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Quality issues with a SIEG SX2.7 mini mill

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Piotr19/02/2019 08:06:18
17 forum posts
12 photos

In a different thread I described a problem I had with one of the gibs on my Sieg SX2.7 mini mill. I ended up making a new one and solved that particular issue.

Next I started working on squaring the column, but shimming didn’t seem to work how I expected so I disassembled the mill completely only to realise that I opened pandora’s box filled with all sorts of issues:

The two pads, to which column was mounted, were uneven. In some places up to -0.35mm. They were also convex which led to mounting bolts not holding the column firm and stressing the casting. It all looked as if it was ground to “fit” with what could only be an angle grinder.

SX2.7 column mounting pads

(red markings were done with a straight edge across, not touching the middle part)

I reground the pads flat on a surface grinder (I used the ways as reference, assuming they were good, and shimmed the base underneath). Then I shaped the bottom of the column flat and square to the Z ways I assembled it back together and squared the column with the table. I got really good result on the nod, pretty much 0.00mm over 75mm, but I couldn’t get sideways tilt to be better than 0.015mm over the same distance without disturbing the nod. It would also change slightly depending on where on the table I put the reference precision square.

I accepted that, after all it’s a hobby machine, and proceeded to verify the head/spindle tram/squareness to the table. It was square front/back, 0.01mm over the table width which is fine, but the left side of the table was 0.20mm high over the same distance.

I was disappointed and kinda surprised. I did verify the spindle was square to the head itself. I removed the table and the saddle and measured them on a surface place. The saddle was "fine" I guess. Both top and bottom sliding surfaces were slightly concave so the table was supported only by four small high corners points but at least they were pretty much same height and got quickly fixed on a surface grinder.

The table wouldn’t fully fit on my surface plate, I only have a 40x40cm one, but it is definitely not flat. Using marking blue revelas very few points it rests on and a hammer sound test confirms that there are hollow areas on its sides. Measuring its ways shows 0.07mm variation over its ~60cm length which is acceptable.

The last and the worst part are the cross travel slide ways on the base. They are neither parallel nor flat. The left one is between 0.05 and 0.12mm higher than the right one. I made a short clip showing the measurements. I did verify the jig on my surface plate both before and after checking the base.

Measuring fixture 1

This, together with the lack of precision of the table itself results in left/right tram being 0.20mm off over 14cm.

I can now either scrape the ways flat and parallel, which with my limited experience is definitely a challenging task, or take it to a friend with a larger milling machine and try fixing it that way.

Am I simply expecting too much from a ~ £1200 machine or purely out of luck with my unit? I’ve seen other owners of that very same mill showing their measured precision and it seemed to be much better.

Hopper19/02/2019 09:34:05
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6393 forum posts
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Posted by Piotr Gertz on 19/02/2019 08:06:18:

...

I accepted that, after all it’s a hobby machine,

I'm trying to think of another hobby where equipment that did not work or do what it was supposed to do right out of the box without major work would be acceptable.

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Still trying.

Disappointing to be be sure. But I'm guessing that now you have torn it all apart you have no chance of getting it fixed or replaced under warranty. The best thing you can do is persevere and try to find someone who can mill or surface grind those surfaces flat and level for you.

Edited By Hopper on 19/02/2019 09:34:24

Edited By Hopper on 19/02/2019 09:38:07

Piotr19/02/2019 09:53:16
17 forum posts
12 photos

The machine was out of warranty as I started checking it. When I first bought it I didn’t have the skill, tools or need to measure it properly. I was just learning to take cuts basically. Then my son who’s born and my time got limited. Lesson learnt! It first became apparent when I recently worked on a larger project and the slot didn’t end up in the middle.

The problem I see is that there’s no accuracy specified in the “manual” or stated on the resellers website for such machines.. so all expectations are pretty much best wishes.

Ketan Swali19/02/2019 10:58:14
1420 forum posts
133 photos
Posted by Piotr Gertz on 19/02/2019 08:06:18:

Am I simply expecting too much from a ~ £1200 machine or purely out of luck with my unit?

