The ins and outs of what we found and would like to share with you, our reader.
Last updated on: 12 May 2013 --> In anticipation of yet another lathe, see Kart E2N link on the index page.
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Greetings, My name is Danny and it is my pleasure to take you on a trip through some of the things that are involved when restoring or refurbishing a lathe. Mind you, I'm just the editor of this story. We'll meet the real owner of this lathe as we go along. And believe it or not but this is just a hobby!
This is the lathe I will write about, seen here in its finished state.
It is a German made Matra, type D 25 with serial number 2250.
It weighs about 2 metric tonnes, and has a center height of 250 mm above the lathe bed.
The name MATRA is an acronym (an abbreviation formed from initial letters) of the founders' names MArx and TRAube.
Everyone is good at something, be it at work or at home, we all find something that we enjoy doing. For the ones who like to get their hands dirty and tinker with mechanical items often the need arises to "turn" a replacement for a broken or missing part. Turning is a process used to produce parts that are of cylindrical form. It can be done manually - as in this case - or on a Computer Numerical Controlled (CNC) machine.
When turning a piece of material (metal, plastic, wood, etc.) that is called the workpiece, it is given a constant rotation and a cutting tool is traversed along 2 axes of motion to produce precise diameters and depths. Turning can be either on the outside of the cylinder or on the inside (known as boring) to produce tubular components to various geometries. Turning can be performed manually on what is known as conventional machines with center lathes which are non computerized. In this case, they require constant supervision and manual adjustments to cut away any excess material from the workpiece.
It all begins with a need for something. In this case a lathe, that can be used to make cylindrical parts for things that are broken, have excess wear, or are not yet existent. Buying a lathe is expensive and a lot of thought went in to it before the owner decided to jump into the unexplored journey of buying a secondhand lathe. He had some experience with a much smaller lathe that he had bought before, but was not satisfied with what it gave him in terms of performance and size (you know how men are). So that small lathe was again sold. Mind you, he had taken it all apart. Cleaned it, painted it, and adjusted everything back to standards. Now he had some experience to aid him in further journeys. But something bigger was needed. And so it happened that he found a German made Matra lathe. Being much larger and having more performance sounded good. But with a catch! Although the price was right, the lathe was advertised stating that the spindle became hot and ceased-up after a short time running in the higher RPM range. This is a show stopper for a lot of people, hence the low price that the seller was asking. With the additional information that could be gathered from the seller, and a lot of debate between us, it was decided to go after it and buy it!
Cashing in, cashing out.
As a date was agreed on to collect it, so we had to procure the means to transport it home. And so Geert, as the owner is called, rented an enclosed van that was big enough to hold the lathe and not buckle under its weight. On our way we went, consoling ourselves that if we would find something totally amiss with it, we could always back out and leave it at that. Once we arrived at the seller and looked the lathe over, we could not find anything in particular that would result in not buying it. The excitement grew stronger. Loading the lathe in the van was no problem at all, and before we knew it the lathe was paid for and on its way to its new home.
Now that the lathe was home, the unloading caused us to scratch our heads a few times. So we proceeded as carefully as we could, trying not to tip the whole thing over and making a few dents in the pavement. And this is how it all looked when at last the lathe was out of the van.
Lathe unloaded from the van, but not yet on solid ground.
In fact, solid ground is still four pallets further down.
Legs of jello!
Well, you can see in the above picture what we're up against. Getting this behemoth on solid ground, or better, on a pallet for ease of transportation is not for the faint of heart. The pallet truck can only lift 1000 kg and therefore a fulcrum and the weight of the lathe had to be used to swivel it up and down, and in doing so reduce the height with one pallet at a time.
Your editor flipping some levers.
As mentioned earlier, the lathe had one big apparent problem. The spindle would seize after a short time, when running above 500 RPM. That is why the spindle cover was removed by us, to try and see if we could spot anything that looked like it had turned blue due to excessive heat. Alas (or better, thank God) nothing was found that pointed in that direction. Therefore the problem had to lie deeper and had to be tackled at a later date.
