July 17, 2010
I get a lot of queries about restoration projects and I've always wanted to put up a lavishly illustrated web site on machine tool restoration. Unfortunately, this is not that document and I'm only publishing this as a way to avoid writing a constant stream of small email replies with tidbits of advice. In fact, that's where I collected most of these pedantic screeds: from old emails I sent out to people asking about restoration projects. Perhaps over time this page will grow and eventually contain some useful material.
Restoring a machine tool is a big project, but it is very rewarding to end up with a perfect-running factory-new-looking machine that would have cost you thousands to buy new.
The most important resource is your own character: Determination to do things right no matter how long it takes and a general attitude of not cutting corners, rejecting "good enough" thinking and, in general, taking time to learn from others, "knowing what you don't know," and never doing things that destroy or degrade the machine itself so it can never be restored in the future.
Patience is perhaps the number one asset: If you need a gear puller or a special tool, set aside the work and go buy the tool. Don't grab a hammer or some other stopgap that will damage the machine.
The above remarks may sound like unreasonable perfectionism, but I can assure you that your first restorations, no matter how determined you are to do a good job, will be a great disappointment compared to the ones you do later. Although it looks and smells like auto body and engine repair, machine tool rebuilding has a lot more in common with watchmaking.
Some things can only be learned by experience and it is better to get that experience on machines of lesser value: If you have been lucky enough to "steal" a fine old tool room lathe, don't try to restore it as your first venture.
Needless to say, background in restoring and fixing less demanding mechanical devices is important: If you've never repaired and restored cars, engines, or antique machines, you are very likely to destroy a precision machine tool just taking it apart. This kind of project is not a good place to begin amateur mechanics.
This is a controversial area. Machine tools of historic interest, usually from the 19th century or earlier, require special consideration.
When you restore a machine, your goal is to make it look and work exactly like it did the day it was made. This is generally the sort of machine you're likely to want for daily use in your shop.
But very old machines, things that you might see in a museum for example, should not in most cases be subjected to this treatment. The reasoning is that such machines have historical features that will be lost forever if subjected to sandblasting, painting, and wholesale replacement of parts.
Museums and conservators try to arrest the decay of these instruments without attempting to restore their appearance. If they are made to operate by adding new parts, no attempt is made to hide the fact that a new part was added. In some cases, new parts are fabricated in such a way as to draw attention to the fact that they don't belong in the original mechanism. This is avoid misdirecting future conservators as to the provenance of the machine.
I do occasionally work on and even totally restore antique machinery. Before doing this, I consider the relative rarity of the tool: If there are a great many examples already in collections and museums, I don't see any great harm in completely restoring an example. I feel that by making such a tool available for actual use, another aspect of historical knowledge is preserved: The actual experience of operating the machine. This knowledge is lost when a machine is only displayed in a glass case. This is the same defense offered by those who restore antique violins for use by modern performers.
I want to emphasize that this is not a safe hobby: You will work with massive objects, toxic solvents, explosive fumes, exposed gears, high voltage electricity and a host of other minor and major hazards that I can't possibly enumerate, not the least of which is seriously annoying your wife. In a "real" industrial setting, you'd need half a dozen licenses and certificates to do this work.
I am an amateur and this site is published to share what little experience I have with other amateurs. If you are not a responsible adult, you will be well advised to give up this project and take up knitting, basket weaving, or some other safe activity approved for the modern well-conditioned citizen.
Be aware that industrial suppliers have a limited tolerance of amateurs. Ask questions when they aren't obviously busy selling railroad cars full of goods and keep your questions short and to the point.
It is better to visit in person than to try and solicit advice over the phone after you've ordered a 30 cent pin. Also remember that the rules of commerce in the industrial world are different from those in the sewing supply shop: You can't expect to return open packages or even unused parts you've mis-ordered. You are expected to know what you're doing and eat your own mistakes.
If you look like someone doesn't belong in a machine warehouse or act like someone who might avail themselves of a trial lawyer, you'll be asked to leave or get a "we don't sell to the public" brush off.
Learn to blend in. Most machinery dealers and industrial suppliers are conservative. They don't like people with blue hair standing on end, nose piercings, or any other outlandish garb. (Although my mother-in-law, for some reason, always fits right in.) I hope it goes without saying that you must leave your dogs and children at home. On the other hand, I can report that I've met some interesting dogs in machinery warehouses as well as one naked fashion model.
