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Hand scrapping help

Kylehangloose

Plastic
Joined
May 17, 2022
I'm thinking about hand scrapping (would be my first time) a heavy 10. I have no idea what I need to get it done. I know there are different size scrappers and I need some help with what size I need to be using. All help would be much appreciated.
 

texasgeartrain

Titanium
Joined
Feb 23, 2016
Location
Houston, TX
I would also recomend not starting that journey till you gain a bit of knowledge in the area. Its not just scraping with a scraper. You're running checks for straightness and flatness. That's take straight edges and blueing at least.

Without scraping, you could run tests of your parts to see how well each contacts with the other, using bluing.

The best section for these sort of discussions would be here:

If you really want to begin diving into it, I'd start there.
 

neanderthal mach

Hot Rolled
Joined
Dec 18, 2008
Location
princeton b.c.
I'd fully back up what others have already said. And without more than enough experience and knowledge, then if you were to start scraping on that lathe you'll soon be scrapping it. Scraping for flat on one surface only using a "known good" reference surface isn't that bad, parallel & flat on two opposing surfaces a bit harder. In three dimensions it's exponentially tougher. If you can't take an actual scraping course, start with this guys videos, https://www.youtube.com/channel/UCD1jVjhwma9Ehj8BQqDMPHw Then pay the roughly $100 to get a copy of this, http://www.machinetoolpublications.com/ It's not optional imo, but pretty dry reading. Even if you never rebuild any machine tool, the book will return it's costs far more than that just in finally understanding the cleanliness and lube requirements all machine tools have if you want them to last. After that maybe start with a simple cast iron angle plate, and when you can take something like a rough condition 6"-8" cast iron box parallel and scrape it properly to .0001"-.0002" for flat, square and parallel on every surface, you then might be safe enough to do small projects like cross and top slides. And unless you have at least a half dozen machines to rebuild in your future, the tooling costs to set yourself up to do it properly simply aren't worth it. For one or two machines paying for someone who knows what there doing on a surface grinder and how to set up and re-grind machine tools would be cheaper. Then maybe oil flake the bottom surfaces yourself. If that's good enough for Bridgeport to do it ought to be good enough for most of what any of us may have in a home shop.
 

Richard King

Diamond
Joined
Jul 12, 2005
Location
Cottage Grove, MN 55016
Hello, I teach scraping and have several of the members plus 40,000 others around the world. Search YouTube- Richard King Scraping and you see several shows my students produced. I'm a Journeyman Machine Tool Rebuilder. If someone asked me to scrape a South Bend lathe bed, I wouldn't and get it planned or ground as the double V's are a real pain to get coplanor. Also several of my students will tell you they read the Connelly book and watched YouTube, but until I stood behind them they never figured it out. I have cut back on my classes as I'm 71...I do have one in July here in Minnesota in my small workshop. Its a 5 day class where you learn to scrape a small surface plate by hand Biax Power Scraper. I have taught in Germany at the BIAX factory and if you look at DAPRA.COM the USA distributor they advertise my classes. Keith Rucker a famous YouTuber has hosted several of my classes and has shows about them, so does NYCCNC John Saunders and Stefan Gotteswinter in Germany. Another good one is one produced by Biax Germany. In my classes you could bring the compound of your Heavy 10 and after 2 days of learning to scrape i would help you rebuild the compound. Several of my members can teach you too. Paolo MD teaches in Maryland at Tuckahoe Museum. Lance Baltzley and Adam Booth in Florida could too. Kieth Rucker , Warren Jones, Pete or Demon in the UK and 2 Brothers in Austria. There is also a Research Center in Taiwan where I taught that also has 2 of my best students teaching. PMC. I have a couple of people talking about hosting classes. Denver, Springfield VT, Portland and near Los Angeles.. they would be in late 2022 or 2023 as I'm as busy as I want to be. The July class now has 3 students, so I have room for 1 more. The cost is under $2000.00. If you wanted to scrape you 1 machine, be prepared to spend a minimum of $1000 for the tools as you will need master straightedges, handscraper, etc.
 

Kylehangloose

Plastic
Joined
May 17, 2022
Thanks everyone, I think these replies have help set me straight lol. I would love to get this lathe as close to perfect as I can but I think I'll just have to take it into someone to get it done. I'd love to go take a class, I'll have to save and schedule some time to do it. Thanks!
 

