Machining Tapered Threads for a Steam Locomotive Try-Cock Repair
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- Опубліковано 20 лют 2020
- Turning tapered threads on a metal lathe using the taper attachment to repair a steam locomotive try cock out of brass.
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All the years of machining, and metrology, that is the first actually seeing a taper mic. Thanks Keith.
I'd never seen a tap mic.
Yep, I've been in the game 40 years and on some places with a lot of inspection gear and I've never seen one either.
same
there are also micrometers to measure chamfers, radii, internal tapers, all sorts of wacky things that if you were to buy them all you could probably just buy a cheap manual CMM instead
@@SuperAWaC The problem is you have to remove the work from the machine to use a cmm.
Keith, in 84+ years I had never heard of a taper micrometer. Thanks for enlightening me!
I have never seen or heard of a taper micrometer before in 50 years of engineering. I served my apprenticeship in a company that made components for the aircraft industry in the UK and spent time in the gauge room and I never saw one of those or in any of the other companies that I worked for.
Regards from Redruth
Arnold
One is red brass, and one is yellow brass. If you look through Grainger, and McMaster Carr, red brass fittings are listed as such, and is what we use on high pressure steam in the Pipefitter Trade. Its higher content of copper (thus redder color) makes it a much better material for the high temperatures, expansion and contraction, erosion (wire drawing), resistance to de-zincification, and pressures of steam.
if math was taught in a machine shop in school I would have learned more. this makes it way more interesting. thanks for the lesson. as always I love your shows. thanks
@@marionette5968 Years ago I bought a Burke mill that came from a local high school when they purged the " skills " classes . I now have grandsons , 11 and 13
that are showing some interest. 1 teacher and 2 students is not a bad ratio .
Just another day in the shop of a true master machinist !! God blrss you sir
My father would understood all this better than me, he made many pieces on his old lathe.
He once made a special nut for a Russian tractor, the nut had five threads inside it, the dealer for the tractor wanted $2000 for the nut, dad made it for $300! Dealer wanted some to sell he said No thank you!
With all this work, then the locomotive owner wonders why the repairs cost so much.
Great job Keith, pity for such a nice made piece to end with marks from a pipe wrench, but that is how he wanted it.
First time i see a taper micrometer. Thanks for this interesting video!
Learn something new every time I watch one of your videos. Most times more than one thing. The taper micrometer is something I had never heard of before. Of course, I am not a machinist either. The only machining I ever did was way back in junior high school. That was 54 years ago! Enjoy your videos.
I've never heard anyone say boller so much in my life.
Great video.
Bowlar?
Great job Keith! Never be afraid to share the little glitches that may happen during a job, we learn a lot from them. Thanks.
Quick fix is bore out broken section then, re-tap internally to suit, turn a nipple to thread into bored and tapped section. I have had to do just that a couple times in the past. As I said it is a quick workable fix in an emergency. You did a very fine job doing it the long hand version.
I am a woodworker. But I always watch your videos, I guess because metalworking makes woodworking look alot easier!
However when I saw the subject of "TRY-Cock" I knew exactly what it is used for!
Regards,
David J. Janis
I've never seen a taper micrometer before. Combining a sine bar with a micrometer is a really ingenious idea.
That was a fine job you did there sir, plus you helped keep an old piece of history alive by remaking that part. I'm glad there are people like you that don't mind manufacturing the unobtainium parts for these kinds of projects.
I quite agree with Charles Ham, I suspect 'brass disease' is caused by the de-zincification of the brass. In the UK we use gunmetal or as Mr Ham suggests lead free bronze. My Yarrow boiler has many such fittings.
Great video Keith on taper turning, also I had never heard of a taper micrometer before. Thank you!
And as soon as they get the valve back they are gonna ape it with a pipe wrench.
Yeah, a nice strap wrench comes to mind.
You made my perfect Friday morning. A cup of coffee and a new Keith Rucker video. Thank you.
When ever we at Orchid Engineering make anything we have to send the original material away to be analysed, they tell us the exact metallurgy and we order new stock. That way it conforms to their safety standard.