As a rule, train engineer's garb or farmer's bib overalls are very good. Wearing the right kind of dirt is important. After you've been a regular for a few years, you won't have to be as careful: I've been visiting the same machine tool dealers and builders for so many years that I can show up in my regular white lab coat and propeller beanie.
Although this web page is aimed at people who are restoring machines for fun, you do need to consider what your time is worth relative to the expected gain.
If you were thinking about making your machine from scratch, pouring your own iron castings with a shop vac blower and barbecue grill charcoal, you can skip these warnings because you are either mad or experienced enough to succeed with any pile of junk.
In some cases where rust and ruin have taken a heavy toll, you could earn enough bagging groceries to buy a better machine for the extra time you'd otherwise spend breathing solvent fumes, paint dust, and industrial acid vapors.
Machine tool rebuilding where precision surfaces or spindles must be restored is beyond the scope of this introduction. However I would like to recommend a great book available on this topic: "Machine Tool Reconditioning" by Edward F. Connelly. If you are new to the idea of precision scraping, I strongly recommend the books and videos offered by Michael Morgan at machinerepair.com. I was a scraping "wannabe" for 20 years and I fooled around with various procedures I got from antique books. I never got the knowledge or confidence to repair a "real machine" from these sources. After watching Michael's video, I went out and got the right tools and immediately succeeded in creating a flat precision surface. Finally, I would suggest downloading the "The Art of Hand Scraping" by Robert Wade. It's a scanned pdf in three pieces from TBD.
Every type of machine tool has it's own characteristic ways of wearing out and going wrong. Dave Ficken presents sage advice at Meridian Machinery such as "How to buy a Lathe" and "How to buy a mill." These articles are about avoiding problems when buying a used machine. Even if you plan to rebuild a wreck, it's good to know what you're getting into.
Experience with owning and operating the kind of machine you hope to restore is perhaps the best preparation. If you've never owned or operated a blast furnace for example, buying one you expect to recondition is probably a mistake.
You will need everything a automotive mechanic would usually have on hand. In addition, you will need to buy or possibly rent an assortment of gear pullers. An arbor press with lots of adapter pins, rings, and V-blocks is essential for working on bearings and spindles.
Hammers are used only sparingly, but you will want a plastic sand filled "dead blow" hammer and assortment of small brass or even lead faced hammers along with lots of drive pins made of copper or brass. For knocking out taper pins, a set of good quality drive pin punches is necessary. Even for these, I prefer to use the arbor press or jacks when possible.
I use wooden carpenter's shims a great deal for prying things apart. I tap them in with a plastic hammer.
For pushing things apart held by precision dowel pins, I use a collection of miniature machinists jacks, often several at a time to apply even force.
To go with the jacks, I have a pile of 2x4 cutoffs to use as gap fillers.
Eventually, you will have to deal with alignment issues. Sometimes you'll find old machines that were at some point "rebuilt" by inserting shim stock between parts to restore alignment. When these fall out in a rusty pile, you have to be prepared to scrape the surfaces or otherwise restore the precise alignment of the parts. To do this, you need one or two precision straight edges, angle plates and one or more surface plates. This gets into the territory covered by the Connelly book and it is deep water. If you think such measures will be required, you may want to postpone working on those parts of your machine.
Making replacement parts potentially requires an advanced machine shop or even a foundry. When you are fixing an old machine, it is very often necessary to avail yourself of a working example of the same machine. If you have a network of friends interested in machine shop work, this won't be a problem, but sometimes you need to have a "grinding lathe" just for making and finishing rough parts or for use with strips of abrasive paper. (Something you will NOT do with a fine lathe of course.)
Another asset that is very nice to own or have access to is a bead-blasting cabinet. This is the very best instrument for finishing parts to factory-new condition. People who might let you use their blasting machine are generally not too happy to see you arrive with grease and paint covered parts.
A chain hoist or some other kind of lifting device is essential because most machine tools have parts far too heavy to safely lift by hand. Along with your hoist you will need appropriately rated slings, rings and other tackle. Dealing with hoists, hooks and slings is worth another whole article. If you aren't used to working with "heavy stuff", you should take time to get proper instruction. A common mistake is spare no expense on the hoist and rigging, but then pull the garage roof down on top of yourself when you lift the machine. This is expensive, embarrassing, and might even scratch the paint on your machine.
