Total cost + import for Tormach PCNC 440, and alternatives?

Ady1. I worked for a company that was a large CNC machine supplier some years ago and can understand how difficult it can be. A CNC machine these days can be complicated chunk of metal needing mechanical, electrical pneumatic and hydraulic engineers before you even get to the CNC control and cutter technologies. The company i worked for more or less started from scratch with CNC imports, learning over the years and creating the staff to handle all aspects, a very expensive buisness. When you call out an engineer and you are talking probably a £1000+ a day it starts out as being expensive and I doubt that the types of machine you are thinking of have professional installation and tuition at the start. If you adapt your own machine at least you will be able to service it and know what makes it all do what it does also you will have a choice of control software.

Alan, you have been most helpful thank you. I really like the idea of the US socket distribution board, that is a no brainer now you've given me the idea.

The Tormach user manual for the machine I am looking at, (770MX), clearly states that no RCD (their US terminology is GFCI for ground fault circuit interrupter) may be in the circuit supplying the machine. This is a common issue with the harmonics from VFD drive circuits causing quite a lot of RFI (interference), and therefore having to have a decent sized RFI/EMI filter on the front end. It is this filter which then sinks the interference to ground causing a 'nuisance' Residual Current Device trip.

The problem lies in the fact that in the UK domestic situation, we really ought to have a RCBO supplying our ring mains. Especially a ring main supplying your tools in your garage!

I think I have found a solution, and maybe this warrants a new thread. We mentioned earlier about autotransformers being your choice. A good choice, they are more efficient and "smaller per kVA" than isolating step down transformers. And clearly this is working for you. However, I am looking at a machine with a slightly bigger spindle power and servo drives on X,Y and Z (I don't know for sure, but I assume the servo drives also have RFI filters so I am potentially looking at much worse fault currents which will trip my mains off) so I really think I need to have the Tormach machine NOT on the RCD circuit just as they suggest in the manual. I figure if I use an isolating step down transformer, with a CTE (centre tapped earth) secondary at 115Vac, and my domestic earth connects all the way through to the transformer, to the Tormach, and to the CTE secondary, then I will have a machine which has earth reference for the filters to function, earth reference so worst case scenario human electric shock to machine metal is 57Vac, and the machine will not in itself have residual current protection (which is good). The rest of my domestic ring main will still be protected by my RCBO at my distribution board, but this is isolated from the Tormach. The Tormach will still produce 'nuisance' earth leakage currents but these will be isolated from my domestic residual current protection because of the transformer NOT being an autotransformer. So I think this is a solution.

For the avoidance of doubt, I have posted this is rather great detail, not to try to sound clever, but to welcome comments and advice from anyone who knows better on this subject. I really want to get this right, and be totally safe in the process. On the other hand, totally happy to be told I am wrong and would love to hear others' input to this issue.

I am looking at RS122-6718 or RS122-6716 which are quite expensive but will be sturdy.

I think there will be a lot more Tormach machines being imported into UK in the future, and the issue of hobbyist customers using domestic mains with RCD devices is going to feature heavily as an issue.

For those looking at the larger machine, the 1100MX, this runs from a 230Vac single phase supply, so no step down required. At first glance, this is without issue! But I think there is an issue in UK domestic homes with normal ring mains protected by RCD devices. Again, my solution would be to use an isolating transformer, but no step down, so 230Vac in, 230Vac out, with centre tapped earth on the secondary in exactly the same way as above.

I think this is really important to keep people safe.

I've written too much. What do others think?

Very envious of the 770MX Steve, I wish I could have squeezed a 770 into my space but couldn't.

I don't think I am qualified to advise on the RCD issue. There is a question in my mind that this problem has obviously been experienced by users in the US where the machine is directly connected to the electrical wiring circuits in properties. The breaker therefore had a direct visibility of the transients etc coming from the machine. Our use in the UK puts the autotransformer in the way and intuitively this ought to look like a lot of inductance to these emissions.

That is probably utter tosh and I stand to be corrected by those more knowledgeable on the physics involved.

There are no RCDs on my Tormach 1100. As stated the main spindle runs from a nominal 220VAC supply. In my case it is one phase from my 3-phase distribution board. I have added a high speed spindle and VFD (with external EMI filter) and that runs from the ring main in the garage. The same supply also powers the computer and monitor. However, the garage ring main is derived from a different phase on the 3-phase panel. So we can safely say that the two supplies in the 1100 are truely isolated, as the manual states. My 3-phase panel does not have RCDs. The updated single phase house consumer unit has RCDs. The only thing it supplies in the garage is a recently installed spur with sockets behind the lathe and vertical mill.

