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How To Make A Clock In The Home Machine Shop – Part 18 – Making The Pendulum

How To Make A Clock In The Home Machine Shop – Part 18 – Making The Pendulum

G’day Chris here, and welcome back to Clickspring. In this video I make the oscillator at the
heart of the clock, the Pendulum. If there’s one common attribute across all
mechanical timepieces, its that each must have a component that provides a fixed and consistent interval of time. For a watch, that’ll most likely be a small
weight acting against a balance spring, and for a clock like this, its a pendulum
acting against gravity. The pendulum on this clock is a nice clean
design. A brass bob at the end of a length of thin
rod. The plans call for a simple brass disc for
the bob, but I think it’ll be a bit more interesting
with a contoured profile like this. There’s a hook fitting on the other end to
catch the suspension thread, and a small block that fits axially on the
pendulum rod, to receive the impulse from the clock escapement. For materials I have this slice of 2 inch
diameter brass for the bob, some rod stock for the hook and pendulum rod, and I’ll use a small piece of this offcut
left over from crossing out the large wheel, to make the pendulum block. So lets get started. Now although the profile of the bob is quite
simple, its shape makes it quite a challenging part
to hold on to, while making the required cuts. The other challenge is to make sure that the
various surfaces are kept true to each other as the part is
released and then re-held to make subsequent cuts. One solution is to drill a hole in the disc
and then use a threaded mandrel to hold it. But of course that leaves the issue of what
to do with the hole when all the cuts have been made. It could be plugged easily enough I guess, but I think it’s preferable to avoid that
if possible. So I’m going for what I think is a much neater
solution, and that is to turn a reference spigot in
the center of each face. The surface and the spigot together define
the axis of the part. Providing I hold it while registering these
two features, I can be sure that the part is located on
the central axis of the lathe. A
matching super glue arbor can be turned up, and a central hole drilled to accept the spigot
just formed. Once the glue has set, the outer perimeter
can be trued up, and the second face and spigot put in place. The top slide was set to 15 degrees, to make the taper cut for the contour, although you’ll have to take my word on that, because the markings on this lathe are well
and truly on the way out. The taper cut removes the bulk of the material, and so reduces the workload for the form tool
that follows. Now t hat surface finish needs to be improved, so I wrapped abrasive paper around this file
to maintain the contour, while I sanded and then polished the surface. As usual, heat from a small torch breaks the
super glue bond, and then the arbor can be cleaned up and refaced to hold the bob the other way
around. The second spigot and face locate the part
on the axis of the lathe, and I can profile the other surfaces exactly
as I did the first, knowing that all features will be true. Acetone cleans off the superglue residue, and its over to the mill to put in the hole
for the pendulum rod. So that sorts out all of the main features
of the pendulum bob, I just need to remove that last spigot, to
complete the part. I’d like to protect the perimeter of the bob
while I make those cuts, so I’m using some thin strips of aluminium
sheet to cover the chuck jaws. Starting with the work loosely held in the
chuck jaws, you can see that initially its not running
true. But an excellent way to correct that, is with
this bump centering tool. The tool is gently brought into contact with
the work, until the bearing starts to continuously rotate. At this point the lathe is stopped, and the
jaws further tightened. Visually I can see that the part is running
quite true, but an indicator shows just how effective
this simple tool can be. Next I gently faced that spigot clean off, and then took a light pass to leaving a nice
satin finish fresh from the tool. I’m going to leave that as the final finish
for that surface, as a contrast with the polished perimeter. Now I’d like to get a coat of lacquer on the
bob as soon as possible, to preserve those surfaces surface, and I’ll
need a way to hold it as I do that. So I prepared the pendulum rod next. I’ve already cut the stock to length, so all it really needs is a quick tidy up