Talk about job satisfaction! You can hear the pride of a job well done in Keith's voice at the end of the video. I totally agree my friend. There is well deserved feeling of accomplishment when machinists or cabinet makers skillfully create something useful and beautiful from raw material, whether a professional or a hobbyist.
Thank You for your time to teach but also tell how things are made. I really like the Turning Tapered Threads.
I had to see what everybody was saying they've never seen- because I work with some entirely unique tooling that's fairly exotic. Congratulations- I get exactly how it works, but here's a rare example of a tool I've never seen before either! Very cool- I want one now
Nice, Very Nice machining job Kieth.
Thank you for showing a lot of the machining process, very enjoyable video to watch.
really cool to be able to make parts like that , thanks for the video
Loved the explanation of the taper attachment. Thanks. Nice video.
Interesting and informative as always. Thanks, Keith!
I love watching your videos, I am an amateur machinist and I have learn a lot over the past few years, just watching your videos. I wish I could have a taper attachment on my lathe it would make machining tapered threads
so much easier.
Looks good as always. I've always wanted to try tapered threads but never really had a reason to do so. Really looking forward to the metal planer running!
Such unassuming skill ! thank you for posting !
You are a Master at what you do
Very nice looking project Keith.
watching a master write poetry in metal
Thanks, I have wondered how that was done. I'm new to metal working, and that was pretty exciting to me and educational as well.
Nice work, Keith.
THANK YOU...for sharing. A very nice job enjoyed very much.
Keith, that is an awesome video, the machining calculations amazing. A great job, congratulations.Johnny in Oz
You are Outstanding my friend!!’ I’ve heard of tapered threads yet I have never seen one maybe on pipe. Watching you ensiles in me to be a better carpenter. Thank you for sharing... Bob
I love how you say boiler ❤️
Joe Pie does an excellent video demonstration of threading to a shoulder using a foolproof (?) technique.
What's the technique?
@@BravoCharleses tool upside down and running away from the chuck. Worth giving a try if your reactions aren't up to stopping the cut at just the right point. If you haven't heard of Joe Pieczynski, where have you been? 😑
@@littleworkshopofhorrors2395 Cheers!
No fair, Joe's a real machinist. :-)
@@Craneman4100w indeed he is.
Nice project there Keith. Looks like that will be fixed for years to come now... Thumbs Up!
Thanks Keith
That was definitely awesomeness Extreme. Thanks for sharing.
Thanks for another great video.
always interesting ,thank you keith for sharing with us..........
Great job loved the video
Great video! Well done sir!
Great, really interesting video, thanks Keith.
That came out quite nice !
Nice work !!
Well done.
Thanks for the video.
Great job kieth
Great video this one. Thanks Keith
Very nice work, Keith!!
Nice work.
Very nice. Enjoyed a lot.
"There are usually three of these... sometimes two, sometimes four... five is right out." What I wish Keith had said.
The holy try cock.
Nor shall the count be one... only to be followed by two...
It's always gratifying when someone gets the reference.
The proper word for these valves is "try-cock" not "tri-cock" for trial not for three. If there is only steam from the bottom or lowest valve then the appropriate action is pull the fire, dump it, or put is out.
Brother Maynard.
Nice job on that tapered thread
Awesome video, one of my favorite channels on YT. I was watching one of the amazing Tom Hanks war movies but, I think Tom will have to wait as Keith’s content is just a bit better. 😉
Very interesting Keith. thanks.
I would love to see more about the stocker engine. It's just a small part of a locomotive but engineered interestingly on its own.
Keith, that is a novel micrometer. I've never seen one like that before. On running the 7 tpi thread to the shoulder,the technique I often use is to put the headstock drive gears in neutral and just rotate the chuck by hand. It is only a short thread and there is no likelihood of a crash into the shoulder. The upside down tool and cut away from the shoulder technique is also good in these circumstances.
Grate video Keith thanks of sharing.
No grates shown here. It was a lathe machining some brass.
Nice work Keith. Would be great to see it in action. Thanks for sharing
I bet after those two pieces have been heated up for awhile the colour difference won't be a big deal. Fun project and very instructive. Thanks Keith!
