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SJorgensen
04-23-2003, 02:47 AM
When hand fitting parts I've used primer paint to help show the high spots. There has to be a better material. Is it prussian blue? And if so is it available?

Joel
04-23-2003, 03:13 AM
Yes, pussian blue, non drying. Enco sells it, pg386, part#505-1387, $4.88 a tube. Loctite sells it also. I got mine from an auto parts store. I use it mostly for setting up differential gears.

Dr. Rob
04-23-2003, 01:26 PM
Jiffy Marker? My fave anyway.

SJorgensen
04-23-2003, 02:22 PM
Thanks for the tip. Both sound handy to have around.
Spence

hms50
04-23-2003, 02:47 PM
This isn't what you were asking about, but it made me recall an old timer told me to use magic marker on pieces to be ground on a surface grinder. He said it did not clog up the wheel as dykem does. If you lower the wheel so it takes off just some of the marker, you're into the steel about .0002". It works for me.

SGW
04-23-2003, 04:22 PM
One brand is Dykem "Hi-Spot Blue." One tube of the stuff will likely last you several lifetimes, as a little goes an extremely long way.

These days I'm not sure it's actually Prussian blue, but it serves the same purpose.

Al Messer
04-23-2003, 07:32 PM
I'm a cheapskate--I use my wife's outdated lipsticks.

FredT
04-23-2003, 09:48 PM
Hey that old timer could have been me. I been telling guys that for years. No one believes me though and I am glad to hear it from another source. The wheel loading isn't really noticeable with a 40 grit wheel but you make the jump to 60 or eighty and you'll notice it in a big hurry.
Fred t

docsteve66
04-23-2003, 10:42 PM
For close fitting, Use a Mark-A-Lot pen (like sharpies but more oil tolerant), Finest "lapping compound" (valve grinding compound), touch the parts and move while pressing. Then use contract or break cleaner to spray away the residue. The shiny parts were touching.

The penmark must not dissolve in what ever you spray on. The spray must remove the lapping compound. Works well.
Steve

spope14
04-23-2003, 11:02 PM
Magic Marker - Marks A Lot. Prussian blue is good, but spreads out too much. Markers are standard gear in my shop, and cost less for three doz than a bottle of dykem or prussian. Very thin coating they do leave and are more accurate than pressian.

I have done this with no marking compounds at all. Rub the part lightly on a surface plate to find flatness. The high spots will shine more than the low spots. Takes a bit of practice to master, but this is the best method. Lap, rinse with say kerosene and then laquer thinner, then do again. This is how I learned it in apprentice school, my teacher said wussies used dykem or such.....except in layout, or for bluing handles on machines.....

Oso
04-23-2003, 11:21 PM
Marker, except for scraping.

The tube of blue always leaks, and is the nastiest thing to have around when it does. Everything is blue it or you touch.

I need to try the Canode blue, I hear it is nicer to use, but I dunno where to get some.

T Wise
04-25-2003, 10:16 PM
I've been using some oil paints from an art supply store. They have a great selection of colors. prussian blue included. I find it works best when spread very thin.

Tim

SJorgensen
04-25-2003, 10:39 PM
One of the reasons I have used the primer paint in the past was it's quick drying property. Is the prussian blue for metal-work the same as the prussian blue in a paint store? I wouldn't want to have to wait for an oil based paint to dry. The magic marker method is looking better all the time.
Spence

Cass
04-25-2003, 11:24 PM
Prussian blue is much more precise than magic marker. It can be wiped to a thickness of about 2 millionths of an inch and still be visible. We use markers but it is rough paint compared to Prussian blue. Marker is much better than Dykem layout dye which is heavily pigmented and designed to build up a layer to allow clearly visible lines. Marker has pigment in it also but much more course than Prussian blue. The greasy consistency of the Prussian blue allows it to be wiped to very thin layers. It is key to high accuracy scrapping. Very messy. The stuff in art stores used to be the real thing. I am not sure about that now. The High Spot product works ok.

