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Old 01-08-2015, 05:06 PM   #1
Chuck Sea/Tac
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Default Prussian blue

Can anyone explain how to use Prussian blue? tia
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Old 01-08-2015, 05:18 PM   #2
Tom Wesenberg
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Default 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.
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Old 01-08-2015, 05:30 PM   #3
Patrick L.
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Default 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.
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Old 01-08-2015, 05:37 PM   #4
Jim in Wisconsin
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Default 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.
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Old 01-08-2015, 05:38 PM   #5
Joe K
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Default Re: Prussian blue

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

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Old 01-08-2015, 05:53 PM   #6
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Quote:
Originally Posted by Jim in Wisconsin View Post
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.
Never seize works good too. I agree with the black magic marker. It is very thin and not as messy.
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Old 01-08-2015, 06:30 PM   #7
Terry, NJ
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Default Re: Prussian blue

It's great on eye loupes too!
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Quote:
Originally Posted by Jim in Wisconsin View Post
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.
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Old 01-08-2015, 06:37 PM   #8
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Default Re: Prussian blue

Commode handles or the front lip of the seat, too.
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Old 01-08-2015, 08:20 PM   #9
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Default Re: Prussian blue

You guys had too much fun
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Old 01-08-2015, 09:04 PM   #10
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Default 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
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Old 01-08-2015, 11:55 PM   #11
Chuck Sea/Tac
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Default Re: Prussian blue

Anyone ever use it to check engine bearing contact?
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Old 01-08-2015, 11:59 PM   #12
J Franklin
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Default Re: Prussian blue

Yes, it shows amount of contact or voids
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Old 01-09-2015, 12:55 AM   #13
ian Simpson
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Default Re: Prussian blue

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Originally Posted by noboD View Post
Commode handles or the front lip of the seat, too.
As an apprentice that would have got me a three day unpaid vacation.

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Old 01-09-2015, 02:21 AM   #14
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Default Re: Prussian blue

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Yes, it shows amount of contact or voids
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
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Old 01-09-2015, 06:38 AM   #15
Patrick L.
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Default Re: Prussian blue

Quote:
Originally Posted by Jim in Wisconsin View Post
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.



For gags we also used loaded condensers.
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Old 01-09-2015, 09:48 AM   #16
Terry, NJ
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Default 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.
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I use Dykem as it is a fast drying liquid. Not as messy as blue and wipes off with a little solvent. Rod
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Old 01-09-2015, 10:25 AM   #17
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Default 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
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Old 01-09-2015, 12:10 PM   #18
Bob Bidonde
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Default Re: Prussian blue

Bluing was commonly used to layout parts on sheet metal using a scratching awl and to check contact between rubbing surfaces.
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Old 01-09-2015, 02:52 PM   #19
Chuck Sea/Tac
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Default Re: Prussian blue

Quote:
Originally Posted by colin1928 View Post
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
So if the mainline was bored, then you should have 100% contact, and Russian blues basically a waste of time?
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Old 01-09-2015, 06:24 PM   #20
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Default Re: Prussian blue

Quote:
Originally Posted by Rowdy View Post
It has never caused me a problem as long as it is cleaned off and re-applied between checks if adjustment is needed. Rod
I don't wipe it off, I just brush it to erase the pattern for the next pattern check.
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