PDA

View Full Version : reviving an older small Lathe



Alistair Hosie
03-21-2003, 06:55 PM
I am in the middle of a complete strip down and respray and obviously rebuild of an older Lorch LLK lathe. It is a lovely little machine however the topslide crosslide and carriage have the usual discoloration from old age .I suppose it is mild surface rust damage which has been allowed to accumulate over the years, but it is not really rust as I know it .In other words if I can describe it as not being the rust that comes of and leaves your fingers orange/brown when rubbed . Obviously I can sand everything down to revive the old surface by exposing a new underlayer but hat seems to be not quite right to me besides it would be quite a job and could cause damageto the fitting surfaces. I have tried polishing it in small parts with a scotch brite mop, this helps but does not bring it back to (as new condition) which is what I would ideally like.Am I being too optimistic or is this achievable.I have seen a few pics of other lathe owners bring back lathes in much worse condition and some old chucks which are in a very poor state are often brought up to a beautiful shine what am |I doing wrong any revivers out there Alistair

Forrest Addy
03-21-2003, 07:07 PM
What you may be referring to is acombination or tarnish and oxidized oil. I suggest you use steel wool and lacquer thinner. If rust is present you might need something more aggressive.

I use wood paint stir sticks to back up a single layer of wet or dry abrasive sheet cut to suit, ScotchBrite and kerosene (lacquer thinner decomposes ScotchBrite), and the like to work over exposed non-bearing metal surfaces. You need to change abrasive sheets frequently. Bare paper will not cut efficiently.

It's detail work where the quality of the finished product depends entirely on the pains taken. as for bearing surfaces, that will take care of itself wiht the hand scraping.

Dave Opincarne
03-21-2003, 08:41 PM
Alistair, To me what your describing sounds like the more stable form of iron-oxide. I forget the chemical formula, perhaps someone can post it. This is the same oxide formed when parts are "blued" (real bluing, not the bottled stuff) and it has the same benifits. You may want to consider leaving it alone. It can make a nice pattena. May I suggest that you try pollishing it with some steel wool (nothing abrasive like scotch(Scots?) brite) and kerosen or light oil then take a step back and ask yourself if you realy want to make this venerable machine THAT bright and shiny.

-Dave

G.A. Ewen
03-21-2003, 10:05 PM
Alistair, I'm with Dave on this one. I would really like to see a photo of it when your finished.

BC21OSH
03-21-2003, 10:17 PM
Alistar,

I believe Dave is correct on this one. That nice pateena is considered very desirable on antique firearms and the value actually decreases if it is removed, however I realize you have a lathe and not a firearm but as long as it doesn't effect the operation of the machine it does protect the surface from serious corrosion. The old time gun makers would use nitric acid to produce that brown finish that Dave describes as a type of blueing. This would then keep the steel from actually rusting when exposed to the elements. Some real fine steel wool with some light oil will clean it up if it is getting a little dirty or if it has a build up on it that is causing things to stick.

Bernard

gizmo2
03-21-2003, 11:27 PM
ooo, ooo! I know the answer to this one! Rust is an oxide with three oxygen atoms, and 'bluing' has four of 'em, a more stable compound.

Jaymo
03-21-2003, 11:43 PM
I'm with Dave, too. Gunsmiths have gone to GREAT pains to achieve quality blue and brown finishes. Plum brown is beautiful to behold. I think I'd polish it with 0000 steel wool and kerosene or oil, and be very happy with it.
Hell, my little chicom minilathe has started to develop this in a few spots. At first I thought I had missed some spots with the oil rag, but no. It's been properly oiled since day one, and the places don't deposit rust on my hands when rubbed, either. Course, mine could be oxidized oil, but I'm hoping it's just browning, 'cause it looks pretty kewl.

CCWKen
03-21-2003, 11:43 PM
I'm with Forest on this one. I had the same thing appear on mine. After oiling and buffing with a little steel wool, nothing happened. I took a little lacquer thinner on a shop towel, wiped it and it was gone.
I think it's just stains from "cheap" oil or something. Ouch!

Dave Opincarne
03-22-2003, 01:43 AM
Does it look like metal only dark or does it look like varnished crud. If it's smooth and hard it's oxide, if it's built up it's not. Simple test, try a little acetone or engine cleaner in an inconspicuos (sp?) area. If it disolves it's gunk and should be gotten rid of, if not then it's probably oxide and up to you, just sit on it a while before you decide to get rid of decades of patena. If it does turn out to be crud then try oven cleaner. Usual cautions apply.

