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Advice for a mini milling machine

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Alex Twigg23/07/2019 22:48:04
11 forum posts

Hi,

I'm wanting a mini milling machine to go into my workshop. There seem to be so many options that I want to know what people have and how they've got on.
I need something that it very accurate ideally 0.01mm as thats the tolerances I work to.
I'm only going to be working on small projects (clock parts) and don't intend to put a rotary table on it or any jazz, so a small compact machine would be needed.


Weight isn't an issue as it will be sitting on 18mm marine ply with wooden legs underneath each corner of the mill. I reckon that should be enough, but if you have thoughts then let me know please.


I've been eyeing up the SIEG SX1L. It looks like alright and people have said that Seig are good, and it uses MT2 like my Myford.
Budget is factor, but if something is the dogs bananas then it's not an issue.

I appreciate all responses from people, I'm sorry if I don't respond to you personally and instead do general messages replying to lots of replies at once.

Many thanks in anticipation.

Alex

Bob Stevenson23/07/2019 23:15:28
285 forum posts
6 photos

At Epping Forest Horology Club we have a Aciera F1 which is a miniature precision milling machine well adaptable to any clock/watch making task, Most model eningeering mills have not really been up to the job due to (relatievely) poor accuracy and low spindle speed. Having said that, the Proxxon mills have been successfully adapted by our members for high speed milling using amall cutters as well as the Cowells small mill. Also, older jig borers such as the 'BCA' can be adapted for high speed milling and we have one in the workshop. We also have members who have effectively built their own mills for clock work, but the small model making mills seem a poor route to this.

When considering a particular machine for small clock parts it would be useful to start by ascertaining the spindle speeds....you need about 4000 rpm as a starting point.

Phil P23/07/2019 23:22:35
486 forum posts
128 photos

I have a friend with a BCA mk3 jig borer for sale in North Yorkshire, if you want to PM me a phone number I can pass it on to him.

Phil

John Haine24/07/2019 07:11:53
2577 forum posts
133 photos

An Aciera would be ideal as made for your application, but haven't been made for years and expensive to buy.

the X1 is an excellent cheap'n cheerful machine but would need bringing up to a better standard for your target accuracy, a lot of work and time with uncertain outcome.

overall probably the Cowells is the best bet for a new machine, again targeted at your application, but it ain't cheap at the thick end of £2500 new. Or the BCA.

Barrie Lever24/07/2019 08:29:41
323 forum posts
1 photos

Alex

Might be worth your while looking at the Sherline milling machines, people speak very highly of their lathe and mill range.

They have a huge range of accessories to go with the machines, I visited the factory in California a few years ago and just about everything is made by them in that facility.

Regards

Barrie

Nick Clarke 324/07/2019 08:32:33
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334 forum posts
8 photos

Arc Eurotrade sell the SX1L. It works well out of the box, but have a look at these preparation notes on their website on how to get the best out of it.

**LINK**

Edited By Nick Clarke 3 on 24/07/2019 08:32:55

Ketan Swali24/07/2019 08:42:34
1101 forum posts
91 photos

Alex,

The SIEG SX1LP reaches 5000rpm, and will happily do the job.

The issue is the user, rather than the machine. If your experience is low, the learning curve for adjusting to 'your specific requirement' will be high. If your budget is low, the same statement applies. This machine, in our opinion is better than it nearest comparable Proxxon, if properly adjusted.

If you are into perceptions of accuracy, go with the Proxxon. Many clock makers do! (meant as an observation rather than an insult). ARC has turned away many potential customers from the horology hobby custom base, even though many new potential buyers have been directed to us by the horological institute. Over the years we have found that their general understanding of engineering is low, expectations and understanding of accuracy for the price, are outside the scope of what ARC is able to offer.

Having said all of the above, we do have experienced clock makers who have various ilk of small SIEG mcahines from X0, SX1L, and SX1LP, who are happy with their purchase. But they have experience and have made adjustments to the machines to meet their specific requirements.

The X0 is discontinued. The SX1L is soon to be discontinued (hence the very low price), as we are concentrating on the brushless machines now. The SX1L will not reach the 4000rpm+. All machines run fine out of the box. Accuracy is directly linked with user expectations and ability.

