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11-08-2009, 08:08 PM #1
How do I clean a dirty CNC machine?
I recently purchased a dirty old neglected CNC machine (the only kind I can afford). It's a small Kitamura VMC (MyCenter Zero). I have no idea how long it's been since it last ran or if it was unplugged because it needed repair. The guy I got it from didn't know the history. He was simply selling it for someone that was cleaning out a building.
Anyway, it looks as though this machine cut about as much dirt and grime as it did metal. It's awfully dirty. I have been trying to clean it up as best I can. However, I'm wondering if there is a way that I can go about it more effectively. Trying to get all the dried dirt and grime off with some picks, a wire toothbrush, and a few rags is proving to be an extremely tedious process. I'm starting to wonder if careful use of some pressure washing would be a better idea. I know that using pressure to clean precision surfaces (ways, ballscrews, etc...) is generally frowned upon, but I don't want to spend the next two years taking everything apart and cleaning out all the gunk.
Now, I'm not implying that I would put this thing on a trailer and head to the carwash. I'm just wondering if using a small pressure washer and a gentle cleaning agent might be good for washing away a lot of the crap that has accumulated on this machine. It's a relatively small unit (probably around 4500 pound), but it's big enough where I would have a hell of a time trying to take the entire thing apart to clean it all out. Has anyone had to tackle such a job before? Would a little LOW-pressure washing be a mortal sin that would render the machine useless? The machine has obviously been neglected throughout its life, so I'd think that I wouldn't be able to damage it all that much. If you have any pointers about how I can effectively clean this thing up (without completely tearing it apart), please let me know. Thank you for taking time to read my post!
11-08-2009, 08:25 PM #2
Purple Power (auto parts store)
11-09-2009, 12:27 AM #3
I'll give the Purple Power a try. I've just been using some Simple Green as needed. It's not so much that I'm having trouble getting the dirt off. It's just the seemingly endless array of nooks and crannies that have become home to all sorts of dirt, grime, and metal chips: under the table, all over the tool changer, up on top of the spindle motor mount... It doesn't look as though the machine had a heck of a lot of use, but I'm guessing that this is the first bath it's gotten since it left the factory. I look at all the gunk and just feel compelled to clean every square inch I can find. I'm not a neat freak by any means, but it bothers the heck out of me when precision machinery is rode hard and put away wet. I can't believe some people let these incredible machines degrade to such a state. Guess that's what happens when they aren't the ones that own or paid for them.
11-09-2009, 01:23 AM #4
Car wash would be a bad idea (salt, grit, etc.), of course. But I suspect you meant to say you are NOT implying that.
Even with clean water, corrosion is an issue with pressure washing. Raising the pH might help some (but keep it away from electronics). But you are going to force water into all manner of places it could linger and cause trouble.
High pressure washing could be abrasive with existing grit, though probably not as bad as leaving it there.
If your machine has moglice surfaces, the moglice may absorb emulsified water and expand causing the ways to seize:
I am also reminded of the time a friend cleaned some oil off the bottom of car by tossing some laundry or dish detergent up till it stuck and hosing off with a garden hose. Rusted very quickly. If you are removing oil, you need to replace it quickly; if you are removing oil in places you aren't aware of or can't reach, you could have a problem.
You run the risk of degreasing bearings, ball nuts, forcing crud into the encoder scales, etc. At 1500PSI, you might not just get dirt in the encoder scales, you might damage them.
A CNC machine is likely to be designed to deal with a fair amount of spray but with a pressure washer the spray is likely to be coming from angles that would not occur in normal use and doing so far more vigorously. Parts that can deal with spray raining down from above would be subjected to spray coming upward.
I have never tried cleaning a machine in your condition, so take this with a grain of salt. If I was going to resort to draconian pressure washing, I would probably try a light oil or a soluble oil cutting fluid. Most of that crud was probably dissolved in oil or soluble oil at one time. Might even use the machines coolant pump with a hose and a nozzle made from a piece of tubing crimped around a thin piece of feeler gage (then removed) or other somewhat aggressive spray nozzle (and even these may be too aggressive) and just slowly guide it along the surfaces to be cleaned with wetting and soaking time as well. And filter anything that returned to the sump before re-using. And mask off areas where over-spray could do damage and try to catch as much overspray as I could (maybe direct the overspray into a shop vac). You shouldn't need absurdly high pressure. And I would still restrict that to areas where I could contain the side effects. One place I worked put parts in a dishwasher to degrease (these came from hostile environments including coal mines). A dishwasher doesn't use 1500PSI, it just sprays continuously for about an hour so you have a combination of spray and soak time. High volume, low pressure. If I thought the machine could handle it, might chuck a dishwasher spray assembly in the spindle; the result would be somewhat compatible with the direction and pressure of coolant spray in normal operation. I.e. outward from the spindle and down. You could get about the same results by chucking various different shaped tools (including a slitting saw or disk for a high spray onto the walls) in the spindle with coolant to get different spray patterns. Or use a disk/slitting saw and a variety of spindle speeds. But I might be inclined to disassemble and only subject individual parts to draconian treatment if I was going to get drastic. If the surfaces you can see need cleaning, the ones you can't see probably do as well. And there would be less collateral damage. Disassembly isn't without its hazards, either. But if the machine has been neglected, how much of that crud has worked its way into the areas you can't see? This section deals with some possible precautions for making a foolish activity (pressure washing) slightly less foolish.
