View Full Version : Old Mill, needs a bath-repaint?? maybe

10-24-2007, 07:31 AM
Id like to clean up my "new" old mill, im bringing home today, before placeing it in my shop,

im figuring a power-wash,,is a no-no,

whats the best way to scrub off 43yrs of gunk, oil and grease??

brush, elbow grease


oh while im at it,
anybody out there ever resored and re-painted an old mill??
what type of paints best for it??

10-24-2007, 08:09 AM
It depends in part on how thorough an overhaul you're going to give it. Are you planning on a total disassembly, paint strip, repaint, reassembly? If you're talking about repainting, IMO that's pretty much what you need to do to do a proper job of it. I think I would I would avoid that, however, unless the old paint is REALLY bad and you just can't stand it, because it's a huge amount of work.

As far as paint to use, I've used Rust-Oleum primer and brush-on enamel in the past, with pretty good results. Just give it plenty of time to dry before you subject it to rough handling -- a week, maybe -- because it stays soft for quite a while. I'm sure there are better products, but that does work.

A friend prepped his lathe for painting then took it to an autobody shop and had them shoot it with Imron. Since he'd done all the prep work it didn't cost all that much and came out looking great.

But if you just want to clean up the machine, yeah. Some kind of solvent and rags and small brushes and hard work.

Forrest Addy
10-24-2007, 09:26 AM
OK You asked for it. Here's my canned DIY machine cleaning rant: There is no shortcut to doing a good systematic job cleaning a machine tool. It's work. First a general washdown with a pressure washer is the fast track to endless future problems. DON'T do it regardless of who reccommends it. I've been in the trade many years and I know all there is to know about machine cleaning.

First asesmble your equipment. Basic mechanic's tools, a gallon of mineral spirits paint thinner, a gallon (or a quart) of lacquer thinner, a hardwood stick charpened like a chisel, a putty knife, a kitchen grade cleaner, paper towels, rages etc, a few coffee cans, a camera, throwaway paint and wire brushes, note paper and pencil, a clean stretch of floor.

First take a few picture of "before" in good light. Don't count on the "wink" light of the camera; use strong shop lighting.

Remove all easily detachable parts like splash guards, attachments, hardware coolant lines etc. Take notes and picture as you go so you can reassemble what you removed with minimum fuss and bother.

Starting from the top and work down, use a putty knife to remove encrustations and catch them in a cardboard box. Sweep the floor regularly so the loose crud doesn't get walked in the concrete. Dig out and clean all crevices, nooks, and crannies.

Wash the machine down a square foot at a time with mneral spirits top to bottom. Focus on each square foot missing nothing. Use mineral spirits a cup at a time in a coffee can. When it gets too contaminated, discard in a designated slop can and pour fresh. Wire brushes paint brushes, and even old tooth brushes are handy at this phase. After two or three cycles of this you have removed all the oily dirt and accumulations. Use rags sparingly but don't skimp either.

Again working in small areas use kitchern cleaner (409 etc) to remove water soluable dirt with brushes, wire brushes etc. Be careful not to allow it into vertical crevices. Wipe wetted surfaces dry.

By now you are down to stained paint and tarnished metal. The original paint may be distressed or even crumbling. Chances are the machine may have been repainted in the past and it may or may not be separating from the original paint. It's a judgement call as to how much preliminary paintwork you wish to do at this stage. Old paint can often be brightened by a quick wipe with laquer thinner. I mean a quick wipe with a clean rag damp with thnner and not a slosh with a dripping brush. You don't want to lift the paint.

There is bound to be much stained metal. Clean tarnished cast iron does not have to be cleaned to bright metal to function. It may need to be lightly stoned to remove burrs and dings. Rust may be removed with scotch brite or if severe a proprietory rust mitigation product. Follow directions. Many of these contain phosphoric acid. Use them carefully around mixed metals.

Detail clean all the small crevises removing the bolts one at a time to clean the heads and the parts they attach, remove inspect and repair way wipers, clean and oil lead screws and table ways, doctor up lube lines and oilers.

Clean up the removed parts, attachments and accessories.

