message

Goto Forum Home
Responses

  1. Some respondery.... Doc Nickel, Aug 6, 2017
    1. agreed. ydna, Aug 6, 2017

Quantcast

eXTReMe Tracker