thin film between machined surfaces on milling machine

[Mainiac Mat]

Hey gang,

I'm in a perplexing situation as we are repairing the head on our Grizzly G0757 milling machine vertical head. The seals were leaking like a sieve and upon disassembly, the lower bearings in the gear train were all loosey-goosey, as a result of a ~1/8" layer of fine ferrous gunk accumulating in the gearbox (I guess we should have flushed it). This is likely the result of inadequately hardened gears... but we were never under any illusions that this machine was the equivalent of a Bridgeport.

So we have the cast gear box off the machine, dissassemled on the bench, and sourced new seals and bearings. We're essentially ready to put it all together again..... but.... there was a very thin, even film between the mating machined surfaces of the gear box casting and the plates it mounts to on top of the headstock.



The only penetration in the bottom of the gear box casting is the quill shaft (which has two oil seals on it) so I'm don't think this is really serving as a gasket intended to prevent oil from seeping out (the oil leek we have dribbles down the quill onto the table below).

So I'm looking for a recommendation for what to do here.

Thinking about getting some Permatex spray gasket adhesive/sealant and calling it good.

Any recommendations are much appreciated.

 

[kmacht]

Very thin layer of RTV and a piece of dental floss embedded in it like you would with an engine case half.

 

[Doozer75]

No RTV unless you want to fight getting
it apart again.
For intimate matched cases (no gasket)
there are a few things you can use.
If you want to take them apart again
you can use Hylomar sealant. It is
expensive and hard to find in the US,
so Permatex #2 or Avaition Permatex
(also called Gasgasinch) is also good.
These you can take apart easily.
For something you can still take apart
but it requires a jarring loose with a hammer,
just use regular old Indian Head shellac
type sealer. This was the original
Permatex formula devised for patching
tires. You know, Permanent Textile repair
(for tires).

-Doozer

 

[bwringer]

Hylomar. You can't get the old formula any more, even though it was amazing stuff.

The new formula isn't nearly as useful in other situations, but it'll work perfectly for this application.

 

[paulsomlo]

Search "Hylomar Blue". Also available as "Reinzoplast" and Elring Curil T Liquid Gasket.

 

[Firebrick43]

In the machine repair trade we almost always used permatex #2 or loctite 510

Hylomar sometimes but not often was called out by the manufacturer

RTV squeeze out is a good way to plug oil passages and after several yokels fubar machine up with it we took it out of the crib so they couldn’t buy it.

One of the was so bad with orange RTV we named him the “silicone bandit.”

 

[BillK]

Was it a hard film ? Might be an anaerobic sealer. Used in a lot of newer engines at metal to metal joints. Something like this:

Permatex® Anaerobic Gasket Maker, 50 ML – Permatex

www.permatex.com

 

[LXCam]

I’m a fan boy of loctite 515.

 

[oldmachinenut]

I like Loctite 518

 

[My Old Tools]

If it were older it might be shellac. Old Triumphs were sealed that way, and they leaked like a seive.