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Relieving stress built-up in iron when reduilding

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.
 

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Good morning.

The reason we do this is it shows how a thin grinder table "moves". I had a student who took a class down in Tennessee a few years ago who had a small surface grinder, I think they're real popular with hobbyist. I think they're called a Sanford. It has a 5 x 8 inch chunk I think. Anyway he brought the table to the class, died the before and after test it moved .004". The student was shocked. Just think you didn't grind or scrape the work hardened stressed iron and you scraped the table ways, match fit the table to saddle ways and then ground the table top to clean up. Bo-ingg the table bends high in the middle. When you grind the table rocks like a rocking chair when you reverse directions. That's why I tell people to never grind the table top on a old grinder. Just grind the chuck.

Another thing that's important to be a detective and when scraping the saddle top or female ways - before match fitting the table to saddle is to pre-scrape the saddle top with a scraped straight edge. Think about if the saddle ways are concave or convex from wear. You blue up the scraped longer ways flat and then match fit the ways. How do you hinge a V - Flat ways. You can't and you rub them and if it's high in the middle it blue's up, but it's a false reading from rocking in the middle. Another thing I teach is to Never Assume anything, Prove it. Have a nice weekend. Suppose to be 10F here tonight...burrrrrr
 
Good morning.

The reason we do this is it shows how a thin grinder table "moves". I had a student who took a class down in Tennessee a few years ago who had a small surface grinder, I think they're real popular with hobbyist. I think they're called a Sanford. It has a 5 x 8 inch chunk I think. Anyway he brought the table to the class, died the before and after test it moved .004". The student was shocked. Just think you didn't grind or scrape the work hardened stressed iron and you scraped the table ways, match fit the table to saddle ways and then ground the table top to clean up. Bo-ingg the table bends high in the middle. When you grind the table rocks like a rocking chair when you reverse directions. That's why I tell people to never grind the table top on a old grinder. Just grind the chuck.

Another thing that's important to be a detective and when scraping the saddle top or female ways - before match fitting the table to saddle is to pre-scrape the saddle top with a scraped straight edge. Think about if the saddle ways are concave or convex from wear. You blue up the scraped longer ways flat and then match fit the ways. How do you hinge a V - Flat ways. You can't and you rub them and if it's high in the middle it blue's up, but it's a false reading from rocking in the middle. Another thing I teach is to Never Assume anything, Prove it. Have a nice weekend. Suppose to be 10F here tonight...burrrrrr
 
Hey to all my students who've met Alex my 37 year old son. He got a new full time job working as a repair and new machine installer for Mere Toledo Scale Company. They make grocery store meat packaging and weighing machines. If you buy a steak and it's in a shrink wrapped package with a table with weight and $ tag on it. The Swiss based company sends him to grocery stores im MN, SD, ND and Iowa where he repairs these machines. They furnish a truck, uniform, tools, has great benefits and pay.

I'm sad he can't take over my trade or company, but as many self employed people know small companies can't supply good health insurance and pay. One good thing is when I croak he will know the value of my tools. I'm really proud of him.
 

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Nice words from the heart. Thanks Rich for sharing your knowledge and the story about your son Alex. Don’t feel too bad that Alex cannot take over your trade. I believe you are spreading this old trade much more than anyone else has done in the last 100 years or so, with many real and virtual students embracing this knowledge.
 
Hi Rich,
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.
Here in Germany in the Munich area there is a small family company called Franz Singer Werkzeugmaschine. Their niche is Deckel milling machines, and it's a fantastic place. Franz worked for Deckel first as a trainee then in the repair department, and started his own company many years ago, taking some people from Deckel with him. They know everything about the machines and have a huge collection of new and used parts, with customers all over the world. One of the things they have traditionally done is rebuild Deckel mills. Their work is simply beautiful, because they have the equipment and knowledge and motivation to do things right. I have seen their rebuilt Deckel machines all over the world, for example last summer while visiting a CSIRO facility in Australia, there was a Deckel mill with a Singer rebuilt badge in the workshop, right next to an impeccable Schaublin 150 lathe.

Anyway, Singer is no longer doing rebuilding because their in-house scraper (that was all he did, all day long) has retired and they don't have anyone who can take over that work.

So the story you tell above is being repeated in other places.

Cheers,
Bruce
 
The armaments corporation in South Africa set up a machine rebuilding facility because they couldn't get anyone to do a good job. Wonder where that is now. ARMSCOR was sold off in pieces to Rheinmetall and BAE etc. I struggled to find anyone in Sydney capable of grinding the V's on a surface grinder.
 
Hi Rich,

Here in Germany in the Munich area there is a small family company called Franz Singer Werkzeugmaschine. Their niche is Deckel milling machines, and it's a fantastic place. Franz worked for Deckel first as a trainee then in the repair department, and started his own company many years ago, taking some people from Deckel with him. They know everything about the machines and have a huge collection of new and used parts, with customers all over the world. One of the things they have traditionally done is rebuild Deckel mills. Their work is simply beautiful, because they have the equipment and knowledge and motivation to do things right. I have seen their rebuilt Deckel machines all over the world, for example last summer while visiting a CSIRO facility in Australia, there was a Deckel mill with a Singer rebuilt badge in the workshop, right next to an impeccable Schaublin 150 lathe.

Anyway, Singer is no longer doing rebuilding because their in-house scraper (that was all he did, all day long) has retired and they don't have anyone who can take over that work.

So the story you tell above is being repeated in other places.

Cheers,
Bruce
I'm happy I've taught students like you and Paolo who can teach other what I taught you. I had a hobbyist come to a class I had up here in MN last spring. When he got home he called a local rebuilder looking to buy a used straightedge and as they talked they offered him a job as a scraper tech. He called me and told me. He said the same story as their old scraper died and hadn't taught anyone over the years. Rich
 
The armaments corporation in South Africa set up a machine rebuilding facility because they couldn't get anyone to do a good job. Wonder where that is now. ARMSCOR was sold off in pieces to Rheinmetall and BAE etc. I struggled to find anyone in Sydney capable of grinding the V's on a surface grinder.
There used to be a member here named Mac tool. He is in Melborne and has a way grinder. His real name is Phil Fleming. Another name was RCtool I think he imported a Churchill grinder from the UK I think. Email me and I can forward it to Phil as he and I Email now and then. They quit the forum when some jerks were allowed to comment. It's a shame as we lost many super smart people. I recall phill helping a member who had a hydraulic problem on a surface broach. I miss him a lot. My Email is [email protected]
 
Back to the topic of hardening in tables. So a while back I was watching a video by Steve Watkins where he was truing the ways on a BP table with his planer. He was speculating that one of the reasons those long skinny tables take on a frown comes from the “peening” (for lack of a better term) of the iron on the top of the inside of the T slot “T” where the T slot nut or bolt head bears when tight.
 








 
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