I'm trying to turn some spring guides using Delrin but the finish isn't coming out very smooth. Currently I'm using 450 RPM (based on some online advice) on a less than 1" diameter piece. I've used both a carbide insert as well as HSS bit. Any advise on what is the best approach? I've tried higher RPM with no better result.-Marty
Low rake used so the tooling does not want to be drawn into the material while cutting. same reason as brass .... SUCKAGE !!
Quote from: Motorhead on April 03, 2021, 06:58:45 PMLow rake used so the tooling does not want to be drawn into the material while cutting. same reason as brass .... SUCKAGE !!Hummm....when machining steel I would grind my bits with about 8-10 degree side relief and rake angle but I used about 15 degree for Delrin. LOL.....didn't know I was doin' it all wrong!
Quote from: nced on April 03, 2021, 07:44:49 PMQuote from: Motorhead on April 03, 2021, 06:58:45 PMLow rake used so the tooling does not want to be drawn into the material while cutting. same reason as brass .... SUCKAGE !!Hummm....when machining steel I would grind my bits with about 8-10 degree side relief and rake angle but I used about 15 degree for Delrin. LOL.....didn't know I was doin' it all wrong! Ed,You do what ever you wish & getting smart azz is not productive for anyone.Geez ...
Us old guys are sure a crotchety bunch !!!Old school, new school or no school .... do what works
MartyWhen I first started working in Lorin's, Deserts Metal's Machine shop, I was having a hard time finding the center of the round stock I was turning etc.Lorin gave me one of these little Jewels, and I have bee using ever since, works perfectly for critical finishes, and on all round stock. Like Motorhead said, having the proper ground tool bit works wonders also etc.https://www.ebay.com/itm/THE-LATHE-LEVEL-MADE-IN-USA-CENTERING-TOOL-HEIGHT-SET-INSERT-HEIGHT-GAGE/252784910713?hash=item3adb27a179:g:j3kAAOSw4CFYr7IVHtH's,Don
Oh boy, I did some chores around the house and so many suggestions waiting already! Thank you guys, I really appreciate it. So I came back to the mini-lathe for some practice runs an hour ago and after reading your suggestions and doing some further research all the signs are pointing to rake and point radius as the primary culprits. I don't have any tool bits with low rake nor a grinder to make my own (yet) but I tried a carbide insert that had a little bit of nose and that helped along with slower feed. I guess in the short term I will be buying some aluminum specific inserts. Funny, I had no issues with brass but delrin is a different animal.-Marty
Quote from: MartyMcFly on April 03, 2021, 09:27:54 PMOh boy, I did some chores around the house and so many suggestions waiting already! Thank you guys, I really appreciate it. So I came back to the mini-lathe for some practice runs an hour ago and after reading your suggestions and doing some further research all the signs are pointing to rake and point radius as the primary culprits. I don't have any tool bits with low rake nor a grinder to make my own (yet) but I tried a carbide insert that had a little bit of nose and that helped along with slower feed. I guess in the short term I will be buying some aluminum specific inserts. Funny, I had no issues with brass but delrin is a different animal.-MartyI never tried to use inserts with Delrin however this video has prompted me to give them a try..........