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Using the Cross Slide for Threading

darkzero

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#32
Looking good Mike! Try this, before taking your last couple of final passes, run a long angle lathe file or mill file over the crests and/or scotchbrite to get rid of most of those burs. Then take your final cut & a spring pass if needed. And when you get close to your final passes, take very light DOCs before the final. Your threads should come out beautiful like this!

(This feels weird, I can't believe I'm giving The Doc advise. :confused:)

This was done on my old HF 8x14
 

darkzero

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#33
To add to this thread... (well not much really)

I always thread using the compound. That's how I was taught & that's what I'm used to. I've tried threading with just the cross slide & it came out fine on aluminum 20 TPI, 304 not so much. I don't like it, just not used to it I guess. I only tried it cause this subject came up a while back on another forum. Never knew it would make a difference for coarser than 20 TPI (good to know) but then again I never did try any coarser than 20 TPI.

I thread harder materials like SS & Ti often. Using the compound gives me better results. As Bob mentioned, another reason I like using the compound cause it's easy to keep track of DOC. When threading with the cross slide I quickly lost track of where I was at. However lots of times I will thread with the compound, then make my final pass with the cross slide.

Threads on Ti 6Al4V (grade 5)

IMG_3021.JPG

Img_1397.JPG
 

Ulma Doctor

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#34
and finally the 304....
to add to the challenge i pushed myself further than my comfort level and added the challenge of making the thread be an interrupted thread, in stub scrap 304 SS.

304ss 1.jpg
(this is the same piece of material)
IMG_2696.JPG

i used anchor lube and took .002" cuts and dialed in .031" for the stop.
i think the threads turned out very well.
i feel kinda stupid that i thought it was going to be a lot worse than it ever was :oops:

take my lead, the dragons are what you make of them.

don't waste too much time ,slay each dragon one by one!;)
 

Ulma Doctor

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#35
Looking good Mike! Try this, before taking your last couple of final passes, run a long angle lathe file or mill file over the crests and/or scotchbrite to get rid of most of those burs. Then take your final cut & a spring pass if needed. And when you get close to your final passes, take very light DOCs before the final. Your threads should come out beautiful like this!

(This feels weird, I can't believe I'm giving The Doc advise. :confused:)
I'm ecstatic that i learned something new and was able to do things differently.
i'm very appreciative of you and all the good folks here on the forum that share knowledge freely.
i can't ever be too knowledgeable to listen to good advice.
thanks for giving it to me straight :tranquility:
 

Ulma Doctor

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#36
To add to this thread... (well not much really)

I always thread using the compound. That's how I was taught & that's what I'm used to. I've tried threading with just the cross slide & it came out fine on aluminum 20 TPI, 304 not so much. I don't like it, just not used to it I guess. I only tried it cause this subject came up a while back on another forum. Never knew it would make a difference for coarser than 20 TPI (good to know) but then again I never did try any coarser than 20 TPI.
I thread harder materials like SS & Ti often. Using the compound gives me better results. As Bob mentioned, another reason I like using the compound cause it's easy to keep track of DOC. When threading with the cross slide I quickly lost track of where I was at. However lots of times I will thread with the compound, then make my final pass with the cross slide.
Threads on Ti 6AL4V (grade 5)
Wow Will, that looks beautiful!
very nice threads
 

darkzero

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#38
I'm ecstatic that i learned something new and was able to do things differently.
i'm very appreciative of you and all the good folks here on the forum that share knowledge freely.
i can't ever be too knowledgeable to listen to good advice.
thanks for giving it to me straight :tranquility:
I hear ya! Learning from your mistakes & through experience is one thing but it's great to learn from the experienced ones too. That what makes this place so great, lots of knowledgeable people with different ways of doing things!

I don't know any machinists around here but I was lucky to learn from an experienced machinist at the local CC. If it weren't for my little brother who decided to take the class cause he needed technical credits, I'd probably still be scared to single point threads. Inwas his ride there & back so I figure why not take the class with him. He took 1 semester, I finished the entire course. Good timing cause my instructor retired when I completed the course.

When I got into machining I was set to make things out of titanium. It took a lot of cussing, burnt tools, scrapped ti, & sore feet to learn, even caught my lathe on fire too! After that, most other common materials seemed so easy. I guess all beginners should start learning using Ti! :)
 

expressline99

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#39
I would say I learned from this thread...but I need compound DOC VS the dial reading of the compound explained. If this isn't on topic enough I can start a new post....and also relate this 14.5 degree setups. :)

Mike that looks great!
 