In addition to the hoist, small tackles called "come alongs" are very useful. These are cable or chain tackles with hooks on each end and a ratchet bar. You use them to drag things, lift smaller parts or pull things into alignment when assembling.
For waltzing the machine around the room, I use a big "Johnson bar" which is is a 7 foot long hardwood shaft with two small iron wheels on the floor end. There is a short metal prying plate that extends out from between the wheels. You use this to lift a machine so you can insert metal rollers or special machine mover's casters. After that, you can use the Johnson bar to drag the machine across floor. When a roller comes out of the trailing end, you bring it around and insert it under the front. Think Egyptian. I use sections one inch steel pipe for rollers.
Every now and then, I have to lift something so heavy that it worries me. On those occasions, I always invite my mother-in-law or another "tooly" friend to help or at least supervise in case I get into trouble. My wife likes to visit her horse on days like that.
A digital camera is big help to document how things go back together. Keep it in a clear plastic bag and shoot right through the plastic by stretching it over the lens.
I use dozens of little zip-lock plastic bags, each with a set of screws, pins, associated small parts and a note written with a permanent marker telling me where they go.
I usually aim for total restoration, which requires disassembly down to the individual screws.
Nameplates are a special case. You want to get these off the machine early to avoid damaging them. I usually take them off and put them in a safe place before any other steps are taken.
Nameplates are usually attached with small pins that don't go completely though the casting. The only way I've found to get them out is to cut off their heads and drill out their remains after the plate is off. I do this by masking off the the entire plate and then using a tiny end mill held in a power drill with a drilling guild make of a block of steel I clamp to the surface. The steel block has a hole to clear the end mill. The mill must be of the plunge cutting type. If the pins are big enough, you might be able to center punch their heads and drill, but I've had a few accidents trying to drill out pins freehand where I ended up scratching the name plate.
Restoring nameplates: These are often embossed aluminum with the background in black and the foreground exposed metal. 1) Clean off all the old paint with paint remover. 2) Buff up the surface with the finest 3M pad. 3) Spray them with semigloss black paint. 4) Lap them on a plate with very fine sandpaper to remove the paint from the lettering. 5) Apply a coat of clear matte spray to protect the exposed aluminum from oxidation.
Never hammer on things when you are taking a machine apart except possibly small taper pins. When you think you must pound on something, consider using small jacks instead. I have a half dozen of the little Starrett machinist jacks I use to push things apart. When I must beat on something, I used a plastic "dead blow" hammer full of sand and/or little brass and copper rods.
When pushing out pins that retain gears or other round things on a shaft, it is much better to use an arbor press and V blocks. Hammering on these pins is very likely to bend the shaft.
In general, wooden wedges, gear pullers, jacks and your arbor press are your friends. Hammers are a last resort.
When something is really stuck on, I sometimes insert a few single edge razor blades and tap them in around the edges like tiny wedges. When a gap opens, I can start using my carpenter's wedges.
Sometimes old paint obscures your view of taper pins and dowels. So don't get too violent taking things apart. For some parts, waiting for a round of paint remover is necessary because the old paint has glued things together.
You need a well ventilated place to work or you will decompose your liver. I work in a garage with the doors and windows open and a big floor fan blowing the fumes away from me.
I fill a dozen little plastic tubs with methylene chloride. There are many brand name paint removers that are essentially methylene chloride. Avoid "nurf" paint removers or any with claims of being Safe, E-Z-2-Use, or "Eco-friendly."
It's a good idea to test the plastic tub to make sure it won't dissolve overnight. My wife's Tupperware works really well, but I have painfully learned that it works out better to go out and buy my own set. This involves attending tedious afternoon parties with suburban housewives. I've introduced several of them to machine tool rebuilding but I've never been invited back to see their progress.
Into each tub goes a set of painted/greased screws and, if it will fit, whatever they attached to the machine. Goop the paint remover all over them. You can loosely lay the lid on top to contain fumes, but don't snap it down because the vapor pressure will blow it off later, throwing paint remover and goop everywhere.
For larger parts, scrape off the grease and loose paint, spray with solvent and wipe off excess oil, then brush on the paint remover. This has to been done about 10 times, with a few elapsed hours or even overnight between attacks.
I use lots of cheap disposable wire brushes. These come in regular brush shapes and also as "test tube" brushes which are great for cleaning out bolt holes.
It isn't necessary to remove every bit of paint: large areas that are coated with undamaged paint should be left alone, even though you are creating divots where the paint remover is allowed to act.