Hello Piotr,

The answer to your question is complex. Most of your observations have been covered over time on this as well as other forums, as well as in magazines, especially the seating of the column to the base. For what I am about to say, you can consider them as an explanation to the situation:

  • all machines in this price range are assembled manually on an assembly line, be they SIEG, or any other. at present, most of the castings are processed by manual operation. Some parts are starting to be produced via CNC process, as labour costs increase.
  • after the machines are assembled, relevant checks are made at the factory for alignment. Only at this time, they look for errors and correct them. This results in scraping (which look like grinding marks as you have seen).
  • The original castings are cured fast through modern methods. Not the old fashion way being left outside to be weathered for a while. The reasons for this are that the demands for this size of machine are high.
  • the machines are built at different times of the year, in different climates - hot, cold, or damp conditions. This has its own effects on the machines. Note: The adjustments are made in the different climates. At this point, in certain cases, certain sellers issue an accuracy certificate. ARC does not, as things are likely to change moving forward.
  • machines are now moved forward in their respective containers to their destination, first to importer and then to the end user. Again, effected by climate as well as handling.
  • once the machine reaches you, it settles in its environment. How accurate the adjustments which were made in the factory after assembly, are now open to question.
  • Add to this, how and where you put the machine, bolt it down, on to what, was any twist introduced inadvertently during installation, will all effect the original adjustments made at the factory after assembly. A machine tool fitter is not supplied with the machine... like in the old days.
  • until you took the machine apart, mechanically, the machine would have operated as it is supposed to, within reasonable limits for hobby use. Over time, how has the machine been used? what has it been doing?, have you adjusted gibs, are you using the right tools?, etc., what experience do you have?... how much of youtube you have seen is correct or applicable to your machine, smaller or bigger machines? how much of the advice is correct or in-correct?
  • then comes the day you decide to take it apart and start to make observations. Note at this point before proceeding further, that the factory had made the adjustments after assembly, to deal with potential issues, which in most cases are fine, until one decides to take a machine apart. Now your experience and advice you listen to comes into play.
  • At this point, i would say that what i have said above, applies to ALL machines of this size, made on a MANUAL fast production line set up like this, be they in CHINA, GERMANY or even in USA, so at this point before we proceed further, my simple answer to your question is that you have been supplied with a great machine at £1,200.00. And yes, I would say that, keeping the above in mind.
  • NOTE: If you make a small change in one area of the machine, it WILL effect others, and then the list of changes to be made can become endless.
  • EXCEPTIONS to the above: we used to offer a 'preparation service' at a cost, in which we stripped the machines, and worked on every component from the ground up. e.g. we would turn the base upside down and mill the base corners, turn it back up, mill the ways and top of the base, and carry on in this way and re-build the machines from the base up. Long and time-consuming job, with a long waiting list. As explained the factories do this after the machines are assembled. If they do in our way, the cost 'currently' would go much higher than many are prepared to pay. To get an idea, one needs to look at prices for certain other German machines in a size range similar to this, which are 'Made in Germany'. If one wants a machine without question on accuracy then one should look at paying upwards of £2500.00 for the SX2.7 equivalent, at current labour costs, and be prepared to wait on a long waiting list, as demand for the SX2.7 as supplied is very high.

Continued...

Ketan Swali19/02/2019 10:58:35
1420 forum posts
133 photos
  • The reason we stopped the preparation service was:
    • a. cost and not too many people were prepared to pay. Even then, we had a six months waiting list
    • b. some of our competitors put out negative marketing comments which suggested that our preparation service was either not necessary or in some way made the machines inferior then theirs, which was wrong thing to say considering that assembly was in the same way
  • Once we stopped the preparation service, our sales increased tremendously.
  • The point is, at this size of machine, the customer decides what they want to pay, and this is what is available for the price.
  • your machine came from the same batch as Jasons!... if he took his machine apart, I have no doubt that he will find similar/different issues.
  • Sales for these machines in the U.S.A are at least 3 x the whole of Europe. Most of them want the low price, and many work with what they have, and some dismantle and do what they want to the machine to get it to their precision requirement.

All I will say is that you have a great machine at a great price. You can watch what ever you like on youtube and listen and believe what ever you want. That is really up to you, and I say this with the greatest of respect.

Ketan at ARC.

Ketan Swali19/02/2019 11:01:19
1420 forum posts
133 photos
Posted by Hopper on 19/02/2019 09:34:05:

Posted by Piotr Gertz on 19/02/2019 08:06:18:

...

I accepted that, after all it’s a hobby machine,

I'm trying to think of another hobby where equipment that did not work or do what it was supposed to do right out of the box without major work would be acceptable.

Still trying.

Disappointing to be be sure. But I'm guessing that now you have torn it all apart you have no chance of getting it fixed or replaced under warranty. The best thing you can do is persevere and try to find someone who can mill or surface grind those surfaces flat and level for you.

