I cleaned up a Delta DJ-20 jointer about a year ago. It’s not used weekly so it gets a little bit of surface rust.

It’s been waxed with Butcher’s 20 times. I soak waxed it a couple of times immediately after rehabbing.

The outfeed table and fence are fine. The infeed table rusts very quickly to the point you can wipe it with your finger.

I used this jointer daily from 2000-2010. Never had this issue.

Once cast iron has rusted despite removing the rust, the surface remains pitted and the small pits are a site for moisture to condense and rust to re-occur. Some cast iron is more prone than others probably because of the metallurgy and casting process.
Wax is nice for friction but sucks for rust resistance. I don't know of a good alternative though for everyday use.

I had to leave some machinery unused for about a year. To prevent rust I coated all tables with WD-40 and then put plastic sheeting over them. This did a great job of protecting the surfaces.

I do not know though even if wiped dry the WD-40 would be a problem with your wood surfaces. It was not a problem for my situation because I only had to do one major clean up before putting the machines back into service. I wouldn't want to have to do that clean up every time I needed to use a machine.

There are other table coatings out there other than wax. I've seen spray on products that I believe are supposed to add both slickness and protection.

Guidecoat and Black Ice are two spray products that claim to be dry lubricants that do not transfer to the wood.

B H Davis has the treatment correct - WD-40, lots of it. Let some time pass.

I have to agree. WD 40 for long term storage. Glidecoat ( used to be Topcote) for every day use.
Paste wax is great for making table plates slick and feed easily but is ineffective as a moisture barrier.

Before you guys posted I cleaned it up and soaked it with glide coat. I found some guy on some forum??? Who puts the wax over the glide coat.

I bought a can of glide coat when it first came out. I didn’t like it and the can say there for years.

Interestingly the fence has bowed and cupped over time. I remember it not being perfect before I stored it. Delta had used a magnetic table and ground it. Apparently it’s not the best cast steel/iron.

I dropped it off at the machinists to have him flycut it.

How old is that machine? 30 years old? And the fence just went south? Hard to believe it relaxed getting rusty just now.

I have heard that good machine makers let their castings 'relax' or 'age' for several months before machining and finishing off. Capital Machine Company in Indianapolis has produced the finest veneer slicing machines for over 100 years. For many years they had about an acre and a half that had castings sitting and rusting, amongst the weeds. I notice now that there is no longer that lot full of future work/aging castings.

The new Chinese and other Asian machine makers do not do this, in order to help keep costs down.

I did once see an EMA (SCMI clone) shaper table top do a 1/2" twist like a potato chip about a month after I bought it. The thing was about 350 lbs, and just warped.

It’s a Delta DJ-20 circa 2000. Made in Taiwan. I bought it new. It started to get a bit of a cup maybe 5 years later. Now, the fence is bowed enough to justify machining it.

They made the fence by milling four points on the back. Sitting it on those points with a magnetic table and surface grinding it.

My machinist is milling a bit off the edges of the rough casting, so he can grab onto it with the vise.

It’s a bit harder than cast iron.