Newbie- how to adjust speed of the transmission

[scampo77]

is there a chart that helps me determine the speed that the table travels? right now it is moving super fast and i need to slow it down. also ill need to know how to have the correct speed for cutting corse or fine threads or even machine threads. i have figured out what the #2 gear does it seems to determine which way the bed travels. and the #7 gear is attached right to that long worm gear (what is the correct name for that?). i have a box of gears that came with it so i can start digging for the correct numberd teeth if someone could just point me in the right direction.

i do plan to most be making bolts with my "new" lathe, once i get the speed figured out is it the same speed for all diameter bolts? ie; when i get it adjusted for corse threads will all diameter steel be cut with corse threads on it?

how do i sharpen my bit? is there a guage i can buy to make sure the thread pitch is correct? do i just sharpen the bit into a triangle shape and start cutting or do i need a special bit?

[hoss2006]

This page could help,
He explains the change gears on the Myford 7 and even wrote a program to tell
you which gears to use for different pitches.

The change gears you posted in the other thread look rough, if you need new ones
they sell spares here.

If you're grinding your own 60 degree tools this gage is good.
Or you buy some cheap carbide threading tools.
Hoss

[LUCKY13]

I would also suggest you joining this forum and searching the SouthBend section very much. You will find all kinds of links, info and things that will help with your lathe and using it. These guys are all about using there manual lathes so they tend to come up with a lot of info one way or the other. It will take a lot of time really but its worth it for knowing how,what and when you need it.




Lathe Forum


Jess

[scampo77]

ok i am going to try this again. i have the program and im reading the tutorials that come with the program. i dont understand which one of these gears is an idler and which one is a "lead screw". the instructions say

The settings are: First stud (furthest from the lead screw), second stud then
lead screw. The lead screw always has just a single gear. The stud's have
either a driver/driven pair, or an IDLER.

most of the settings say to put an idler on the "lead screw". how do i know if its an idler gear?

[HimyKabibble]

Originally Posted by scampo77 ok i am going to try this again. i have the program and im reading the tutorials that come with the program. i dont understand which one of these gears is an idler and which one is a "lead screw". the instructions say The settings are: First stud (furthest from the lead screw), second stud then lead screw. The lead screw always has just a single gear. The stud's have either a driver/driven pair, or an IDLER. most of the settings say to put an idler on the "lead screw". how do i know if its an idler gear?

An "idler" is simply any gear inserted between a driven gear and a driving gear. It's called an idler because it contributes nothing to the overall ratio of the gear-train. Rather, it's there simply to either put the driving/driven gears in the required spatial positions, and/or to reverse the direction of the driven gear. Suppose you have a gear train consisting of an 80 tooth gear, driving a 40 tooth gear. This will give a 2:1 speed ratio, with the driven gear turning the opposite direction from the driving gear. Now insert a 60 tooth gear between the 80 tooth and 40 tooth gears. The overal ratio remains 2:1, but the driving and driven gears now both turn the same direction. You can just as easily slip *any* gear between the 80 and the 40, and the operation will remain completely unchanged.

Regards,
Ray L.

[scampo77]

but according to the picture i have posted, which one is an idler? and according to this program which is the stud 1 and stud 2.

do i ever change the very first gear on the end of the head stock?

[HimyKabibble]

Originally Posted by scampo77 but according to the picture i have posted, which one is an idler? and according to this program which is the stud 1 and stud 2. do i ever change the very first gear on the end of the head stock?

In your picture, #2, #3, and #6 are all idlers. Any gears that are not directly driven by the input power source (as #1 is), or directly driving the load (as #7 is), or locked to another gear (as #4 and #5 are), are idlers.

Not having one of those machines, I can't tell you for sure what they call stud 1 and stud 2, but I'd guess stud 1 is the stud on which gear #5 is mounted, and stud 2 is the stud on which gear #6 is mounted.

No, you never change the gear on the spindle.

Regards,
Ray L.

[scampo77]

so i have taken off gear 3,4,5 and 6. gear 3 i suspect has been turned into an idler because it is 2 gears on top of each other with the same amount of teeth (25) you cant see this from the picture but #3 is actually 2 gears

the program says this

tpi actual stud 1 stud 2 lead
20 20 idler idler 50

i am tryiing to cut 7/16 UNF thread for my first attempt. i beilieve this is 20 tpi

so if i eliminate the double gear thing on #3 and #4,5 and put power directly to any single gear in position #4,5. leave #6 in place and put a 50 on the end of the lead screw. will this be correct?

[scampo77]

i tried and it didnt work. the threads are out a bit

[scampo77]

is it possible that the gear on the end of the headstock has the wrong amount of teeth? if i put a 50 on the lead screw and the rest are idlers. it should be a simple calculation to figure out what the head stock gear should be. im tryiing to cut 20 TPI and its not working.

[HimyKabibble]

Originally Posted by scampo77 is it possible that the gear on the end of the headstock has the wrong amount of teeth? if i put a 50 on the lead screw and the rest are idlers. it should be a simple calculation to figure out what the head stock gear should be. im tryiing to cut 20 TPI and its not working.

Calculating the proper gears is quite simple. First, you need to know how many teeth on the spindle gear. Count them, if necessary. Next, you need to know the pitch of the leadscrew. Here, you must be sure you know *exactly*, by measuring very carefully. Sometimes you'll have a metric screw that's *close* to a nice Imperial pitch, or vice-versa.

The TPI will be:

S = # of teeth on spindle gear
L = # teeth on leadscrew gear
P = pitch of leadscrew, in turns per inch

TPI = S * P / L

So, if we assume:

S = 80
L = 40
P = 10

TPI = 80 * 10 / 40 = 20

Or, in reverse:

L = S * P / TPI

So,if you're after 20 TPI:

L = 80 * 10 / 20 = 40

Regards,
Ray L.

[scampo77]

i went digging through the box of goodies that came with the lathe and i found what apears to be a pitch guage for gears. i can get one to fit in the gears but i dont know what the info on the guage means.

.0500 ADD, .1079" full depth, 20 D.P., .1571 CIR. PITCH

and they seem to be the same both the spindel gear and the lead screw gear. the spindel gear is 25 teeth and the spindel is 50. this is what the speed program is telling me what is correct and it still wont cut at 20 TPI