Machining metric threads on sae lathe

[bsaint]

I want to machine 1.5mm thread pitch. So would I machine it so I have .0625" between threads?

 

[MadMark]

1.5 mm divided by 25.4 mm per inch equals 0.0591 inches so I dont think it will work

Is 0.0625 the smallest you can go.
I have never machined threads, we had one machinist who could and he retired.
let me know if you know of a site that shows you how.
Good luck

 

[gj67stang]

What lathe do you have? I can do SAE and Metric threads using my little 194X 6" Craftsman lathe.

 

[bsaint]

1.5 mm divided by 25.4 mm per inch equals 0.0591 inches so I dont think it will work

Is 0.0625 the smallest you can go.
I have never machined threads, we had one machinist who could and he retired.
let me know if you know of a site that shows you how.
Good luck

Sorry in the sheet metal industry we do sloppy conversions.

.060 is doable.

I don't know the lathe that well, its at the machine shop at work. I was going to screw around with it, but the guy says he doesn't think it'll do metric threads.

 

[Ign]

The best you might get is rough it in with the closest fractional thread and then run the proper die over it. Don't go to full depth beforehand. Go maybe half to 2/3 of ultimate depth, or until it looks like a cross between acme and 60 degree threads.

Don't use it to hold the space shuttle together.

Do a practice piece before, and if it works record depth you went to on compound or cross-slide (depending upon how you prefer to thread).

Use a fractional thread pitch gage on the corresponding metric fastener to see what looks closest.

 

[NASTYZEN]

Usually ,you have to change the gears in the lead screw from sae to metric to acheive a proper tread.

 

[MBfreak]

Usually , you just alter the drive gears of the lead screw, NOT the lead screw.
Ola

 

[OccupantRJ]

1.5 mm divided by 25.4 mm per inch equals 0.0591 inches so I dont think it will work

Is 0.0625 the smallest you can go.
I have never machined threads, we had one machinist who could and he retired.
let me know if you know of a site that shows you how.
Good luck

One for you, MadMark. Chasing threads on a lathe.

http://www.metalartspress.com/60 degree threads.pdf

 

[A_Pmech]

You need a 50 tooth gear and a 127 tooth gear on the quadrant. This may or may not be supplied with your machine and may, or may not fit on the quadrant, depending on the design. There are other approximate ratios that may work for short threads. Other gears will be necessary to get into the QC box, but that will vary machine to machine.

127/50 = 2.54

There are 2.54 centimeters to the inch.

With an Imperial leadscrew, you won't be able to use the threading dial. Keep the half nuts locked until the thread is complete.

Then work out your new leads though the quick change box to find 1.5 mm / rev.

Another way to approach this, again using a 127 tooth translating gear is to pick the closest Imperial thread to your metric thread. In this case, 16 TPI.

Then, use the formula that Moltrecht provides on page 352 of volume 1, "Machine Shop Practice"

5 * gearbox setting in TPI * pitch in MM to be cut     Driving gears
------------------------------------------------   =   ------------
                           127                         Driven gears

5 * 16 * 1.5        120
------------   =   ------
    127             127

Checking:

120 / 127 = .94488

1 / 16TPI = .0625" lead

.06250 * .94488 ratio = .05906" lead

.05906" lead * 25.4 MM per Inch = 1.5001 lead in MM.