Adapting a dial thread gauge Metric Vs imperial

piscov

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Hello all,

I have a Optimum 180X300 lathe with metric set up but that can also do some thread sizes in Inches .

My problem is that this a a very basic lathe and does not have the dial thread gauge to help me threading. I am doing the threads by "eye" and some times I make mistakes.

My question are:
1) Can I adapt a dial thread gauge on my lathe? I think that yes,I can, and this lead me to the next question:

2) Will it work when I am doing an Imperial thread for instance 36TPI, or its going to work only when I am doing metric threads?? ( I am assuming i can only install a metric dial gauge as my lead screw is metric.

3) is this easy to install?

Best regards

Vasco
 
Vasco
A thread dial allows you to pick up the leadscrew in the same place each time you engage the half nuts. Depending on the thread pitch you can engage it at different segments of the dial indicator.
If you are making/adapting a thread dial for your lathe then the number of teeth on the dial gear will affect how/where you can engage it on your lathe. However if you only re-engage the half nuts on the same mark on the dial each time then you should be good to go. It may be a little slower waiting for the mark to come around, but it will be faster than reversing back to the start each time.

Cheers Phil
 
from what i now you can not use the metric thread dial for imperial threads
ore visa versa the problem is not the dail but the leadscrew it never returns to the exact place
so the treads will change every cut
so you need to keep the halfnut ingaged al the time and reverse the motor to go back
if you got no ververse direction on the lathe you need to do it by hand ore change the feed direction
please correct me if I am rong
 
That is how you must do it to cut Metric on most Imperial lathes, so it seems reasonable that it would work the same the other way around.
 
As I understand it, if you try to use the segments on the dial you wont pick up the same spot on the leadscrew but if you only use the one same mark on the dial each time then it should be ok to use.
But I stand to be corrected:whiteflag:
I will have to try this on my lathe and see what happens :bitingnails:

Cheers Phil
 
Phils right, although I am not into metrics but I think the lathe doesnt care what threads are being cut.
Its just a matter of timimg. The feed screw, the half nuts do not change, rather its the when and where
to engauge half nuts. Dials are like a vehicle speedometer a driver (feed screw) driven the dial. One
of my SBends never had one (dial) way over priced so I put an Atlas dial (dime a dozen ebay). Problem
is Atlas dial gear is a lot smaller and less teeth than the correct one, so what happens is lines and
number will not work. But it does work only on ONE mark. What I do is turn chuck by hand and when
the half nut slides in, I will engauge the mesh on the dial on say No.2. And No 2 will be the number
through out the operation. I write this if you wish to make your own. I use to run a speedometer
cable off the leed screw to a cardboard dial with a pointer it did work, didnt look good, then the old
timers use to paint gear teeth at engaugement points. Also I was never a beleiver in reversing the
machine that only puts more wear Now, on both sides of the half nuts. samuel
 
As I understand it, if you try to use the segments on the dial you wont pick up the same spot on the leadscrew but if you only use the one same mark on the dial each time then it should be ok to use.
But I stand to be corrected:whiteflag:
I will have to try this on my lathe and see what happens :bitingnails:

Cheers Phil


Hi Phill,
If you could try it would be great. Please let me know.

I will only buy the dial thread if I'm certain it will do the trick. The threads I need to do have 3-5 mm long and no more than 1 mm deep. Maybe I will be ok doing JT says. I will not even use the motor, I will rotate by hand. This threads are made on plastics.

Cheers

Vasco
 
i wonder how mutch wear will occure on the half nut after backing up the cutter en reversing the machine
i tought it was that way most modern machines are used to cut threads
another thing he will not need the dail
 
Normally, the half nut is disengaged at the end of the thread, and the carriage is run back to take another pass, with the thread chasing dial used to synch the half nut to the previous pass.

For such a shallow cut in plastic, I'd be tempted to do it all in one pass, once I have proven what the DoC should be. Not necessary to hand feed it, unless you are very close to a shoulder and don't feel comfortable under power. If done in a single pass, no thread chasing dial needed at all.
 
Something that helps clarify the concept of a thread dial is to set a ruler on the ways and with the power off and thread dial engaged move the carriage noting the inches of travel and what numbers are indicated on the thread dial. Conventionally one number on the dial represents one inch of travel..... but not always if the lead screw has an unusual pitch. When operating that dial is simply an imaginary ruler travelling down your threaded piece.
Logically if you are cutting threads per inch you can pickup on every inch. You cannot pickup on a half inch mark on the thread dial if you are cutting 11 threads per inch because you would be five and a half threads along your work. Having a imperial thread pitch on your lead screw prevents you from picking up on a metric thread. If you had a 3 mm pitch lead screw you could easily pickup on threads that were a multiple of 3mm such as 6mm but you would have difficulty picking up on a thread pitch of say 2 mm.
 
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