Sacrificial anode for machine tools rust prevention

[minilathe22]

Hi there

So I am taking delivery of a lathe soon which I will be restoring, and once I have got all the rust off the bed I want it to stay that way, I have been looking at the various common ways of doing this and I don't see any mention of using a sacrificial anode such as a block of zinc or magnesium attached to the bed. This is common I believe for underground/underwater pipes and metal boat hulls, I wonder if anyone has tried this with a cast iron machine tool before? If I bolt a piece of zinc to an unpainted part of the lathe bed, perhaps underneath, would I see it protect the top unpainted surfaces from rust completely I wonder?

 

[Dee J]

I think you need the whole system to be immersed in an electrolyte for it to work. Whether that's water or damp earth. Don't think air works. For sacrificial protection in air you need galvanising.

 

[AES]

I'd agree with the above. I'm not completely sure, but unless your lathe is immersed in water, or at least in a VERY damp hole in the earth, I don't think the sacrificial anode idea will work.

Much better to try and ensure your shop is free of damp air/condensation, etc. After de-rusting some tool finds (electrolytic, works wonders and is easy) I've had no further rust problems 'cos the stuff stays in my shop which is free of damp air.

 

[Rorschach]

If it were that easy then we would all be doing it.

 

[minilathe22]

It seems you are right and the water is part of the "system" to make it work. I guess galvanized metal works without liquid water, as the sacrifical zinc is always very close to the protected metal.

 

[Rorschach]

Galvanising works because it is a coating for the most part, like paint. But unlike paint, when scratched it is still effective because it is close enough to the metal underneath to be "sacrificial" when there is water present. When the areas of wear get too big though the system breaks down and rust occurs.

 

[Inspector]

The best way to prevent rust on a machine is to keep the shop it is in warm, above the dew point. Since many people don't want to / can't heat the space the next best thing is to keep the machine itself warm. A canvas cover with a rod type heater will keep it warm and toasty, preventing any moisture from condensing to form corrosion. Lee Valley as an example sell these but there are other brands at different price points to do the same. https://www.leevalley.com/en-ca/shop/tools/workshop/tool-maintenance/69378-goldenrod-dehumidifier Some brands attach directly to the metal and some heat the air just above.

Pete

 

[bussy]

If your workshop is cold/unheated all you need to do is ensure you have air flow through your shop. No heating in mine but good airflow never had any problems with rust. The problem with heating is that you will need to maintain that heat as, if your shop cools overnight the moisture in the air will condense out particularly on your cast iorn surfaces,

 

[clogs]

My last house was a converted 17th century water mill.....everything was damp....
My workshop was a big open barn.....
all my machines were covered in an old Duvet and a blanket with a 11watt curley whirly bulb underneath...
left on 24/7..... they were on from the first time there was a nip in the air till around March.....
never notised the elec bill at all....
plus the metal working machines all used coolant.....never a problem with rust.....
also got sick of chucking out big rolls of MIG wire that went rusty over the winter....
so put a bulb holder in the welding wire compartment and covered with an old blacket ...
again never a problem...
take just a few mins to roll up and remove coverings....well worth it....

 

[Myfordman]

If your workshop is cold/unheated all you need to do is ensure you have air flow through your shop. No heating in mine but good airflow never had any problems with rust. The problem with heating is that you will need to maintain that heat as, if your shop cools overnight the moisture in the air will condense out particularly on your cast iorn surfaces,

As Pete said above heating the machine is the secret and ideally thermostatically controlled not to a specific temperature but to a few degrees above ambient. In that way condensation cannot form. Heating cost are therefore minimised.

 

[--Tom--]

One of these under a cover should do the trick,

https://uk.farnell.com/pentagon/ach20-20w-230v/heater-anti-condensation-20w/dp/3183166

Once I sort out a tool chest for my decent stuff I’m planning to put one of these in the back, and then running it through winter

 

[pe2dave]

Treat the exposed steel with a wax treatment to keep moisture off it?
Works with a band saw bed, should with a lathe?

 

[minilathe22]

I only moved recently and have found surface rust is worse than I am used to. I decided to examine the walls and floor and have discovered that on a wet day there is visible water seeping through the wall just above the damp proof membrane above the floor. I believe rainwater is running down the outside of the wall but yet to confirm as I can't get to it easily. On drier days there is nothing obvious to see. Its in one spot about 2 feet long, I hope solving this will be a big improvement!

I have seen very small self adhesive pad heaters, that way I can stick one out of the way and leave it there on some of the bigger machines.

 

[ptturner]

As pe2dave says wax treatment is very cost effective. You can buy cans of 'waxoil' brand from any car repair shop it is quite expensive cheaper to buy a larger quantity and sprayer if you have a lot of steel tools to protect. However toolstation did sell cans of Tectane 'protection wax', last time I checked they they were sold out for online purchase, but it does work wonders. My car has loads of it slathered on, holding back the rust!

 

[minilathe22]

I have been using Carnuba wax and so far I have not seen any new surface rust.

Incidentally since my last post I looked on the other side of the wall which is in a neighbours garden and the guttering was full of soil, and water was running down the wall. There was also soil buildup above the damp proof membrane around 2 walls of the garage. Since I dig out the soil and emptied the guttering I have seen an improvement in the dampness. I suspect it will not fully dry out until the summer weather (if we get any this year!).