Richard King

Diamond
Joined
Jul 12, 2005
Location
Cottage Grove, MN 55016
Thanks everyone, I think these replies have help set me straight lol. I would love to get this lathe as close to perfect as I can but I think I'll just have to take it into someone to get it done. I'd love to go take a class, I'll have to save and schedule some time to do it. Thanks!
I do offer the class to folks Who have a hardship and can't afford it. Just message me.
 

dalmatiangirl61

Diamond
Joined
Jan 31, 2011
Location
BFE Nevada/San Marcos Tx
Thanks everyone, I think these replies have help set me straight lol. I would love to get this lathe as close to perfect as I can but I think I'll just have to take it into someone to get it done. I'd love to go take a class, I'll have to save and schedule some time to do it. Thanks!
Why not just put it together and use it? Why is there a perception by new lathe owners that the $500 garage sale lathe must be made to better than new specs?
 

Kylehangloose

Plastic
Joined
May 17, 2022
There is a low spot about 6" long roughly .0015" deep on the front way. I can't afford to get it ground so I was hoping I could correct it myself. There are also a number of dents and dings within the first 12" of the spindle.
 

10KPete

Hot Rolled
Joined
Dec 21, 2008
Location
Nordland, WA
There is a low spot about 6" long roughly .0015" deep on the front way. I can't afford to get it ground so I was hoping I could correct it myself. There are also a number of dents and dings within the first 12" of the spindle.
Minor stuff. Any lathe that has seen service will have those marks. It's the larger surface that matters. A scratch .0015 deep is nothing!
 

neanderthal mach

Hot Rolled
Joined
Dec 18, 2008
Location
princeton b.c.
Try and visualize any worn areas on the lathe bed itself in this way. The cutting tool doing the actual work is attached to the carriage, as that carriage travels into that worn dip in the bed it will of course slowly drop to the extent of the wear. However and lucky for us it changes the tool height on the parts DIAMETER in a straight vertical direction. So the actual measurable change on the part size in the longitudinal cutting direction is far less than the wear amount. It's affect is and will be more noticeable on smaller part diameters than larger. Any bed twist works in the opposite way because of the vertical height of the tool tip above the bed ways, it's measurable amount of change on the part diameter as it's being cut can be multiplied.

One of the first tools you need is a good high accuracy machinist's level. Save your money and that's one of the more important tools to have as a lifetimes investment in your shop just to properly set up what you already have. And certainly so for when you can afford to at least have that bed re-ground. Maybe even more important would be a good 10ths capable dti. While there's other ways of doing so, they make centering the tail stocks Morse taper side to side easy. Because of the inevitable effects of gravity, they normally can't be used to accurately check that MT in the vertical orientation. But one can be used to check for any wear deviation in how that tail stock quill is pointing. And with .015" of bed wear, it's pretty safe to assume your tail stock quill is already pointing down more than enough to be measurable. As a temporary measure it could be shimmed between the tail stock casting and it's base to be a lot better than it currently is. If you own even one machine tool, that precision level and dti are in my opinion non optional and just as important as anything else. If you can't accurately measure any wear or misalignment's, there's zero hope of making any corrections that can in some cases greatly improve on what you already have.
 

animal12

Cast Iron
Joined
Apr 9, 2009
Location
CA USA

bentwrench

Cast Iron
Joined
Oct 25, 2007
Location
North Dakota
Consider the change in diameter that a drop .0015" would create. Do some right triangle math and you can estimate it for a given part diameter. At 1/2" diameter that wear would cause about 9 millionths change in diameter... There are far more significant factors in the accuracy of a lathe than just bed wear. You should already have leveled your machine with a NIST calibrated master precision level in strict temperature controlled environment if you are concerned about one and half thou.

Twist, bow, and other deformation are probably far more prevalent than wear. We are net even talking about work holding, or tool and part deflection and all the other fun stuff that affects the final cut. Just trying to put things in perspective.

I re-did a bed on a 9" south bend quite a while ago, that had about .040 in wear with a slight bow over about 6 ". Even then I only fit the saddle to the bed after it was cut on a planer. As someone said above, the 3 small v-ways on that bed would be quite a challenge to scrape.

All that said if you want to learn to scrape, go a to a class and make a straight edge. Some people really enjoy the process, some people like to chase zeros for fun.(finish and measure to ultra precise tolerances).
 

SteveM

Diamond
Joined
Sep 22, 2005
Location
Connecticut
"If someone asked me to scrape a South Bend lathe bed, I wouldn't and get it planned or ground as the double V's are a real pain to get coplanor."

When Richard King makes a statement like that, that says a lot about the degree of difficulty.

If this were a flat bed Atlas or Myford, it would be a lot easier, but think that you have the pair of inverted vees that need to have each side of the V's be straight, flat AND match the opposite side of the V ANS the one on the other side.

When I see South Bend saddles for sale on ebay, my first thought is "how are you going to be sure that when it sits on the bed that each side is resting on all four surfaces?"
 








 
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