Sieg SX3 Mini Lathe improvements adventure

Rob Pulham

Western Thunderer
Further to my question in talk, this thread will cover my Improvements/modifications to my recently acquired Sieg SX3 mini lathe.

I have posted the photos and some of the text in this post before in the what's on your workbench thread, but include them again here for completeness.

The photos will also outline (I hope) why, as well as financial considerations, I couldn't keep both my Unimat III and the Sieg.

Besides the Sieg being bigger and more powerful than the Unimat III another consideration in the purchase, is that it has Digital Read outs fitted to both the cross and compound slides. Although so far I have only made a few small items, the DRO's along with a carriage stop (which I planned to make for the Unimat but you can buy for the C3/SC3 off the shelf for £13) make repeatability a doddle on this lathe.

This is my workbench, covered in lathe chucks which I was in the process of stripping down, cleaning and deburring. I decided to do this after seeing a few YouTube video reviews of Chinese lathe chucks. Which are basically sound, but to keep the price down there is no post machining work done of them. So when they arrive many are full of grinding grit and very little has been deburred.

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I bought the lathe used, and it came with two 3 jaw and one 4 jaw chucks. The 4 jaw chuck had so many burrs inside that one of the jaws wouldn't actually close properly. On the basis of this I suspect that it's had little or no use.

To the left of the workbench sit's the lathe

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Then the milling machine

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And finally the Warco Mini Formit combination guillotine/roller/bending brake.

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The top cupboard to the right in the first photo, houses my spray booth which has an extractor fitted into a chimney and below all the worktops are storage cupboards for the kit mountain. Moving along from that is a small worktop which has my Ultrasonic cleaner on it and then a sink with a drainer.

This is all housed in an underfloor heated room within the house (part of the former Integral garage, the rest is my office/library space) so no excuses for putting lathes on the dining table etc. but I do have a limited amount of space and a 7 x 14 lathe is the biggest that I can fit in.

I sincerely hope that it's the last lathe that I buy.
 

Rob Pulham

Western Thunderer
With the scene set, we move on to what I am doing with the lathe itself. When I saw it advertised I did quite a bit of research while procrastinating as to whether to go for it or not.

From that research I determined that there are three or four companies in China producing what are basically the same lathes in different bed lengths (7" x 10", 7" x 12", 7" x14", and 7" x 16"). Sieg is the only one of these companies that I know the name of, but they are sold in many different guises by resellers in the UK and abroad badged as Sieg, Warco, Chester, Axminster, Clarke, and Little Machine Shop to name but a few.

It's also interesting to me at least, that apparently the original design was East German and taken back to the US by a serviceman. How it then got to China is unclear but probably the serviceman who took the design commissioned a Chinese company to produce them for the US market.

Again from my research, it seems that although basically sound, the lathes as supplied lack rigidity . Thankfully while it involves stripping the lathe down and carrying out modifications, these mods are very cheap to do and can be done in a basic workshop.

The key things that are lacking and contribute greatly to the overall rigidity, particularly when making facing cuts or parting off, are locks on the carriage, cross and compound slides. Something that I made much use of on the Unimat.

Fitting locks to the cross and compound slides is a relatively simple matter of drilling more holes along the line of the Gib adjusters and adding some M4 cap screws to tighten down to lock the slide.

For those that don't know what Gibs are (and I counted myself among them until I got more interested in machine tools) Gibs are diamond profiled strips of steel or brass that sit alongside the dovetails on the slides. - the brass bit in the photo below.

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These can be adjusted by the means of grubs screws and locking nuts to allow the slides to move along the ways without having any slop that would allow chattering of the tool when cutting.

Having first stripped the compound slide down I marked and drilled an extra four holes, two for the locking screws and two for additional adjusters - I had picked up from one video on YouTube that fitting additional adjusters near each end of the compound slide gave more support to the Gibs when the slide is extended beyond the mounting block.

You can see the new holes which have black ink where I marked them out.

It's also worth noting that although I had the tap held in the chuck, I was winding the chuck by hand not power tapping. having it fitted to the chuck just ensured that it went in straight. The idea being that I would start the tap with the chuck and then move to the bench to finish it with a conventional tap wrench. In the event it proved quite easy to tap by twisting the chuck and I ended up going right through all holes using them chuck.