Edited By Hopper on 19/02/2019 09:34:24

Edited By Hopper on 19/02/2019 09:38:07

Sorry Hopper but I have to strongly disagree with you.smiley

Ketan at ARC.

Nick Taylor 219/02/2019 11:46:24
102 forum posts

So we're saying that it because it was a different humidity/temperature in the factory the day it the machine was made that means that the ways and mounting pads are magically no longer ground correctly when its setup in your customer's house?

Sorry, but what a load of rubbish.

Also I think 90% of the people on this forum know the difference between a 'scraped' surface and a 'hacked up with a hand held grinder' surface.

Chris Trice19/02/2019 11:51:56
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1375 forum posts
10 photos

At the price point, I expect the vast majority are going to beginners who don't know any better. I doubt less than 5% are being stripped and remachined beyond small adjustments within the skill set of a beginner. Which hobbyist has access to a surface grinder?

"The machines are built at different times of the year, in different climates - hot, cold, or damp conditions. This has its own effects on the machines. Note: The adjustments are made in the different climates. At this point, in certain cases, certain sellers issue an accuracy certificate."

Seriously? If changes of climate affect a machine accuracy that much, why aren't we all readjusting our equipment between winter and summer, rainy days and hot dry days? I would have thought the clamping together of two flat surfaces would remain unchanging with temperature changes? If it's possible to grind the important surfaces that can be seen, it should be possible to grind the important surfaces that aren't seen. I appreciate the spirited defence of these machines and without sounding like I'm having a swipe at them (or Ketan who I've met and like) but a lot of that does sound like a politician's spin.

The fact is, the price reflects the standard of manufacture rather than other outside forces which would also be regular topics for discussion on more expensive machines. For the price, they are good but the problem is they are oversold raising the expectation of the buyer beyond what is likely to be delivered. Disappointment is based on expectation. There will now follow a number of people saying how good their machine is and that's probably an honest statement but I doubt it will quell ongoing threads about quality issues that even at the low price, shouldn't really be present. Even hobbyists expect a machine to meet certain basic stated accuracy standards and one of them is an expectation that what the weather was doing on the day it was assembled and measured plays no part in changing its accuracy between the factory door and delivery.

SillyOldDuffer19/02/2019 12:11:42
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8683 forum posts
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Posted by Hopper on 19/02/2019 09:34:05:

Posted by Piotr Gertz on 19/02/2019 08:06:18:

...

I accepted that, after all it’s a hobby machine,

I'm trying to think of another hobby where equipment that did not work or do what it was supposed to do right out of the box without major work would be acceptable.

...

 

Certainly true of Amateur Radio in the past, less so today. And I think for exactly the same reason, that is a smallish hobby - not millions of people and a lot of money - wanting equipment of a quality they can't or won't pay for.

When I first played radio, most people bought and adapted second-hand commercial equipment, mostly ex-military. Although well-made this stuff usually needed tlc. It was possible to buy new at affordable prices, but what you got was basic with indifferent performance. Part of the hobby fun was modifying new or second-hand to better suit the owners needs. Coughing up a few months pay would get you an altogether better new radio, but they were still considerably inferior to professional equipment costing a year's plus plus salary.

Home metalwork being a relatively small market there isn't much money in it. It's not like cars where the trade is worth billions and makers have to constantly improve value or go out of business. Far eastern tools are pitched at prices hobbyists are actually prepared to pay. Unfortunately there's not much on offer for chaps prepared to spend, say, 100% more on 'quality'. Instead, if you want 'quality' you have to buy an industrial machine, and new ones aren't cheap! Not many hobbyists spend appropriately serious money on a home workshop.

Amateur radio has benefited from developments in consumer electronics and computing. Very large number of customers chasing the best they can get coupled with a technology where Moore's Law applies. Wonderful! The market for machine tools doesn't have the same dynamic.

Perhaps Piotr has been unlucky to find an example of old-fashioned manufacturing technique done poorly. Castings have been poured and machined. As castings are often flawed, when the mill was assembled someone had to fit the parts together. Fitters were once important men in British factories, but - where labour is expensive - it's soon cheaper to eliminate fitting by making precision parts that assemble without needing more work. To quote Mr Jeremy Clarkson on the subject of unreliable super-cars, 'there's only one thing worse than hand-finished and that's handmade.'