You did say low pressure. I would define low pressure as anything that was as low as the original coolant system pressure, or lower. But angle still needs to be considered. Same pressure directed in ways that do not occur during normal machine operation may do more harm than good.
I would also ask if this is a, if it isn't broke, don't fix it situation? Be a shame to convert the machine into two tons of scrap metal trying to fix a problem that was really minor to start with. Is the grime in places where it will cause trouble or is it just the cosmetic effect of the coolant evaporating overnight and depositing suspended/dissolved grime from poorly maintained coolant on the walls and floor of the enclosure and other non-critical surfaces? How much of that might just go away on its own with normal coolant use (well filtered) and wiping the surfaces dry at the end of each day (to prevent further deposits and do some cleaning), replacing coolant frequently at the beginning, and following the directions for machine cleaning when replacing coolant. Of course, you probably have biofilms which you would do well to get rid of (as they will cause bacterial growth to reemerge after a coolant change) - and they might account for some of the appearance. But giving the machine a fresh coolant change and letting it do some simulated running (without actually cutting anything) for 8 hours with an hourly wipe down or scrub, might loosen up a lot of crud. If you really think the ways are up to operating without disassembly, then include some random table movements or sweep patterns so the spray reaches other areas. A soluble oil cutting fluid bears some resemblance to soapy water. This would create conditions somewhat resembling the inside of a dishwasher (including high humidity). Then change out the coolant (don't omit the disinfecting stage). Do it again the next day. Then maybe use the machine normally while being scrupulous about cutting fluid maintenance and end of day wipe down. Since you are exploiting normal operating conditions for cleaning, you shouldn't damage the machine like you might by trying a manual low pressure wash as long as the spindle bearings and ways are free of grit and properly lubricated. I figure the machine is probably designed to deal with any amount of spray within normal coolant system pressure or centrifugal force propelled spray as long as it originates from the bottom of the spindle and is directed horizontal or lower and consists of approved cutting fluids. Violate any of those conditions, and you may be asking for serious trouble. Too much pressure or from the wrong direction and you could violate the seals or physical barriers that depend on gravity or point of origin. It is like the difference between rain falling on your roof and being driven against the walls by normal winds and standing on the ground spraying a garden house up through the eave vents and up through the joints in the siding. That is part of why you aren't supposed to use compressed air or pressure washers to clean the machine.
Here are a couple online books on cutting fluid maintenance:
I have assumed here that the grime was deposited during operation and any operations wouldn't do more damage than the last few days of operation of the machine did. Some of it may have been deposited after the machine was taken out of service. I.e. dust, etc. embedding itself in oil residue during storage.
dkmc didn't mention if purple power had actually been tested on machine tools. The website is rather devoid of useful information. The MSDS says the concentrate has a pH of 10-11 which would presumably inhibit rust (actually, it is too high and might cause corrosion) but diluted the pH might be too low. But letting things soak and then cleaning before it dries sounds good to me. I am just suspicious of undocumented chemicals, especially those that weren't designed specifically for a particular application.
This is outside my experience and I haven't even seen pictures of your machines condition, so it is up to you to decide what, if any, of this is appropriate to your situation.
Lastuneste liked this post
11-09-2009, 01:28 AM #5
A cheap pump up garden sprayer is quite effective at getting liquid cleaners into the nooks and crannies. Needs to be a cheap one because odds are the cleaner will eat the seals after a coupla or three weeks use and you will probably want to bend the lance for access. The jet is relatively gentle too so its pretty safe to use it as a very low power water jet to push the crap out. Finish off by running a dewatering / lubricant mix through to stop corrosion.
