Prussian blue
 

Can anyone explain how to use Prussian blue? tia

Re: Prussian blue
 

Use a small brush, such as the small flat acid brush plumbers use, then wipe a thin coating on the gear teeth. Turn the driving gear back and forth so it wipes across the blue and shows a pattern of contact. You want to see the pattern on the drive side of the teeth, and on the coast side of the teeth. Old Motors Manuals have a section showing how to read the patterns.

Re: Prussian blue
 

Prussian blue can be used in just about any machining/checking operation.
Its lightly brushed on and filed, milled, ground or worn off to show contact/noncontact area.
In most automotive stuff I find it tedious. To check tooth contact I use white grease and to check valve face/seat contact I use pencil. These are far easier to remove for recheck after adjustment. But, the blue is fine if thats what you chose.

Re: Prussian blue
 

In the shops I used to work in, it was mostly used to play jokes on guys. A little dab on the back side of a knob of his machine and after a while he was blue all over and mad as hell.

Re: Prussian blue
 

I've used blue, but I like black magic marker better on gearing.

Joe K

Re: Prussian blue
 

Never seize works good too. I agree with the black magic marker. It is very thin and not as messy.

Re: Prussian blue
 

It's great on eye loupes too!
Terry

Re: Prussian blue
 

Commode handles or the front lip of the seat, too.

Re: Prussian blue
 

You guys had too much fun :)

Re: Prussian blue
 

I use Dykem as it is a fast drying liquid. Not as messy as blue and wipes off with a little solvent. Rod

Re: Prussian blue
 

Anyone ever use it to check engine bearing contact?

Re: Prussian blue
 

Yes, it shows amount of contact or voids

Re: Prussian blue
 

As an apprentice that would have got me a three day unpaid vacation.

Ian

Re: Prussian blue
 

That's what it is made for
from back in the day when Babbitt bearings were hand scrapped
I like for checking valve seat contact

Re: Prussian blue
 

For gags we also used loaded condensers. :eek:

Re: Prussian blue
 

Dykem is a great layout fluid but it is actually too thick for a high spot "paint".
It tends to flake off or bunch up in tight (Say, .001 clearance) places. Prussion High spot blue must be nearly all wiped off to avoid having an indication of a contact where none exists. It must be thinly applied.
Terry

Re: Prussian blue
 

It has never caused me a problem as long as it is cleaned off and re-applied between checks if adjustment is needed. Rod

Re: Prussian blue
 

Bluing was commonly used to layout parts on sheet metal using a scratching awl and to check contact between rubbing surfaces.

Re: Prussian blue
 

So if the mainline was bored, then you should have 100% contact, and Russian blues basically a waste of time?

Re: Prussian blue
 

I don't wipe it off, I just brush it to erase the pattern for the next pattern check.