The color difference is a symptom of a bigger problem.
They are different materials, so the colour is not of relevance. The material of the new part is probably wrong for this application.
I'm..... Gonna be honest with you.... I messed up.
Thanks bud, I'm a layman when it comes to machining, but I'm certain you had machinists yelling at the screen when you made that adjustment. I love the honesty
Nice job!
I didn’t know that the taper/angle micrometer existed. Thanks for the video.
Same here, I've been a machinist for over twenty years but it really doesn't surprise me that it does exist I've just never seen one.
Sure. Rub it in that you have a taper mic for this. Nice demo of setup for the taper setup and a fine job in all. I have worked with guys that hate using a taper attachment, but I actually love it. They would always set gibs too tight and end up with rough feed. For plain turning, no need to back out for clearance, as properly set gibs on the guide bar will give a few thousandths backlash. Course, doesn't help when threading. For long taper thread runs (studs, cocks, and so on, to go through sheets), it was, in many shops, practice to run the thread out of the taper rather than stop at the fat end like a pipe thread. This prevents the fitting from jamming without a seal. You can see the run out approach the sheet easily, and can still maintain a seal and strength even if one or two turns of incomplete thread go below flush. Glad this was 3/4 per foot, not an odd on (1-1/4 per and 1-1/2 per not being uncommon for plugs and appliance fittings)
I was always taught that steam fittings, especially boiler fittings under pressure, should be bronze. Never brass. Brass has galvanic corrosion on steam boilers and gets really brittle. I only use brass (if I have to) for fittings if it's not under constant steam pressure.
The steam will leech out the zinc from the brass and make it porous and brittle.
DZR brass is fine and commonly used for steam fitting
I thought to myself that looks more like bronze than brass, I never knew that about boiler fittings though.
Absolutely Simon van D.
De-zincification of the brass.
That's true of a part that is used reasonably often, however for this application I don't see that being a problem.
I did my first taper and tapered pipe thread on a 16” Monarch. Sadly, it wasn’t mine and the company I was working for sold it. ☹️
I used dial indicators to get the taper right. I’m not sure if it was perfect but it worked perfectly so I guess it was close enough.
Nice video as usual.
Thanks,
John
Alway interesting Keith thanks for sharing 👍🇦🇺
HI KEITH, IN THE U.K. ALL FITTINGS THAT GO IN A BOILER ARE MADE OF BRONZ. WHICH MIGHT OF BEEN A BETTER COLOR MATCH! . REGARDSAND, TA FOR SHARING..
I was thinking the old stuff looked more like bronze.
I thinking the same was self ! Was jus about to write nice job Keith never turned a taper thread myself but surprised bt your choice of material !
Isn't it a safety issue too? Many brasses will dezincify and eventually become brittle when immersed in water, worse when it's hot...
@@cooperised I don't think that the zinc can migrate through the brass that way. You might get a surface layer deprived if it, But it should change the metal as a whole.
@@siggyincr7447 Unfortunately I think it can... www.werc.com/2016/07/28/dezincification-failure-of-brass-components/
Nice job on the taper, I never knew why a taper is needed on a lathe since I bought a used one last year. I thought all I needed to do was adjust the cross cut on my compound.
Being a retired electrical engineer, I mentor students in a high school Robotics class and that is the first time I ever saw a taper used. That was very interesting.
I can't wait to get a tread wheel for the apron on my Lablond Regal round head 15" and cut threads.
Thanks again for another great video! The public schools are trying to bring shop classes back. Typical hindsight is 20/20.
That is good to hear. Kids were sold a lie years ago down playing blue collar work as being below them and they should all aim for alternative careers. Problem is not everyone has the inclination or aptitude to be an IT god. Sadly many of them now wait tables in the "hospitality industry" or the like having turned down a career path that was better suited to their skill set. Despite the downturn in manufacturing in Western country's there is still plenty of work in maintenance and repair where every day is different with new challenges . Leave the production line work to the robots, making the same widget day in day out is soul destroying.
