Milling Machines

What are people thinking is precision? (for amateurs)

I'm quite pleased to get accuracy of a thou and modellers needing better fits traditionally lap them to achieve that.

Commercially on smallish bits like 2mm I'm offered and happy with a tolerance of 0.02mm as any tighter costs more.

Steve,

here is the nub.

Take a set of engineering drawing made by professional draftsmen for part that have to go out into industry and be made, probably in different locations.

These parts then come back and are built up into a precision article.

Those drawings will have tolerances laid out, surface finishes and sign that relate to concentricity, perpendicular and parallel.

Now we come on to the steam trains you mention. The person designing these is probably not a designer as such, it's their interest. Most of these drawing have no tolerances, limits and fits and surface finishes. In fact in the latest Nemett engine in ME it doesn't even tell you what material the part has to be made out of, steel ? alloy ?

Most hobby builder work on the fit to part routine, you bore a hole and make the shaft to fit it.

Something these hobby machines are perfectly capable off.

I have a milling machine here I regard as precision it's capable of holding 2 tenths of a thou all day BUT it cannot run all day using the same settings as during the day due to temperature, slideways warming up, etc, it alters sizes and has to be compensated for by routine checking.

BTW it cost £32,000

John S.

What's precision? A thou? a micron? half an angstrom? The Mars lander got within 100m of its target. Everyone was pretty pleased with that. Tolerences are for production engineers making thousands of parts to fit thousands of other parts. Models engineers make one offs and so they make pieces to fit other pieces. For example; If you want to make a shaft to fit a bearing you turn the bearing first to something about the right size and then you turn the shaft so that it is just too big and then take off a smidgen at a time until the fit is just right. What you don't do is make everything to a drawing and then try to assemble all the bits. For almost every thing you would make in model locomotive or stationary steam or i.c. engines being able to work to 1 thou (0.02mm) will be quite good enough. I think any machine you can buy today should be good to work to this sort of accuracy. The issue with CNC machines is a bit different since they do just try to make the part to the specified dimensions - you don't, in the first instance, have the opportunity to tweak the dimensions as the program is executed.

Don't worry about precision, that way madness lies. Buy a machine and start cutting metal.

cheers,

Rod

Yes, what degree of precision was meant? I wasn't sure. Those figures you quote sound reasonable to me, I can live with that.

If I were to buy a mill with plastic gears/drive and wanted to convert it to belt drive I take it that this is the kit to buy, is there a stockist of such a kit in the UK?

http://www.stirlingsteele.com/beltdrive.html

Really Steve?

Having read all your comments up to now, combined with years of dealing with potential buyers, I dont really think you know what really is or insn't reasonable. If I am wrong, I apologise. As I asked before, are you from the Greater London area and have you done any milling or lathe work before? what skills do you have?. Also, you really failed to answer Neil earlier about what exactly it is you intended to do with the machine. All I have heard from you is a list of negative 'pissing in the wind' comments.

If this is how you mean to start, based on experience, there will be a list of assumptions coming from you without knowledge, which you will expect any seller to address. So, if you are from down south, in your particular case, I would suggest that you strongly consider to buy from Amadeal, or Warco, or Axminster, or Machine Mart, located in your region, which is what I think you were going to do any way. This way, when you get stuck, which I guarantee you will, you can go to your nearest dealer for assistance.

ARC recently made a mistake of 'coming across as being too helpful' to a buyer, pre-purchase. Although we were clear about everything relating to the machine including limitations, very blunt infact, we figured out post sale that we had made a mistake in this particular case. We should not have even sold him a machine, as this particular buyer 'down south' mistook our openness with someone he could call every few days to ask why the machine was made in a particular way, and if one thing was normal or abnormal or how to do something with his machine, just really questioning the 'fitness of purpose'!.

In ARCs opinion, in that persons case, the issue was the person and not 'fitness of purpose' of the machine. There is always a limit to how much a seller is prepared to discuss before it gets too much. At the end of the day, we are here to sell a machine and not to hold peoples hands. We went to the extent of tell the guy that we did not feel that the machine would ever meet his expectations, and we offered to take the machine back - an SX3, and we would refuse to get into any further discussion with him. Still he has kept the machine.