I used a Killaspray unit for mumble-mumble years as a washer on my motorbikes and never had a problem with water going where it shouldn't. Not even with magnetos and dynamos from Uncle Joe Lucas. Also had a brace of Flit sprays. One full of Gunk to shift any oil and whiten up the alloy castings (this was way back before they changed the formulation) and one full of petrol-oil mix as an anti-corrosive. I stole the petrol-oil mix from the can kept for Mums moped and, obviously, used it with a light hand allowing plenty of time for the petrol to evaporate before using the bike.
Still use a Killaspray to clean off the rotovator.
11-09-2009, 01:44 AM #6
A car wash or high pressure sprayer will get water into places you DO NOT want it to get. We use Beaver foaming degreaser available from Beaver Research in Michigan. It will cut through the worst grease and grime imagineable. Use a scrub brush if it is caked on thick then just wipe it off I carefully bow out hard to reach places with the air hose.
11-09-2009, 03:04 AM #7
Chances are, if you keep away from electronics, a light pressure wash won't hurt it. (It isn't in all that great a shape right now, is it?) It is sometimes necessary when a machine has to be refurbished. Just remember to blow it dry with air afterwards and spray with light oil to prevent rusting.
Many shops have an extra "tee" on the back of their coolant pumps with a garden hose sprayer attached so the machine can be hosed down after a shift is done. just hit M8 and flip the valve in the back. This is especially useful if it cuts cast iron. A bunch of cast iron chips packed into place and allowed to rust can be more damaging than a good cleaning.
11-09-2009, 04:00 AM #8
Get it decently clean as gently as possible and then get it running. If you start getting aggressive now and then she's dead as a doornail after you'll never know if it was from the cleaning or from something previous. As said above, pressure washing of any kind is going to push crap and water into all kinds of places it shouldn't be. Better that it stay clean where it's important than look shiny and have crap in all the important bits.
I'm curious how it works out for you. I was looking at a Mycenter Zero a couple of years ago but couldn't find any info on it and wasn't in a position to open a potential can of worms. Looks like nice little VMCs though.
11-09-2009, 04:40 AM #9
I used hot water from the bottom of the hot water heater to flush out the funkies. Bucket of tide and dish soap mixed, brushed on, left soak washed away. Many cycles but the hot water seamed to loosen the old sticky coolant.
11-09-2009, 05:22 AM #10
You said you've tried Simple Green. Are you mixing it with water or using it undiluted, right out of the jug? I recently had a similar clean-up job to do and undiluted Simple Green worked like magic.
I never had much use for the stuff, before, but using it at full strength made a believer out of me.
11-09-2009, 07:22 AM #11
I once bought a VMC that had been taken out of service and allowed to sit long enough that the remaining coolant had dried to a hard caked varnish. I tried many types of cleaners including some that would take off the paint better than the dried coolant. None actually 'cut' the dried coolant.
I eventually tried plain water in a consumer grade portable steam cleaner with a wand and a small brush. Progress was still slower than I would have liked, but the results were great, and it didn't damage the paint. It worked well in the crooks and crannies as well. I used a vacuum to suck up the water right at the 'work zone' in moisture sensitive areas.
Only took a couple hours to remove 80% of the sheet metal (including way covers, axis motor covers, door/enclosure) and that made things go much faster.
If I had to do it again I would take the sheet metal outside and clean it with a pressure washer.
11-09-2009, 07:31 AM #12
Ok.....you've never tried cleaning a machine like this before.....
And.....what makes you think (or not thinking maybe) that I would randomly suggest 'some sort of cleaner' that I haven't ever used before??
Of COURSE I've used Purple Power!
And I know it works, and that's why I suggested it in the first place.
And, I've pressure washed many machine tools, BUT you have to have a brain to know where to NOT aim the wand so you don't force water where it should not be. NONE of the machines I have pressure washed (2000 PSI) suffered ANY ill effects from the exercise.
All powered up afterward (and after a through dry out).
But all this is outside your experience.....
Ain't that special.....
11-09-2009, 08:02 AM #13
What's the objective with all the cleaning?
Seems like if you really want to restore it, you may have to disassemble it. Once disassembled, it is a lot easier to clean.
You certainly should figure out how well it runs before you go down that road. I'd be tempted to start with a little troubleshooting before I got too into trying to clean the machine. The troubleshooting may naturally lead you to disassemble certain aspects anyway, at which point they can be thoroughly cleaned.
11-09-2009, 09:54 AM #14
I have had the pleasure of cleaning up several machines in this condition. I have not found an easy way to do it. When the previous user does not clean the thing for years, chips, coolant, dried oil gets into every possible space. I use a combination of methods: anything that can be easily removed can get pressure washed, sometimes after soaking with undiluted simple green. A pressure washer will not get all the dried oil soaked swarf though. For that, and places I do not want to use a pressure washer, I go after it with a shop cloth soaked in Stoddard solvent. It eventually soaks through even the worst crap, normally without harming anything. I use a bucket of solvent, keep dipping and rinsing the rag in it, and then attack difficult places with toothbrushes, plastic scrapers, and solvent soaked maroon scotchbrite. Helps to be wearing thickish nitrile gloves - latex will melt or be punctured by metal slivers very quickly.