@@RobB_VK6ES Rob, We mentors even coordinate tours with our sponsors for the Robotics team, so kids get to see what the real workforce is like then ask them, what they think. We tell them, it doesn't matter what you do as long as you enjoy what you do, then it's not a job! But don't give up on education because it opens other doors.
Now our government is starting to put investments into the publics school systems where before they only offered tech schools but, those kids are getting a bad rap.
I went through a tech program at my iner city high school system back in the 70s and could not get a good job until I joined the Navy and was recognized for my knowledge and background. I went through their schools and worked on the Corsair II, A7E jets electronic systems on the flight deck of the Eisenhower. Because of that it opened doors and was a very nice career.
In the final stages of cutting the threads around 23:00, the cutting seems to happen intermittently, as if the work is off-center from earlier passes.
Obviously. The chuck either wasn't tight enough or he took to deep a cut and moved it. I personally would have put an indicator on the piece and recentered it before "finishing" the thread. He doesn't usually mind the mistakes.
I wondered if I was the only one that noticed that, something happened at around that time. Most likely Keith had the tool dig in hard at the root of the thread & pulled it off center in the chuck, you can see it wobble & as you mentioned the intermittent cut.
Unfortunately there are several things gone wrong here. Keith should have mentioned if he cut the tapered thread profile parallel to the center line or to the taper. That's a huge difference if you want to get a good seal without using teflon tape like a plumber. It also depends on what profile the thread in the boiler sheet has and how it was cut. As well as the run-out after switching to the second thread, it doesn't look like both threads are concentric with all the wobbling. At least the valve seat was cut at the end, but lapping on such a high rpm is not a good idea, to get a nice finish. Usually the lapping is done in 3 steps with coarse, medium and fine lapping compound. Standard brass is not the right alloy for steam boilers as it is usually sensitive to dezincification.
@@svenschlenkrich Usually the threads in a boiler are made with a tap.
Nothing wrong except the tool wasn't quite sharp enough for those last very light cuts. It was cutting and skipping intermittently.
Enjoyed the video. Using brass for stem is a no-no, it will erode. They use a specific type of bronze.
At approx. 1539, when you started the scratch pass, and the insert contacted the work, the tool holder moves
That is a micrometer that I have never seen, Interesting! I thought you were moving the taper attachment the wrong direction, I was correct. Would it be better if the valve body was made from bronze, stronger than brass? The bonnet looks to be red brass which is really a bronze.
The explanation is right on about the taper. What I would like to know is where did you find the taper micrometer ??? Thanks Keith.
Awesome
wonderful thread info video....sure seems like there should be a simple fast safe way to contain the metal chips. even small parts make a big clean up mess. i watched a video on huge rocket aluminum panels being honeycombed with the subtractive waste going everywhere. the egg head rocket scientist pleased as punch describing this space age multi axis milling machine. then the crew was sweeping the floor and blowing off the huge machine just to send all the special metal back to make the next panels. a great opportunity for a 3rd party do it different inventor. thanks a lot..:)
Taper per foot is diametric change not per side.
ATB, Robin
Hi Robin,
I was looking for someone who had already commented on diametrical change vs. per side. I didn't expect to find myself in such esteemed company. Your note is brief and to the point. Mine is not; I thought I would offer a bit more explanation.
NPT (National Taper Pipe Thread) is 3/4" per foot _diametrical_ change. Equivalently, this is 1" per 16" or 1/16" = 0.0625" per inch, again, diametrical change. The angle per side ( _not_ the included angle) is determined from a right triangle whose height is 1/2 unit (if the diameter is one, the radius is 1/2, which is the height of the triangle) and whose base is 16 units. The angle is then given as arctan(0.5/16) = arctan(1/32) = 1.7899106 degrees or 1 47' 23.68". The included angle is twice this, or 3.5798212 degrees = 3 34' 47.36".
I've never seen a taper micrometer, but it looks like Keith used the included angle to set his taper attachment and then committed the same error with the taper micrometer. I can't tell if it is the power of mental suggestion or an artifact of recording, but it looks to me like the taper on the new part is larger than on the old part.
