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If you're even considering steel, stainless, titanium and inconel then I would not even consider the 770.
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My background: Mechanical/Metallurgical Engineer with ~4 years machining on manual machines and dabbling on a VMC with Mastercam.
Ive decided on a Tormach PCNC for hobby and educational use, but can't decide between the 770 and 1100. Anticipated use would be ~50/50 steel and aluminum, with occasional Stainless/Ti/Inconel. Probably not a lot of 3D surfacing that the 770 would be better for. But I also cant think of many parts that I wouldn't be able to fit in the 770 work envelope. Speed/productivity is not a serious concern.
Original thought was go for 770 because of cost and then be able to afford some tooling. Now I'm reconsidering saving for the 1100. So how many 770 owners wish they had the 1100 for its bigger travels, spindle power, and rigidity?
If you're even considering steel, stainless, titanium and inconel then I would not even consider the 770.
You can buy good parts or you can buy cheap parts, but you can't buy good cheap parts.
The weight to travel ratio is very similar. I don't know that there is such a big difference in terms of rigidity. But it is true that you probably would not need much the faster spindle and if you can afford the difference in price, the larger travel are a definite plus.
Christian
Originally Posted by Steve Seebold
I own an 1100 and wish I had a 770 right beside it. I do a lot of small intricate parts with 3d surfacing. The rpms would be a bonus.
Fortunately, I didn't have the choice. I've got an 1100.
I have never, ever regretted having more horsepower, travel, or capabilities than I initially needed. I never need to make smaller parts. This may be a character flaw...
If you need the 10K spindle, buy a speeder for the 1100, or add a secondary spindle (my solution- I've got 30K rpm at 1 hp at a small cost in X or Y travel).
Fortunately, this is not a choice between right and wrong. They are both Tormachs.
I have had a 1100 since last July and my workload is such that I am beginning to consider another one.
I'm going to wait about 6 months to see if the workload continues before I make the jump. If I do buy another machine, I'll get another 1100.
You can buy good parts or you can buy cheap parts, but you can't buy good cheap parts.
Just a thought, but a 40K rpm pnuematic spindle with a 3/4" shank can be had for less than $1500 on ebay (sold a brand new one a few months ago for $1300 - Air Turbine Spindle) that can be converted to tts for repeatable height offsets. Fast tool changes, no sacrifice of X or Y space, 4 times faster than 770 spindle, and when you remove it you have the power and travels of a 1100... buy more than you need unless you refuse to grow... in which case its cheaper to just party someone else to make parts for you.
Mr. Shiddy,
One thing I don't think you have considered is the size of the air compressor you'll need to maintain 40,000 RPM with your pneumatic spindle. I would guess you'll need a 10 t0 15 HP just to keep up the air pressure. Once the ait pressure starts to fall off, so does the RPM so unless one is ready to spend $3000.00 to $5,000.00 on a compressor, I don't think the air spindle is such a great idea. JMHO
Steve
You can buy good parts or you can buy cheap parts, but you can't buy good cheap parts.
Not completely true. The Air Turbine Tools 625J model spins @40Krpm and requires ~15SCFM @ 90psi: that is within my 5HP compressor’s capability and cost was less than $1K for my compressor.
Don
Don is spot on. My 602JS claims maximum 6CFM at full load which IIRC is .15 HP on a <1/8" tool... thats less than most die grinders, sanders etc.
I have spoken with the engineers at Air Turbine Tools about de-rating the aire pressure and was told it will maintain 30-40k rpm under load even down to 70psi... I asked because I only have a 2.5hp HF compressor ($149 new) and was worried. I program assuming 30K, run it at 70psi and my compressor cycles off during use. I do have a lot of air storage for that small compressor which helps.
Just finished running 240 to a new panel in my detached garage so that I can run the 12x37 lathe I bought (sitting in the crate for two months now ), the 24"x24"x20" PC Oven I bought the month before that, the 5hp compressor I'm getting soon, and the Tormach I plan to get later this year.
5hp is more then enough to run these spindles AND a mist system on top of it if needed.
concombrefrais, have you tried any of the tougher materials on your 770? The reply from support at Tormach said the 770 should do fine. I know its only 1018, but the youtube video of a 770 facing steel looks fine.
Working on trying to find a 770 to demo in the Denver area now...
I have a 770 and am happy with my choice. However, it comes done to what you want to do and your situation. In my case, The 770 had only a couple of inches to spare to fit in my shop so a 1100 wouldn't fit. Also I am doing mostly small parts so wanted the 10K rpms. I have done a bit of 1018 steel with a carbide EM and had no problems and cuts right through it. Actually, the biggest problem Iv'e had is that you really need to put 25 - 30 ftlb on the drawbar and have it greased properly to keep the EM from pulling out of the TTS. Having more horsepower would make this potentially even more touchy. Frankly, if I had a real business and doing production I would get a Haas, but my 770 is great for my use.
Bruce
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