Cass
04-25-2003, 11:45 PM
Prussian blue is much more precise than magic marker. It can be wiped to a thickness of about 2 millionths of an inch and still be visible. We use markers but it is rough paint compared to Prussian blue. Marker is much better than Dykem layout dye which is heavily pigmented and designed to build up a layer to allow clearly visible lines. Marker has pigment in it also but much more course than Prussian blue. The greasy consistency of the Prussian blue allows it to be wiped to very thin layers. It is key to high accuracy scrapping. Very messy. The stuff in art stores used to be the real thing. I am not sure about that now. The High Spot product works ok.

Jim Wilson
04-26-2003, 01:30 AM
I bought 2 tubes of Prusiian Blue High Spot Marking Paste part number 6165 K11 from McMaster Carr this week. $2.83 for a .75 oz. tube. Great place, I ordered via their web site Sunday night and got the stuff in the mail Tuesday afternoon. Their URL is www.mcmaster.com. (http://www.mcmaster.com.)


Jim


<font face="Verdana, Arial" size="2">Originally posted by SJorgensen:
When hand fitting parts I've used primer paint to help show the high spots. There has to be a better material. Is it prussian blue? And if so is it available?</font>

SJorgensen
04-27-2003, 12:33 AM
Thanks Jim,
I'll check it out. Sounds like just the thing.
Spence

Dave Opincarne
04-27-2003, 03:53 PM
OK guys, lets clear this up http://bbs.homeshopmachinist.net//wink.gif

The markers and dykem are drying and used to create layout lines or to indicate where material has been removed. Hi-spot or prussian blue is used to indicate where contact has occured between mating surfaces.

The term "Prussian Blue" refers to a color or more specificly a pigment. What machinests refer to as prussian blue is prussian blue pigment and grease. It does not dry so you'll be waiting around a long time if you expect it to. Prussian blue oil paint is made from the same pigment but mixed into a paint base, either linseed oil, acylic, or water color.

Other types of marking compounds (high spot) can be made with other pigments in non drying bases. Contrasting colors can be created for working multiple surfaces as in making surface plates.

-Dave

gamachinist
04-27-2003, 04:10 PM
Hi all.All of the gunsmithing books teach to use soot or lamp black in a bottle to check fit when inletting a stock for the action.I don't know if it will work for this aplication or not.It won't be as messy as Prussian Blue in a tube but it is meant for a press contact not a sliding contact.Robert.

Oso
04-27-2003, 10:40 PM
Actually, anything that transfers or is rubbed off on contact areas will work.

The only detail is that it should be thinner than the accuracy of the surface you want.

For some things chalk works fine. Marker is easy and available, and more accurate than chalk for closer fits.

I have used ordinary pencil lead, artist's crayon, ink, etc, depending on what was available at the time I needed it.

The hi-spot blue is great, the bees knees, but it is a pain for getting on you and everything. Especially when scraping, when you are always re-bluing your marking tool.

Take your choice..........

docsteve66
04-28-2003, 09:42 AM
Again, Oso has it right to basics. I have used carbon paper (remember that stuff?). Rub the paper to xfer carbon to one part, touch other parts and (usualy) move slightly. The carbon will transfer to the other part where they touch. soft lead pencil works.

Joel, You got ripped off on your price for Prussian blue- but keep it till you use all up. Price will be up to $488 instead of $4.88. My tube is old, old. It leaks so I keep it in a pill bottle. Tube is made of tin (I suspect the new stuff is in plastic), can't read the lables any more, but just touch the stuff and you konow what it is. I bet my tube (probable one ounce) could paint a barn if you made the coating uniform and no darker than needed. The barn is speculation but one tube in a tool box will coat every tool, your hands, clothes, toilet seat. The stuff should be a restricted item in any shop. Causes lots of trouble with the Joker types. Thus my preference for markers.
Steve
edit comment: Joel: reason I said you got ripped off was that I think my tube (pased on by my dad, probably cost less than 50 cents back in the 1930- 40's. Was speaking only of inflation making things cost more. PB was always expensive for the amount you got.

[This message has been edited by docsteve66 (edited 04-28-2003).]