of the ends. I’m holding it with this shop made hand vise, which is perfect for this sort of task because
it can accommodate long stock through the body of the tool. And it allows me to easily put on a light
chamfer with the belt sander. Some Loctite 603 bonds the pendulum rod in
place, and a rinse in solvent removes the excess
adhesive. With the bob and rod complete, I can move
on to the pendulum hook, which again, is a difficult little part to
hold, especially once a few of the features have
been formed. The basic profile is straight forward enough, consisting of a cylinder and short tapered
section, as well as a central hole to accommodate the
pendulum rod. The part was then reversed, and pressed onto
this stub arbor, while I used a graver to shape the other end. A light sand and polish brings up the surface
finish, and its ready to have the features for the
hook formed. First up I’m drilling a cross hole to define
the top of the hook slot. The cross hole diameter is 1mm, and I’ve used
the drill bit to help me align the workpiece in the vise. And I’d like the slot to also have a keyhole
cross section, to hold the suspension thread towards the
top of the slot should the pendulum be lifted slightly during
handling, so I’m using a cutting blade thats just a
bit thinner at 0.8 of a mm. A quick tidy up of the burrs from the saw
blade, and the hook is complete. The final part of the assembly is the pendulum
block, which is nice and straight forward to make. It simply needs to be brought to size, and
then drilled axially to accept the pendulum rod. A few drops of loctite bond these last two
parts in place, and I’m taking care to align the hook and
block perpendicular to the face of the pendulum
bob. And thats the pendulum assembly complete,
so lets have a look at it in action. Now there are 2 crucial properties that make
a pendulum useful as a timekeeping oscillator Firstly, for small swings, the time it takes
to swing to one side and then back again remains approximately the same even if the
size of that swing slightly changes. This is known as Isochronism. And secondly that time interval is approximately
proportional to the square root of the pendulum length
divided by gravity. This gives us two things. We can tolerate some small variations in how
wide our pendulum swings, and still have an accurate clock. And most importantly, we can also set that
time interval by simply making the pendulum a certain fixed length. Now you’ll have noticed I said “approximately”
a few times there. Everything I’ve mentioned is correct up to
a point, and was true enough to spark off several centuries
of scientific discovery, but there’s a lot more to it than what I’ve
mentioned, so check the description box below for some
links if you’d like to know more. The take out message is that pendulums need
to be a specific length to keep a clock in time. And whilst the pendulum for this clock has
been fabricated to a specific fixed length, I can still make some small adjustments, by
using the suspension regulator. I’ve set up a timing machine to measure the
time interval of a complete swing, and at the moment it’s a little less than
1 a second. But as I lengthen the pendulum suspension
thread, I increase the effective length of the pendulum, and so that time interval also increases,
in this case, to just over 1 second per swing. The pendulum needs to receive a regular push to replace the small amount of energy that
it loses to friction, and it receives that push from another crucial
part of the clock mechanism that I’ll complete in a future video. The escapement. Thanks for watching, I’ll see you later. And if you’ve just made your way into this
clockmaking series, thanks for checking it out. This is just one episode of a longer series, where I show all of the steps to make a mechanical
clock from raw metal stock, so be sure to check out those other videos. If you enjoyed this video and would like to
help me bring you more project videos like this one, then consider becoming a Clickspring Patron. As a patron of the channel you get access
to exclusive Patron only video content, free plans for the patron projects, and the chance to win the actual project at
the end of each build. Like for example this useful little hand vise. Find out more by visiting And finally, if you’re looking for some new
projects for your lathe or mill, then take a moment to visit where you’ll find a range of plans available
for download, including plans for some of the tools I’ve
made to help me construct this clock. Thanks again for watching, I’ll catch you
on the next video.