John Haines's comments are on the right track.

Ketan at ARC.

Ketan Swali24/07/2019 08:49:38
1101 forum posts
91 photos

Generally, now days we say... use the machine as it comes out of the box. Make small adjustments and changes to the machines, if required, to meet your specific requirements, after using the machine, and based on your ability.

Ketan at ARC.

SillyOldDuffer24/07/2019 10:07:12
4536 forum posts
971 photos

Alex said: 'I need something that it very accurate ideally 0.01mm as thats the tolerances I work to', which rang my alarm bells!

Milling machines that will do that are thin on the ground and my perception is that few of them reach the hobby market, particularly in the desirable small sizes. Aceira and BCA have been mentioned; only available second-hand and will need searching for. They aren't lightweights either! And condition is vital: a clapped out machine won't meet that specification however good it was when new.

Proxxon, Sherline and Cowells mini-mills come to mind as popular with clockmakers. Not used any of them myself but Cowells has the best reputation (it's the most expensive), Sherline lathes are well thought of, but I don't know anything about the mill, and Proxxon have a following too. I'm not sure any of them claim 0.01mm accuracy!

Much depends on the operator. With patience and skill a lot can be achieved with ordinary equipment. Mostly (I think) out-of-the-box accurate machine tools save time rather than being essential, they're also less frustrating to operate! Very few basic milling opertaions can't be done by hand with drills and files. It just takes longer and needs more skill. A not-very-accurate mill can always be supplemented by hand tools or other techniques, which is a potential money saver.

Alex also said: 'Budget is factor, but if something is the dogs bananas then it's not an issue.' With respect that doesn't help because we don't know what 'not an issue' actually means. My type-of-work and budget envelope means if I wanted a mini-mill I would probably go for the Seig; (actually I own a much bigger machine costing about 6 times as much and don't need a mini-mill as well). I could stretch to the Cowells but it's really more than I like spending on a hobby, particularly as it wouldn't get used much. Others are far more serious, and might consider buying a new tool-room mill costing £40,000. My point is, when selecting a machine it's worth thinking carefully about the relationship between accuracy and budget. Most of us have to compromise and we're all different. If budget wasn't an issue I'd drive a Bugatti Veyron!

Whatever mill you get, I recommend fitting a DRO. Again not essential but I found it made milling much quicker to do and far less error prone than driving on the dials. As might be expected, DRO's good for 0.02mm are markedly cheaper than DRO's accurate to 0.01mm

I'm always a little wary of giving advice because what I say is highly coloured by the sort of jobs I tackle in the workshop and my limited experience of metalworking. I care more about fitting things together than absolute dimensional accuracy, for which purpose 0.02mm is 'good enough'. If necessary I can work to about 0.01mm ( ±0.005mm ish), but it's hard work and usually unnecessary. My views may be irrelevant - I'm not a clock-maker.

Dave

JasonB24/07/2019 13:27:56
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Moderator
15773 forum posts
1650 photos
1 articles

Bit of an odd one, you say you work to 0.01mm but in other threads you have been looking at buying general spec ER collets and even from a supplier that does not state their Runout? You also say in the same thread that you can't afford MT collets yet these are still considerably less than High or Ultra precision collets that would give the less than 0.01mm runout that you say you work to.

Don't see much point is buying a machine that is capable of giving the accuracy you say you need then equiping it with lesser spec tooling.

Either your budget needs to go up a lot or your expectations need to come down.

Barrie Lever24/07/2019 14:56:18
323 forum posts
1 photos

Jason

Alex did not say that he worked with a runout of 0.01mm, he said he worked to tolerances of 0.01mm and who are we to say if that is right or wrong.

Whilst having a cutter running out and prescribing a circumference somewhat larger than expected, as you well know this is factored out as you creep up to final finished dimensions, this is even standard practise on one off jobs on brand new plus £100,000 machining centres.

0.01mm means nothing taken out of context, it is trivial in connection with a large assembly (read large model), but it is way past acceptable in a small assembly of certain types.

