A
adam250r
Guest
need info on how to cut double lead threads.
all help appreciated.
thanks
all help appreciated.
thanks
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halfnut
Cast Iron
- Joined
- Apr 15, 2001
- Location
- Jasper,MO U.S.A.
They always say there is more than one way to skin a cat.
About 3 ways that I can think of to cut a double lead thread, it depends what double lead thread you are cutting, also internal or external.
The classic method is to index with the change gears, as in marking gear on headstock, rotating spindle 180 and remeshing at correct point. Some lathes have a set of divions on end of spindle and a gear disconnector for this purpose, others one must count teeth and mark.
Some double lead threads can be cut by using the thread chasing dial, this works on quite often.
If you are working between centers you can index the drive dog. If you mount center in 4 jaw chuck you can index a 2 lead of a 4. Want to cut a triple lead, use a three jaw chuck and index against the 3 jaws. Kinda hard to cut internals between centers, but there is another method for internals and a 4 jaw, if you have a shoulder to control chucking depth, one can accurately scribe indexing marks on part and locate in relationship with the chuck jaws.
Whoops I think I count 4.
Easiest and quickest way is splitting it up with the chasing dial, if possible.
What pitch are you wanting to cut, and what is your leadscrew pitch. I'll try to explain if and how it works.
About 3 ways that I can think of to cut a double lead thread, it depends what double lead thread you are cutting, also internal or external.
The classic method is to index with the change gears, as in marking gear on headstock, rotating spindle 180 and remeshing at correct point. Some lathes have a set of divions on end of spindle and a gear disconnector for this purpose, others one must count teeth and mark.
Some double lead threads can be cut by using the thread chasing dial, this works on quite often.
If you are working between centers you can index the drive dog. If you mount center in 4 jaw chuck you can index a 2 lead of a 4. Want to cut a triple lead, use a three jaw chuck and index against the 3 jaws. Kinda hard to cut internals between centers, but there is another method for internals and a 4 jaw, if you have a shoulder to control chucking depth, one can accurately scribe indexing marks on part and locate in relationship with the chuck jaws.
Whoops I think I count 4.
Easiest and quickest way is splitting it up with the chasing dial, if possible.
What pitch are you wanting to cut, and what is your leadscrew pitch. I'll try to explain if and how it works.
Forrest Addy
Diamond
- Joined
- Dec 20, 2000
- Location
- Bremerton WA USA
Another way to index multiple threads is to position the compound parallel to the bedways and dial off a pitch for each lead.
You have to cut striaght in with the cross slide unless you do a little trig and coordinate the compound with the cross slide so your tool runs down one slank.
I used to cut 23 1/2", 3 1/8 lead, 5 start ACME threads on torpedo breech rings with this method. I had the boss buy me a brand new 4" travel Starrett indicator and had it calibrated so I had a positive means of compound positioning for accurate indexing.
[This message has been edited by Forrest Addy (edited 02-21-2002).]
You have to cut striaght in with the cross slide unless you do a little trig and coordinate the compound with the cross slide so your tool runs down one slank.
I used to cut 23 1/2", 3 1/8 lead, 5 start ACME threads on torpedo breech rings with this method. I had the boss buy me a brand new 4" travel Starrett indicator and had it calibrated so I had a positive means of compound positioning for accurate indexing.
[This message has been edited by Forrest Addy (edited 02-21-2002).]
I like the ways halfnut says.Was taught Forests way.To try to explain it and make it easy to understand,sayyou want a 2" double lead.I set compound parallel to ways.Cut your first thread as usual.Feeding straight in with cross slide.Set dial indicator on compound.Advance compound half of the desired lead.In this case it would be 1".Then cut the second thread to finished size.If done correctly you will split the first thread right in two.To check measure width of thread and move compound so both sides of second thread measure the same.
