IH CNC vs. Tormach for my situation

[wildcat]

First off, I am not trying to start a IH vs. Tormach flamewar - simply trying to obtain the sage opinion of this group. There was recently another similar thread and that person purchased an IH mill I believe. Both the IH and Tormach CNC machines appear to be really nice machines (best as I can tell from the webpages). The main guys at both locations seem to be great and know more than I ever will about machining. I am a hobbiest though have built some small automation assemblies for pay. I would like to get a mchine that I can grow as I learn more and is not the limiting factor. It would be nice to be able to produce a few parts for pay once in a while but mainly remember hobbyist descriptor. I already have the IH mill and have been using it manually and it has probably about 50 hours of chip making hours on it. I like being able to raise the head but honestly I prefer the HF round column mill for the most part when it comes to table/quill motion (hate the round column though). I have used Bridgeports and Enco Bridgeports clones at the local college and they're great by not practical (expense, size, expense) I have been writting modeling software for many years and the thought of having a machine that can produce what I can draw or that I can write software to control is really exciting. I have considered doing a custom CNC on a mini-mill but they are so small... So, I am considering a IH CNC or a Tormach. Has anyone seen or preferably used both machines and can provide an unbiased opinion which might be better for my situation? Perhaps these machines do not have the same target audience. In which case how do you think their audience differs? Tormach is pretty close so I might go visit them. Unfortunatley there does not appear to be another IH close by. I don't mind tinkering a bit to get a machine working well I am just tring to understand the comparative limitations and abilities of these machines.

Thanks

[MichaelHenry]

I've never seen the IH mill in the flesh but did get a demo of the Tormach at their WI offices. It seems like the IH mill has the edge in work envelope and Tormach has the edge in being ready to run pretty much out of the box.

You already have the IH so if you like projects you might as well go ahead and get the CNC kit for it and have at it.

I elected to get the Tormach as I already have too many projects. It should get delivered in a few days.

Mike

[Richards]

Navigate to the Industrial Hobbies web site and then click on CNC Comparision. You'll find a straight-forward comparison that addresses the major differences between the IH and other mills. Although Tormach is NOT mentioned in the comparison, you should be able to draw your own conclusions.

The main reason that I bought the IH over the Tormach (or any other mill) was Aaron's honesty. When I visited him, he told the truth about his CNC kit, what it would do and what it would NOT do. Last week, a week after I'd purchased the IH, I had to travel to L.A. again, so I dropped in on Aaron. He waved me into his office as he finished a telephone call to someone inquiring about his mill and CNC kit. In short, the customer wanted to do something that was not a good fit for one of the options that Aaron offers. Aaron plainly told the perspective customer why that particular option wouldn't be the best solution. It takes an honest man to value personal integrity over sales. Aaron is that kind of guy. In short, I believe that if Aaron says his mill fitted with his CNC kit will do something, then it will (assuming that the operator follows standard procedures both in installing the CNC kit and in machining the part).

[MichaelHenry]

FWIW, I got the same impression from Greg at Tormach during my vist there last June. He was pretty clear on the limits of the mill and answered all of my questions honestly. For a small operation they seemed to be very well organised and professional.

Mike

[wildcat]

Mike and Richard, I completely agree - I have talked with both Aaron and Greg and receive no negative feelings from either one and don't feel they are pressuring me in the least. That plus similar pricing but different design leads me to beleive that they must have different markets as a opposed to quality. Perhaps the difference in market is as simple as the group that wants the machine ready to go from delivery and the group that wants the maximum work envelope possible and don't mind being in charge of the final assembly. Other than that is is pretty safe to safe that a person will be happy with whichever machine or are there charactersitics of each machine that makes them better at a different task? Or are there tradeoffs? Eg. the IH machine is faster but does it give up in another area to achieve greater speed?

