RezRocket Posted March 20, 2020 Share Posted March 20, 2020 Ok boys I need some help. I just bought a 1911 milling jig from 1911 builders. Normal set up indicated level and decked the frame. Problem came in when I went to mill the rails. Used a 3/32 woodruff cutter to cut the rails. Touched off and cut first rail 0.005 with a slow feed rate no problems on a 600 lbs. bench mill. Moved over to cut the other rail half way through the 1st cut my cutter suddenly dipped into my jig. I stopped and indicated and was out by 0.020. Reindicated level and really cranked the vise down. And again same story stupid jig moved. Any recommendations on how to hold it still or any better jigs out there....angle plate....lateral jig? I don't know. Any one else with experience would be very appreciated. Thanks guys. Link to comment Share on other sites More sharing options...
38super Posted March 22, 2020 Share Posted March 22, 2020 Back lash. Link to comment Share on other sites More sharing options...
ltdmstr Posted March 22, 2020 Share Posted March 22, 2020 Sounds like the vise isn't clamping evenly. First guess would be poor machining on the fixture. Link to comment Share on other sites More sharing options...
RIIID Posted March 22, 2020 Share Posted March 22, 2020 Start with the part, is it held in the jig securely? Then jig to the vise, vice to table, table to the knee. Indicate the travel of the table, some where along the line of testing you will find the problem. Rich Link to comment Share on other sites More sharing options...
RezRocket Posted March 22, 2020 Author Share Posted March 22, 2020 7 hours ago, 38super said: Back lash. Have a Digital Read out on 3 axis (x,y,z the head and the quill) it isn't moving and the DRO negates backlash. Head is in tram vise indicated is still perfect and square to the table. Link to comment Share on other sites More sharing options...
RezRocket Posted March 22, 2020 Author Share Posted March 22, 2020 6 hours ago, ltdmstr said: Sounds like the vise isn't clamping evenly. First guess would be poor machining on the fixture. 1 hour ago, RIIID said: Start with the part, is it held in the jig securely? Then jig to the vise, vice to table, table to the knee. Indicate the travel of the table, some where along the line of testing you will find the problem. Rich I did not consider the jig being out. With a micrometer at the base is 0.020 thinner under the dust cover than the grip side. Enough to make it move apparently Link to comment Share on other sites More sharing options...
38super Posted March 24, 2020 Share Posted March 24, 2020 DRO prevents backlash, use that for your next job interview. Link to comment Share on other sites More sharing options...
RezRocket Posted March 24, 2020 Author Share Posted March 24, 2020 12 hours ago, 38super said: DRO prevents backlash, use that for your next job interview. I am not the authority on milling and am certainly not a machinist as evidenced by my asking questions here. I mean no disrespect but am just seeking to learn as much as I can to improve. Correct me if I am wrong. I thought that backlash was a play in the gears or screws that affected movement in the table and head relative to the dial on the handle. Maybe my choice of words was incorrect with "prevents" as I understand that the DRO more so negates the need to ensure backlash is taken out of the gears before starting a measurement based on the handles readings as the Digital Read Out only measures actual movement of the table. If I am wrong in this I would appreciate help to understand better and am open to any input. Link to comment Share on other sites More sharing options...
MikeBurgess Posted March 24, 2020 Share Posted March 24, 2020 2 hours ago, RezRocket said: I am not the authority on milling and am certainly not a machinist as evidenced by my asking questions here. I mean no disrespect but am just seeking to learn as much as I can to improve. Correct me if I am wrong. I thought that backlash was a play in the gears or screws that affected movement in the table and head relative to the dial on the handle. Maybe my choice of words was incorrect with "prevents" as I understand that the DRO more so negates the need to ensure backlash is taken out of the gears before starting a measurement based on the handles readings as the Digital Read Out only measures actual movement of the table. If I am wrong in this I would appreciate help to understand better and am open to any input. Backlash is the movement allowed by the slop in the lead screws, a DRO will allow you to get to a position without worrying about taking the slack out of the lead screws but the lash is still there and can allow the table to move if it is not locked in place, yes this movement will register on your DRO but it likely will happen during a cut when its too late. Not saying this is what is happening just an explanation of the point made. Link to comment Share on other sites More sharing options...
38super Posted March 24, 2020 Share Posted March 24, 2020 Just because I have machinery, doesn't make me a Machinist. To describe every step would take 3 pages of text, and it would assume the user has a working knowledge of machining. So in simple terms, your jig should measure equally across all 4 corners while secured in your mill vice. A word about back lash, it can cause the mill table to jump when you reverse direction. Practice on some scrap, learn your machine;. https://www.hobby-machinist.com/forums/ http://www.homegunsmith.com/cgi-bin/ib3/ikonboard.cgi http://www.weaponsguild.com/forum/index.php?PHPSESSID=h4c7ugkcsn3ko8rj9bujbj8ec0;wwwRedirect https://www.cncguns.com/ Link to comment Share on other sites More sharing options...
assaulter Posted March 29, 2020 Share Posted March 29, 2020 Are you climb milling the side that is jumping? Link to comment Share on other sites More sharing options...
RezRocket Posted March 30, 2020 Author Share Posted March 30, 2020 Resurfaced the jig and added hex head support screw under unsupported side of base of the jig. Indexed it to the right height and Problem solved. Rails cut and no more moving. Thanks for everyone's input. Link to comment Share on other sites More sharing options...
38super Posted March 31, 2020 Share Posted March 31, 2020 Dang, you didn't launch the part. Links to this old tony, oxtools and robrenz. I like TOT's humor, the last two are worthy of master model maker. The last is a word about shop safety, pls do not become a casualty. https://www.youtube.com/channel/UC5NO8MgTQKHAWXp6z8Xl7yQ https://www.youtube.com/channel/UCZC9LGZLfyjrKT4OZne-JNw https://www.youtube.com/channel/UCn4U3aEr6L2nLe1m_3as6JQ https://www.youtube.com/watch?v=S0o8kdh8HWs Link to comment Share on other sites More sharing options...
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