Headstock cover removed for inspection.
End of day one.
As the rented van needed to be returned and the evening drew near, work was put on hold and the lathe was placed out of harms way until work on it could continue.
Above and below is the lathe as bought.
A diamond in the rough? Read all about it on the following pages.
What to do next? Use the lathe "as is" and carry out minor repairs, or tear it down and build it from the floor back up again? Well, the latter option seemed big fun! And in doing so you create a feeling for all the parts that make up a lathe and maybe learn a thing or two. But remember, you know when you start but never where and when it ends. Persevere! So put on your thinking cap 'cause here we go!
Note: Before tearing down a lathe you should first know the exact state it is in and the defects it has. Most of the time much of it will reveal itself when you open it up but you will sleep better at night when you have a fairly good idea about what you're up against. Know your limits and keep both feet on the ground! For example, it is unlikely that you will succeed in rescraping worn ways when you never saw a scraping iron in real life or have any scraping experience under your belt to speak of. It is not so that scraping is always necessary but the other side of the coin will be that you need to console yourself with the fact that your finished lathe will be a little less accurate then you dreamt it will be. ;-) Be advised that you need an understanding of how to align things in a logical order when you put it all back together again. If it is your first project there will be enough stumbling blocks on the road to completion. Plenty of times you will need to educate yourself on a subject before you can start to tackle it and then move on. And you better know a friend who has a lathe himself and can make simple replacement parts for the lathe you're working on. Costs can add up quickly if you need to have everything done for you by a professional machine shop. All this being said, let's have a look how Geert manages with his project.
The biggest "heavy" lifting equipment that Geert had access to. It has a 1 ton lifting capacity.
Electric motor and electrical cabinet removed.
Removing the change gears that drive the quick change gearbox at the bottom right.
The motor is 5,5 kW at 1,440 RPM.
Change gears and casing.
Spindle with DIN 55027 mounting flange size 6 and MC6 internal cone. Spindle bore 55 mm.
Disconnecting all the wiring.
Removing the headstock by lifting it up, ...
... and away.
Quick change gearbox in the foreground, lower right.
Saddle with cross slide and apron.
Detail of the back side of the apron. The key in the outermost drive gear has lost a lot of width due to wear.
Quick change gearbox removed, along with the lead- and feedscrew.
Lathe feet and chip pan are all that remain after the lathe bed has been removed.
Having disassembled the lathe into manageable parts, cleaning can now commence. And where better to start then with the lathe bed and feet.
The lathe bed is attached to wooden skates.
With the help of a pressure washer, hot water and some detergent all the grime from years of use is removed.
Warning: When using (hot) water on blank lathe surfaces corrosion is quick to follow. It happens in a matter of minutes! so, when you are done with washing, wipe all blank surfaces dry with a towel. We want it clean, but not turning brown due to developing rust. Surfaces that are still covered with paint are not prone to corrosion and will dry up nicely.
If everything in the world was easy, no interesting stories would ensue of heroism, courage and ingenuity. A person performs best when baffled by a problem that still needs to be solved, with tools that are at hand. And the next problem that had to be addressed was how these big and heavy parts could be safely transported down a slope and into the workshop, located in the basement of the house. We let the pictures tell the story.
Then the unit could be lowered down the slope by means of a sturdy rope and a pulley block. this pulley block is attached to the towing hitch of the car. And the car is not being moved at all. It is put in gear with the parking brake on. The actual lowering is done by slowly unwinding the rope from the pulley block. A ratchet mechanism on the pulley block guards against unwanted unwinding of the rope.
The car is positioned at an angle to the slope and the front wheels of the car are turned all the way to the left, so when the unthinkable would happen and the car starts to move, it will not disappear down the slope with the lathe bed in front of it. ;-) Mind you, the car didn't move a hair, but it is always good to think ahead at what could happen and take the necessary precautions.
It is in the basement workshop that we meet Geert, the owner of the lathe and his dog Raki.
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