By now a few days should have elapsed and the machine should be spandy clean and ready to re-assemble. This is the stage where you assess the paint options. Resist the temptation to apply a lavish paint prep and exotic expensive paint systems. A good featheredge and prime followed by a brushed-on color coat of industrial grade alkyd enamel will be far less expensive and time consuming and easier to touch up. It's just a damn machine not a piece of antique furniture. Normal use will damage the paint. Carefully wrought spray paint jobs are overkill and, in a functioning shop, soon to be eroded in areas of chip flow.

Once the machine has been cleaned and painted you can reassemble it (notes and pictures) and put it into service. Resist the temptation for fix what aint broke. Get it running first.

It's nice to walk into a clean well ordered shop were work is actually done. Parts under manufacture are laid out in readiness, there's a place for everything and most everything is where it belongs etc. It's a shop in active use; things happen there.

I've visited several shops where every thing is excruciatingly clean and neat, there are no stains on the tiled floor, no chips, racks of material may be on hand but there's nothing much in process, every machine tool gleams with beautiful paint. I have to think: is this a trophy shop? Does anything heppen here?

Then there are shops like mine where all is chaos and progress is paralysed for lack of places to put stuff you have to move to get at other stuff. That's not good either.

Clean and well ordered is good. Obsessively neat or junky is not. Strive for balance, Grasshopper.

Bill Pace
10-24-2007, 09:42 AM
Whew!! Dang, Forrest, I'm worn out just reading it-------

But,-- as usual,-- excellent, descriptive, knowledgable...etc,etc, for a dirty, hard, lengthy job, but one that can have a great "puffing out of the chest" feeling when its done.

Wing, this is a BIG job if done right,---- but it sure can boost the "feel good about something I did" factor.......

10-24-2007, 11:10 AM
Forrest gave a great reply, as usual. i'll add that i use the shop vac as i'm scraping to suck up all of the small debris and paint flakes and such so they don't get into the machine. yes, it means you need to empty the crap out of the shop vac, but it's easier than trying to get it out of the machine by wiping or brushing. also, DO NOT use compressed air to blow things out. you can use it to lightly blow of surface dust (even that i don't do), but don't try to clean cracks and crevices by blowing 100 psi air into them.

yes, it takes time to clean a machine, and in fact most of my machines are older so every time i use them i end up doing a little more cleaning. i doubt they will ever be truly totally clean. i haven't repainted any yet, but i have an old horizontal mill that i may do this winter.

andy b.

10-24-2007, 12:50 PM
Id like to clean up my "new" old mill, im bringing home today, before placeing it in my shop,

im figuring a power-wash,,is a no-no,

whats the best way to scrub off 43yrs of gunk, oil and grease??

brush, elbow grease


oh while im at it,
anybody out there ever resored and re-painted an old mill??
what type of paints best for it??

Put it in your shop and use it.

Don't even think about restoring, that requires knowledge, experience and equipment beyond what most any of us have.

Mad Scientist
10-24-2007, 02:03 PM
Excellent post by Forrest Addy but he forgot one important point you must use green paint. :D:D:D


10-24-2007, 03:48 PM
I've gone through a bunch of my machines now. The biggest mess (and job) was the lathe. Fortunately, my Bridgy came from a shop like ideal Forest described. Not gleaming, but clean and relatively neat, so it was the only one that really needed nothing but a wipe down on arrival.

My cleaning routine has become astonishingly close to what Forrest describes.

Get the big crusty crud off mechanically.

Wipe down the sticky/slimy mess with solvent (I use several depending on what it is) and do a moderate detail grunge digging in corners.

Then evaluate where it is and what I want. This may be all that's done. But if I have the energy and interest...

Disassemble, cleaning each piece. Usually this is done in my free standing cleaning tank thing (from HF). But I don't keep it wet, too big a mess. I keep it completely dry with a small ~2 cup bucket holding (for small jobs) usually about 1/2 cup of Purple Zep industrial degreaser. I apply to each piece using an old tooth brush, or for bigger stuff, a 1" or 2" chip brush. Let sit a bit, rinse with hose, repeat as needed, blow off, wipe with oily rag to prevent flash rust. I also sometimes use oily flux brushes to get in places an oily rag won't. You have to be generous with oil to prevent rust as the ZEP leaves it completely unprotected. I use DTE-10 R/O so it's light and flows/wicks in. This requires a (light) degreaser again before painting on paint surfaces...

