howitzer Posted January 16 Posted January 16 I have had the idea of a metal lathe bubbling in my mind for a long time, and this is the perfect contest to make it reality. Originally I thought it impossible to do properly as there was no way to make long enough screw for the feed but that changed with the release of 73763 with which can arbitrarily long screws be made. Another significant problem was the need for a suitable main bearing which can take the weight of the spindle and has a large enough hole through for the bore. This was enabled by the hoop parts 3250 and 77107 along with the steel ball 99948. I tried GBC balls but as expected, the rolling was very rough and not what I wanted for this kind of thing. While I'm not attempting to replicate any real product exactly, I'm showing here the lathe I bought years ago to give the general idea of what I'm aiming to make: I intend to replicate most of the important functions such as: Variable speed for the spindle Centering chuck (not sure yet if three or four jaws but we'll see) Manual and automatic feed, manual cross feed and manual top feed Thread cutting with automatic feed Tailstock It's a big project though and I have limited time available for building so there's no telling how many functions I'm able to build, but I hope to get it to some degree of completion. So as the first part of my project I set out to make the main bearing from the aforementioned parts which is shown here: Few more photos at https://imgur.com/a/RwcEqqJ Wish me luck! Quote
2GodBDGlory Posted January 17 Posted January 17 The scale of that is really cool! Those are some seriously serious bearings! Would a series of standard 2L worm gears not work for the thread cutting feed? Or maybe the 32L axle that would limit you to just wouldn't be long enough. I was planning on using 2L worm gears for that on my lathe project, but before figuring out whether I could make it work or not, I realized that I don't actually have enough worm gears left over either way, so I think I'll have to leave thread cutting out of my model, unfortunately. (Actually, as I type this, I'm realizing there's another option. Instead of having a full-length worm gear, I could have a full-length rack with a standard worm gear that translates along it. It wouldn't be realistic, but it might be workable) I can't wait to see what comes of this! Quote
schraubedrin Posted January 17 Posted January 17 That's incredible! I love the idea of such a machine built in Lego. Looking forward to following your process. Quote
ord Posted January 18 Posted January 18 Nice! How is the performance of the bearings? It looks like you've kept a 2L space between both the inner and outer rings? Quote
howitzer Posted January 18 Author Posted January 18 On 1/17/2025 at 2:31 AM, 2GodBDGlory said: The scale of that is really cool! Those are some seriously serious bearings! Would a series of standard 2L worm gears not work for the thread cutting feed? Or maybe the 32L axle that would limit you to just wouldn't be long enough. I was planning on using 2L worm gears for that on my lathe project, but before figuring out whether I could make it work or not, I realized that I don't actually have enough worm gears left over either way, so I think I'll have to leave thread cutting out of my model, unfortunately. (Actually, as I type this, I'm realizing there's another option. Instead of having a full-length worm gear, I could have a full-length rack with a standard worm gear that translates along it. It wouldn't be realistic, but it might be workable) I can't wait to see what comes of this! The limit of 32L axle indeed is the reason why I opted not to even try it with the old worm gears. It's true also that you could have the worm gear in the carriage and pair it with stationary rack gears but not being realistic I didn't consider it either. 8 hours ago, ord said: Nice! How is the performance of the bearings? It looks like you've kept a 2L space between both the inner and outer rings? Yeah, the spacing is 2L. I haven't yet built a solid support structure for the bearings so I haven't tested them properly but we'll see when the project goes forward. Quote
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