Reader Comments

  1. Do you only use HSS tools for lathe works and if so what stops you from using indexble carbide tools?
    Additionally to that I personally experienced brass as a horrible material to machine on a lathe, the chips are like dust and spray around the whole workshop, how do you mange this problem and are there special brass alloys that are easier to machine.

  2. Your craftsmanship and ingenuity are absolutely astounding Chris. Keep up the good work.

    I'm also curious (because your work seems so flawless) as to how often you make major mistakes with this build/your work?

  3. 2 things I will never do: 1) I will never build a clock like this. 2) I will never stop enjoying, watching the magic of machining parts from raw hunks of metal. Nicely done.

  4. I just watched 1-18 non stop. I know nothing about clock work and some about machining having ran a lathe in a prior job. Great videos and detail explaining. Just for gigs what would you sell the finished product for with all that time effort part cost and such detailed work. You obviously didn't cut any corners. Went out of your way to make an absolute quality product.

  5. Mate… I'm in awe. I've never given a moment's thought to the incredible craftsmanship that goes into making a clock like this. I'm not sure how long we've had clocks and watches in the world but it kept occurring to me as I watched, that the further back you go in time (you see what I did there…) the more hand work must have been involved in creating these incredible devices. Old school clock makers must have sunk hundreds of hours into this. Gears without a milling machine! How long did this build take you?

  6. Hey Chris, love the videos! I was wondering though, what do you plan on making once you've finished the clock?

  7. G'Day Chris. I've been with you all the way on this project and greatly enjoyed watching each and every of your professionally produced videos. I can see that you want to ensure that the parts that you use are totally within your control, e.g. by using a silk thread for pendulum length (I'd probably have utilised a ready made pendulum spring suspension).

    Given that you chose to go with the silk suspension method, I would say that by using this method, any fine adjustment is 'out of the window'.

    Personally, given that your silk suspension method was set in stone, I would have gone for a brass pendulum with a 'clearance' hole and a screwed pendulum rod with a beautifully turned and knurled adjustment screw.

    As a pendulum rod, I would have chosen 'Invar' with the finest screw thread possible for the adjustment nut… FeNi36 (64FeNi in the US), is a nickel–iron alloy notable for its uniquely low coefficient of thermal expansion (CTE or α). The name 'Invar' comes from the word 'invariable', referring to its relative lack of expansion or contraction with temperature changes.

    Pendulum rods made from 'Invar' are more accurate (temperature-wise) than wooden pendulum sticks.

    Invar is not expensive… eBay, 1270 mm long x 6mm diameter, £39.99, GBP so work it out to your ozzie dollars, mate.

  8. I'm always amazed at the skill of machinists.

    I'm going to be lazy and not search… You've made metronomes, haven't you?

  9. Just had an idea Chris…….your lathe's topslide guage is losing it's indicators…..
    Well why not use your auto indexing system to cut a new set of indicator marks and use the black shellac used in making the clockface to highlight them?

  10. Why don't you use thread + loctite to secure pendulum to rod? Is the loctite tough enough to carry weight of pendulum for years?

  11. After seeing six or seven videos i became an Clickspring addict …….. nice edited and commented clips !

  12. hola estoy impresionado por su exelente trabajo, no se imagina como puede ser la construcción de una maquina de medir el tiemp hasta que se lo presentan como usted lo hace, sencillamente maravilloso. . desde México felicidades!!! su admirador del arte que usted posee Félix.

  13. Chris i admire you very much how you can make your own tools ! I am trying to learn grinding hss blanks to use on brass, can you do some video's where you show how to make your own tools ? like a curved tool for the internal cut of a pulley for example, thanks !

  14. Using steel for the pendulum rod has one classic weakness: thermal expansion causes the clock to slow down in heat. Short of using a complex temperature-compensation design, the simple, classic alternative is to use a wooden rod (with the grain running down the length of the rod).

    Another detail worth considering is that, optimally, the rod should be attached to the center of the bob, so that the bob's thermal expansion is symmetrical around the attachment point.

  15. Incredible both the quality of your vids and your workmanship…would you please name the oil or greas you polish the brass shiny.   .Keep up the great masterwork.

  16. I have to turn off the sound in order to escape from the endless background synthetic musical accompaniment. Why is it always present on your otherwise excellent video tutorials? It becomes truly irritating the longer I watch each episode. I think your commentary together with the sounds of the machines in use are all that is necessary and would be so much easier to understand and enjoy without any unnecessary further accompaniment. If others want some music while watching, they can provide their own!

  17. if I could be rich I WOULD GIVE YOU GOLD, MUCH GOLD, brcause I'm just cryibg about your videos…. Dude you're awesome!!!