I would first draw your attention to the remarks in the introduction: If you have significant rust on precision surfaces, it may be the case that this machine is not worth restoration or that that it is beyond your ability and/or resources.
For non precision surfaces, I use abrasives and powered wire brushes.
For finer work, I use a plastic tub full of strong vinegar and as much salt as will dissolve. The parts must be free of paint and degreased. This works well for small parts, gears, levers, etc. For taper pins, dowel pins, and screws, I prefer to buy new ones as described above.
For parts you can't immerse in a plastic tub, I use a product called "Naval Jelly". This is some kind of jellylike acid. Another product I really like is called "Knorrostol." I think it's a European thing. Anyway, it is really good for bright work: knobs, handwheel rims, etc. I think it contains a fine abrasive paste mixed with a rust solvent.
For rusted hand wheels and other exposed surfaces that are damaged beyond the scope of polishing paste, I use powered wire brushes followed by the metalworking grade of fuzzy 3M abrasive pads. If the surface is not a precision area, I will use fine grades of sandpaper with an appropriate block. Extreme care must be taken when using any kind of abrasive to make sure dislodged grit doesn't end up in bearings, gears, or other places that can be harmed.
For mating surfaces that must be flat, I will sometimes put a sheet of fine black sandpaper on a glass slab and lap the part back and forth. (Don't use your surface plate with abrasives!)
It is never a good idea to use hand-held abrasives on precision sliding parts or bearings. If a precision surface is damaged badly by rust, it needs to be re-machined and then scraped and/or lapped to restore the finish and accuracy.
This is the most time consuming step.
When all your parts are degreased, de-painted and completely clear of debris, you are ready to start "filling".
This is done using automotive body work tools and chemicals. In the U.S., there is an epoxy like putty called "Bondo." This is used to fill big cavities and smooth out exposed irregularities in the castings. You will also find various light putty compounds and pastes for filling small cracks and chips. Use the "Bondo" first and don't try to get it all smoothed out. You want extra to sand off. Power tools are a must because this stuff dries as hard as a rock.
I sand with power tools and silicon carbide paper backed with wooden blocks. I also like the fuzzy 3M pads made for metal working. Your goal is to get a totally smooth surface to both sight and touch. If you have a friend who restores old cars, you should go watch and ask questions. A lot depends on having the right lighting.
I find that I can't see all the defects at this point because the parts and castings are a multicolored mess of bondo, old paint and other filler putty blotches. So after one or two rounds of filling and sanding, I apply some primer. There are two kinds of primer: red and gray. The red primer is used on areas that are bare metal, the Gray is used on top of that and everywhere you are covering old paint.
Before the primer, you need to protect all the precision surfaces and holes that should not have paint inside. I used regular painters masking tape and razor blades to trim. For each project, I buy a big bag of assorted corks to plug dowel pin holes and other round cavities that shouldn't have paint.
I should mention that the old paint areas you left alone must be sanded before applying primer.
With the machine and parts all one color (the Gray primer) it is a lot easier to see defects, bumps and cracks. Fill these with a compatible auto restoration putty. Sand again, apply more Gray primer and so on until you are satisfied.
There is a special "thick" sandable primer sold in the U.S. that builds up a heavy coating rapidly. It also dries in about 1 hour, so you can work quickly.
It takes a lot of practice to get a real "show car" finish and I have a long way to go. Auto hobby magazines go into these issues and there are lots of resources on car painting out on the web.
Machine tool painting is not well covered on the internet, but I did find this blurb:
This article is of more than passing interest because modern machine tool cutting oils and fluids are very corrosive to older enamel finishes. I nearly wrecked my Deckel by running it with a modern water-based cutting fluid. The WWII-era enamel started to fail immediately.
Clean up the room, put all your tools away, vacuum up dust, drape and tape newspapers everywhere.
You must use some kind of spray paint. In the U.S., hardware stores are no longer allowed to sell really good industrial enamel. I get my paint at auto restoration supply places or from an industrial paint supplier. You want the kind that says: "Danger - Industrial use only", "Immoral", "Accursed by the Goddess" etc.
I've used both rattle cans and sprayers. It is really not worth the trouble use a sprayer unless you are going into the restoration business.
If you decide to paint at home, be aware that the room you are working in and everything it contains will be contaminated with paint despite every effort you make to drape things and cover the floors.
