They said go big!

All discussion about lathes including but not limited to: South Bend, Hardinge, Logan, Monarch, Clausing and other HSM lathes, including imports

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vair8
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Location: Ogden, UT

Re: They said go big!

Post by vair8 »

BigDumbDinosaur wrote: Sun Feb 28, 2021 2:53 pm How accurate does this circular hole pattern have to be? While I have fudged in the past and laid out a circular hole pattern in a lathe (key word: laid out—the drilling was in a drill press), the layout wasn't all that accurate due to cumulative slop and I ended up redoing the part in a mill. It's best to not use a hammer to put in a wine bottle cork.
So It doesn't have to be super accurate on this first part, it's just an end cap for a suppressor, and I planned on drilling holes to use a standard armorers wrench to take the end caps off. the bolt patterns for rotors will probably need to be a bit more accurate.
mklotz wrote: Sun Feb 28, 2021 3:05 pm How about old-fashioned hand layout? Draw a circle of diameter 'D' on your stock, then set your dividers to a chordal length 'C' given by:

C = D * sin (180 / N) ; where N = number of divisions

and use them to strike off N points on the circle.
I thought about laying it out on the lathe but my drill press tends to wobble a bit, and my marks will be accurate, but I won't be able to get it to drill where I want haha.
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rmac
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Re: They said go big!

Post by rmac »

Again if manual procedures would be accurate enough, you could bring Marv's idea into the 21st century by laying out the bolt pattern in a CAD program, printing it on paper, and pasting the paper onto your part. That would at least eliminate any inaccuracy introduced by imprecise manual drawing.

-- Russell Mac
vair8
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Re: They said go big!

Post by vair8 »

rmac wrote: Sun Feb 28, 2021 5:14 pm Again if manual procedures would be accurate enough, you could bring Marv's idea into the 21st century by laying out the bolt pattern in a CAD program, printing it on paper, and pasting the paper onto your part. That would at least eliminate any inaccuracy introduced by imprecise manual drawing.

-- Russell Mac
And I've done that with parts when I built my CNC plasma table, but I just couldn't manage to get my holes to actually be really centered. It was good enough for what I was doing. I printed it, and used a spring-loaded center punch, then a center drill, and then my drill size, but I would always be off by just a little bit.

I think I'll do that for this part I'm trying to make, but I would like a way to be more accurate for future parts.

Maybe I should scrap the idea of doing it on a lathe and just wait and save up to buy a mill.
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Harold_V
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Re: They said go big!

Post by Harold_V »

vair8 wrote: Sun Feb 28, 2021 5:20 pm I printed it, and used a spring-loaded center punch, then a center drill, and then my drill size, but I would always be off by just a little bit.
I never recommend the use of a center punch unless you're drilling with a drill motor, by hand. They are usually the reason a hole isn't where it's wanted, as they are easily deflected, plus difficult to locate at the outset.

You can improve your degree of accuracy immeasurably by simply picking location with a wiggler, followed by a center drill or spot drill to establish the hole location. That works exceedingly well if you have reasonably good vision and can layout well. A fine line really helps ( a sharp scriber, and, even better, lines scribed with a height gauge). I've seen locations consistently held to ± .005" that way. If you use a drill press, clamp your work to the table, so once you've established location it doesn't move.

H
Wise people talk because they have something to say. Fools talk because they have to say something.
vair8
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Re: They said go big!

Post by vair8 »

Harold_V wrote: Mon Mar 01, 2021 2:03 am
vair8 wrote: Sun Feb 28, 2021 5:20 pm I printed it, and used a spring-loaded center punch, then a center drill, and then my drill size, but I would always be off by just a little bit.
I never recommend the use of a center punch unless you're drilling with a drill motor, by hand. They are usually the reason a hole isn't where it's wanted, as they are easily deflected, plus difficult to locate at the outset.

