Talk Me Out of a Tormach 770

[CL_MotoTech]

Hookers and blow are great, but why not all three? The real question is which is more addictive. I'd argue machining is.

That said, you can build a machine out of another Chinese machine and get the same or better results than a 770 provides and do so for less money. It does take access to a lathe, another mill, and a lot of patience though. Probably not a great option for somebody without access to those things or time to diddle about. It's probably not for everybody...

[Kenny Duval]

I will be redoing the conversion on my BF20 once I take delivery and get familiar with my new machine. It'll be ready to go to a new home before the summer gets here. I'm going to linear rail it, add the oil circuits and redo all the motor mounts. Should be a good machine for someone to do what I did with it and learn on it.

[Advil]

I love my 770. This would be my opinion for you:

You listed all metals in your list of materials to work with: "Aluminum, steel, and titanium." "Mild steel in bigger parts."

I'm speaking from experience owning a 770. Get the 770 and not the 440 if you are going to spend any real time in steel or titanium. It's a bare minimum machine already for this kind of work. I make small titanium parts on my 770. It's what I primarily use it for right now.

The VFD in the 770 has been more bulletproof than in the 440. The spindle is 1hp (or more on the new ones) instead of .75 on the 440.

You'll already be learning the sweet spots to work with steel and titanium on a low power machine, don't compound it by getting even less power.

Take a 770 with less up front options rather than 440 with more options. Skip the full enclosure and get a shower curtain if you have to to make up the price difference, but get the 770. You'll be more likely to be happy with it long term.

Even on the 770 you have to LEARN how to cut steel and titanium with only 1hp. I personally wouldn't want 25% less spindle HP than I currently have... the sweet spot is narrow enough already. A 5/16" tialn / altin / nacro coated end mill is already about as large as the 770 can handle well in steel or Ti.

[lens42]

770 for sure. After you add up cost of tooling, work holding, cooling, etc. (which are pretty much the same for 770 or 440), the 770 is probably about 10% more $. 440 only makes sense if don’t have the space. Also, I get the impression from my un-scientific survey forum posts that the 770 is more reliable.


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[Bob La Londe]

You CAN tap on the 770 without an encoder.
Depth-control is the only drawback.

I use the R32 Collet- Tension/Compression tap holder from TORMACH.
And without an encoder, depth control isn't exact. (+/- 2-3 threads)
When tapping, the holder will "stretch" at the end of the cut when the spindle reverses.
It will cut an extra 2-3 threads while the tension head "stretches",
This isn't really a big deal when tapping thru holes, but nerve-racking in blind holes.

Also, the largest tap I can push with the tapping head is 5/16" (8MM).
Anything larger, and the spindle wants to stall.
For 3/8" (9MM) and up, I have to threadmill.

Threadmilling is actually the better choice, for depth control (in blind holes), and finer quality threads.

Excellent review of TC tapping. I have kind of embraced it with premade styles in my CAM software for tapping with the TC tappers. I have one Tormach TC tapper, and have made a few of my own on the PM1440 lathe so that I can have my most common tap sizes preloaded and premeasured. 10-32, 1/4-20, 5/16-18, and 6-32 (in that order). I tap the smaller sizes in aluminum in high gear at 500 RPM. I do switch to low gear in steel or for 5/16 or above. I also have tapped 5/16-18 aluminum in high in aluminum because I forgot to change gears before. The 1100 is slightly higher power, and slightly better low end torque. It is pretty scary in blind holes. So far for thread milling I just have single form tools (multi flute), and they take longer than TC tapping if I have more than a couple holes to tap. Are you using muti form tools? Of course you can turn higher RPM so it might be faster on a 770.

Anyway, I like the TC tapping so much I have been spending some of my time thinking about how I would make them for my Hurco KMB1 retrofit machine. Other than just sticking one in a tool holder. Its already quite long, and putting one in a tool holder would leave me cranking the knee up and down for a while. LOL It also does NOT have C-axis spindle control. I currently do single form thread milling with it.

[maker of things]

I think generally people are more prone to spend the time to review a negative experience than one that met expectations. Some of the negative comments IMO are from 1) people who do not own a machine at all, but think it's fun to tell Tormach owners that they should just get a Haas because in reality they are jealous of anyone that owns a machine, 2) people that had expectations much higher than the product they bought and 3) capable people with legitimate problems who got a bad product. Possibly in that order.
I can tell you from personal experience that you are not going to do your own conversion and get the functionality and accuracy of a Tormach for the money. If you did, you probably could have made more money running the Tormach than spending hundreds of hours building something that turns out to be very difficult to sell because it's a one off.
Sorry that probably didn't talk you out of it.