[Richards]

Let's assume that both the IH and the Tormach are fully assembled and properly trammed so that any limitations cannot be attributed to poor assembly (mine in the case of the IH, the factory in the case of the Tormach - not saying that Tormach would not be properly assembled, but I know my own limitations; therefore, my assembly would have to be checked and double-checked). Let's assume that both machines would be used at full capacity - meaning that the cuts would be as heavy and as fast as possible - within the limitations of the mill and the CNC electronics. Given those two conditions, I have to vote for the IH. Here are the reasons:

1. Servo motors with final gear ratio of at least 10:1 vs 5:1 (I assume for the Tormach 5:1 direct drive ball screws).
2. Servo motors with constant torque over the entire speed range of the motor vs good/high holding torque on the Tormach but very limited torque at faster speeds.
3. Faster speeds 120 ipm vs 65 ipm for the Tormach (granted, cutting speeds would be similar if the same chip-load calculations and motor RPM were used).
4. Electronics built for flood coolant on the IH, meaning that there would be no limitations because of overheating the cutters and no fear of shorting out the electronics because of coolant seeping into the motors.
5. Large work envelope on the IH of about 31-inches X axis, 11-inches Y axis after the CNC kit is installed.
6. Similar cost ($5,800 for the IH, plus $1,000 or so for the electronics cabinet, 2hp motor, VFD, Mach3 software, switches, etc.)
7. Electronics cabinet placed wrong on the Tormach. The cabinet is behind the active work area - meaning that you have to reach over moving axes and spinning cutters to do an emergency shutdown. Also, the cabinet is directly in the path of flood coolant - meaning that their seals had better be totally water-proof.
8. IH mill uses standard Gecko drivers for the standard CNC kit and Rutex drivers for the Light Industrial CNC kit (It seems to me that most serious users posting on the CNCZone forum use Gecko drivers or Rutex if power requirements are higher). Tormach does not use Gecko drivers. (Personally, I have torture tested Gecko drivers for almost a full year on my test bench to determine whether they are as good as they're purported to be. Using over a dozen different stepper motors and a ID3004 servo motor, I have not been able to harm the G212s or the G340, even after removing the pulse multiplier boards and driving the G212s like G202s and the G340 like the G320. They are tough little drivers that deserve serious respect. The two times that I've called Gecko support and talked directly with Mariss, I was greatly impressed by both his knowledge, and by his absolute willingness to help solve even the most mundane problems.)

That's it in a nutshell. When all is said and done, I voted with my wallet for the IH.

[Ron111]

Wildcat,
Looks like a win-win situation. It's good to have two good choices out there. Both machines are capable of precision, with one it is out of the box and with the other it is after 40 hrs. of building and assembly. Things that most of us like to do, and some would rather put something together than buy already put together.

The main advantage that the Tormach may have over the IH would be the ground ball screws.

The main advantage that the IH may have over the Tormach would be the massive table. A secondard would be in using Gecko drivers, which should be available for a long time (but then again Tormach might be with us for a while too)

So it comes down to, what size work area do you need and what footprint area do you have available in your shop.

The way I see it, you are in a no lose situation.

Ron

[MichaelHenry]

It looks like the bare IH mill weighs in at 950 lbs vs 1150 or so for the Tormach, though that includes the control cabinet and steppers. OTOH, the IH has a larger table. Is the weight difference significant?

The answer won't affect me (my Tormach should be delivered Friday) but others might be interested in discussing that possible aspect.

The bottom line seems to be that owners of both mills are happy with their purchases.

Mike

[Richards]

Ron,

I'm wondering about "ground ball screws" on the Tormach. Their site specifies P4 grade. Does that mean 'ground' or does it mean 'rolled' to P4 specs? As far as I've read, "ground" ball screws would cost more than the selling price for either machine. I really don't know. I've just spent an hour Googling various ball screw accuracies and haven't been able to reach a definitive conclusion. All that I've learned so far is that Cx means carrier grade, Px means precision grade and Tx means transport grade (with x being a number from 0 to 7 or so - the higher the number the greater the 'slop'). Does that mean that a C4 = P4 = T4 or are there other parameters that I haven't discovered yet?

[philbur]

The Tormach also has the following significant advantages:

1) A VFD.
2) A top speed of 4500 rpm against 1600 for the IH.
3) A one shot oiler.
4) Ground, coated and covered ways.
5) An extra 200lb for a smaller envelop - makes for a much stiffer machine.