As a runout, I think 0.01mm is high and certainly I only have one piece of equipment that runs out more than 0.01mm and that is my old faithful Jager spindle (26 years old) this uses a dental collet (KaVo), I will have to take a look at it at some stage.

B.

speelwerk24/07/2019 15:20:36
325 forum posts
1 photos

For clock parts it is not necessary to work at 0.01 mm accuracy. Clocks are driven one way and normally 0.10 mm is more than accurate enough. Niko

Edited By speelwerk on 24/07/2019 15:21:44

Alex Twigg24/07/2019 22:29:11
11 forum posts

Not too sure what Jason's problem is? My circumstances have changed so I can afford a milling machine now? I don't get how a previous post of mine is relevant to this? And so what if I have general purpose ER25 collets, theyre for a lathe not a milling machine? I'm not going to be taking the material in and out all the time so it makes no difference to the lathe too ...

I appreciate Duffers comments. I currently make parts by hand but wanted something that could be used for roughing out shapes and then hand fininshing, and for drilling and milling, holes and slots, in my parts. They need to be this accurate as the type of clock I'm making doesn't allow for depthing of the wheels, so it needs to be pretty close.

Speelwerks, I know that 9 times out of 10 they don't need to be that accurate to work, but due to the clock I'm making and the precision that I desire, I want work accurate to 0.01mm.

Many thanks for replies. I feel I'm going around the houses. I'm just looking for peoples ideas on what they have or know people have and how accurate their machines are.

Edited By Alex Twigg on 24/07/2019 22:46:31

Michael Gilligan24/07/2019 22:40:32
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13573 forum posts
586 photos
Posted by Phil P on 23/07/2019 23:22:35:

I have a friend with a BCA mk3 jig borer for sale in North Yorkshire, if you want to PM me a phone number I can pass it on to him.

.

Alex, ^^^

If Phil's friend's BCA is in good condition, it should do what you need ... easily

[although you may need to work in inches]

MichaelG.

Edited By Michael Gilligan on 24/07/2019 22:43:44

Alex Twigg24/07/2019 22:50:34
11 forum posts

Alex, ^^^

If Phil's friend's BCA is in good condition, it should do what you need ... easily

[although you may need to work in inches]

I've fired him a message. I can work in inches :P

Phil P24/07/2019 23:05:36
486 forum posts
128 photos

Alex

I have just sent the details you need to make contact, the BCA is in excellent condition and is on the original makers stand, my friend is also a very accomplished clock maker, so you will have an interesting conversation when you make contact.

Phil

JasonB25/07/2019 07:23:48
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Moderator
15773 forum posts
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Alex, I find it useful to look at new members postings when they start asking questions as I have no idea what they are capable of, what tooling they already have, etc.

From your previous posts about collets on the Myford I got the impression budget was a large factor in your choice as you said you could not afford MT collets. You have now told us that budget is not an issue so that is one of the two options at the end of my post dealt with and that now saves people time suggesting options that may not be within budget or under it. The collet factor is also worth thinking about when it comes to machines like the BCA where collets can be extreamly hard to find for the old machines and when they do crop up they fetch a premium. There are some new items available but they may not be made to the same accuracy as the originals so you need to bear that in mind and work around it as needed.

You also said that you knew nothing about lathes except how to use them, I assume the same is true for mills in which case it may not be ideal for people to suggest an entry level machine that may need tweaking to get the best out of it as that may not be something you are able to do. The same could well apply to a second hand mill that needs any refurbishment work, maybe you could confirm if you know more about mills again to help narrow down answers.

As mentioned by Ketan and Barry, the final accuracy is really down to the operator if you are simply wanting to mill a bit of material to length within 0.01mm, If on the other hand you want it to be square and parallel sided to withing 0.01mm over say 100mm then the machine will play a bigger part in that.

Just one thing to bear in mind with the Jig borers like the BCA is that they have limited X-Y movement so make sure they will cover the size of your frames if setting out on the mill if you want to avoid having to reset the work with the risk of errors creaping in.