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The hardest bit was marking out, being cast the slides were relatively easy to drill and because of the high carbon content didn't require any lubrication.

Although my lathe is an imperial version it's only the lead screws and gears that are imperial, all the fixings are metric and these were drilled then tapped M4 to match the existing adjusters.

I probably shouldn't have started it between Christmas and the New Year because I am now waiting for hardware deliveries.

I also did the cross slide while I was at it and all told it took about 2 hours.

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bambuko

Western Thunderer
It's also interesting to me at least, that apparently the original design was East German and taken back to the US by a serviceman. How it then got to China is unclear but probably the serviceman who took the design commissioned a Chinese company to produce them for the US market.
It goes back further than that :)
Austrians (Emco), knocked off by DDR(Praezimat) , since than knocked off increasingly cheaply further and further East.
You get what you pay for, but I would feel a lot better about the whole deal if you were told from the beginning, that you are buying kit of bits that will require extensive work to make them usable :D
Good luck :thumbs:
 

GrahamMc

Western Thunderer
I've had a C2 for a couple of years, bought new but for a bargain price, not the £850 you now have to pay and TBH I don't think these lathes at their current price represent good value for money. It's all up to individual choice but at current prices, and for model making I suspect a good second hand lathe, Emco, Hobbymat etc would give better value for money, something people might want to consider.
I haven't fixed the compound slide issue yet, mine is still in 'nodding donkey' mode but I don't think I should have to. By nodding donkey mode I mean the compound slide tips towards the workpeice all to easily, something that simply shouldn't happen. It seems you either have to have the gib screws so tight the slide doesn't slide or you have it loose enough to slide but it tips.
That said I'm happy enough with it bearing in mind it cost around £360. It helps that you can get spare compound slides from Arc Euro trade for about £20 so if I make a mess of the modification I can get a spare.
IIRC there was an earlier thread on this and the holes were drilled .5mm nearer the edge to make the gib plate more secure.
I don't want to be negative but at the same time I'd like people to know what they're getting. They'll need to be confident they can do the modifications.
Thanks for starting the thread.
 
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Chris Veitch

Western Thunderer
You get what you pay for, but I would feel a lot better about the whole deal if you were told from the beginning, that you are buying kit of bits that will require extensive work to make them usable

How true. My similar Warco machine has sat in the garage almost new and unused for a couple of years now. It was bought some time ago when I was looking at doing some 16mm narrow gauge stuff but shortly after that circumstances changed and meant that I had little time or scope for that, and for now I must confine myself to much smaller fare indoors for which a Unimat-sized machine is far more practical (OK, I could probably do the larger stuff on that anyway at a pinch, but I had the cash and aspirations at the time).

It's very true that these Chinese machines are a hobby in themselves - I'd rather like to spend time on getting my Warco into decent condition but as that'll have to wait until "life" calms down a bit.
 

GrahamMc

Western Thunderer
I believe (could be wrong) that the compound slide issue is the main problem, not the only one but a compound slide that doesn't work isn't good. I'm hoping I won't need a machine shop to fix it, just a simple jig made from a couple of bits of scrap and a drill.

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The drill is an M4 tapping size drilled through a bit of scrap steel as a drill guide and I'll space the bit out from the aluminium angle (make a gauge, shim it, etc etc.), tighten the bolt, clamp to the slide and drill. I should be able to get the .5mm nearer the edge. As jigs go it's not very posh but it'll do the job. No excuse now for not getting on with it.
So, it doesn't have to be that big an issue, but if I'd just bought a new machine I wouldn't be comfortable about making holes in it.
 
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Rob Pulham

Western Thunderer
Hi Graham,

Knowing you can get spares relatively cheaply is what gave me the confidence to go ahead and have a go.

Although I have read/seen videos of a good many similar improvements I hadn't picked up on anyone drilling the holes .5mm lower down, so mine are that same centre line as the originals.
 

Rob Pulham

Western Thunderer
One of the other recommended improvements that people make to Chinese mini lathes is a swarf guard to the back of the apron. For those that don’t know the terminology, the 'apron' is the gear housing for the carriage hand wheel, it also houses the auto feed mechanism.

