Making a flat scraper out of a File

[Rickabilly]

Hello All,
Recently in another thread here at MWF the question was raised, How to make a Flat Scraper out of an Old File, Having had quite a bit of experience in the field I posted the following and was subsequently asked if I would mind setting up a "How to thread" so here goes.

Best Regards
Rick

Hello All,
Please see attached sketches showing the process of converting an old file into a flat scraper.
   
The dimension "X" is the file/scraper length and while a bought scraper will have no teeth on the faces when I make one from a file I usually just dull the teeth off on a belt sander as the pattern actually makes it easier to control when oily.

The edges are necked in as can be seen in the second image on the scraper sketch as this allows scraping close to a stepped edge,

The front is radius-ed so that the corners never dig into the work piece,

The front 1/3rd of the tool is tapered to half of the original file thickness as this helps control-ability, if the front edge is too thick it is difficult to see the scraping in progress,

Grinding the cutting edge is critical there is no "bevel" but the edge is hollow ground on a 4"-6" ally oxide wheel, I do it by eye nowadays but was taught to use a jig as drawn, the scraper should point directly at the axis of the wheel which will give an edge that is just less than 90 degrees on both sides of the scraper, and it is best to leave the grinding marks as these aid in starting a "Scrape",

To finish sharpening the tool, lap the top and bottom faces either on a stone or diamond lap, do not use wet and dry paper as this blunts the edge, some people hold the scraper at 90 degrees to the stone and polish the hollow ground edge, but I find that this reduces tool life and grooves the stone badly which ends up rounding the edges badly which means a blunt scraper.

[DaveH]

Rick,
A very useful 'How To' Very nicely explained.
Thanks

DaveH

[Rickabilly]

Hello Dave,
Hopefully it'll be of use to someone.
Best Regards
Rick

[truckin23]

Rickabilly ,
I hope you don't mind I cleaned up your pic so it can be seen better with my old eyes . Thanks for taking the time to explain this very usefull .
Bob

[Rickabilly]

I'm Horribly offended

Just kidding, Of course I don't mind, I did this sketch in a bit of a hurry, and to be completely honest wasn't too worried about the "gloss" just wanted to get the info across as quickly as possible.

Thanks for putting in the effort to scrub it up.

Best regards
Rick

[TomG]

Rick,

Files do make excellent scrapers. I used one when I scraped the ways on my dad's Atlas lathe. About the only thing I could add to your design is to wrap the file in tape to protect the hands. You can probably guess how I figured that out.

Thanks for posting the drawing.

Tom

[Rickabilly]

(08-19-2012, 08:28 PM)TomG Wrote: Rick,

Files do make excellent scrapers. I used one when I scraped the ways on my dad's Atlas lathe. About the only thing I could add to your design is to wrap the file in tape to protect the hands. You can probably guess how I figured that out.

Thanks for posting the drawing.

Tom

Hiya Tom,
yes, if you leave the teeth sharp then expect to lose your finger prints

I think I mentioned somewhere that the teeth should be ground smooth on a belt before grinding the rest of the features into the scraper, but just taking the edge off is preferrable to grinding until completely smooth, as the very blunt teeth help with grip when the scraper gets oily. but of course wrapping with tape works too, and don't forget the edges too a nice radius on the corners makes all the difference to how a sceaper feels to use.

Best Regards
Rick