Went to an estate sale this morning, and found a Goodell-Pratt bearing scraper
in salvageable condition. Don’t need any more bering scrapers, but just couldn’t
leave it behind for a dollar.

Decided to prep it correctly so y’all can see what such a beast looks like. Few
people have ever seen a correctly prepared bearing scraper. I included 2
pictures of the Hirsch tool I found last week, which several people insisted is
a bearing scraper. A quick comparison should dispel any notion that the Hirsch
tool is a bearing scraper.

If you lay a nicely prepared scraper on your arm and drag it sideways you will
shave hair. That’s how you know it’s right.

https://picasaweb.google.com/102358420595488787966/October252014?authus
er=0&feat=directlink------------------------------------------------------------
------------">https://picasaweb.google.com/102358420595488787966/October252014?a
uthuser=0&feat=directlink-------------------------------------------------------
-----------------

On 10/25/2014 7:41 PM, JAMES THOMPSON wrote:
> Decided to prep it correctly so y’all can see what such a beast looks like.
Few people have ever seen a correctly prepared bearing scraper. I included 2
pictures of the Hirsch tool I found last week, which several people insisted is
a bearing scraper. A quick comparison should dispel any notion that the Hirsch
tool is a bearing scraper.
>
> If you lay a nicely prepared scraper on your arm and drag it sideways you will
shave hair. That’s how you know it’s right.

Jim:

When you prep a bearing scraper, are the flats on the two sides in the 
same plane? If not, what is the angle between them - or does it matter?
I have one of those, but have only ever used it to scrape flat surfaces.

Don

> I included 2 pictures of the Hirsch tool I found last week, which
> several people insisted is a bearing scraper. A quick comparison
> should dispel any notion that the Hirsch tool is a bearing scraper.

That certainly is a classic bearing scraper, but it isn't the only
form.  Mine is a simple triangular piece, hollow ground on all three
sides to keep the edges very sharp.  There are, I believe other shapes
as well.

The Hirsch tool still bother's me as a burnisher.  The surface, not
being polished, will abrade the surface on which it is used, and
abrasion is not what I want from a burnisher.  Still, the Hirsch
doesn't look like a bearing scraper either.

Mike in Sacto

On 26/10/2014 12:41 PM, JAMES THOMPSON wrote (in part):
> Went to an estate sale this morning, and found a Goodell-Pratt bearing scraper
in salvageable condition. Don’t need any more bering scrapers, but just couldn’t
leave it behind for a dollar.
>
> Decided to prep it correctly so y’all can see what such a beast looks like.
Few people have ever seen a correctly prepared bearing scraper.
G'day Jim,

I don't dispute that your GP scraper is one form of bearing scraper: 
there is one  of that form in my father's toolbox from his days at sea.

> I included 2 pictures of the Hirsch tool I found last week, which several
people insisted is a bearing scraper. A quick comparison should dispel any
notion that the Hirsch tool is a bearing scraper.

But see

http://store.apextoolgroup.com/nicholson-
21667n-3-1-4-machinist-s-scraper.html">http://store.apextoolgroup.com/nicholson-
21667n-3-1-4-machinist-s-scraper.html

for a Nicholson bearing scraper of the same form as  your Hirsch tool.  
The answer may come down to whether your find has a convex, flat or  
hollow grind on the faces.  I checked my  Dads' and they both have flat 
faces.  As far as I know he never used a cabinet-makers'  scraper, (I 
never saw him with one and and there is no cabinet-makers' scraper 
amongst his gear) so he didn't use them as scraper burnishers, but 
rather I believe, as he told me, as bearing scrapers.

But then I have never worked as a fitter nor a machinist, nor engineer, 
so I can only go on what Dad told me.  Or maybe it was a case of making 
do do with what was to hand during WWII when a bearing  failed at sea. I 
suspect that when the pressure is on there are more ways of skinning a 
cat than twirling it around your head by the tail...........

Regards,

Tony B
Hobart, Tasmania

On 10/26/2014 6:35 AM, Tony Blanks wrote:
> for a Nicholson bearing scraper of the same form as  your Hirsch tool.

That one is hollow-ground. the Hirsch sems to be flat. So are the Blu-Dans.

Don

Tony called our attention to a type  _machinist scraper_ 

> But see
> 
> http://store.apextoolgroup.com/nicholson-
21667n-3-1-4-machinist-s-scraper.html">http://store.apextoolgroup.com/nicholson-
21667n-3-1-4-machinist-s-scraper.html
> 
> for a Nicholson bearing scraper of the same form as  your Hirsch tool. 
 
Now, note that ad says "MACHINIST SCRAPER". No where does it say a word about
bearings !!!
 
If the bearing was wide, that scraper would not be of much use. On a wide
bearing, you'd only be able to scrape with the curved part right near the tip.
It could readily scrape narrow bearings such as the poured babbit in early auto
engines, but only up a width corresponding to the straight part of the edge.

> The answer may come down to whether your find has a convex, flat or  
> hollow grind on the faces.
 
This, I think is "the rub".  The convex creates a "relief" on the back of the
blade which I think is vital to scrape Babbitt to a smooth surface. The flat-
sided, sharp-arrised scrapers may in indeed be scrapers, but they are not
_bearing_ scrapers. They will do general scraping such as deburring, but aren't
going to make a fine surface on Babbitt. That's my uninformed opinion and I'm
sticking to it! (But, see below, because open-minded John just found a
counterexample.)
 
Now, just to muddy the very waters I indended to clarify, I present this for the
Porch's perusal:
 
http://www.csosborne.com/brscr
ape_1.htm
 
and, the "killer" reference:
 
http://www.csosborne.com/no29B.htm">http://www.csosborne.com/no29B.htm
 
Because, here, BOTH hollow-ground ( concave ) and flat-sided triangular scrapers
are referred to as "bearing scrapers".  !!!
 