Therefore, in your particular case Steve, I think that you will be better served by someone in your region other than ARC. If you were considering to buy from us, please don't. We may be able to sell you accessories if you want. This is nothing personal, just a polite comment. I am guessing by now that even if you were considering to buy from us before, you are probably not now . Just be honest about your own limitations before trying to get answers from others, without using a negative style. Non of us know all the answers. If you ask a question in a straight way, you will get straight answers on here.

Good luck with your purchase over this weekend.

Ketan at ARC.

Edited By Ketan Swali on 17/01/2013 21:21:15

That's the first time I have heard being trueful stinks

Don't confuse "precision" with "resolution".

Speaking for lathes. I ( at work) can set tooling to maybe 1 micron. programme a tool path to 0.1 micron. Achive "mirror like" finishes. all fine and dandy..when you measure the notionaly parralel features..you may have 10 microns of taper barrel shaped..large in middle...stock itself moves away from the tool...what price for precision?.....

Some bloke (or bloke -ess) verifing it with a mike Thats what!.

and programming a counter taper into the part...then the tool wears or the coolant "stutters" and we have a new shape again.....Milling will be the same

What precision?..Well what are you checking the part with?..the part it needs to fit? micrometer? a digital calliper? a 6" rule?....

Btw I would appriate someone like Ketan putting a honest answer and ultimatly good advice before a sale.Bravo Sir.

Yes really

This industry feeds me. I respect the skills and knowledge to be found on forums such as this, along with the custom its brings for ARC. We get a lot of custom from new comers who are open with us about their limitations - be they skills or budget. We guide them in our own way.

I am sorry you feel that my attitude stinks. You are entitled to your opinion, which I also respect. All I would say is you are confusing my openness with an attitude problem. Rest assured, ARC, along with many people on this forum have always tried to help new comers, especially when these new comers have been open and clear about what they want to do, and what exactly their skill limitations are.

With regards to assumptions, I have already apologised earlier. As far as I am concerned, ARC has already helped by answering your loaded questions, even though you failed to answer Neils or my questions. How is one know if you what you want a machine to do if you dont answer?. Is it possible that you want it for some business idea you have?. Oh sorry, yet another assumption, I apologise.

What ever you want to do, where ever you are from, what ever your skills limitations are, are all unknown issues. So what is one to assume?. Be honest and open about all of this, and you will find everyone bending over backwards to help you.

It is a pitty you cannot see old specific members post on here. 'Wolfie' is a good example of a new comer who has been on here for coming on one and a half years. He is always honest and open about his limitations, and I for one always like reading his posts as he develops his skills with the help of members on here. ARC has also helped him, even though the mill he uses is not from ARC.

Life is too short. The show opens today. Go and get yourself a bargain and start making some swarf. Good Luck.

Ketan at ARC.

Edited By Ketan Swali on 18/01/2013 05:21:53

Hi Steve,

I promise that this will be my last post on this subject. Precision as you call it does not lie in the quality of the machine necessarily. It lies in the hands of the user, and these skills comes with experience and training. You could spend thousands on a 'quality' milling machine and still not get 'precision' if you are not skilled enough.

One of my other pastimes is cabinet making. I often get to hear the comment -'oh, I can't cut a straight line', while I can cut a precision dovetail by eye with the same saw they are using. Those novices then spend a fortune on Lie Nielson tools but still can't "cut a straight line or plane a surface flat".

Manual machines are just that - manual, you decide on the settings and you control the cut. The ability to make lovely things accurately is called craftsmanship and you can't buy that.

Best regards

Terry

I've dropped a couple of posts into this, as per Terry these are my last moments.