Andrew

Andrew, you have a 3 phase supply, so I can see what you are doing, but for the normal domestic single phase garage setup, I still feel there is a problem. Your setup is slightly more industrial if I may say so. So fair play to you.

Alan, I haven't got it yet, I am in the processing of making the deal, and was keen to make utterly sure I had the mains in my garage to do this!

I don't think the breaker tripping out issue is to do with transients, Alan, more it is to do with Earth leakage current which is intentional (the EMI filter does it purposely to quell the EMI) and then the RCD device in the distribution board under the stairs senses this as a fault. Which it is not, but nevertheless still trips the breaker!

Well, anyway, I will report back, if I may, as and when I finish this project.

Just my pennyworth.

The Denford range is based on Sherline machines. Have you considered a Sherline - or are they too small?

Peter, I fully see where you are coming from, and they look super machines. I am planning on teaching myself 4th axis CNC coming from an engineering background but no CAM experience. I have researched this endlessly and what draws me to Tormach, every time, is the fantastic effort they have put in to the marketing by way of their own Youtube site, other Youtube user enthusiasts, and many videos and documents made by them to help newcomers. It is the 'open source' ethos I really like and it will pay them back.

I looked at the Pocket NC V2-10 for a while but realised that 5th axis is tricky on the brain. I need to walk before running.

When I moved in the electricity supply was 60A and had a wind yer own fuses distribution box. So it needed updating and it seemed sensible to install a 3-phase supply rather than just an updated single phase. I'm glad that I did as all my other machine tools are ex-industrial, and some would be difficult to run from a VFD while maintaining functionality.

Andrew

When I bought my Tormach I also ordered the 4th axis kit. The reasoning was that I wanted the kit and it was cheaper to ship everything at once rather than have to deal with specialist shippers again at a later date.

The key to 4/5 axis is the CAM software. It starts to get pretty expensive for true 4 and 5 axis control. It was some years before I used my 4th axis. The first item I made was a 2tpi worm:

Finished worms:

Despite having a CAM package with some 4th axis capability the code for the worms was hand written. Subsequently I've used 4th axis indexing to machine bevel gear pinions:

Finished gears:

I'd highly recommend getting the 4th axis capability, even if you don't use it initially.

Andrew

Not true Peter although Denford did do a small lathe and mill using Sherline machines within Denford enclosures operating with Denford software.

The other cnc mills and lathes in Denford's range are much larger machines than Sherline products.

Emgee

I would echo Andrew's comments about making sure you get as much as you can afford in the shipment to consolidate the costs.

I would include the power drawbar and the new microArc 4th axis (which is a lovely piece of kit). The TTS tooling system makes life easy with the power drawbar. If you buy the SuperFly and the ShearHog tools then make sure you get a pack of spare inserts as I find these very difficult to source in the UK.

A minor purchase which I have found useful is the USB expansion board which allows you to control external devices using GCodes within your program. This has four I/O ports.

A tooling plate is another ideal item to have. Tormach front the SMW parts but they don't offer metric thread versions. Bit of a chicken and egg situation as you need a CNC to make a plate but the plate needs to be bigger than the cutting envelope of the machine you want it for ... I chatted up a local machine shop to cut one for my 440.

Andrew, that is some really nice work there, thanks for showing. I'm intrigued you can write G code from your head to cut in simultaneous 4th axis. I think we all need lessons from you!

I am definitely going for the microArc 4th axis as, in the scheme of things, it is not a huge additional expense. And just for simple A axis indexing, will be invaluable, let alone what else it will do once I get to learn to use it simultaneously.

Where I am really struggling with a decision, budget restricted, is whether to specify an ATC. On the MX machines now, the power drawbar is standard anyway, so it sort of makes sense to try to go for the ATC, rather than come back to retrofit later. But, in a hobbyist shop environment doing one-offs, it is probably irrelevant as I will be babysitting the machine every inch of the journey. But I kinda still like the idea of the ATC - it is exciting that you can have this in your garage. I could only dream of such industrial luxury literally a few years ago. Trouble is, with the VAT, the ATC is an extra £5k. Hmmmm.

Alan, can you share the sort of thing you are getting your 4 I/O ports to actually do? I am intrigued but cannot think of what I need to happen!

