Why Bother Measuring Threads At All? Quick Machining Tip #19
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- čas přidán 27. 08. 2024
- Another viewer question answered! Why should we bother to measure threads when mating parts exist? This is a great question courtesy of George Georgiev and was asked in my video "Fitting a Boring Head Shank to a Tenthset Boring Head".
• Fitting a Shank to a T...
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/ stuartdeharo
Lacking a formal technical education, I spent 7 years studying economics, I rely on the Machinery's Handbook and tips from experienced machinists for my education. Didn't fully understand why wires were used until now. Took, what, less than 30 seconds to explain. Thank you so much for the videos. They help enormously as does your willingness to answer questions, no matter how basic.
excellent job explained perfectly keep up the good job
WOW! This is very timely for me,lol. I am currently pursuing my “ plan B “ ( tech school, “ Precision Machining “ ) . I am working on a project that has two threaded parts that, to be brutally honest, have been kicking my butt! However, having shared that, I have finally gotten the hang of it ( and also of using the thread micrometer. Haven’t graduated to the 3 wire method yet ) . Thanks for the video, and the rest of your stuff so far 👍 ( I don’t know what the praise of the oldest freshman in Precision Machining is worth…. But you’ve got it buddy!)🤙
Some of the best students I've ever had have been older and going through a career change. They have already gone through a bit of life and figured out what works for them and what doesn't. Most importantly, the know that they need to work for what they want. The worst students are generally the ones that are fresh out of high school and still think they know everything.
Interesting 😄 …… 👍👍😎👍👍
Also, removing the part from the chuck to test fitment on a larger assembly is impractical. Worse, if making parts requiring strength in assemblies(such as aviation parts), loose vs in-spec can mean a difference not only in strength but in wear and ultimate failure. Since there are classes of threads with various tolerances, guessing and test fitting won’t hit the numbers and that’s what customers pay for.
If we’re talking a swing set or wheel barrow thread, who cares? We wouldn’t likely use a lathe for that anyway. Hardware stores exist for such things. For those who can’t believe or don’t care that there’s a difference in thread tolerances, there are regulations.
Timely,
I’m so frustrated with thread wires I broke down and bought a 0-1” and a 1-2” thread micrometer set.
I have a problem with something that needs to be threaded to a stub Acme #8. It's the nut for my lathe cross slide. I have already replaced it once for $193.00 and the replacement was already .012" oversized on the bore when new so it will wear very fast and introduce hellacious slop into the dials. The manufacturer has no other replacement parts and they have little if any QC. I will need a way to measure the internal thread when I go to make it which is an upcoming project. How do you measure inside threads correctly? Also, what would you recommend for a bronze alloy fit for purpose that is readily machinable?
Hi Scooter. This is an instance where test fitting with the mating part would be in order. It only has to fit that one piece, so once it fits you're good. Just start test fitting early and sneak up on it. I'd use cored bronze rounds for it. Should be alloy 932 which machines beautifully. It's sold in nominal sizes such as 1-1/2 x 3/4 but the OD is always oversized and the ID is undersized so you can finish to those dimensions. It's usually around 1/16 or 1.5mm over/under. Good luck! BTW Don't forget to check if it's right or left handed!
@@StuartdeHaro Thank you for confirming what I had already suspected which is a custom fit to the worm. Fortunately I have another worm to work with so it would not be a terrible trial. I shall be looking at McMaster Carr for material requirements. Thread is definitely right hand. Another thing I have toyed with is the possibility of making a tap but that could prove to be a fools errand so it is a secondary idea.
I was looking at ebay listings yesterday and saw something called thread triangles. I was wondering if you have had any experience with using them to measure threads. They seen to be easier to use than thread wires.
Thanks
I've seen them but never used them. Maybe I should buy a set and see what they're like.
Nowadays they also make holders for the thread wires recognizing the difficulty had by most in holding them and then measuring across them.
Stuart or anybody i have a older bridgeport that was doing fine but even trammed in to within 4 tenths in x and y its still leaving a small ridge you can feel with your finger nail and it never has before i wish someone had some suggestions on this problem oh and its not the cutter it does it with my 3/4" 1" and 2" the bigger the cutter the worse the ridge, its about to drive me crazy and i have checked the tram before and after and the tram shows within 4 or 5 tenths every check
Hmm. That's an odd one. What's your method of checking the tram?
