Scraping cast steel?

1dogandnoexes · Dec 3, 2022

I'm looking at a surface plate advertised as "cast steel" made by the Challenger Machinery in Michigan. It's a vintage item which appears to have been machined at some point, but is unlikely to be super flat. Is there any such thing as scraping cast steel. Is it anything like scraping cast iron?

sfriedberg · Dec 3, 2022

Here's what Reliance Foundry says about cast steel: what is it and how it differs from cast iron. It's going to behave mostly like steel. However, as you noted "cast steel" is a historical term that covers a bunch of territory, and different foundries at different times probably produced very different product.

Richard King · Dec 3, 2022

Years back you had to be careful as some sold Ductile Iron as cast steel surface plates. If you could attach the add so we could see what it looks like I could possibly figure it out. Challenge used to mfg. and sell straight edges, surface plates, bench plates, angle plates and paper drill/hole punches. They went bankrupt and then opened again. I just looked them up and it seems they are only making the punches now.
Steel is a pain to scrape by hand and Biax Power. If your hand scraping use a carbide tip ground at a 60mm / 2.4" tip radius and a neg. 5 degree rake on booth sides. If your using a Biax Power scraper use a 60 mm / 2.4" tip radius with a positive rake. Yes a positive rake, like a wood chisel - one side. Try to keep not to have a long stroke - no more then 3/8" for roughing and down to 1/8 for finish. I would deburr it with a dull file and med grit sharpening stone. Steel and ductile gets a lot of burrs and slivers in the fingers. I would wear some leather gloves when deburring. I hate scraping steel. Have fun

hvnlymachining · Dec 3, 2022

Interesting timing, I too have a very likely possibility of needing to scrape steel in the near future. Searching posts and YT videos of the process and tool geometry grinding is interesting but few and far between. Not a lot of info out on this subject. My upcoming job presents itself in the form of a European made knife grinder currently in use and not able to be removed from such. I will have to do repairs two days in each week until complete! The surface beneath the hardened ways is both rusted and warn creating highs and lows ( the ways which are only about 1/8" thick, are only laid in place with one bolt at each end and not fastened down anywhere along the length of travel) I have an appointment for inspection on Wednesday to find out just how much wear exists, I've been told it's more than .005" overall but rust is lifting the way material some of that. A very brief (and spur of the moment) inspection yesterday using a standard aluminum level showed a very pronounced high spot near the middle of the machine.

jwearing · Dec 3, 2022

1dogandnoexes said:
I'm looking at a surface plate advertised as "cast steel" made by the Challenger Machinery in Michigan.

My money is on a clueless seller that doesn't know the difference between iron and steel.

Richard King · Dec 3, 2022

hvnlymachining said:
Interesting timing, I too have a very likely possibility of needing to scrape steel in the near future. Searching posts and YT videos of the process and tool geometry grinding is interesting but few and far between. Not a lot of info out on this subject. My upcoming job presents itself in the form of a European made knife grinder currently in use and not able to be removed from such. I will have to do repairs two days in each week until complete! The surface beneath the hardened ways is both rusted and warn creating highs and lows ( the ways which are only about 1/8" thick, are only laid in place with one bolt at each end and not fastened down anywhere along the length of travel) I have an appointment for inspection on Wednesday to find out just how much wear exists, I've been told it's more than .005" overall but rust is lifting the way material some of that. A very brief (and spur of the moment) inspection yesterday using a standard aluminum level showed a very pronounced high spot near the middle of the machine.

I have had experience on that type of blade grinder. The plywood mills in northern Minnesota where the only supply stores were auto part stores. They use those types to sharpen blades used to remove bark from logs. The machine I worked on had a steel band, much like steel banding used to hold parts on skids. They set inside a milled slot in the cast iron machine base. When new they had steel ball bearings that rolled on the banding. When we removed the rusted banding the iron under it was rusted .030" deep in some place and less in others. It was an emergency and like you these machines could not be pulled out of the building.

What I did was I had them clean out the rusty groves and we used a propane hand torch to cook out the lubricating oil that had soaked into the iron. Then we bought some plastic steel and also some plastic lead or Bondo material used on auto's. Then we made sanding blocks that we attached to wood blocks and sanded down the excess Bondo. We never scrape it we just sanded it. We depth mic'ed the slots. I had gone there to quote the job, but they were so desperate they had me stay and do the job then. I had learned long ago to always have a spare set of work clothes in the car. I needed them. It took us 3 days to do the job, we worked 18 hour days. They had already ordered the new stainless steel banding and new ball bearing rollers. About 2 years later the maintenance tech called me and said he had to do the repair to their 2nd machine and wanted to thank me for teaching how.

hvnlymachining · Dec 3, 2022

@ Richard King; I'd sure like to attend at least one of your courses, been watching your work in various videos online. I'm no professional scraper, but I'm working on it.

This machine very similar to the one you described with the difference of being steel, a lot of it welded. But still has the steel way material in shallow channel.