I bought my SX2 plus from arc and received excellent service. I was limited to a budget and spent an anarokish amount of time looking at the options. Part of that was not only looking at machine specs, but looking at the type of projects that people were turning out on them. There is loads of stuff on the forums. It was clear to me that many of these individuals were streets ahead on me in skill level, but I'll catch up (one day). I bought my SX2 with an understanding of its limitations, and a broad idea of the scale and type of work I can produce on it. I'm new to the hobby and have a few ideas about the type of things I want to make, but haven't bought it to build a dedicated project or type of model. I think Ketan's comments are honest, and its refreshing in my eyes to find a supplier who would rather not sell you something than have an usatisfied customer. He is only managing customer expectation, which is difficult if your not sure what your buying. In my experience of asking questions on the forum all advice is open, honest and given with all best intentions. I have no regrets with my purchase, and have Made a few tweaks and improvements to it, but hey perhaps I'm turning into an engineer now! Watch out guys I'm coming after you!

Bob P

Well said, Bob !!

I have never bought a Chinese Mill, but I do have a background in Procurement.

Ketan's integrity is self-evident and; if I was looking to buy, ARC would certainly be on my list.

MichaelG.

If you want precision, you can have it with a hammer and cold chisel, a file, then a scraper, but with one of these little vertical milling machines you'll get to the same place quite a bit quicker, and you can still scrape the surface if you want to. Ian S C

Right, let me clear up some points here, firstly I joined this forum to help me narrow down my choice of mill and gain some knowledge on the different bit holding systems, it really is that simple, I had no idea which suppliers of such machines were/were not connected with this forum.

In my very first post I did state that I've already had the "what are you going to use it for" question, I can only have this size of machine period so what does it matter, if the parts are for a train, remote control car, boat etc etc?

What on earth has my location got to do with anything either? I travel all over this Country, going to many different types of shows throughout the Year so don't assume I live in the South! What next, will my race or religion come into it?

You know after all the recommendations on here on the SX2 and the fact that it's belt drive, I was actually considering one, funny that you all of a sudden stated that you wouldn't sell me one.

Ketan, I must say, it would appear you have a 'big chip' on your shoulder about something or maybe you just can't stand any negative comments about the machines you sell, jumping on my post about the holes being drilled slightly out for example, that actually originally came from someone else by the way!

You know I didn't want to say this but I've actually spoken to you, some time ago I phoned you, asked a couple of general questions on lathes and the mere suggestion of a competitor's machine resulted in a big huff and you slagging them off!

I were most shocked and surprised, how unprofessional of you and you know what, I found them to be the complete opposite, most kind & helpful, I did end up purchasing a lathe from them.

Sorry but from my own telephone conversation and the way you have responded here I couldn't recommend Arceurotrade to anyone.

Anyway, many thanks for all the info from the other members on this forum, much appreciated.

Steve,
I have found Ketan and others I have spoken to at Arc Euro Trade when I have phoned them most helpful. They are one of the few companies where you get to speak to someone that knows about the products they sell. My only connetion to them is as a satisfied customer.

Les.

.

Sorry but I don't  see this at all with Ketan.

I have seen him sell an inserted miling cutter to a punter at a show and when the guy has asked for spare tips he's pointed them to Jenny's stand at J B Cutting tools because she has better quality tips than the ones the tool comes with.

This is just a sour grapes post because you have been told a few home truths.

John S.

Edited By John Stevenson on 18/01/2013 23:04:09

Hi Steve,

Believe what you want to belive. You are entitled to your views just as much as I am to mine.

By being open in response to your comments you beleive that I am slagging off, or anythting else - be it on the telephone, in person, or on here, you are entitled to your belief.

Having re-read my comments, I have over reacted in places in the way I have responded to your comments, for which I apologise. However, I still stand by my views, be they on the telephone, in person, or on any forum. I have no chip on my shoulder about anything. I only say what I believe.

You do not have to agree with me. This is life and we are all different, and we all have a choice.

Enjoy your hobby and have a good life.

Ketan at ARC.

Steve when buying milling machines lathes etc I always

use this rule buy the biggest you can afford

because there is always a job that comes up

which is bigger than you intended

Best Wishes Martin