I use a fan to remove condensation from a big planer and jointer I use in an unheated space - but in my climate, condensation on the machines only happens a few times /year.
I use a fan to remove condensation from a big planer and jointer I use in an unheated space - but in my climate, condensation on the machines only happens a few times /year.
It's my opinion that the moisture settles on the cast iron. In our farm shop, if you left a crescent wrench on the drill press table, you could see a clear outline of the wrench while the rest of the table was covered with flash rust.
Learn what the term "Dew point" is and take steps to avoid the temperature/ humidity ratio where dew point becomes a problem. Dew point is the temperature at which the relative humidity in the air at that temperature becomes 100%. If the air temperature drops below this point moisture in the air will begin to fall out of the air or form droplets on colder surfaces like your cast iron. Keep your cast iron above this temperature or the humidity below it and you will have no rusting problems.
Charley
Keep in mind that no matter what you put on the top you are not protecting the internal parts that are bare. Conditioning the air is the only way.
I see these threads here from time to time. The focus seems to be on protecting cast iron tables. I always wonder what's happening to the un-waxed bare metal, like insides of machines, electrical connections everywhere, and all kinds of hand tools. I have bought old machines with the insides of the electrical control boxes all corroded from moisture.
Perhaps a bigger concern is the lumber. I store lumber in the shop, so that it will be dry when I need it. If the wood gets cold and damp, it will be wet. Sheet goods don't bounce back from being wet.
Finally, if your shop is so wet that moisture is forming on everything, you have good potential for a mold problem.
I even deal with moisture and wood problems in my wood sheds. The sheds face south, and are open on four sides. I dry firewood to 11% moisture content. However, when it gets warm and wet after being cold, water will condense on the wood. The sheds are lined up to catch the west wind, so when fair weather returns the west wind blows between the spaced stacks in the shed, and the wood dries out again.
A lot of the problem is the change in temperatures. Metal once cooled down (say at night when the temp drops) will stay cold as the air warms up. Moisture will then condense on the colder metal. It doesn't just fall down but it will pool on the top of flat surfaces. The underside of a tablesaw table will also rust but it's not going to impact anything. Of course gears, rods/ bearings, and machined parts do need protecting but since they don't come in contact with the wood for your project different sources of protection can be used. Any moisture that does collect will either run off the underside or evaporate. The idea of using a magnetic sheet is that the magnetic force will create a seal so water that collects on top of the sheet can't find a way between the sheet and the cast iron.
I have a climate controlled shop, but here in NY I still get a little surface rust if I don't keep the heat or ac on. I just repolished some cast iron tops on a PM 60 jointer & am going to try clear coating them & see if that works, I have been covering with card board as I don't use the equipment often & that seems to really keep any moisture off.
Larry Edgerton and Alex Zeller mentioned "conditioning" the air. Besides the HTC covers, I run a Modine Hot Dawg heater with a low temperature thermostat. Also keep the doors on the shop cabinets open to allow better air circulation and prevent rust on the tools.
Larry: I keep the thermostat at 46 degrees. Next season, just might turn it down another notch or two.
As an aside, I recall reading about a woodworker who had his tools in large metal wall and free standing cabinets and kept the rust at bay with Golden Rod heaters. I have Golden Rods in both of firearms safes and they work very well and last a long time. The last one replaced worked for about 15 years. Am thinking about a small one for a wood tool cabinet.
For Those-Not-In-The-Know 'bout Golden Rods: http://www.best-dehumidifier-choice....umidifier.html
Last edited by Ray Newman; 03-28-2020 at 5:23 PM.
Got my 24" x 10' roll of magnetic sheet today, thank you Amazon. I'll be cutting it to match various machines tomorrow.
Since I layed down sleepers, 1" dow board, and t&g flooring, the temperature in my shop does not fall as low as it used to, and have not noticed any rust at all on any machines. Did wax the table on my shaper a week or so ago, helped the power feeder feed some frame material. BTW, I bought some slipit, and it did not seem to want to dry. What is the proper procedure on using Slipit?
Gary you added another method to combat rust,thank you. I always keep sheet over my equipment,its not the answer but it helps.