It isn't a pretty process. A small milling machine takes about 4 days of labor, but I have gotten them looking pretty good by the end.
11-09-2009, 10:00 AM #15
409 and a ordinary toothbrush, works great, hiring a kid to do it, priceless! A shop vac helps alot to pick up the crud as you lossen it up, newpapers are handy. good gloves etc. The Zep Purple cleaner is lye solution, and it will remove paint, also it sucks the fat out of your skin. so keep that in mind.
11-09-2009, 12:13 PM #16
Thank you for all the great pointers and info. I've never considered using something as high as 2000 psi to pressure wash this thing. I was just thinking more along the lines of something that uses liquid under pressure but isn't going to remove paint or blast through seals. I've taken a few photos to give an illustration of what things are looking like. From a distance, the machine doesn't look too bad. I've removed some of the covers and cleaned a lot of the big/flat surfaces. It's when you get up close that you can see all the dried on crap. The picture that shows the X-axis ballscrew and under side of the table is a good one. You can see the kinds of little areas that I'm trying to clean out. It's actually a lot smaller and cramped than it looks in the picture (the machine only has about 12" of X-axis travel.)
Anyway, I'm just wondering if there is a better way to go about this than scraping all that crap away by hand. Little picks and scrapers work, but I'll be here until the end of time doing it and it doesn't even get to some of the crud. I'm sure there are plenty of cleaners that would work on loosening everything up, but I would want to be able to wash it away if I were to do so. Otherwise, you just end up with a bunch of slimy sludge that gets spread around when you try to wipe it away. I was hoping that I might be able to flush things out from top to bottom. I like the idea of using a small steam cleaner, but I'd be afraid it would remove paint right along with all the dirt and chips.
Well, take a look at the pictures. I don't know how it rates when compared to other used/neglected CNC machines, but there sure seems to be a lot of gunk left everywhere. The covers on the ends of the X-axis wouldn't even slide because they had so much crap built up underneath them!
11-09-2009, 01:09 PM #17
Fill your coolant tank about half full of 20% coolant mix and rig up a coolant spray hose if you don't already have one on your machine. Use this to hose things down repeatedly. The coolant will just keep recirculating. I have found that strong coolant will do wonders to loosen old dried on coolant.
You could also do the same thing with your favorite cleaner mixed with water in you tank. The bigest issue with detergent is that you need to get all the detergent residue rinsed out before you put you coolant charge in. Strong detergents can cause problems with you new coolant.
Lots of soaking in my experience is the key.
11-09-2009, 01:16 PM #18
Looks like any ordinary old used CNC to me. Unfortunately, I think what happens before we get them is they are shoved to the back of the shop and used for odd jobs, mostly neglected and not "owned" by anyone. I prefer to think of it that way, anyway, because the alternative is that the machinists were consummate slobs. It takes some effort to keep a machine clean, that effort is often forgone if it is known the machine is going to be sold?
My experience is that there is very little, beyond either VERY high pressure washing, or mechanical scrubbing that will do the job. I am surprised how ineffective a 2000 psi washer can be. This is why I use the shop towel and Stoddard solvent. It think you can imagine the potential problems if high pressure water is used in some of those locations, soaking ball screws, etc; also potentially carrying swarf with it even further into where it doesn't belong. Rinsing it with a soaking rag tends to wash it off and down. I have used a garden sprayer filled with solvent either to reach places my hand couldn't, or in larger open areas where you want to hose stuff down to the bottom.
You just need to dive in. It won't actually take that long, and there is the constant positive reinforcement as you see how much nicer it can look.
11-09-2009, 01:16 PM #19
One other benefit of using steam is that you'll not be scrubbing nearly as much as with a soap or solvent, which also means you'll not be scratching up the paint with all the chips that are embedded in the varnished coolant.
The machine I cleaned had a Blaser decal stuck to the front. I made a mental note, steamed off the decal and ordered some Trim-Sol.
11-09-2009, 01:37 PM #20
Just leave the pump running and coolant spraying we're talking sort of days here- extra hoses help.
Any muck left is likely to be soft and will prob' come off with a paintbrush and coolant stream.
OK you'll be left with the mineral oils, but IME, as they don't amount to anything like the rest of the mess, they're easy to clean up.
Plus of course you have the bonus of a nice clean coolant system