I didn't go for the ATC as like you say in a small shop you tend to keep an eye on things and there is not likely to be a dark milling session. With power drawbar and TTS system tool change is a few seconds but clearly important to make sure the Tool Table is up to date ... you will need a digital caliper and granite block for this but I find the Tormach one I bought to be very small for the footprint of the caliper. Probably a local kitchen granite supplier would provide an offcut providing they can cut a hole for the inverted tool for you.

I was probably a bit premature on the expansion board recommendation. I use it for clock wheel cutting. I have a Sherline CNC rotary table and I increment the table from the expansion board. Note that this was before the microArc came on scene as prior to that there was not 4th axis for the 440. I could now do the same with the microArc but I have a short piece of code that runs reliably so no great incentive to migrate this activity to the microArc. Other uses are for alarm signals as a result of IF statements, beacon lights etc.

Other thoughts - I have just fitted a second nozzle on my Fogbuster coolant kit. The system is very good for giving an air jet and a coolant mist but a single nozzle was not clearing pockets very well so I added the second nozzle. I think you have to order the upgrade kit for this and not get a dual one as standard. Have a look at the Fogbuster site direct. Note that the Fogbuster runs on 10 to 15 psi and you have be able to support this with a compressor that can cope. I have a Bambi PT50 which just manages on a long job but does get a bit warm. The plus side is that it is not too noisy,

I didn't buy any probing from Tormach. I had a Haimer already and I subsequently bought the Hallmark ITTP probe which works very well.

Alan

Thanks Alan, all useful thoughts. For the tool setting, I was thinking not to go down the route of granite table. They do two options, an electronic setter which sits on the table and plugs into their kit (£1100 inc VAT) or a spring loaded vernier thing you place on the table, jog the tool to it and enter the data yourself which is more like £100.

The only advantage I can see with the electronic one is you can auto test tools after each use and between tool changes to make sure there have been no breakages at each stage. Again, if I don't go down the auto tool changer route, which I probably won't, then really no need for this either.

There is a lot to think about when placing an order like this, and I thank you for your input and thought provoking ideas.

Andrew, just a thought on your 4th axis: I see you have a decent 'tailstock' for it. How on Earth do you go about setting up the tailstock to centre on the A axis? Can anyone recommend a good book to buy? I looked on Amazon and there are loads of books, when you peek inside, they start telling you that CNC stands for computer numerical control and that the z axis is the up and down one blah blah blah. I need a good book aimed at the educated newbie. Any suggestions?

Check your Message box Steve, top menu bar envelope flashing.

Emgee

All understood Steve

So long as you have a means of measuring tool height from the collet edge to tool tip you can manually enter this value into the Tool Table on PathPilot. Assuming no breakages, no significant wear and no movement in the collet grip you don't need to change this value. The tool number and the tool diameter are common to both Fusion 360 but the tool number is the only field that is the link between the two tables

You make the tool number in PathPilot match the tool number in Fusion 360 and the exported GCode automatically asks for the right tool and uses the tool height you have entered in the PathPilot tool table. The tool table in Fusion is used by the CAM processor to watch for tool length, collet size etc that could lead to clashes when calculating the CAM whereas the PathPilot value is used to set the tool height relative to Z0.

Not sure that was very well explained ....What I am saying is for basic operations you will probably believe the tool table in PathPilot unless you are nervous about the job or something happened during the last job that made you twitchy. There are automatic routines in PathPilot that let you set where the tool measuring device is located on the table and auto updates the tool table after a measurement (assuming you have selected the right tool number ..).

I came to CNC some five or six years ago and fumbled my way watching John Saunders on NYC CNC. The early videos are very much as he was learning.

CNC Milling in the Workshop by Marcus Bowman is worth the investment.

Alan

Thanks Alan, I really appreciate your help.

Ordered the book just now! Great.

Hi Steve, I can say from experience that the ATC is not essential but the Auto Drawbar is. I got fed up with my ATC ripping up the nylon bolts that hold the holders in place. They are prone to developing backlash that becomes too great and eventually this exceeds the tolerance that allows the spindle to descend over the tool holder shank. There is a cure for this and I have done it but I now rarely use the ATC. When placing your order go for as much stuff as you can afford, the quality is really good and I am sure you won't regret buying a Tormach machine.

Bob, thank you for this, makes a lot of sense.

The Tormach 770MX is definitely standard BT30 and standard Power drawbar, so that's a given. I really cannot justify £5k for the ATC when I can spend that on more tooling instead.

What are your thoughts on tool height setting options?