Bob Korves

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#40
I would say I learned from this thread...but I need compound DOC VS the dial reading of the compound explained. If this isn't on topic enough I can start a new post....and also relate this 14.5 degree setups. :)

Mike that looks great!
The depth of cut is the cosine of the angle times the tool travel. For your 14.5 degree angle, I assume you would set the compound to 7.25 degrees. Then you multiply the distance moved on the compound times .992 to get the achieved depth of cut. (It is really close enough to 1 to be disregarded...)
 

expressline99

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#41
The depth of cut is the cosine of the angle times the tool travel. For your 14.5 degree angle, I assume you would set the compound to 7.25 degrees. Then you multiply the distance moved on the compound times .992 to get the achieved depth of cut. (It is really close enough to 1 to be disregarded...)
Oh I meant included angle of 29 degrees so 14.5 compound setting. So distance moved times .968 ? So 100 thou in and I'd be less than 4 thou off? That's a maybe mess with maybe not....

Paul
 

Guv

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#44
To add to this thread... (well not much really)

I always thread using the compound. That's how I was taught & that's what I'm used to. I've tried threading with just the cross slide & it came out fine on aluminum 20 TPI, 304 not so much. I don't like it, just not used to it I guess. I only tried it cause this subject came up a while back on another forum. Never knew it would make a difference for coarser than 20 TPI (good to know) but then again I never did try any coarser than 20 TPI.

I thread harder materials like SS & Ti often. Using the compound gives me better results. As Bob mentioned, another reason I like using the compound cause it's easy to keep track of DOC. When threading with the cross slide I quickly lost track of where I was at. However lots of times I will thread with the compound, then make my final pass with the cross slide.

Threads on Ti 6Al4V (grade 5)

View attachment 241232

View attachment 241231
Nice thread but I really like the knurling on that handle



Sent from my iPad using Tapatalk
 

British Steel

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#45
there is a thread that I have cut that requires using the cross slide the compound is set at 90 degrees so you can advance the tool bit 1/3 of the way around the thread I was cutting was a triple lead thread that I was cutting for an apprentice project so you had only the cross slide to advance the toolbit bill
I'd have walked the spindle gear (does need it to be divisible by the number of starts though), and used the topslide at the thread angle-minus-a-bit, especially if it was a "foreign" thread, like metric cut with an Imperial leadscrew...

Dave H. (the other one)
 

Bob Korves

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#46
I would say I learned from this thread...but I need compound DOC VS the dial reading of the compound explained. If this isn't on topic enough I can start a new post....and also relate this 14.5 degree setups. :)

Mike that looks great!
The depth of cut is the cosine of the angle times the tool travel. For your 14.5 degree angle, I assume you would set the compound to 7.25 degrees. Then you multiply the distance moved on the compound times .992 to get the achieved depth of cut. (It is really close enough to 1 to be disregarded...)
Oh I meant included angle of 29 degrees so 14.5 compound setting. So distance moved times .968 ? So 100 thou in and I'd be less than 4 thou off? That's a maybe mess with maybe not....

Paul
You have the idea, Paul. .968 is closer to .003 off than .004... You will find that this job will also be tactile and visual, using your sight and hearing as well as numbers from equations... The wear will not be even, and the cuts won't be, either... Just be careful and do the best you can, no impetuous moves.
 

expressline99

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#47
The depth of cut is the cosine of the angle times the tool travel. For your 14.5 degree angle, I assume you would set the compound to 7.25 degrees. Then you multiply the distance moved on the compound times .992 to get the achieved depth of cut. (It is really close enough to 1 to be disregarded...)

You have the idea, Paul. .968 is closer to .003 off than .004... You will find that this job will also be tactile and visual, using your sight and hearing as well as numbers from equations... The wear will not be even, and the cuts won't be, either... Just be careful and do the best you can, no impetuous moves.
Wouldn't it make sense to use a 90 degree setup and use only the cross slide on existing threads(Large Acme)? Using a tool that is ground to fit the profile of the majority of the existing screw thread....the most worn part. With the side reliefs done virtually the same. If done really lightly I can't see that it would load up the tool too much. As well, with a follow rest behind the tool.

Closer to .003 :) I knew you'd catch that Bob. This is why I like having discussions with you guys. I can't get that kind of feed back from anything else I do. I think on most of the equations if there isn't a calculator on the Internet for it...basically I'm stumped. :(

Paul
 

Wreck™Wreck

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#48
i have never cut threads with the crosslide.
i was taught to use the compound @29.5*.
i should try some crosslide threading to see the differences for myself.

i'm a little reticent before starting the process, that the method may not be ideal for 304 stainless steel, which galls terribly.
but i'll give it a go!
As I mentioned below, touch off the tool and set the CS and compound to Zero, advance the compound for the first cut and leave it there, retract the cross slide to clear the thread then return to the beginning, crank the CS back to zero and advance the compound again and leave it there. This has 2 advantages, you do not have to rotate the compound dial several times to clear and it records the depth of cut on the dial. You may have never spent 40 hours per week for several weeks turning threads on a manual lathe but it quickly grows tiresome.
 

