Chris Hi, You may want to cut a 27TPI thread its a 1/8 NPT standard. yours J.B. > Message Received: Jan 27 2007, 04:44 PM > From: "Chris Crosskey" <chris.crosskey@xxxxxxxxx> > To: modeleng@xxxxxxxxxxxxx > Cc: > Subject: [modeleng] Re: coarse threads > > I've cut a lot of funny threads (ie metrics and BA) on my gearbox kitted > ML7.... I do own (because I'm weird) every single Myford changewheel bar > the 96 and I've found that if I swap the 12/25 compound that runs the > gearbox normally (it's an early one so it uses a 12/25 rather than the > later 24/25) for the normal Myford 25-tooth compounding gear it will > take any gear up to 48T on the stub before it interferes on the > reversing gears. That gives me a range of 28 gears (IIRC one of the > 40-something gears isn't made but I think I have all the 20's and 30's) > that can go in there all of which will produce coarser threads if the > lathe is run in normal screwcutting setting on the gearbox, flip the > finefeed gear over so that it's in finefeed (divide screwcutting TPI by > 9) and run the numbers on the wheels and some remarkably close > approximations to an awful lot of threads drops out, most of the small > metrics, the BA's down to about 10 or so etc.... If they're not enough I > can always reach for the DAG Brown extended range banjo and run two > compounds of changewheels into the gearbox.... I refuse to believe > there's a thread between about 1TPI and 100TPI that I can't get to > within a percentage error of less than 0.5% on....... Still don't know > why on earth anyone would design a standard lathe to cut 27TPi though, > it means you'd probably have 13.5TPI and 54 TPI in the box too, though > if the numbers dropped out easily enough I suppose it's only costing you > half an inch of box width and one gear...... > It's still a bonkers number though..... > > chrisc > > -----Original Message----- > From: modeleng-bounce@xxxxxxxxxxxxx > [mailto:modeleng-bounce@xxxxxxxxxxxxx] On Behalf Of Jesse Livingston > Sent: 27 January 2007 16:17 > To: modeleng@xxxxxxxxxxxxx > Subject: [modeleng] Re: coarse threads > > Jesse, my old Logan-made lathe will cut 27 tpi. > > Al Messer > > I wonder why? There is no use for 27tpi except in 1/8" pipe threads. > Seems > that it would require a bunch of extra gears to the QC box- - -- -or > does > your lathe not have QC? Easy to do with change gears, but apparently > not > for a QC box lathe. > > REDNECK Jesse > > MODEL ENGINEERING DISCUSSION LIST. > > To UNSUBSCRIBE from this list, send a blank email to, > modeleng-request@xxxxxxxxxxxxx with the word "unsubscribe" in the > subject line. > > ________________________________________________________________________ > This e-mail, and any attachment, is confidential. If you have received it in > error, do not use or disclose the information in any way, notify me > immediately, and please delete it from your system. > ________________________________________________________________________ > MODEL ENGINEERING DISCUSSION LIST. > > To UNSUBSCRIBE from this list, send a blank email to, > modeleng-request@xxxxxxxxxxxxx with the word "unsubscribe" in the subject > line. > > MODEL ENGINEERING DISCUSSION LIST. To UNSUBSCRIBE from this list, send a blank email to, modeleng-request@xxxxxxxxxxxxx with the word "unsubscribe" in the subject line.