Most people that I have seen make such a cover, have done it from thin Perspex sheet. This works fine but I was delighted when I saw that mine had already been fitted with a nice cover made from sheet brass .

The back of the Apron showing the rather neat swarf guard.

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I was even more delighted when I took it to bits and found out just how well it had been made. You will also note the grease nipple. Grease nipples have been fitted to all the bearing housings.

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GrahamMc

Western Thunderer
Just found this from the same thread,

In conversation it appears that as a guess approximately 70% of the machines from Sieg have this problem, which is actually the cross slide rather than the tool post per se. I also found out that almost all the manufacture is by hand rather than CNC or jig which will allow some tolerances in where holes are placed. Additionally the dimples in the gib strip do not align with the adjustment screws hence knocking it all off. Restorative measures are in hand.
 

Rob Pulham

Western Thunderer
I must confess that although I read it at the time, I had completely forgotten about it in the meantime.

I have been exchanging PM's with Martin and his advice on the subject has been invaluable,
 

Rob Pulham

Western Thunderer
A small side job that I forgot to mention while we were talking about the compound slide is the ball handle.

As you buy the machine when new, both ball handles look like that on the left (which is the handle for the cross slide)

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I am not sure whether the smaller one was broken off by accident or deliberately cut off for some reason. But when I received the lathe the stem of the handle was missing and the remains had been quite crudely cut, leaving a rough surface. I am pretty sure that I could have bought a replacement had I searched the internet, but where's the fun in that.

My plan was to drill it right through and then turn up a handle similar to, but hopefully more shapely than those that I made for the Unimat Tail stock.

The reason that I was going to drill right through was that I didn't think that I had an M6 bottom tap, and I did briefly consider cutting the end of a spare M6 taper tap with a grinder but quickly dismissed that idea as being far too cold and miserable (the grinder is deep in the shed at the minute and a couple of days ago when I was considering this problem we had very high winds).

As luck would have it, I made up a fixture from an M8 cap screw, a couple of nuts and some washers. I had just run and end mill over it to tidy up the rough cut edge when I was rummaging in a drawer for drill bits and found a small plastic box with an M6 bottom tap in it. So I drilled about 2/3rds of the way through, very much by eye. Then tapped it ready for making a handle as the first job when I get the lathe back together.

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Although in the photo the hole looks to be off centre, it's due to the not quite perfect shape of the underlying casting. When you screw in a new handle it does fit exactly centred. I know because I temporarily borrowed the handle from the quick change tool post to test it once I realised that it was:
a. loose so could be removed with ease.
and
b. threaded M6
 

Martin Shaw

Western Thunderer
Nearly 5 years ago I see and my words are coming back to haunt me, doesn't time fly. I would point out that these were my stumbling amateur attempts to improve the machine, I am by no means an expert. My thanks to Rob for the kind words. I would also in light of the experience add something, none of these mods are essential, immensely desirable and certainly worth doing but the lathe as supplied works out of the box in the vast majority of cases. Additionally it's shortcomings around the compound and top slides are as much down to the inadequacies of the original Emco design as they are to manufacturing in China.

I would also ask what is the alternative, none as far as I can see. I have found a few 2nd hand Myfords of various ages and types, in unknown condition at well in excess of Sieg prices. You might get lucky and get a one owner well cared for example, but more likely an expensive piece of scrap. Decent used Unimats seem less common and whilst they work aren't that brilliant, so the less than stellar Chinese made machine bought with a warranty from a UK retailer is far from the disaster some would care to paint it as. Ultimately it reflects what the market is prepared to pay, which is of course as little as possible.

Martin
 

michael mott

Western Thunderer
I'm only 73 so I hope to get at least another 20 years out of my 52 year old Myford ML7 long bed. I paid $350 for it brand new ready to run with a 3 jaw and 4 jaw chucks, That was the same price as a plane ticket from Edmonton to London in 1970. I chose wisely in my view. That said a quick change gearbox would be nice.

Michael
 

Stephen Freeman

Western Thunderer
I'm only 73 so I hope to get at least another 20 years out of my 52 year old Myford ML7 long bed. I paid $350 for it brand new ready to run with a 3 jaw and 4 jaw chucks, That was the same price as a plane ticket from Edmonton to London in 1970. I chose wisely in my view. That said a quick change gearbox would be nice.

