Possibly a dumb question about table saw rust

[Steve Morrissey]

Hey folks,

Still fairly new to woodworking, and I have a question about imperfections appearing on the shiny new tools I got last summer.

For context, in August of 2020 I got a new Powermatic PM1000 table saw and a Powermatic 54A jointer with a shelix head. From the beginning I put paste wax on the cast iron tops of these tools, but I live in Minnesota and the shop is in a non-climate controlled garage. Humid summers, freezing winters, and large temperature swings are the normal.

I'm starting to notice marks appearing on the cast iron surfaces on these tools. They aren't huge, but they aren't scratches either -- they look like tiny rust marks perhaps? Maybe? So I went forward assuming it was rust. I used mineral spirits to get the paste wax off, used WD40 and some 400 grit sandpaper to attack the spots, but they don't really seem like they're going away.

So now I'm reaching out to you experts, with photos, to determine if I need to stress and work hard to get rid of these marks before my tools disintegrate before my eyes, or if they can be left alone because they're harmless.

IMG_2012.jpgIMG_2016.jpgIMG_2013.jpg

Thanks in advance for looking!

[Jacob Mac]

If rust is a concern, I’d look into getting a dehumidifier, and Boeshield T9. I am in he Midwest with similar swings and paste wax didn’t stop rust. A combination of all three helped me

[Carroll Courtney]

I don't blame you for wanting to keep that surface new looking for as long as you can. You will get several suggestions on what each of us use so be prepared. They all will work but its going to be required to be repeated several times through out the yr. Myself I use this product and I really like it, but I also keep my machines covered up with old bedding sheet just to help. I never consider questions as being dumb cause advances is being made all time so there may be new product out there that us WW'ers need to know about. So old questions become new again.

[Alan Lightstone]

Living in Florida, I feel your pain regarding rust prevention, albeit my shop is climate controlled.

A few of the woodworking magazines have published reviews of the effectiveness of many products for this. And all have their boosters, and neigh-sayers.

This is the link to Fine Woodworking's test: https://www.finewoodworking.com/memb.../011227030.pdf


Personally I use CRC Industrial 3-36, which I can get on Amazon. It was highest ranked on one of the reviews. Boeshield T-9 has lots of supporters as has Johnson's Paste Wax, but the reviews weren't that fond of the effectiveness of the wax (flaming start in 5,4,3,2,1...)

As has been said, keeping the humidity out of the shop is important, but not necessarily easily done in some climates.

Oh, and welcome to Sawmill Creek!

[Charles Coolidge]

Here in the Pacific NW rain forest where Boeing resides and Boeshield T-9 was invented and it can rain every day all day 4 weeks in a row...Boeshield T-9. When machines are not going to be used for a bit I apply petroleum based past wax then Boesheild on top of that, apply it wet with a blue paper shop towel (they sells rolls of this in auto parts stores, basically a fancy paper towel) and let it dry. When I need to use the machine I remove with low odor mineral spirits, apply paste wax and use the machine. When done I reapply the wax and Boeshield until next use.

[David Lageman]

Not that it's needed, but I'll cast another vote for Boeshield T-9 in the mix. Works well in swampy SW Florida.

[Marc Fenneuff]

Powermatic used to recommend cutting a sheet of hardboard or similar and laying that on the CI table when not in use. Stops moisture from condensing on the surface. Maybe try that in addition to the paste wax.

[Charles Coolidge]

Powermatic used to recommend cutting a sheet of hardboard or similar and laying that on the CI table when not in use. Stops moisture from condensing on the surface. Maybe try that in addition to the paste wax.

But I once drilled holes in some wood to put all my Forstner bits in, it was dry wood, they all rusted like the wood absorbed the moisture from the air.

[Charles Coolidge]

I'll also add gravity is a factor. On a flat table surface that's fine, but on a round or vertical surface where the product can basically fall off you have to watch it. Learned that lesson on my metal lathe after treating it then coming back a couple months later and seeing the rust.