@@StuartdeHaro 2 dial indicators on a bar chucked in the spindle in a r8 collet set to zero at the same point on the table
@@le3045acp Double check it by sweeping in the head with an indicator mounted in the spindle. I had my apprentice make up a spindle square like that at work and something ended up not quite right with it. I had him drill, bore, and ream all the holes in the same operation, but something got misaligned and it never works. My guess is the center pin went in a little crooked and it sweeps around in a plane that is angled to spindle axis, so even if it is zeroed at the same point on the table it will be too high or low when swept to the other side.
I've only used a single,
tenths or .002mm dial gauge, sweeping larger in X than in Y.
And patience.
4 tenths isn't good enough, sorry.
Your problem is you set the tram on the table. A universal mistake. No one seems to know that you must set the tram to the TRAVEL and not the table. Setting to the table only works if everything is perfect. Do This:
Take a piece of scrap big enough to tram off of (ex: 6x6 or so) and clamp or hold it to the table or vice. Machine a strip in the scrap in X at least 6 inches and machine another strip in Y the same length. Tram your head to THOSE surfaces.
A second issue is that the alignment of the machine can and does change under power vs in neutral because the motor torque pulls it out. If you trammed as I said and it still has steps then you have to find out what is loose, the quill , the bearings, the casting etc and fix it or compensate for it.
When you are done you should have even cross hatch marks (not the pretty scallops)when facing across in both directions in X and Y if not , its still not square keep going at it. A square machine will always have the trailing edge of the cutter leave a witness mark in every feeding direction.
Okay burning question, why do you keep a propane tank so close to a hot chip maker? Just a joke, my space is multiple purpose also, the jeeps live there, lol.
Hot stuff to me. Not right or wrong.Not proper or improper.Not mountain or beach.Either you set the rules for your project or somebody else does it.Both cases are legitimate and real.You just act accordingly in either case.In my case I managed so far to get my lathe-mill in a fairly high precision working conditions after many years of up and down learning and trying and keeping buying.And now,what?I have to decide.I don´t want to make another tool and putting it in a box and so on.This is my challenge.At the same time I made my motorized almond cracker and I use it all the time and made some kind of support to cut my fire wood in a good size and use it.I decide what is right and what is not and keep trying.Thank you.
Or, if you use wires and know its right but a nut doesnt fit there is likely a burr. If you try a nut and machine to fit, irrespective of burrs, it will be like p***k in a shirtsleeve when the burrs get rubbed away.
But in the real world are you doing a quick and dirty or making a micrometer?
I do what the job demands, but usually that means I'm measuring.
@@StuartdeHaro absolutely! Leave the rough stuff to bolting hinges to garden gates. 😉
Not real sure how to phrase this question, it's kind of an ambiguous concept. I know every generation thinks that the next are fools and that their culture is silly. I'm middle-aged now, and I certainly have that reaction to modern music and youth politics, pretty much everything about young people other than their recent organizing for general strikes is odd to me. None of that is my question though. While trying to separate my generational biases, when I look around at youth culture these days, I am particularly struck by the change in art. There seems to be an enormous utilization of auto-tune and no effort to disguise this. I guess it is cool to sound robotic? Leaving that aside, because music seems to be a particularly difficult thing for a different generations to relate to, The print art is, well... Bad. Very little art these days seems to even attempt to convey an emotion. Everything seems focused around technique, every other art piece is drip paint for somebody has hung a paint can with a hole from a pendulum, string art, etc. It seems like modern appreciation is solely around the technique and perhaps how interesting The finished piece is. Even the titles, nothing seems to be even trying to convey emotion. So why do you think gen z sucks so much? I didn't think anything could get more self-involved than the boomers.
I use full profile inserts, problem solved
That wouldn't actually solve the problem since the pitch diameter is the issue here. The thread just isn't in spec.
@@StuartdeHaro How can one get an incorrect pitch diameter using a full profile insert?
@@smallcnclathes By not cutting deep enough or by cutting too deep. The insert forms the profile of the thread, that's it. It isn't going to hit your tolerance for you.
@@StuartdeHaroyou simply measure the outside diameter. You can't do this using any other tool as the root and crest are sharp corners.