Best regards,
Gottfried
I have never done boilerwork but I believe that these aren't NPT threads but just tapered threads, correct me if I am wrong, but there is no strict standard for old boilers
@@SuperAWaC Sorry. I could have done a better job writing the above. Where is my @!#$%^ editor? I was trying to make the point that these tapers, including NPT, are measured as the _diametrical_ rate of change per foot vs. the _per side_ rate of change (taper). Pipe threads on older boilers often used 12-series threads ( _not_ NPT). Still, they were tapered 3/4" per foot _diametrical_ rate of change (taper). As another example, sometimes boiler staybolts were threaded with a taper. These varied from shop to shop from 3/4" to 1-1/2" per foot. Again, this was _diametrical_ rate of change vs. _per side_ . (Note: Staybolts were sometimes threaded with 55° threads, not 60°. I don't know if these are truly British Standard Whitworth threads, but before you ruin a boiler staybolt thread by chasing it with a 60° tap, confirm the thread form.)
The observation that Robin and I are making is that we think Keith conflated the taper as _per side_ instead of what we believe is the correct 3/4" per foot _diametrical_ taper. [Robin, if I'm misrepresenting your view, please correct me.]
Hope this helps.
Best regards,
Gottfried
@@gottfriedschuss5999 ah i misunderstood, fair enough
@@SuperAWaC there is a strict standard. To find it, you have to use old editions of Machinery's Handbook. They plainly call out boiler tapered threads and washout plugs.
The original part may have been bronze rather than brass. When exposed to boiler water (not just steam) the zinc will gradually leach out of the brass leaving the metal brittle. Bronze is not prone to the corresponding effect of tin or lead leaching out.
Joe Piezinski had a great method for cutting threads away from the work. But interesting video all in all.👍
I was screaming through the screen when you moved that .030 lol
I was always told that brass should not be used for boiler fittings as it is susceptible to dezincification. I was taught to always use bronze.
I've heard the same thing. The original part looks pinker than the new one, so it may actually have been bronze, i.e. an alloy of copper and tin, with little or no zinc.
@@chrisarmstrong8198 Yes you are right, the original parts look to be bronze.
Couple days later I have made something similar two start screw 6 tpi od is almost 3/4 Acme thread that was a bit challenge I also made tap for the bronze nut it has broken old bronze screw and it worked great the new screws made it of stainless-steel. 😀😀
Keith what worried me was the taper thread depth, or lack of. The guy with the wrench who broke the original would make short work of the replacement! Liked the taper mic though.
Agreed - the new "threads" looked like scratches, and were not fully formed. I couldn't even see any threads when compared with the original - refer video at 31:28
Kieth, Mate you always have the best gear to do any job. I need an attachment like this for my lathe too now & how does that thing work anyway?
Lifehack: making threads to the shoulder use left-hand spindle direction, right feed and the cutter upside-down.
Where can I find one of these micrometers? Taper mic dont bring anything of interest up on google, many thanks great video
You can make the same measurement over the whole length of the taper tachment with the cross slide for a more accurate measurement
Yes, but then the maths would be far more difficult. In the video he based the calculations on One Foot, which was what, 85% of the entire length of the bar. Watch again from 10:26. He is deliberately starting at the pivot point, rather than the farthest end of the whole bar.
Remember, he's American and has the limitation of working with a base 12 (Inches to Feet) specs and numbers. The taper spec is 3/4" per Foot, and Americans are comfortable with working in divisions of 12. HIs Taper Micrometer is working in Thou per Inch, so it's very easy to measure & calculate the adjustment in Thousandths of Inches based on a 12" run of bar, but it'd be an absolute bastard to calculate if it was based on the whole bar which is (say) 1ft 2.678" long.
That's because you'd have to convert the whole bar length to decimal inches, then factor the adjustment it with complicated calculation the (Micrometer) Thou per Inch into the required distance. Basically, Keith rounded his bar length down to 12" to simplify the calculations, just like Metric folk would round the bar length down to multiples of 10cm or 10mm or whatever, just so they were working with whole numbers rather than something odd like 326.792mm.
