Tyler here with projects in metal calm I wanted to make a quick video for you guys describing how you would set your compound on your lathe so that you could take very very small cuts accurately and I'm talking you know a half thou three tenths you know the normal hobby lathe is set up so that the dials have one one thousandth of an inch increments on them and so they're good for accuracy's you know up to a thousandth or so even a half thousands if you want to try and split measurements between two markings on your dial but you know if you try and get three tenths or eight tenths or anything other than about a half thou work and so I wanted to show you guys the pretty simple method that's been described in a couple books that I've read one of which is the machinists bedside reader by guy la tarde and he goes through this process in great detail including all the math involved and then basically describes the process for you know not only setting up your lathe so that as you advance the compound one one thousandth of an inch in Zee you're advancing the tool in one ten thousandth of an inch in X and that's basically by setting your compound at five point seven five degrees but you don't really need to get your compound set exactly at five point seven five degrees to use this method you could use two degrees four degrees any any convenient graduation on your compound will work you just need to be able to do the math so like I said guy Letarte describes that in the Machinists bedside reader and Herald Hall also goes through a little bit different method in his book lay the work a complete course he also describes the process using metric measurements whereas guy describes the process and the machinist bedside reader using inch measurements or imperial measurements so let me go ahead and get started explaining how this process works basically like I alluded to earlier I have my compound set it approximately five point seven five degrees I also have this surface here parallel to the z-axis simply so there isn't any error factored into this demonstration this is not necessary you do not need to have this surface set perfectly parallel to Z I like I said I have it set parallel just so that there's no error when I try and demonstrate this this is not a tenth indicator this is a thousandth indicator and so for me to show how this works I'm basically gonna have to turn the dial here ten thousandths of an inch for it to go one one thousandth of an inch on the dial and if it was a tenth and a tenth indicator I would be able to turn the dial here one one thousandth of an inch and it would show one tenth on the dial and so let me go ahead and just show you it's set to zero the dial shows zero I'm gonna move it ten thousandth there is ten and you can see that it moved it looks like it moved a little bit over one one thousandth of an inch so there's probably some error here in my five point seven five degree attempt obviously my graduations here on my compound are at every two and a half degrees so I was eyeballing that but the point is if you set your compound at approximately somewhere between five and a half and six degrees you're going to be able to turn the dial ten thousandths here for every 1000 to advance the the tool in X so if you needed to go three tenths in X you would basically turn the dial three thousandths this direction and that's how you do it now a couple words of caution first of all why would you need to know this method most hobby machinists don't need to work to such tight tolerances every once in a while you'll have a project like I did where I had a Atlas MFC mill that I was rebuilding and the pulley that goes around the spindle was worn out and the bushings had been probably hadn't been oiled in years and so they had basically disintegrated so the pulley was damaged and I needed to turn new bushings and they were designed to be a press fit so I board the pulley out to a few thousandths over its original size so I could clean it up and then I needed to bore the bushings so that they were about a half a foul our Jerr their outside diameter was about a half a cow larger than the inside diameter of the pulley so that they would press in and and be a nice press fit to try and do that on a lathe that has one one thousandth graduations on it Stiles isn't that easy especially for a hobby machinist an amateur so it's basically what I did was I got to within about two or three thousandths of the final size and I had this set up already at the proper angle so that I would be able to take off those last two or three thousandths using using my compound here and so I basically went I think five thousandths at a time in this direction and it was a half cow in that direction when I took the last two or three or four passes about a half a thought at time until I got exactly the size I was looking for so that's the way you would do it normally I wouldn't recommend trying to take off one ten thousandth of an inch per pass because I mean even with a really really sharp high-speed steel tool but you're not going to be able to take off a tenth at least not reliably so what will happen is you'll try and shave a tenth off and nothing will cut so then you'll move the the tool a tenth closer and try again and nothing will cut and then you'll move the tool another tenth so now you've moved it three or four tenths closer to the part and all of a sudden it finally bites and it might take four tenths it might take five tenths because of tool flex do the you know lack of rigidity in your setup so make sure you're not trying to take off a tent at a time I would take you know maybe three tenths at the least I would I would typically try and take a half hour or so at a time but this is just a method to set up your lathe so you can easily move your tool in x2 reduce the diameter of the part by tenths instead of five thousandths so I hope that helps if you guys have any other questions or ideas for additional video tutorials that you think would be helpful let me know and if I have time to put them together I will again the books I mentioned were the Machinists bedside reader by guy'll itard and lathe work a complete course by Harold Hall and I'll put those in the video when I edit it either book is a great book The Machinist bedside reader is full of projects and hints and tips and fun anecdotes and stories from the machine shop and it's as its title suggests is a great book to have by your bedside my wife doesn't get much of a kick out of it but I sure enjoy reading it and there's actually three books now there's the Machinists bedside reader and then there's a second and third bedside reader out as well the other book by Harold Hall is a great book for the the amateur machinist that is just trying to get started in lathe work and it kind of goes through as the title also suggests a complete introductory course to beginning lathe work thank you for watching and like I said if you guys have any questions or ideas for future videos please visit projects in metal calm and let me know thanks