The Tormach also comes with a comprehensive test certificate, which of course is no guarantee but is very reassuring.

The only significant advantage of the IH that I can see is the greater work envelope and table size. If you need it then you have no choice but the IH. however If you don't need it then the Tormach is a much more balanced and rounded machine.

I'm biased of course, as I have one of the two mills under discussion.

Regards
Phil

Originally Posted by Ron111 Wildcat, ........................ The main advantage that the Tormach may have over the IH would be the ground ball screws. ........................ Ron

[Ron111]

Mr. Richards

Trying to stay unbiased, let's approach another angle, the support and documentation issues. Agin both companys are fantastic. Aaron (IH) provided step by step installation instrucions, from drilling and pinning your table in order to accept table fixtures, to installation of the cnc kit.

And like wise, Greg (Tormach) provides a complete manuel with all of the machine spec's, a software manuel on Mach 2 (which is talored to his machine) and a designers note book, which documents the groung ball screws which are made at his manufactor's facility. So, if you burn a couple of days and really look over both of these websites, I think that you will end up with both machines!! hehe!!!

By the way, the new IH has ground ways.

Ron

[Richards]

I'm still stuck on whether P4 means GROUND ball screws or whether P4 could also describe ROLLED ball screws. In looking at some of the Personal CNC Design V1, in the ball screw section it says:

"P3 allows 12um error within any 300 mm. In imperial units, this is 0.0005" per foot. Cumulative error at 900 mm is limited to 21 um (0.0008 at 35")
"C3 allows 12um error within any 300 mm (0.0004" per foot). Cumulative error is not specified, thus allowing as much as 36 um at 900 mm.
"P4 allows 16 um error within any 300 mm. In imperial units, this is 0.0005" per foot. Cumulative error at 900 mm is limited to 22 um (0.0008 at 35").

Later on it specifies that the P4 grade was selected for the Tormach, but the only reference that I can find about ground vs rolled is that the manual states that C7 screws "allows the screws to be manuafactured by a rolling process rather than grinding process"; however I can't find a statement that the ball screws in the Tormach are GROUND. It is implied, but not stated in the Design document. Perhaps it can be found somewhere else. (I can't open the data sheet. It keeps crashing the evince reader on my Linux box; however, the other documents opened properly, as well as all documents from other sites.)

The VFD and motor are also a concern. On my Shopbot Prt-alpha, I have a 3hp spindle that can run at speeds up to 18,000 RPM; however, the torque curve shows that the spindle is only at full torque between 12,000 and 18,000 RPM. That works great when routing wood, since I normally run the spindle at about 13,000 RPM and use a feed speed of 400 to 500 inches per minute. What is the torque curve for the Tomach VFD and motor? Does it give full torque at all speeds? If not, what is lost at the low end? Would I have to be worried about cutting steel at slow RPM? (That is one of the reasons that I'm using the IH in manual mode for a while. I need to see what kind of finish I can get at 1,500 RPM. According to the chip load formula, I should get equal results if the feed speed is adjusted using the formula RPM X flutes X chipload give 1600 X 4 X 0.005 = 32 ipm with the IH and factory motor, or 16 ipm with a 2-flute cutter. If I used Tormach's VFD and motor running at 4,500 RPM, I should be able to cut 4500 X 4 X 0.005 = 90 ipm or 45 ipm with a 2-flute cutter. Unfortunately, correspondance with Tormach told me to expect cutting speeds around 14-ipm. What gives? The math says I should be able to go at least three times faster. Is the machine limited by stepper torque or motor torque or is the chip load formula defective?)

Before everyone thinks that I'm trying to start a war between the two camps, let me point out that I think that if we were talking cars instead of milling machines, we'd be comparing Fords and Chevys. Both would be excellent choices for basic transportation. However, I would be concerned if the sales literature from one car company stated that the engines used in their vehicles were all "blueprinted" when, in fact, they were using standard, off the assembly line motors, just like everyone else.