I think the reason lathes and mills aren't made entirely using modern precision techniques is that the start up cost is prohibitive: huge numbers of machines would have to be sold to recover the investment. Instead, hobby lathes are only precision made with bought in mass-produced components like bearings & motor, and on moving and alignment critical parts like the bed & headstock. Everything else is fitted down to a cost.

I think this explains why some examples of the same model hobby machine are 'good', most are 'OK', and some are 'bad'. It's often possible for the owner to improve these machines by fettling, though I doubt they will ever be 'excellent', and a basket case might be beyond hope.  But you and I might well do a better job than a rushed Chinese worker. If hobbyists had been serious about 'quality' off-the-shelf they would have supported Myford. Poor old Myford got caught making an expensive machine, which their greatest fans usually bought second-hand, whilst competing with much cheaper Chinese lathes that, despite rough edges, are mostly 'good enough'.

Be interesting to know the history of Piotr's machine. We know that ArcEuroTrade and Warco both visit their Chinese suppliers seeking improvements and others likely do the same. We also know duds do creep through reputable sellers and that factory rejects are on the market as well. Those bargain prices offered by an unknown auction site seller might not be such a good deal after all! Or perhaps it's genuine, who knows?

It's an imperfect world.

Dave

Edited By SillyOldDuffer on 19/02/2019 12:19:16

Hopper19/02/2019 12:17:00
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6393 forum posts
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Posted by Ketan Swali on 19/02/2019 11:01:19:
Posted by Hopper on 19/02/2019 09:34:05:

Posted by Piotr Gertz on 19/02/2019 08:06:18:

...

I accepted that, after all it’s a hobby machine,

I'm trying to think of another hobby where equipment that did not work or do what it was supposed to do right out of the box without major work would be acceptable.

Still trying.

Disappointing to be be sure. But I'm guessing that now you have torn it all apart you have no chance of getting it fixed or replaced under warranty. The best thing you can do is persevere and try to find someone who can mill or surface grind those surfaces flat and level for you.

Edited By Hopper on 19/02/2019 09:34:24

Edited By Hopper on 19/02/2019 09:38:07

Sorry Hopper but I have to strongly disagree with you.smiley

Ketan at ARC.

 

I'm still thinking but no luck so far... smiley

Edited By Hopper on 19/02/2019 12:17:55

Martin Shaw 119/02/2019 12:17:53
124 forum posts
37 photos

I think Chris has pretty much hit the proverbial nail on the head. From my experience I purchased my SX2.7 at the end of last year and I had to separate the column from the base to locate it to the workshop. To be honest I did no more than briefly look at the mating surfaces which seemed fine and when I reassembled it all and trammed the head it was plenty adequate for my needs, so I just get on and use it. It's not perfect, but within the limtations of a bench machine it works ok. Temperature and humidity are I think a red herring.

There is no doubt that poorly assembled machines do escape, but this applies to £60000 Range Rovers as much as small milling machines, and ultimately it comes down to the purchaser to verify that his purchase meets his expectations, which for the sum involved shouldn't be too great, as Chris has so rightly pointed out. This isn't much help to Piotr, I would suggest he contacts Arc and discusses the situation to see if there's a way forward.

Ketan Swali19/02/2019 12:18:21
1420 forum posts
133 photos

Nick,

You are entitled to your opinion.

Chris,

I guess you maybe on the right track. But what I have said is not politician's spin. This is my opinion formed over 19 years of working in this industry. Every one interprets it in their own way. I am happy with and stand by my comments.

Ketan at ARC.

Ketan Swali19/02/2019 12:45:22
1420 forum posts
133 photos
Posted by Martin Shaw 1 on 19/02/2019 12:17:53:I would suggest he contacts Arc and discusses the situation to see if there's a way forward.

Mechanically it worked fine when he got it out of the box, as far as ARC is concerned. The control board was replaced as it was faulty/or a fault developed. That is the end of that. What has happened during the year over which it was supplied I nor anyone else can answer. It would be wrong to speculate by either party. This is probably not what Piotr or someone may want to hear, but that is the way it is.

ARC comes onto this forum and says it as it is. It is not a case of fit for purpose, but as the late JS often said, it is a case of fit for purse, and EVERY machine if taken apart at this price will have something which a person does not like. Everyone has their own view. The climate statement IS a fact. Until and unless any one has a proven record in building and supplying such machines, how can they be qualified in saying that what I am saying is wrong?... I am making my comments based on 19 years of experience. But, I am equally aware that because ARC is a seller, some of my comments will be regarded with a pinch of salt.

