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Scraping my own straight edge from cast iron stock

Koba17

Plastic
Joined
Aug 4, 2019
So I’m looking at getting into restoring machines as both an economical way to acquire equipment that can be made to work well, and to have a machining project I can do at home to some degree. One vid I watched on hand scraping recommended I made my own straight edge, which sounds like a way better way to get used to the technique than on the mill table I’d ultimately be working on. My questions are what grade(s) of cast iron is optimal for this purpose, and does the stock need any sort of annealing before scraping? If there’s a thread for this already I’d appreciate a link, first-time poster here
 
Don't worry about grade of cast iron- I'd suggest buying yourself a small chunk of durabar. Machine it flat(ish) and one side a 45 deg angle. You probably should high temp heat treat it pre scraping, but for your first scraping experience, I wouldn't worry about that. More important is do you have a decent carbide tipped scraper and a way to quickly sharpen it?

Enjoy! Scraping's is fun.

L7

And as Rob was hinting- watch both Stephan Gotteswinter's and Keith Rucker's scraping videos. Loads of good info in them.
 
So I’m looking at getting into restoring machines as both an economical way to acquire equipment that can be made to work well, and to have a machining project I can do at home to some degree. One vid I watched on hand scraping recommended I made my own straight edge, which sounds like a way better way to get used to the technique than on the mill table I’d ultimately be working on. My questions are what grade(s) of cast iron is optimal for this purpose, and does the stock need any sort of annealing before scraping? If there’s a thread for this already I’d appreciate a link, first-time poster here

When I milled a piece of cast iron to a triangle shape to use as a straight edge it bent like a banana. It was an utter waste of time.
I later scraped a straight-edge from a piece of already-bevelled cast iron for doing dovetails. It came out well but I have to re-scrape it every once in a while as it tends to bend a couple of tenths.

I guess what I'm saying is buy a straight edge and a surface plate. Use those to make tools if you must but making a straight edge as an early project is a bit of a fool's errand.
 
You don't know how to scrape but you want to design your own straightedge? I think you are getting the cart before the horse so to speak. If you are serious about learning to rebuild equipment and learn how to scrape, buy a used dovetail with the correct angle for your mill and a small cast surface plate to practice hand scraping on. Don't re-invent the wheel!

You can probably get started fairly cheap learning to hand scrape, but you will soon realize you need a power scraper, a good granite surface plate, and carbide grinder to sharpen blades etc. I scrape almost every day for enjoyment on top of owning a CNC repair business. This week in my spare time I scraped a rotary table, a surface plate, and a dovetail straightedge for customers, even though I didn't charge them. You will either learn to love it or hate it. Best of luck!
 
And then you will need a way to check your granite plates etc, and so on, lol. It just evolves on it's own. :)
 

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Don't worry about grade of cast iron- I'd suggest buying yourself a small chunk of durabar. Machine it flat(ish) and one side a 45 deg angle. You probably should high temp heat treat it pre scraping, but for your first scraping experience, I wouldn't worry about that. More important is do you have a decent carbide tipped scraper and a way to quickly sharpen it?

Enjoy! Scraping's is fun.

L7

And as Rob was hinting- watch both Stephan Gotteswinter's and Keith Rucker's scraping videos. Loads of good info in them.

Or You Tube "Richard King Sraping" and see several that Keith, Stefan and another good one is done by John Sainders at NYC CNC

Dura bar is a good choice. If your going to mill on a knee mill be sure to rough on bottom of end mill and finish with the side of the end mill.
 
Other Brother is sooo correct about learning to scrape resulting in more tools/equipment in a guys shop! This is a good thing :-) And yes, Other Brother, the stuff I purchased from you is in frequent use- thanks! Your pic suggests no lack of toys still at your place- two Glendo's?!

To the OP, I'm no professional scraper, but I've learned to scrape flat, parallel and square reasonably efficiently. My first three projects were straight edges of various lengths, and working on them taught me a lot and are now useful tools. Not in my opinion a fools errand. This took time though, so if the OP wants/needs the mill fixed quickly, hire someone to do the work, or buy a new mill.

L7
 
Other Brother is sooo correct about learning to scrape resulting in more tools/equipment in a guys shop! This is a good thing :-) And yes, Other Brother, the stuff I purchased from you is in frequent use- thanks! Your pic suggests no lack of toys still at your place- two Glendo's?!

To the OP, I'm no professional scraper, but I've learned to scrape flat, parallel and square reasonably efficiently. My first three projects were straight edges of various lengths, and working on them taught me a lot and are now useful tools. Not in my opinion a fools errand. This took time though, so if the OP wants/needs the mill fixed quickly, hire someone to do the work, or buy a new mill.

L7

I'm going to brag again....LOL. Both Other Brother and Lucky are students of mine and I am damn proud of them!!
 








 
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