And what do you mean Dave's right THIS TIME! http://bbs.homeshopmachinist.net//wink.gif http://bbs.homeshopmachinist.net//biggrin.gif

Dave Opincarne
03-22-2003, 01:45 AM
Gizmo, what are the formulas Fe2O3 for red rust and Fe3O4?

firbikrhd1
03-22-2003, 09:52 AM
I too am interested in restoring the shiny metal finish as seen on many older machines in the pages of HSM and Machinist Workshop. Rudy Kouhoupt wrote an article about Reconditioning an Atlas Milling Machine in 1997. His black and white pictures of the completed machine show all the unpainted metal parts with a shine, presumably silvery in color. There is a distinct difference between the chrome and natural finished parts. He mentions using a wire wheel to clean the parts. My experience with that method has not given me a shine like his pictures depict. Am I missing something? Is the wire wheel method safe to use on machined surfaces such as dovetails?

Dave Opincarne
03-22-2003, 10:35 AM
I wouldn't do it. I think wire brushes look amatureish especialy on precision surfaces. Try a small arkinsaw stone which has been lapped flat on a surface plate with 220 grit silicon carbide paper. On narrow surfaces use a straight stroke. On larger surfaces use strokes 45* to the ways in both directions to make a cross hatch pattern.Use kerosen or light oil.

NAMPeters
03-22-2003, 10:37 AM
Alistair, my personal approach to this type of situation is to clean with a solvent to remove old tarnish and gunk rubbing with fine steel wool, Then rub down with nonabrasive scotch-brite and WD-40 to remove any loose rust and to give some some rust protection. Keep surfaces oiled from here on. Remember when a surface rusts it grows in size while the non-rusted surface recedes thus too vigorous rust removal will change the surface dimensions, not a good thing. IMHO old machinery needs to look old and being too shiny does not look old but over restored. Strike a balance that you are comfortable with bearing in mind that if you go too far there is no turning back.

------------------
Neil Peters

JCHannum
03-22-2003, 10:46 AM
Forrest has pretty well described what is needed to be done. It is work, no easy way out.
Remove the gunk and crud with solvent or oven cleaner type chemicals. Brake cleaner, carburetor cleaner, and acetone work well. Make sure proper ventilation and fire precautions are taken.
The electrolysis procedure described previously is also an excellent method of doing larger items safely. It will remove rust and crud as well as paint.
When you get to the bare metal, keep in mind that it will rust very rapidly, and protect it with light oil.
The bare metal can now be polished to any degree desired. Use increasingly finer grades of emery cloth, then wet or dry sandpaper, backed up with wood or metal to prevent rounding of corners. Use lubricant, light oil, kerosene, WD 40 or similar.
Avoid use of wire wheels, sand blasters or buffers, as they can do more harm than good in the hands of the inexperienced.
Protect with light oil. Lacquer can be used, but will discolor with use, and take up oils and materials used in machining.
The final appearance is a direct result of the amount of time and effort you wish to put into it.

docsteve66
03-22-2003, 02:18 PM
Next time I hunt for a wife (never hopefully, i shall keep Niels advice in mind- applies to cars too "IMHO old machinery needs to look old and being too shiny does not look old but over restored. Strike a balance that you are comfortable with bearing in mind that if you go too far there is no turning back. Neil Peters"

Several have mentioned steel wool. IMHO, stick to stainless. Old steel wool left tiny slivers embedded (even in chrome) which rustedand left it looking like a freckled girl. And thefreckles are hard to get out (years) andmay leave a permenate stain.

Alistair Hosie
03-22-2003, 03:03 PM
Steve, and others thanks for the information .Actually I have today completed this transformation of the small lathe and it has undergone a complete strip down, although the headstock spindle and bearings remained in place complete with flat belt attached .
The lorch is so designed as to allow all else to come apartquite easily .I have sanded all paint work, and resprayed it completely, and taken my time and spent two days polishing the unpainted metal to the best of my ability.
I would like to show you the before and after results. If some one can help me to download the photos I will do just that regards and thanks to all for your advice ,I am well pleased with the finsished result myself even though it was mainly elbow grease and at times a few different polishing mops scotchguard through to a lambswool mop, and some light polishing paste attached .Kindest regards to my good friends .Alistair