You MUST obtain and use a good respirator and face mask designed for industrial use. A paper cup and rubber band mask will NOT work. Neglecting the respirator or cutting corners here puts you in the same risk-for-cancer category as someone who has inhaled cigars for 30 years. Expect to pay $100 or more for your breathing kit.
Because of the health risks and total devastation of the room , I prefer to do all the body work, sanding etc. and then take my parts to a professional industrial or auto painter. If you go to an auto shop, tell them to use engine paint. If you can find an industrial painter set up to do the work, you can request two part paint. This is very expensive epoxy stuff that will last forever. It is unthinkable to try using this stuff at home.
Anyway, it takes about 5 coats of rattle-can enamel to do this yourself. Some industrial spray paint wants to completely dry between coats, other types insist on by reapplied every 4 hours. You can lightly scuff the surfaces between coats using the 3M fuzzy pads. Be sure to brush off every hint of dust between coats.
When I put the machine back together, I usually buy new black hex cap screws. This makes the machine look "brand new" and costs very little.
If the screws and bolts that got soaked and brushed with paint remover look ok or are too exotic to replace, I brush them clean using a fine wire wheel and a small power tool (Dremel, or flex shaft.)
I like to replace all the small ball bearings and, if possible, the main spindle bearings. When this is not practical, you can clean out the bearing with solvent and then use a grease pusher kit to force grease back into the bearing. It is very important to obtain the right grease for the bearing size, load, and speed.
If you get into the process of removing and replacing bearings, you will need an assortment of gear pullers, arbor press with lots of adapters. Never hammer on any kind of bearing. If you can visit an industrial bearing supply house, you will be able to see all the neat tools they sell for working with bearings and you can meet the kind of people who will give you good advice.
Anyway, that's all I can think of now. A lot of common sense acquired from fixing mechanical things comes into play. If you've never worked on cars, clocks, or machinery of any kind, you might want to get some practice before you try working on a prized machine tool. Old engines, cars or even a lawn mower would be good places to begin. And if you have another less valuable machine to restore, it would be a good idea to do that first. I've rebuilt 6 machine tools and I'm really glad I didn't do my Hardinge lathe first.
My most recent restoration projects are here:
The web is full of good advice on machine rebuilding. The best thing is to do a search yourself with appropriate keys. I will suggest my favorite site:
The Practical Machinist is full of articles about all sorts of machine repair and restoration projects. Many of these are illustrated and you can always post your own questions and results.
And you absolutely must get the catalog from this guy:
Lindsay reprints old machinery books and also modern works such as Dave Gingery's series on casting and making your own machine tools completely from scratch.
Part of my daily routine is to read the USENET news group: "rec.crafts.metalworking." If you haven't discovered USENET, find a local internet geek to help you get started. Your ISP may have a help page about USENET news. You'll need a free piece of software called a "newsreader" although there are some web access portals to USENET as well.
Meeting others who share your interests is a big help with projects like this and you are lucky if you live in a area where you can meet literate resourceful people interested in old machines. Find a local model engineering group or steam engine society and attend a few meetings.
Another great place to meet the "right sorts of people" is at industrial liquidation auctions. These are mostly attended by professional tool scavengers, but there will be a few demented individuals like yourself. You can identify them by their pathetic attempts to bid on small items the auctioneer would rather sell by the pallet load.
You can solve this problem, incidentally, by taking along a few friends to the auction. When something like a "dumpster full of inspection equipment" gets sold for $500, you can buy the lot and divide up the loot later. This is where pennies on the dollar savings are realized. I've seen astonishing bargains go down at these auctions.
And don't neglect the professional tool scavengers: In the dangerous parts of every big city you will find used machine tool dealers. Many of the things they can't sell to real industrialists get melted down. If you show up at the right time, you can haul them away at scrapyard prices.
There is a whole art to negotiating with used machinery dealers that I can't go into here. It resembles the culture found among horse traders, used car mongers, Middle Eastern gun merchants, and church basement charity sales. You have to learn how to behave or you'll end up with a knife in your back - or worse: a house full of junk and a peculiar Jello salad.
As I hinted before, almost everything that auto restoration people do applies to some aspects of machine tool restoration. There are a lot more auto mechanics around than people who put milling machines in their living rooms, so avail yourself.
Please send a photo when you're done. Or for dramatic effect, "before" and "after" pictures: Hugh Sparks