[William Hodge]

Hey folks,

Still fairly new to woodworking, and I have a question about imperfections appearing on the shiny new tools I got last summer.

For context, in August of 2020 I got a new Powermatic PM1000 table saw and a Powermatic 54A jointer with a shelix head. From the beginning I put paste wax on the cast iron tops of these tools, but I live in Minnesota and the shop is in a non-climate controlled garage. Humid summers, freezing winters, and large temperature swings are the normal.

I'm starting to notice marks appearing on the cast iron surfaces on these tools. They aren't huge, but they aren't scratches either -- they look like tiny rust marks perhaps? Maybe? So I went forward assuming it was rust. I used mineral spirits to get the paste wax off, used WD40 and some 400 grit sandpaper to attack the spots, but they don't really seem like they're going away.

So now I'm reaching out to you experts, with photos, to determine if I need to stress and work hard to get rid of these marks before my tools disintegrate before my eyes, or if they can be left alone because they're harmless.

IMG_2012.jpgIMG_2016.jpgIMG_2013.jpg

Thanks in advance for looking!

It's humid in your shop.
Make it not be humid. Things won't rust.
Even if you put whatever on the top of the machines, the rest of the machine is still being exposed to humid air as long as there is humid air. Get the relative humidity below 50%.

[Thomas Wilson]

People also use magnetic sheet sign material on the surface. The way waxes and oils protect the iron is by slowing the diffusion of water and oxygen to the iron surface. The magnetic sheet should do even more.

I had tools in an uninsulated, unheated garage for a while. Rust was a problem. Cold night followed by a warm rain, I would get condensation inside the garage. I was planning to move so I did not actually work on the problem beyond wax and Boeshield, but that did not stop me from thinking about what I could do. If you are in your long term shop, you may want to work on keeping the heat in and the moisture out, and conditioning the air both with heat and dehumidification. Sealing around and insulating the garage door would be huge. Get a thermometer with a hygrometer (humidity meter) to know when you have a problem. Iron (your saw table) starts rusting about 50%, steel varies with composition but 80% is typical. You may need just a bit of heat to get the RH below that. I live on a lake in East Tennessee. It is a temperate rainforest. I have heat and dehumidification in my new shop and no problem with rust. We are death on dehumidifiers around here, but I have had good luck with HiSense dehumidifiers. They have a humidistat so they just run when needed.

Rust is a problem and it is so evident on the brand new table saw. You can find people who routinely condition the surface with fine sandpaper and pad sander to maintain that look. They clean the surface down to bare metal and then wax or oil. I do not use sandpaper unless the rust got way out of hand (someone working in your shop set a cold drink on the saw table). I want that thin layer of oxide to protect the metal. It is that black oxide that is down in the fine grooves from the surface grinder. The surface is still smooth. I let that go, not everybody does.

[Erik Loza]

My experience = Accept or reject as like: All machines rust in shops. Some more so, some less so, but all do. Having a climate controlled space really helps but it’s inevitable at some level. Focus on keeping the cast iron work surfaces waxed, to avoid serious rust, but you’ll make yourself crazy trying to 100% prevent it.

Erik

[Frank Pratt]

Relax, it's a tool. Take reasonable care of it (which you do) & just use it.

[Mel Fulks]

Take a look at the Bullfrog rust blockers. They have treated covers and other products

[Alan Lightstone]

Relax, it's a tool. Take reasonable care of it (which you do) & just use it.

+1

We have a tropical storm / hurricane heading our way (if the cone is accurate). So I just went down and sprayed all my big machines with CRC 3-36. Out of curiosity, I checked the temp and relative humidity with the meter that lives in the shop. It's rainy season here, but the readings are pretty normal. 75F and 63% relative humidity with the split AC set at 75F. Totally normal readings for this part of Florida indoors. Upstairs in the house its 72F with 57% humidity.

No way you could get humidity below 50% here in any reasonable manner. So you take care of your machines, spray them every time you think of it, and do your best. Some minor rust will occur. As Erik said, "All machines will rust".