need help with 3/4" 16 tpi thread

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Anko

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hi to all!

just got this little problem, i need to cut a inner thread 3/4" 16 tpi, for a wood lathe

im making some kind of live face plate for the tailstock, that has a mt1 morse taper (too small for the size of the piece) and a 3/4" 16 tpi thread in the outside diameter.

in the thread chart that comes in my lathe, almost 80% has been erased for the use and years of the previous user, so all the information I got to set the lathe to cut a 16 tpi thead are :-\ :

the configuration onf the gears in the back of the headstock

gearsqlsinch.jpg


the controls at the gearbox are:

the knobs: AD

the levers: NV

my lathe are identically to the 13" x 40" gear-head floor lathe that sells Grizzly

just the carriage is diferent

g9036.jpg


just need the missing gear to continue, if someone has this lathe please help

thanks for your time

Saludos!
 
Hi Anko,

Love to help! tell me the pitch of your leadscrew thread?

It would appear to be metric based on the transpostion gear ( 127/120)

Is the 40 tooth gear on the back of the spindle?


Dave
 
i happen to have this lathe also and if i remember right since i cant look at the moment,the 48 tooth gear is used for most standard threads with the exception of a few that use the 52 tooth. also i believe that only one part of the double gear is used, meaning either the 120 tooth side or the 127 tooth side, not both. like i said im not looking right at it but i think thats right. you could always chuck up a piece of scrap and make one light pass and check the pitch. i will try to remember to take a picture of the chart for your future reference.

zach
 
If you go onto the Grizzly site and select your lathe you can download the user manual, this should have all the gear charts in it.

Jason
 
i thought the sae thing jason but i looked at it last night it just shows the chart for metric threads
 
heres a photo of the chart, i think the one you where looking at is the D.P. chart, i dont know what that is exactally but its not what you want.

DSCN0151.jpg
 
ok!!! thanks

if helps, the lead screw is a 8 TPI or 3mm pitch

i now understand why the bottom gear not have a number, its a arrow!

still the numbers in that part are gone, but looking very hard im able to see a 4 against the light

i believe that is a 40 gear for cut the 16 tpi, but maybe can be the 42

just got the piece chucked, and i dont want to pull out because i will lose the concentricity, so i cant make a test cut, the lathe has a d1-4 camlock, i dont know if I change the entire chuck for the 4 jaw to make a test cut, then when i pull back the chuck it will be concentric just like nothing hapens

what do you think??

thanks for all the responce!

Saludos
 
The way I read the chart is for 16 tpi lever AC and NS with a 48 tooth gear on the lead screw.

You should be able to change chucks with a D-4 camlock and have the chuck seat the same way after all is that not the whole point of a camlock system?

Dan
 
The chart below is for a metric lead screw because the first part of the compound gear train is using the 127 tooth gear to produce an imperial thread.

For something as accurate as a thread knowing the pitch of the lead screw is essential, a 3mm pitch leadscrew is 8.466667 threads per inch. An 8 tpi leadscrew has a metric pitch of 3.175 mm.

As you can imagine this is significant if you want the thread you make to fit the standard bolt/nut of the system you are working towards.

Hope this helps

Best Regards
Bob
 
Hi Anko
Nice lathe u have there.To see if your lead screw Is imp or metric,hold a steel rule against it and count the tpi,
make sure there is an equal number of threads and spaces for imperial eg 8 threads and 8 spaces.
if not u will prob find u have a 3 mill pitch lead screw.
merry Christmas Pete.
 
Dan is right 32 tooth at top, then 127, then 48, levers at NS, knobs at AC. the number of teeth in the middle gear is irrelivant because in this setup its just an idler to move power from one shaft to anothe so has no effect on the overall gear ratio of the train, all that matters is the first and last gear.
 
hi to all!

seems that the hardware in my lathe is siggly different from the grizzly version, because i can see clear that for cut a 16 tpi the gear configuration uses the 127 and the 120 gears in AD and NV lever configuration...

maybe the lead screws have a different pitch

achieved anyway to make a test cut in the workpiece, just pas the tool to make just a tiny line of the thread, then measure with a pitch gauge, and the result was the 40 teeth gear!

finally i was able to cut my first internal thread, and first inch thread too

the piece I was working on get finished:

p1040059f.jpg


p1040057x.jpg


thanks to all for the help!!!!

i will try to rescute the thread chart from my lathe and pass it to paper, because seems that my lathe gear configuration is diferent for the actual grizzly lathe, all the casting and form are identically exept for the carriage and the thread cutting so far..

Saludos
 

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