Richard King
Diamond
- Joined
- Jul 12, 2005
- Location
- Cottage Grove, MN 55016
I was asked to explain why you need to grind or scrape the tops of tables first before scraping the ways.
During a recent class I held here in Minnesota, the students wanted to do a basic 1 week class and they stayed over the weekend to do an advanced second week class.
They worked for Boeing Portland where they used to hire contractors to scrape their machines but in the past 2 years the contractors retired. They have several Gleason Gear machines and even Gleason has stopped scraping machines as their people are retired.
I bought a 6 x 18" surface grinder for them to scrape during the class.
I was telling my FB forum members on how before scraping the table ways you have to either grind the top of the table where the magnetic chuck bolts to or scrape it.
Why? Because the iron under the chuck gets work hardened in or tight. One you get thought it the iron moves or relieves the stress in it.
To prove the point. I had them set the table on 3 points upside-down and blued the bottom table ways, marking the hinge or where the scraped straight edge pivoted. It hinged on the ends.
Then we flipped it over and scraped the table top with a Biax with a carbide blade. The student had to sharpen the blade the blade once while doing it. He figured the hard surface was .003" deep. Once he was down .003" the iron got softer. Then we flipped it over set it back on the same 3 points and blued it up again. The hinge changed and it was now high in the middle, showing them how it changed. This is especially true with smaller machines. I have a DR appointment in 45 minutes. More later.
During a recent class I held here in Minnesota, the students wanted to do a basic 1 week class and they stayed over the weekend to do an advanced second week class.
They worked for Boeing Portland where they used to hire contractors to scrape their machines but in the past 2 years the contractors retired. They have several Gleason Gear machines and even Gleason has stopped scraping machines as their people are retired.
I bought a 6 x 18" surface grinder for them to scrape during the class.
I was telling my FB forum members on how before scraping the table ways you have to either grind the top of the table where the magnetic chuck bolts to or scrape it.
Why? Because the iron under the chuck gets work hardened in or tight. One you get thought it the iron moves or relieves the stress in it.
To prove the point. I had them set the table on 3 points upside-down and blued the bottom table ways, marking the hinge or where the scraped straight edge pivoted. It hinged on the ends.
Then we flipped it over and scraped the table top with a Biax with a carbide blade. The student had to sharpen the blade the blade once while doing it. He figured the hard surface was .003" deep. Once he was down .003" the iron got softer. Then we flipped it over set it back on the same 3 points and blued it up again. The hinge changed and it was now high in the middle, showing them how it changed. This is especially true with smaller machines. I have a DR appointment in 45 minutes. More later.
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