So, now I think we are all, all of us, correct. 
 
 
 
 
------------------------------------------------------------------------

>This, I think is "the rub".  The convex creates a "relief" on the back of the
blade which I think is >vital to scrape Babbitt to a smooth surface. The flat-
sided, sharp-arrised scrapers may in indeed >be scrapers, but they are not
_bearing_ scrapers. They will do general scraping such as >deburring, but aren't
going to make a fine surface on Babbitt. That's my uninformed opinion >and I'm
sticking to it! (But, see below, because open-minded John just found a
>counterexample.)
 
Scraping a bearing or a machined surface does not have the goal of making a
smooth surface. Gauge blocks are lapped to create a smooth surface but bearings
are scraped to create a surface that has a percentage of the area in contact. A
completely smooth bearing will wipe clean of lubricant and quickly gall to the
point of failure. Scraping leaves small pockets in the surface to allow trapped
lubricant to provide a film. The film separates the bearing surfaces so the
bearing actually rides on the film.
Having scraped many a press gib and managed a shop where hundreds of bearing
sections were scraped, assembled, and run in under load, if you make the surface
smooth the bearing will fail.
Machine tools have the beds and tables ground smooth and then scraped. The cross
hatch marking on the surface is the result of scraping. Scraping tools have
rounded cutting edges similar to that of a scrub plane blade. The marks left
have a radius that lets the edge of the mark blend into the surface without a
sharp edge.
Babbitt cuts relatively easily. It is softer than the surface it rides on so it
is sacrificial.  Scrapers for babbitt can be made from old files or various
other metals. In many ways Babbitt scrapers could be used for wood and wood
scrapers can be used for babbit. The materials are similar in hardness. The
purpose of scraping the two materials is entirely different.
Scrapers for steel gibs and machine ways and tables are usually made from tools
steel and sometimes from tungsten carbide to help maintain the edge longer.
Carbide has a tendency to chip so I’ve always favored tools steel.
If you are interested you can venture off charter and find out more about metal
scraping here: http:
//metalscraping.com/w2-Preview.html#01-Metal

Usually, when I want information about something I try to consult someone who
has actual experience on the subject. In this case, machinists and millwrights
come to mind. Possibly some auto restoration people haver also scraped bearings.

When I was serving my apprenticeship (1956 through 1959), the journeymen made a
special effort to show me things. The reason for this was that my father had
some influence in the union. It was a good idea to be on his good side.
Construction unions were strong back then.

So when things like bearing scraping came up, they would send for me so I could
learn. At the time I kinda thought I was being picked on because the other
apprentices were just doing normal work, and I was often being taken from what I
was doing and reassigned to a different task, which meant packing up my tools
and carrying them to a new location. I was too young then to realize what was
being done for me. I thought it was a burden.

So anyway, I got to do a lot of different things, and learned a lot in the
process.

Back to bearing scrapers. There were more than 250 journeyman millwrights
working on constructing the steel mill where I served most of my apprenticeship.
In my 4 years there I got to know most of them. I showed them my tools, and I
looked at theirs. Millwrights are always proud of their tools. I never saw a
bearing scraper that looked much different that the one I posted the pictures of
recently. Long handle, curved end. 250 sets of professional tools, and not one
bearing scraper that looked any different.

I truly believe that if there were other types in use for the purpose of
scraping large babbitt bearings that I would have at least been told about it,
or read about it in my books. So until someone tells me that they have actually
scraped a babbitt bearing with the other kind of tool, I remain skeptical.

A horse is a horse, is a horse, is a horse of course, but there is only one
Mister Ed.


> On Oct 27, 2014, at 8:39 AM, John Ruth  wrote:
> 
> Tony called our attention to a type  _machinist scraper_ 
> 
>> But see
>> 
>> http://store.apextoolgroup.com/nicholson-
21667n-3-1-4-machinist-s-scraper.html">http://store.apextoolgroup.com/nicholson-
21667n-3-1-4-machinist-s-scraper.html
>> 
>> for a Nicholson bearing scraper of the same form as  your Hirsch tool. 
> 
> Now, note that ad says "MACHINIST SCRAPER". No where does it say a word about
bearings !!!
> 
> If the bearing was wide, that scraper would not be of much use. On a wide
bearing, you'd only be able to scrape with the curved part right near the tip.
It could readily scrape narrow bearings such as the poured babbit in early auto
engines, but only up a width corresponding to the straight part of the edge.
> 
>> The answer may come down to whether your find has a convex, flat or  
>> hollow grind on the faces.
> 
> This, I think is "the rub".  The convex creates a "relief" on the back of the
blade which I think is vital to scrape Babbitt to a smooth surface. The flat-
sided, sharp-arrised scrapers may in indeed be scrapers, but they are not
_bearing_ scrapers. They will do general scraping such as deburring, but aren't
going to make a fine surface on Babbitt. That's my uninformed opinion and I'm
sticking to it! (But, see below, because open-minded John just found a
counterexample.)
> 
> Now, just to muddy the very waters I indended to clarify, I present this for
the Porch's perusal:
> 
> http://www.csosborne.com/brs
crape_1.htm
> 
> and, the "killer" reference:
> 
> http://www.csosborne.com/no29B.htm">http://www.csosborne.com/no29B.htm
> 
> Because, here, BOTH hollow-ground ( concave ) and flat-sided triangular
scrapers are referred to as "bearing scrapers".  !!!
> 
> So, now I think we are all, all of us, correct. 
> 
> 
> 
> 
>
------------------------------------------------------------------------
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