Finally, reassemble when done with cleaning.

With a few exceptions, I never paint anything...

10-24-2007, 03:50 PM
thanks all,
i apriciate it,


10-24-2007, 03:57 PM
I am going to be that guy that Forrest thinks is a goober. I sort of power washed my mill and several other machine tools....but only because it was thoroughly a mess and the portion that was power washed was quickly pulled apart and dried. I did *not* use this technique on the head and bagged the table bearing ends to avoid water infiltration. It was later fully stripped down and only the individual pieces parts were cleaned with Castrol degreaser and water. Forrest is certainly right in that a pressure washer can send water where it really doesn't belong due to the high pressures. I found that a high speed fan and compressed air were my friend for the quick dry off after the pressure washing I did....but none of that is a substitute for disassembly...and not a substitute for judgement about what you are willing to get wet in the first place.

If an item is going to be fully pulled apart and stripped, I have found that I do like to use a water based degreaser after anything petroleum is used. The water based stuff really strips all petroleum off, making things nearly ready for paint. Additionally, petroleum solvents will not cut water based coolants at all.

I have found that the caustic degreasers like the Castrol purple jug stuff will also pull off much of the previous layers of paint that were improperly applied to a greasy machine tool. However, this stuff *must* be thoroughly water rinsed, so its only really an option with a complete tear-down. One area I would depart from Forrest's advice, however is that it appears that he is recommending Formula 409 to remove water based gook before painting. It contains surfactants. I don't like the idea of any sort of surfactant like that without thorough rinsing....soap is not a good base for paint IMHO.

Edit-- one other thought I would add is that even if you think its a bit prissy to nearly restore a machine tool (some feel that way and I understand the reasoning having spent too many hours on at least one of them), I would still recommmend the disassembly and cleaning of the functional parts. I sure found plenty of swarf wedged in places it did not belong on the machine tools I have had apart. If you just get it from the previous owner that way and never take it apart, you may end up putting grooves in way surfaces from the previous owner's swarf....same for spindle bearings, bronze cross slide nuts etc. Just keep all the grit you clean out of all the moving parts and ask yourself if it was worthwhile when you are done :-)


10-24-2007, 03:59 PM
Oh, and when it's got multiple flaking coats of "porch paint" (re. D Thomas), I have a 4.5" angle grinder with heavy knotted wire brush that takes it down to cast readily. I did this most recently on my Pratt Whitney 1/4" "sensitive" drill press (weighing at least 100 lbs, for some reason that seems funny when combined with "sensitive" :D ). I then did a light prime followed by paint. It looks fantastic. I did the same thing to my Wilton (7 LAYERS OF DIFFERENT COLORS!!!), and old leather shear (worse then the Wilton) and will do the same to my horribly flaking Bridgeport E slotter head when I get to it. Sometimes the paint is JUST too bad to put up with.

My lathe, mill, big drill press, arbor press, grinders, etc. all still show all their battle scars. I have no desire to paint them. They have skent places, and places where there is NO paint left from swarf and work. But they have the original paint, not multiple paint jobs, flaking and cratered to various levels/colors, so that doesn't bother me at all...

10-24-2007, 08:00 PM
If you just want to clean the crud off the paint there is a simple way to do it and no it won't rust the machine.

Take Castrol Super clean and cut it 50/50 with water,mist it on top to bottom and then gently work it round with a soft nylon brush.

Here is the easy part,rinse it off with water soluable coolant such as Koolant King mixed 40:1 water to coolant.

I'm not saying flood it,just use enough to rinse off the heavy stuff so you can dry the machine off with compressed air and rags.

The coolant has enough oil in it to prevent rusting and not much will dissolve 40 years of crud better than the castrol.

The usual disclaimers about wearing gloves and glasses apply.

10-24-2007, 09:44 PM
Thanks its really not all that bad,
just kinda yellow stained from the oil and grudge in the corners where they never whiped it,
it doesnt have alot of "new" coats of paint on it,
touch up here and there,
and the lower parts, transmission for the power-feeds, are thick yellow
grundge buildup,

just like to get it back to gray,