Edited By JasonB on 25/07/2019 07:25:59

Michael Gilligan25/07/2019 08:12:18
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13573 forum posts
586 photos
Posted by JasonB on 25/07/2019 07:23:48:

Just one thing to bear in mind with the Jig borers like the BCA is that they have limited X-Y movement so make sure they will cover the size of your frames if setting out on the mill if you want to avoid having to reset the work with the risk of errors creaping in.

.

... but, on the bright side, the BCA has an 8" diameter rotary table built-in

For setting out a wheel train to specific dimensions, or for cutting spokes, I find it difficult to imagine a more suitable design.

MichaelG.

SillyOldDuffer25/07/2019 09:41:17
4536 forum posts
971 photos

Hi Alex, very sorry to hear you feel you're going round the houses! As a recent beginner myself, who still has a lot to learn, I know exactly what you mean. Ask an apparently simple question, and you get contradictory answers, and a bit of a grilling.

Don't despair. The forum is keen to help, and members - notably Jason - are trying to clarify what exactly your need is.

Quite a common newcomer mistake is believing that high-accuracy is essential and the more accurate the better. My idea was that a high-quality machine would be capable of anything I required of it, therefore I needed only the best. In my case, I was quite wrong. What I need is ordinary: for my purposes machines in the 0.02mm region are 'good enough'. It's because most of my work is roughing out, and - if needed - better than 0.02mm can be achieved by supplementing the machine with other techniques. My perception is most Model Engineer's are like me, working to about a thou or 0.02mm. Steam engine and many clock makers often recommend even slacker fits, seeing problems in overly tight constructions. It depends on what you are making.

The reason excessive accuracy is a mistake is that it moves engineering costs into a different zone. Machines that can do 0.02mm are easy to find and relatively cheap. Better machines are generally moving into the tool-room class, accurate, but with many disadvantages: small work-holding capacity, high-cost (BCA about £12000 new#), difficult to find, big and heavy, high-maintenance, and vulnerable to wear. It's very bad to tell someone doing ordinary light precision work in a small shed he needs an expensive high-accuracy machine when a £400 mini-mill would do.

Trouble is Model Engineering is a very broad church. While I believe most of us do very well at 0.02mm/1 thou, there are many working to higher standards, some of them for professional reasons. Your question landed on the boundary, hence requests for clarification and guesswork about your real requirement. We don't want to recommend a Chinese mini-mill when something like a BCA is needed, or vice versa. As a £400 chinese mini-mill isn't as well made as a £12000 jig borer, one answer could get you an mill that won't do what you need, the other answer could be unaffordable.

From what's emerged it sounds like you really do need a small jig-borer. Not sure how much heavier they are than a mini-mill, but you should in any case check your proposed stand is good and stiff. There's little point in mounting a high-quality machine on a wobbly base. When working to high accuracy everything matters!

We want you to succeed without breaking the bank.

Dave

# Can Jig Borers like the BCA still be bought new? The £12000 price I quoted is at least 10 years old and I've a vague recollection it was mentioned in an article about closing down.

 

 

Edited By SillyOldDuffer on 25/07/2019 09:44:28

Bob Stevenson25/07/2019 10:09:32
285 forum posts
6 photos

...........Perhaps it would help to look at things the other way around!.........do you actually NEED a milling machine? Personally I make my clocks without one and rarely use those at EFHC apart from the Aciera to mill pinions and i am working on the parts to do that on my small lathe at home.....

Some of the best clock makers don't seem to need mills and some can't do without them so which are you,...by NEED not inclination. if it's really just vutting wheels and pinions then that can be done on a suitably adapted lathe just as well as on a mill,...u.nless you are thinking of going into production runs.......

'Micro-milling' is differen to ordinary milling in several important ways which is why the horology world has it's own specialist machines. You could get into looking fo these but be prepared to spend considrable time away from actually making clocks! You could use an old horological mill such as a Hauser or a Dixi but the hunt won't be quick.

perhaps research 'milling in the lathe' online as there are some intersting sites,...and, if you want to put something together yourself take a look at this first;

http://www.maritima-et-mechanika.org/tools/micromill/micromill.html

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