Gasket for tools

[Dave Lehnert]

I have a 1954 year model Magna\Shopsmith Jigsaw. Under the front table you will notice a cover with the letter "M". That cover is for an oil reservoir that hold 3 oz of oil. Original spec is 10w oil (I use air compressor oil)

Anyway.......That front cover has a gasket that is notorious for seeping oil.
For anyone who has repaired old machinery, what gasket material have you used with success? I picked up a 6x6 sheet of gasket rubber in the plumbing dept at Lowe's. Will give that a shot first.

[Simon Dupay]

Check out OWWM.org they will know.

[Philip Johnson]

Oil can swell and deteriorate some rubbers, I would think you would be better off going to an auto parts store and getting some gasket material and maybe using some permatex or other form a gasket material with it.

Phil

[Dave Anderson NH]

The rubber of choice for use with any petroleum product is Nitrile which is also known as NBR or Buna-N. There are some Neoprenes (polyChloroprene) which are formulated for use with petro products, but with there being almost no price differential between the 2 materials stick with the NBR and don't take a chance that the Neoprene you get is the right one. Under no circumstances use silicone which will swell up to 200% and end up extruding out of position and cause leaks.

When choosing a gasket material base your thickness and hardness choices on the rigidity of the mating surfaces. The softer, thinner, and more flexible the cover and the base are, the softer the gasket needs to be. Similarly, the wider the spacing between fasteners and the more flexible the surfaces, the softer the gasket must be. For thickness, you go as thin as you can get and still not have the fasteners completely crush or over compress the gasket. For solid rubbers you are looking to deflect the material between 10-15% to get a good seal and with cellular elastomers (closed cell sponges) you are looking for a compression of between 20-25% to set a good seal.


A good source of supply for small quantities of gasket material is McMaster-Carr with MSC Direct being an equal quality supplier.

[Chip Lindley]

Dave' s need is similar to mine. I need a gasket for the inspection cover on an old CI Boice-Crane spindle sander. The crankcase is filled with 3 qts. of gear oil. Same on an old Delta/Milwaukee metal/wood 14" bandsaw gearbox.

Will manifold gasket material work between solid CI parts to stop oil seep?

[Josiah Bartlett]

If you don't have to worry about aligning bearings through the gasket mating surfaces, its hard to beat Permatex #2 and cork or annealed copper gasket material.

[Dave Anderson NH]

I would stay away from the manifold gasket materials. They are too hard because they are designed to seal very well machined mating surfaces which are very rigid and the bolt patterns allow the very high torque settings necessary to get a good seal. These materials work well in the proper application, but since most tools, even old ones, tend toward lighter weight stampings or castings, a softer and more flexible material will conform better and require less compressive force. They will also allow for any warping, twisting, and any dinged and dents on the cover which have occured over the years.

In the interest of disclosure, I make my living designing and making gaskets, seals, and other non-metallic items.

[Lee Schierer]

Most of the old gaskets were cork and they would weep oil over time. Loctite makes some removeable gasketing compounds that work well with oils of all types. Try Loctite 509.

[Dave Lehnert]

Thanks everyone with all the info.

I took a small chunk of the rubber I got at Lowe's and put it in a small cup of oil to see if it holds up.

I have not taken the cover off yet but the currant gasket looks to be a very thin paper looking gasket black in color. What material is this?

In this application the gasket is not going to harm anything if I mess up. Just like to know what is correct.

[Rod Sheridan]

Try to estimate how thick the gasket is, then go to an automotive supplier and buy some gasket paper.

Cut it to shape with a sharp utility knife and you'll be ready to go.

Regards, Rod.

[Dave Lehnert]

Try to estimate how thick the gasket is, then go to an automotive supplier and buy some gasket paper.

Cut it to shape with a sharp utility knife and you'll be ready to go.

Regards, Rod.

The other day I dropped in on an Auto parts store and asked for gasket material. The guy came out from back with about 6 rolls. All different. I was confused what would work.

[Rod Sheridan]

The other day I dropped in on an Auto parts store and asked for gasket material. The guy came out from back with about 6 rolls. All different. I was confused what would work.

Any of the gasket materials of the correct thickness would be fine for you.............Rod.

[Jerry Bruette]

For covers that very seldom get removed it's hard to beat good old Blue RTV silicone. If you remove the cover on a regular basis I'd use what the gear box manufacturers use, some Loctite gasket maker like Lee reccomended.

If you need to check the oil, or inspect like Chip needs you could drill and tap a hole for a pipe plug, silicone the cover on and remove the pipe plug when you need to inspect or check levels.

Jerry