Regardless of what you think, at least I respond on this forum. It does not mean that the others are wrong in not responding. They don't want to for their own reasons. With the comments I have made on this forum over the years, if one cares to read them, perhaps there would be a better understanding.

In conclusion, Piotr should carry on and do whatever he wants to his machine, to meet his specific expectations.

Ketan at ARC.

Nick Taylor 219/02/2019 12:51:30
102 forum posts

That's not an opinion actually Ketan, castings that size don't move that much if they are subject to correct manufacturing techniques before and after grinding… and please don’t try to tell me the surfaces in the above pictures have been hand scraped.

Ketan Swali19/02/2019 12:59:01
1420 forum posts
133 photos
Posted by Nick Taylor 2 on 19/02/2019 12:51:30:

That's not an opinion actually Ketan, castings that size don't move that much if they are subject to correct manufacturing techniques before and after grinding… and please don’t try to tell me the surfaces in the above pictures have been hand scraped.

With respect, as I said, you are entitled to your opinion and interpretations on correct manufacturing and curing of castings. I make my comments based on my experience over the years. If you believe me or don't, that is up to yousmiley. In the factory, the scraping is done mostly by an 'electrical' scraper, the finishing of which looks like angle grinder marks. Again, if you have time to go through my past posts, you will see that I have mentioned this before, and again, if you don't believe me, that is really up to you.

Ketan at ARC.

Piotr19/02/2019 13:29:24
17 forum posts
12 photos

Thanks for all your responses!

I do not think, nor have I ever said, that ARC is responsible here. I bought it there because they offered the best price, even including shipping to Sweden. I might have bought it elsewhere and ended up exactly where I am. I intentionally left the reseller out of it as I didn't think it was relevant.

I do not, however, agree that any weather should change machine in such a significant way as to affect its squareness by 0.2mm over ~14cm and I do not think it is the problem. These were not scraping marks either, but again, that's technicalities.

It all seems to be a sum to my slightly high expectations, bad luck with the particular unit and general construction/build quality of the machine. The base casting seems to be too flexible/weak. It was originally mounted on a 4cm thick oak board,, I now moved it on a 3cm steel plate and just that changed the measurements by ca 0.03mm to the worse. Before doing anything else i will make sure i have a flat and stable base that will prevent the casting from flexing.

Have I enjoyed having this machine, definitely yes! Would I buy it again.. probably not. Mostly because now I know what I expect want and can get on the second hand market. I will proceed on fixing it as much as I can with my skills and equipment. It's also a part of the hobby after all.

Edited By Piotr Gertz on 19/02/2019 13:31:16

JasonB19/02/2019 13:43:29
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Posted by Chris Trice on 19/02/2019 11:51:56:
Even hobbyists expect a machine to meet certain basic stated accuracy standards

As most sellers of hobby machines don't state any accuracy standards on their websites or in their paper catalogues I wonder what these hobbysts are basing their expactations on?

From a couple of comments on my channel I suspect Piotr talking about ones I have posted of the SX2.7 that I have which as Ketan has said was from the same batch as his own. He first commented on the one I posted at the weekend regarding the sloping table on the recent Warco thead, which has quite acceptable readings to me. After I took that video I went and did the same test on my well used X3 (a test I have never done on it) and did not get as good a result. Did that make me want to start stripping down my X3 - No. The reason being it has and will continue to make plenty of models that work and are capable of winning awards.

So the question is what accuracy is needed and what accuracy do people think they need? I don't think anyone expects a hobby machine to be upto the spec of a Schaublin or they are a fool if they do but there is nowhere that really states what is an adequate spec to be able to produce perfectly servicable parts on the machine so purchasers start looking for accuracies in the machine that are not really needed.

J

Martin Hamilton 119/02/2019 13:45:14
187 forum posts

'Electrical' scraper, aka belt sander.

Ketan Swali19/02/2019 13:48:19
1420 forum posts
133 photos
Posted by Martin Hamilton 1 on 19/02/2019 13:45:14:

'Electrical' scraper, aka belt sander.

No, it is actually a scraper on steroids... which I have seen. And yes, I do know the difference between a scraper and belt sander.

Ketan at ARC.

JasonB19/02/2019 13:49:49
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Posted by Martin Hamilton 1 on 19/02/2019 13:45:14:

'Electrical' scraper, aka belt sander.

Sounds like a "BIAX" or similar

Edited By JasonB on 19/02/2019 13:50:36

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