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| Modifying a Grizzly 9 X 19 (G4000) |
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| madjackghengis:
Hello Bernd, Having never bought a new machine, I have had to rebuild every lathe and mill I've ever owned, and found they are far easier than they appear. As far as your underside, with only one and a half thousandths difference, I'd use a scraper and straight edge to level it and get it flat. I'd use the same method to increase the contact area of your v ways on the carriage, using prussian blue and bluing the way, sliding the carriage to see the contact patch, and scraping off the blue, doing the flat way alternately, to keep the carriage parallel as much as possible. E.F. Connolly's "Machine Tool Reconditioning" is where I got my info, borrowing the book from an interlibrary loan, and using it to rebuild a machine built in the 1870s. I've rebuilt two logan lathes the same way, making my own straight edges out of cast iron scrap, cut, ground, filed flat, and then scraped to match a surface plate using the prussian blue until I had about an 85% match up. If you don't have a proper scraper, you can take a piece of flat stock, say an eighth by one, braze a small bit of carbide to the end of it, say an eighth by quarter by one inch, with the quarter in side down flat, and then grinding the end square off centered on a green wheel, giving the end of the scraper a very slight radius side to side, so it "bites" in the middle, and sharpening it by lapping it on a diamond "stone" holding the stock vertical, getting a square end, and drawing it edge-wise toward you to get the very slight radius you want. After scraping away high spots, lay the scraper flat and scrape off any burr, and then rub in the blue again, just scraping off the bluing. You can get a tube of prussian blue at any art store or the like, and a tube will last decades, mine is almost thirty years old and only half gone. If I can give any help on this subject, it is my expertise, as I've rebuilt many machine tools instead of running them, when I was a machinist, and use the same methods to fit general machinery together. Mad Jack :beer: |
| Andrew_D:
I've been following this thread as well as reading the threads on fixing Darren's 7x and David's 7x. My plan was to start working on my 7x12, but I haven't got that far yet. Keep coming with the updates. Hopefully I'll finally get through the list of projects soon and start on mine. I'll need all the inspiration and tips I can find... Andrew |
| Bernd:
Mad Jack, I used to work on the assembly floor of a shop that builds gear cutting machines. There was always alot of scrapping going on to final fit some of the parts. Am quite familar with the Prussian blue and other compounds for marking. I don't know if I'll go any further on the lathe from were it is now. I think it will be good enough. Going to go back and check it again just to see how far off it is though. Progress will be slow, as this project is not a priority. Would like to get the saddle done though. Bernd |
| Bernd:
Andrew, As I told Mad Jack, this is not a priority project so will be slow going. I'll be sure to post as I do some work on it though. Bernd |
| madjackghengis:
--- Quote from: Bernd on February 20, 2010, 09:39:48 AM ---Mad Jack, I used to work on the assembly floor of a shop that builds gear cutting machines. There was always alot of scrapping going on to final fit some of the parts. Am quite familar with the Prussian blue and other compounds for marking. I don't know if I'll go any further on the lathe from were it is now. I think it will be good enough. Going to go back and check it again just to see how far off it is though. Progress will be slow, as this project is not a priority. Would like to get the saddle done though. Bernd --- End quote --- Hi Bernd, I'm glad you've got the scrapping background, I didn't want to jump in and lay it all out, but wanted to make sure you knew what to do, and you obviously have had the experience. Scraping seems to be a disappearing art, and it sorts out old machines too well to be lost. By the way, what kind of Logan are you working with? I've got a 1948 820, ten inch, which is showing its age right in front of the chuck now. I bought a couple of different cross slide castings from MLA, when I didn't have a mill, and the atlas type with a hole for the top slide, and slots in the back for rear tools has been on it since I finished machining it, much improvement over the original cross slide and top slide arrangement. Looking forward to seeing the finished project. Mad Jack :coffee: |
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