Nice scraping work

ddickey said:
You know I sent them a message about classes but I never got a response. I'd like to find a rebuilding shop around here that wants to teach someone in return for free labor. I'd jump all over that.
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Get a hold of Uglydog, he was trying to put together a class up that way last year. I think it was more informal than anything, but was guided by an experience scraper person he knows.
 
I was getting the emails just never landed on a day I wasn't working. Seems like the group has not gotten together in some time.
 
Rex Walters said:
I think we armchair quarterbacks tend to dismiss the score. :)

His markups clearly show he's getting the piece pretty flat. And quickly, too.
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Rex
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I would agree with George that you can see and hear the cut dig in on the edges of the straightedge when he's taking the cut. This is further supported by the "chatter marks" on the edges. Just because it prints well does not mean its flat. If the edges are convex it will roll and print in the lower areas. You can scrape a rounded object straight on a plate and it will print well. He has his black on very heavy and that adds to this problem. I did a great job of getting it roughed in with the biax but I would have switched to a hand scraper to finish it up. Having used what all of you admit is a very heavy tool myself it is difficult to control the blade on the edges of a surface. It was for that reason the company I worked for would not allow the use of the power tool on any reference surfaces or finishing on a machine. Taking nothing away from what he was doing there, again great job of getting the straightedge down close very quickly but i would have to agree that that piece shows indications of a convex surface. Now were talking very small numbers but again this is a reference surface.
 
I just watched the video on here. What he is doing is something i do teach Ken in the classes. That's called "Crosses" and he is "machine gunning it" To a pro he is not getting a very good bearing. He has what looks like smeared bluing and maybe has 12 Points Per Inch (PPI) and 25% coverage even with the smears. If that's the Wes I think it is he has a lot to learn. Check out NYC CNC on you tube or Jan Sverre Haugjord scraping a cast iron surface plate. There are sorts of scraping videos my students have shot on you tube. Search my name Richard King Scraping on there and you will see several done here in the USA and Europe.
 
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Im just a rank amateur with no formal training and have learned through my own errors how easy it is to create
bad readings when blue checking parts. I'm still finding I create errors and then have to determine what I did wrong
and how to avoid that problem in the future.
Some of the yutube vids are great,especially those by Mr Kings students, but some are a mess and even a year ago I could pick out
big errors they were making.
Common sense and just caring will make all the difference and I do go back to redo things I had thought were done because thats what
needs to be done in some cases.
 
The thing in any toolwork, but especially scraping, is learning how to measure well. For most things, .001 is 'good enough', but to do a good job scraping, you have to devise means to measure to .0001 (or better) reliably and repeatably, or you will never know where you are at. :courage::encourage:
 
99% of the my student You Tubers are correct in my opinion, many it was there first class others have been to 3 or 4. 50 hour classes. Machine rebuilding is a skilled trade one need's to work for 4 years to be a Journeyman. The ones that are not perfect, I had no control over what they did after the class. They at least are trying to teach. The rebuilding business is a Small World if you see and know as many people as I do you can tell what an experience scraper does.. Some of the You Tubers scrape different then the majority of people do. Suburban Tool has one. etc. etc. I have a DVD that was copied by the presenter in my opinion and never gave me credit. If it is who I think he is he only has a few years working as a helper scraping. He is a good Electrons Tech. and a mechanic, but he is an apprentice scraper who also works alongside Journeymen scrapers. I taught a class at his part-time workplace and he declined to take a class. I offered to teach him for free as a matter of fact. So I know a bit more about what was presented then most do. But he was trying to teach and was better then some.
 
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I think everyone should watch Brian Ives, of K & J Scraping. He has a training video that shows how a pro scrapes, and take note of the smoke.
 
That's a old trick you put mineral spirits on the metal and it smokes. I learned that trick 50 years ago from my dad so we could impress people walking by the work area.
 
The machines I have were built so crappy or were purchased clapped out so I have been doing the best I can without some of the needed jigs and fixtures to get reliable readings in tenths. When I can get a mic on something I take multiple readings till my "feel" of pressure is the same as when checking with the standard and the readings repeat till I'm certain any variance is in the millionths. Then I know I'm within a tenth.
I will build the needed fixtures when I get the machines reasonably accurate.
My little mill/drill was out of square by more than 0.008" per foot and parts just 4 inches long would be about 0.002" thicker at one end than the other. I could shim the column till it trammed within tents but it would still cut out.

I know I'll get some people shook up with this but but the only way I could get some surfaces reasonably close for scraping was by setting up retaining walls and sliding the part under the cutter without moving the table. Large, heavy parts were done without any retainer. Cuts were 0.002" to 0.004" deep depending on my ability to control the part. It worked very well with sharp tools cutting cast iron. Just had to be careful not to climb mill.


One of the tools I need to build is a simple fixture to mount on the surface gauge that will let me check vertical surfaces for square.
Till then I just check the against the cylindrical square and work the part over till it checks square. I can use feeler gauges to read to the nearest 0.005"
but that last bit is just a sliver of light.
At this time I have to clamp a flat plate on the table to machine one side and end which I can then check against the cylindrical square as I can't get a reliable reading when checking the top and bottom dovetails of the saddle for square. My readings did get me within 0.001" per foot but thats not good enough so I cut the plate and check it. Last check it was only a few tenths per ft. out of square judging by the light gap. I'll continue till I'm confident it's within 0.0001" per ft.
I dont trust the squares I have though a couple do check pretty close to square. My cylindrical square checks good.
It's a lot of work.
 
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