Ulma Doctor

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#49
As I mentioned below, touch off the tool and set the CS and compound to Zero, advance the compound for the first cut and leave it there, retract the cross slide to clear the thread then return to the beginning, crank the CS back to zero and advance the compound again and leave it there. This has 2 advantages, you do not have to rotate the compound dial several times to clear and it records the depth of cut on the dial. You may have never spent 40 hours per week for several weeks turning threads on a manual lathe but it quickly grows tiresome.
thank you very much for the information Wreck!
no sir, i have not done 40 hours single point threading in a year's time! much less in a week
i'm fortunate that in my normal work, taps and dies get the most work out.
i machine stuff for fun 70% of the time.
i like to learn 100% of the time :)
i appreciate your valuable input

i do have one observation, not directed at anyone specifically, just an observation.

i appears to me ...
you know you are really good at something complicated or involved , when you get bored doing it.
 
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Wreck™Wreck

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#50
thank you very much for the information Wreck!
no sir, i have not done 40 hours single point threading in a year's time! much less in a week
i'm fortunate that in my normal work, taps and dies get the most work out.
i machine stuff for fun 70% of the time.
i like to learn 100% of the time :)
i appreciate your valuable input
In my normal day any threaded part under 2" Dia. and less then 40" long I do in a NC lathe.

We have a recurring job, 2 1/2-4 X 7" long threads on a 115" long bar of 304 SS, 25 of these will take me over a week to finish on a manual lathe.
Consider yourself lucky mate (-:
 

aliva

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#51
I get much better thread form if I use the cross slide instead of the compound. I've changed the compound angle, changed inserts nothing seems to work better than using the cross slide.
 

expressline99

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#52
I get much better thread form if I use the cross slide instead of the compound. I've changed the compound angle, changed inserts nothing seems to work better than using the cross slide.
Acme as well?

Paul
 

Bob Korves

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#53
Using the cross slide for Acme should cause no problems. The angle is much narrower than 60 degree threads. The cutter should probably be ground a little differently, though, so it does not rub on the trailing portion of the cut. Get your head deeply into both types of cuts and think about how the cutting tool is following the thread form with different tool advances.
 

expressline99

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#54
Using the cross slide for Acme should cause no problems. The angle is much narrower than 60 degree threads. The cutter should probably be ground a little differently, though, so it does not rub on the trailing portion of the cut. Get your head deeply into both types of cuts and think about how the cutting tool is following the thread form with different tool advances.
Is that 5 degree on leading edge and 5 degree on trailing?
Bob could you just move up this way for a month or so....with your equipment . I think we could get some stuff done:)
 

4gsr

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#55
Some of your Acme threads can have a high helix angle on the thread, thus requiring the cutting tool relief angles to be much steeper on the leading edge and nearly perpendicular on the trailing edge. Most of your preformed threading inserts available for cutting Acme threads have plenty of clearance ground on them to take care of most threads on most diameters. I have once or twice gone in and ground a bit off the bottom of the leading edge of the insert off to give it additional clearance if it was dragging. And you can tell if it was dragging by the finish on the thread flank and shiny spots/areas on the lower edge of the insert. And it will not feel right when cutting!
 

4gsr

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#56
Is that 5 degree on leading edge and 5 degree on trailing? ..........
5 degrees should be fine Paul for most Acme threads. Again, it depends on the helix angle of the thread. You can calculate the angle. I'm rusty on the exact formula to use. If you get out your Machinery's Handbook and do some looking under "Thread Milling" I believe it is, the formula is at the bottom of one of the charts. Don't quote me on it, it's something like (pitch diameter) times pi times (1/2 pitch) = angle. Seems like there is a Tangent that is part of the equation. You guys can look and correct me on this.
 

Asm109

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#57
Lead angle= Arc tan( Thread lead/Thread circumference)

For a single lead screw, Lead= pitch Double lead, 2xPitich etc.

So
Lead angle= Arc tan( Pitch/(pi*pitch diameter))
 

4gsr

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#58
Lead angle= Arc tan( Thread lead/Thread circumference)

For a single lead screw, Lead= pitch Double lead, 2xPitich etc.

So
Lead angle= Arc tan( Pitch/(pi*pitch diameter))
That's it! Thank you.
Ken
 

British Steel

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#59
If you're cutting Acme or square threads, remember that at the root the angle's a lot bigger - lead angle will be arctan (pitch/(pi*ROOT diameter)) - this can catch out the unwary! Certainly caught me out...
You'll need to find the root angle then add a few degrees clearance on the leading edge.

Dave H. (the other one)