Anyway, it's largely irrelevant for such a low-tolerance component. The original female tapered thread might not be accurate anyway - no point making the male 0.001% accurate if the female doesn't match. The whole idea of a tapered thread is so it'll seal even if there are slight inconsistencies, which is inevitable. It's brass, not Carbide so the threads deform to match each other., and if any issues they can use some thread sealant in there.
Keith, this was a very interesting video. I've never seen a taper mic before.
Also, Joe Pieczynski did a video showing an easy way to safely turn threads that run into a surface like your 1-1/8 threads did. If I remember correctly, he used an upside-down cutter from the back side (with the lead screw turning backwards, I think?) and started each cut at the surface, cutting towards the tail stock. There's no chance of crashing into the surface that way. If I ever get change gears for my old lathe, I'll start re-learning how to cut threads, including using Joe's technique!
i save myself the setup time and turn the chuck by hand at the end. joe's technique is more for manual production setups.
Bob Vines I tried Joe Pie setup with an upside down threading tool. In the end my quick change tool post was too small for the arrangement
I’m curious, when you were rebuilding the lathe you mentioned bearing noise in the gearbox. Did you repair that or just get used to the noise?
Keith
Typical case of de zinkifcation ie using brass in a boiler. The sink is depleted from the copper and results in a very weak item. At an extreme case in the foundry at the iron works they had coke fired core dryers any brass fittings in the crane electrics turned pink and could be crushed by hand . Always use bronze for any boiler fitting or bushing that is in contact with the 💧
I don't think I could have resisted putting flats on both pieces to keep the pipe wrench away. That valve must have come from the harbor freight level steam supplier back in the day.
Was thinking the same thing. That and center the 1/8" NPT port.
More likely made on a lathe in the works the locomotive built at in their line shaft machine shop.
I thought the same thing Brian.
I agree. I cringe at using a pipe wrench on brass or bronze. A pair of pliers used on a brass fitting will soon deform the fitting; been there.
I actually found that a lot on old equipment, late 1800's to early 1900's. It's a real pain. You have to use strap wrenches but a lot of the old stuff was too tight so I had to resort to using pipe wrenches. You still see it on the spuds for new radiator valves. But there is a special wrench made for it. Oddly enough called a spud wrench and are kind of hard to find these days. The first shop I worked for had one. One time an HVAC shop I was working for started cleaning house and was just throwing stuff away. I saw a couple of them and snagged em. Even my boss, who had been in the trade for over 30 yrs, didn't know what they were even though we did that kind of work all the time. I had to explain to him what they were and how to use them. Then I gave him one. It made our lives so much easier. I wonder if anyone still makes them.
It looked like the broken part was crystallized with "brass disease". Shouldn't these fittings be made of bronze? It is stronger and much more heat and steam resistant.
Yep agree, on steam engines only use bronze fittings.
en.wikipedia.org/wiki/Bronze_disease
green death can happen to anything with enough copper in it
@@markduncker9117 DZR brass is fine and commonly used for steam fitting
What you are referring to is called zinc depletion and it happens to most alloys that contain zinc that comes into contact with steam. It causes the zinc to migrate out of the alloy and you end up with the leftover metal, at a molecular level, resembles a sponge or swiss cheese and is somewhat brittle.
At 28:27 you retract the tail stock quill a tad bit too far and it releases the drill chuck arbor. You can see it seating again as you extent the quill at 28:43. No harm done.
Measuring angles is so much easier using Trig and Dial gauges I'd suggest. I'd be here all day trying to work any other way. In fact I'd most likely not be able to do it. I'm not being critical of doing things how they once were done but given that just about every calculator now has Trig functions, my suggestion is to now measure and set all angles using Trig. I needed to grind a 55deg BSPP tool the other day and how else?
I would try removing the sharp corner on the crests of the stright thread before trying on the mating part. If you don't, then the threads bind on the sharp corners in the root of the female thread. Also the threads will not engage on the flanks, the thread will have to be undersize to fit.