Michael
Actually imho the best mod I added was the clutch, stopping and starting without switching off. Secondly the Quick Change Toolpost. Both make life so much easier. I do have a 4 jaw chuck but seldom use it these days.
 

Martin Shaw

Western Thunderer
Both Michael and Stephen are fortunate in having a good Myford and indeed should with care last a lifetime or longer. I too would have had a Myford if I could get a good one, having said that my Sieg will last as many years as I care to look after it, with the possible/probable exception of the motor and control circuitry. Both replaceable at pretty low cost if necessary. The inescapable fact remains that there is no low cost high quality "minilathe" on the market, so new Chinese, or unknown quality second hand are the options. I may have sufficient knowledge and experience to make informed choices, many potential purchasers don't, hence the general thrust of my view.

Regards
Martin
 

michael mott

Western Thunderer
Secondly the Quick Change Toolpost. Both make life so much easier.
Yes the quick change tool-posts are wonderful, When i purchased my lathe a short time after I purchased a Dickson quick change and loved it used it for 45 years and then wanted to get a few more holders.... my wallet screamed at me so opted to change systems to a type available locally at the Busy Bee tool outlet these ones only cost $25 per holder.

Michael
 

Ian@StEnochs

Western Thunderer
I bought my Myford in the late 80’s and it has seen constant use. Apart from routine maintenance and very occasional adjustments to the gibs it has needed no spare parts. I give it a check over for accuracy every so often and it is as good as the day I cleaned the protective grease from it. That despite being used on some quite heavy work making parts for my local preservation group and machining a couple of large scale steam tractors. Most of it’s work now is a lot lighter and mostly confined to 7 mm scale but sometimes gets called on for the odd classic car part, most recently it skimmed the commutator on a Dynamo. I last used it this morning to drill out some lost wax buffer bodies and turn the steel heads.

I bought new, it was quite a bit of cash then, but over 40 years of use it has certainly paid for itself. I consider the cost of ownership to have been very good value and looking online there is considerable value still in it.

We all have to weigh up how much we should spend on our hobby. Nothing wrong with buying a cheap basic machine and upgrading it and for many that can become the hobby.

Ian.
 

Stephen Freeman

Western Thunderer
Apart from the ML7, I acquired one of the type of lathes in a non-working condition, it just needed new electrical controls, which cost about £20.00. I only have a small of of tooling for it and haven't used it much to date so am interested in improving it. It does offer the prospect of being usable in a smaller space and more easily moved about, which does appeal but I can't think it will replace the Myford, you can just do so much with them.
 

Rob Pulham

Western Thunderer
Next we move on to the carriage or saddle and this is where things get a bit more involved because I plan to not only making it more rigid but to add a carriage lock as well.

This is the carriage as supplied on the SC3, I say that specifically because the previous version the C3 which is still on sale under various brand names has a slightly different carriage whose shape makes the next bit easier.

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The photo below shows (hopefully what I plan. On the C3 lathes where the cut out is at either side of the SC3 carriage, it's solid so in order to make it solid again I need to add some pieces in to make up the space. The idea being to mill out the slot to make it square drill and tap a couple of fixing holes and then cut a piece of stock to fit.

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The two plates that you see on the bottom are the plates that retain the carriage to the ways and they are made from hardened steel. In between the three retaining cap screws are two adjustment grub screws. These allow the plates to be tightened against the underside of the ways and adjusted for free movement without slop. However these grub screws are known to cause the hardened plates to crack over time.

A gent called Steve Jordan (YouTuber) has devised a method of replacing the plates, cap screws, and adjustment screws with mild steel plates, studs, lock nuts and shims to remove the need to manually adjust. Another YouTuber in the US, has taken Steve's ideas and refined them slightly by making a jig to drill holes in the shims so that they slip over the studs and are retained by the plates whereas Steve's shims are small pieces slipped in between the studs and can, if you are not careful become dislodged during reassembly.

Although difficult to envisage from my text alone once I have more of the parts made and the rest of my hardware orders arrive I shall endeavour to make things clearer.
 
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