1dogandnoexes · Dec 3, 2022

Richard King said:
Years back you had to be careful as some sold Ductile Iron as cast steel surface plates. If you could attach the add so we could see what it looks like I could possibly figure it out. Challenge used to mfg. and sell straight edges, surface plates, bench plates, angle plates and paper drill/hole punches. They went bankrupt and then opened again. I just looked them up and it seems they are only making the punches now.
Steel is a pain to scrape by hand and Biax Power. If your hand scraping use a carbide tip ground at a 60mm / 2.4" tip radius and a neg. 5 degree rake on booth sides. If your using a Biax Power scraper use a 60 mm / 2.4" tip radius with a positive rake. Yes a positive rake, like a wood chisel - one side. Try to keep not to have a long stroke - no more then 3/8" for roughing and down to 1/8 for finish. I would deburr it with a dull file and med grit sharpening stone. Steel and ductile gets a lot of burrs and slivers in the fingers. I would wear some leather gloves when deburring. I hate scraping steel. Have fun

Here's the pics. The third photos has a series of lines that appear to be about 1" machining marks along the long axis of the plate.

hvnlymachining · Dec 3, 2022

Look like planer marks, often left by the factory on lower flatness grade surfaces. Probably hasn't been used too hard since they're still visible. But not exactly tool room grade flatness.

1dogandnoexes · Dec 3, 2022

jwearing said:
My money is on a clueless seller that doesn't know the difference between iron and steel.

Could be. My Elgin vertical mill was described in the original literature as "cast steel." It may just be a language issue.

hvnlymachining · Dec 3, 2022

I should have noted, I own a challenge plate of similar size and it's cast iron, but was scraped very nicely flat before I purchased it.

Richard King · Dec 3, 2022

That looks like a cast iron bench plate.

1dogandnoexes · Dec 3, 2022

hvnlymachining said:
I should have noted, I own a challenge plate of similar size and it's cast iron, but was scraped very nicely flat before I purchased it.

My goal is to get something which A, I can afford; B which I can move without a forklift; and C which can be scraped in the future. For the moment, I would have to use it as is.

hvnlymachining · Dec 3, 2022

I happened to find that ad, that will not make a good surface plate for flatness reference due to the thin and non webbed design. I'm not sure what the original use intended was. A good surface plate is heavily webbed and usually has just three "legs" to avoid warping the plate.

1dogandnoexes · Dec 3, 2022

Richard King said:
That looks like a cast iron bench plate.

I have two machines, a lathe bed at 30" L and a milling machine table at 18" L, which are both badly worn. I'm looking at this as an alternative to a camelback, which I would have to purchase already scraped.

hvnlymachining · Dec 3, 2022

I don't mean to hijack this thread but I wanted to ask Mr King; if you had to scrape the machine in question, being steel slots about 7' long, would you power scrape or hand? I'm looking into a Biax for my own use besides but haven't got one yet. And the filler idea, great backup Incase things get ugly. Thanks!

The reason I had this job dropped on me is because the factory techs are unavailable for at least a year, no replacement ways to be available for a year or two and the current grinder hand that knows how to work around the problem is retiring in a few months.

Bakafish · Dec 3, 2022

The downtime requirement is what scares me. I would machine a flat surface on a non-reference area and attempt scraping there before touching the real bearing surface. That way if you end up gouging the crap out of it (which is what happens with most steels from what I've heard) you can move to plan B. This is one of those situations where grinding it and applying Rulon or something similar would seem to make more sense, but maybe you will have good luck with the scraping.

hvnlymachining · Dec 4, 2022

What makes it real difficult is the fact that it has no relief ( undercut? ) in the corners of the grooves that hold the ways. Creating those could be a bit difficult. The more I think about it, the more I like the idea of a filler material of some sort. I've not applied Rulon, Turcite or others before, but I do have experience with body filler plastics and epoxies.

Overland · Dec 4, 2022

1dogandnoexes said:
Here's the pics. The third photos has a series of lines that appear to be about 1" machining marks along the long axis of the plate.

Back in the UK there were lots of "marking out tables" built like this.
The surface was machined on a planer with a flat tool, cocked over a little, to get these lines on the surface. As the table was used it was easy to see the wear as the lines would "widen".
This little anecdote might be interesting.....
I remember, as an apprentice, being in the forge and watching how a crankshaft hammer die was made. They'd start with a block of tool steel maybe 24" long, 12" wide, maybe 16" high. First job was to cut a tapered dovetail about 2" deep, on one of the 12x24 faces. This was used to hold the die in the steam hammer (type FB !).
The other 12x24 face was cleaned up and the edges squared.
The die block was then craned onto the marking out table, where the face was blued, and the shape of the die cavity was marked out using squares and a height gauge.
Then the edge profile was clearly identified by going around and using a small center punch to mark out the full perimeter.
Then on to the manual die sinking mill, with tapered ball endmills the toolmaker would dig out the cavity using a bunch of templates to get the depths and profiles.
Then the finisher would use a hammer and small chisels to round over all the edges, then finish with a die grinder.
All really skilled manual jobs.
After several thousand cranks, the top 3" or so of the die was machined off, and the process repeated.

Hopefully of interest
Bob

Richard King · Dec 4, 2022

hvnlymachining said:
Interesting timing, I too have a very likely possibility of needing to scrape steel in the near future. Searching posts and YT videos of the process and tool geometry grinding is interesting but few and far between. Not a lot of info out on this subject. My upcoming job presents itself in the form of a European made knife grinder currently in use and not able to be removed from such. I will have to do repairs two days in each week until complete! The surface beneath the hardened ways is both rusted and warn creating highs and lows ( the ways which are only about 1/8" thick, are only laid in place with one bolt at each end and not fastened down anywhere along the length of travel) I have an appointment for inspection on Wednesday to find out just how much wear exists, I've been told it's more than .005" overall but rust is lifting the way material some of that. A very brief (and spur of the moment) inspection yesterday using a standard aluminum level showed a very pronounced high spot near the middle of the machine.

You should start a new thread in this machine reconditioning forum. If you can include some photo's that would help the readers and ME understand completely what that machine looks like. You can call me too. I see your in South Dakota too, maybe you need some help out there?

Scraping cast steel?

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