You can improve your degree of accuracy immeasurably by simply picking location with a wiggler, followed by a center drill or spot drill to establish the hole location. That works exceedingly well if you have reasonably good vision and can layout well. A fine line really helps ( a sharp scriber, and, even better, lines scribed with a height gauge). I've seen locations consistently held to ± .005" that way. If you use a drill press, clamp your work to the table, so once you've established location it doesn't move.

H
I didn’t know what that was, but watched some videos, decided to order one and it just shipped in, thanks for the advice!
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Steggy
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Re: They said go big!

Post by Steggy »

Harold_V wrote: Mon Mar 01, 2021 2:03 am
vair8 wrote: Sun Feb 28, 2021 5:20 pm I printed it, and used a spring-loaded center punch, then a center drill, and then my drill size, but I would always be off by just a little bit.
I never recommend the use of a center punch unless you're drilling with a drill motor, by hand. They are usually the reason a hole isn't where it's wanted, as they are easily deflected, plus difficult to locate at the outset.
I can't see well enough anymore to get the point of a regular center punch right on the intersection of the scribe marks. Sometimes I can feel it, but that's not reliable. So I use my optical center punch to mark the hole, and follow that by center drilling in the drill press (mine isn't "wobbly," whatever that means). With the optical center punch and a little patience, I can achieve repeatable accuracy within 0.01".

I have never found a good use for a spring center punch. They don't punch deeply enough to suit me.
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rkcarguy
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Re: They said go big!

Post by rkcarguy »

Nice big lathe!
There is quite a few like that which come up for sale around here, and they go cheaper than a small SB9 because very few residential places have 3-phase power here. Is yours 3-phase?
vair8
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Re: They said go big!

Post by vair8 »

rkcarguy wrote: Thu Mar 04, 2021 2:44 pm Nice big lathe!
There is quite a few like that which come up for sale around here, and they go cheaper than a small SB9 because very few residential places have 3-phase power here. Is yours 3-phase?
Mines single phase luckily. It’s already come in handy having the length. I was able to cut some pipe threads on a 9’ long pipe this week.
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atunguyd
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Re: They said go big!

Post by atunguyd »

Did you just post a picture of a key in a lath chuck?

If I put my ear to the ground I can hear them coming...


Time to run away [emoji846]

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Steggy
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Re: They said go big!

Post by Steggy »

vair8 wrote: Thu Mar 04, 2021 9:50 pm
rkcarguy wrote: Thu Mar 04, 2021 2:44 pm Nice big lathe!
There is quite a few like that which come up for sale around here, and they go cheaper than a small SB9 because very few residential places have 3-phase power here. Is yours 3-phase?
Mines single phase luckily. It’s already come in handy having the length. I was able to cut some pipe threads on a 9’ long pipe this week.
Oh, look! An unguided missile launcher (i.e., chuck key in chuck).
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Music isn’t at all difficult.  All you gotta do is play the right notes at the right time!  :D
earlgo
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Re: They said go big!

Post by earlgo »

Unguided missile launcher: hah. I was 15 when I turned on the lathe with the key in the chuck. At 78 I can still feel the bruise it left on my breastbone. I have not left a key in a chuck since. If it had hit me in the face with no safety glasses, I would have been blinded.
DON"T DO IT!
--earlgo
Before you do anything, you must do something else first. - Washington's principle.
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Steggy
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Re: They said go big!

Post by Steggy »

earlgo wrote: Fri Mar 05, 2021 11:01 am Unguided missile launcher: hah. I was 15 when I turned on the lathe with the key in the chuck. At 78 I can still feel the bruise it left on my breastbone. I have not left a key in a chuck since. If it had hit me in the face with no safety glasses, I would have been blinded.
DON"T DO IT!
--earlgo
Yep! Them unguided missiles can sure hurt when they find their targets.

I got smacked in the chest years ago by a flying 2 inch end mill. The thing snapped off right where the shank came out of the collet. Despite wearing a shop coat at the time the damned thing managed to draw blood. Good thing I wasn't crouched over watching the cutting action!
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Music isn’t at all difficult.  All you gotta do is play the right notes at the right time!  :D
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