  18. + Clickspring 3:24 If you haven't done something with it already, I'd love to see you disassemble That lathe and chemically or electro etch new markings.

  19. Wow man. Between you and uncle bumblefuck (+AvE) I'm incredibly interested in becoming a home shop machinist. Thank you for showing me how awesome and rewarding this hobby can be. Cheers!

  20. Chris, can you explain why you use silk twine instead of something less affected by humidity changes? Nylon or x-linked polyethylene would be more stable… I love your videos, but this has been nagging me… thanks.

  21. I'm surprised you haven't re-marked that lathe part by etching it and engraving it or something crazy like that that you seem to make look like a two second job! 😛

  22. one thing I like is chuckles with say 3-4 inch balance wheel rather than a pendulum, just for the looks

  23. It's impressive that super glue can handle the cutting force of that form tool. Even with light cuts that's still a lot of metal on metal contact

  24. You must be a nightmare to buy gifts for.

    "Should we buy him a clock?"
    "Nah, he'll just make a better one."
    "Make his own."
    "Socks it is, then."

  25. Awesome! Just pure Awesome! Thank you so much for doing these videos Chris. I learn something new from every one of them!

  26. Hi Chris, where do you get all of your brass and metal stock from? Online? I wouldn't even begin to know where to buy "tin" from. Cheers

  27. Oh how inmate are I like this clock and have obsession but I can’t do or have math brain excellent work you did .😱👌👌❤️❤️

  28. Rope to adjust the pendulum freq ? Eww… it certainly works, but that feels cheap, almost substandard when compared to the rest of the clock.

  29. Chris, like many folks, I have ALWAYS been fascinated with Clocks, I fixed my Adopted Grandmother's old "Ben" Alarm clock at age 14! She was not "worried" about it, since it had Not Run for years!

    Now at age 68, I have decided to build a Clock, from the flat metal up.

    I have been a Home Shop Machist for 25+ years, as well as Machining Professionally for the Thayer Valve Company, which developed the First new Patent for Musical Brass Valves since the 1860's!

    My question to you is, do you think the Pendulum Clock you are showing us is more than a beginning Horologist should attempt?

    (And I will soon be a Patreon of your work, starting small as I just finished moving in the State of Oregon.

    Thank you for your Very Concise Method of instruction!

    philip from Eugene, Oregon, USA

  30. I've been a machinist all my life. I have nothing to show you. There are mild differences in work holding on the lathe but if you needed them you would simply invent your way to it. Nice work. Cheers.

  31. Most excellent Chris, TFS. I would love all that fluffy brass it would look beautiful in an Oak bowl, should be able to make my own soon 🙂 G

  32. What is the point of the pendulum swinging once per second? I am guessing you can have it swing at any other rate and just change the gearing slightly.

    Also, what was the point of the spigot??

  33. G'day Chris. Your work is simply gobsmacking. I particularly love the Antikythera videos as that mechanism is also gobsmacking. I'm now enjoying this series and have a question about graving. I see that you use it on steel, but I wonder how large a diameter you can go? Presumably there's a limit before the tool is ripped out of your hands?

  34. Gorgeous!! Just curious: why not make a gridiron pendulum and have temperature compensation addressed? You would have to account for the extra weight, but that should be within reason, no?

  35. Okay, that's it! You've gone straight into my top 3 favorite YouTubers. Chris, say hello to This Old Tony and Abom79!!

  36. I don't have a lathe,CNC or milling machine. Any chance you can show us how to make a clock without all that special equipment? It's a metal working channel so it probably won't fit on your channel. Just would be interesting to see.

  37. Bob's your… O.K. it took me half way through the video for this to pop into my head. But, forgive me, I'm one of those yanks, and it took me at least ten vids to figure out the accent. Yes, it really is hard, but some of us yanks actually can do it, kinda', sometimes.

    Anyway, it happens, I have an uncle named… Really.

    Will I ever really understand the significance of this cultural trope? Doesn't matter. The vids are fantastic. No, they are utterly yummy.

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