Can a mechanical clock be made on the Glowforge?

That was cool!

But, I was thinking more along the lines of just building something to hold the “catapult ammo” I already have…


Made a trebuchet in welding class, itty bity lil thing stood just under 2 feet tall. the basket weight was just under 25lbs. it could throw a golf ball just under a 100yds. with tweaking just over 110yds. It was awesome.


Interesting turn of events… the acrylic clock appears to be suffering from the same problem as the wooden clock?!?

I got it all put together and was surprised that it still needed the larger of my two weights. Then I let it run (it started running immediately and I was excited), but then after about half an hour it stopped.

Since the clock is made out of clear acrylic I can see every piece (unlike the clock made of opaque wood) so I can see that my cross-axle is more a problem than I originally thought. The axle does not sit in the center of the hole. It wiggles around to much, so the gears are actually too close.

So it looks like I need to adjust the frame again and move the axle holes further apart to allow for the variance in distance.

Edit: I felt the need to add how cool it is to be able to see inside the clock. I can see every gear connection and every interaction. So I don’t have to “guess” at what is happening in the areas that couldn’t see before.


That should help dialing it in for the wood also if you wanted to have 2 clocks, or a mix match. :heart: :innocent:


One of my friends built a large wooden trebuchet as part of his undergraduate math thesis. It could throw melons >100 yards. :smiley:


I tried a small tweak to the minute-axle last night. And the acrylic clock appears to have run all night!

I still think I need to adjust the axle-hole location, but I might be able to get this version working after all.


I strongly suspect that 1/4mm too far away would work better than 1/4mm too close, though I believe the idea was to have the same size contact gear to gear throughout the range of contact.


You are exactly right. There is a small gap between each tooth, that is designed to not touch the tooth to the inside part of the gear. It is designed for only tooth-to-tooth contact. If that gap is closed (by the gears being to close) the tooth will rub (causing friction) on the main part of the gear. This can even cause the gears to catch and bind. So I need to be sure to keep the gears at the proper distance.

I probably have about 1 millimeter of wiggle room (at this size – maybe more). As long as the gears don’t get to close or to far away, the clock will run fine.

Currently, (after adjusting the minute axle) the clock has only stopped one other time. I was very frustrated when it stopped the second time, because I could not find any of the “normal” things wrong. It turned out be that one of the brass-rod axles had actually slipped out of place (the are not cut down yet). Ever since putting the axle back, the clock has been running nonstop!

Clock 1.6.0

I think it is time to finish the rods, install a face, and start time testing so I can dial it in.

I think I will reduce the weight for now also, and start designing a pulley system.


That green acrylic clock looks sharp! Congratulations @bill.m.davis


I was showing the progress I am making on the clock to some friends, and the clock fell off the table…

I don’t think it is damaged, other than the pendulum snapping in two places. Two brass rod axles slipped out also, so I need to put it back together.

I need to just get the axles cut down and secured in place!

But, I have been playing with making a ratchet design to make winding easier. Ratchets seem so simple in design, but complex in implementation…

(Edit) Here is my initial ratchet design for inside the weight drum.

But, initial tests are not as good as I had hoped… So I will probably have another version soon.


Several problems with the first ratchet.

  • The pawls were to light and not falling with gravity
  • Gluing the ring in place was a horrible idea
  • The teeth of the ratchet were just to small and skip under the pawl
  • Using small rods to axle the pawls is not easy to keep in place
  • Need a better way to hold the drum together

Resulting in the next iteration.

Ratchet Design 1.6.1

Changes in this version:

  • Larger, thicker pawls (more effective use of gravity)
  • Outer ped holes to hold the ring in place and hold the drum together
  • Deeper teeth for the pawls and ratchet to catch on
  • Replaced the rods with additional pegs and increased the pawl holes
  • The eight additional pegs hold the drum very well, allowing the pawls to move freely

The old part that I haven’t tested from these changes are the deeper teeth. (I ran out of time.)

I may need to change my peg system with the drum axle itself though. The longer pegs are much harder to work with. (Especially if the material is just slightly to thick.)


Do you really need all those pawls? Why not just one near the top?


The only reason I added four pawls was because the drum turns. And since I rely on gravity for the pawl to engage the ratchet, I need to make sure I always have at least one pawl on top when it is turning. Well, that is my thought process anyway…

I guess if the pressure can hold the pawl in place, once it engages I shouldn’t need so many…

If the pawl stayed stayed stationary, I would only need one, but since the point is for it to turn it will not be guaranteed to be on top and forced to engage with gravity. (So I added as many as I could fit in the space…)


Ah. Makes sense.


My daughter just got a very nice German made pendulum clock. She is having problems getting it to run continuously and was told that the beat needs to be adjusted.


Yep. This has been one of the hardest parts. I don’t think I have it perfect yet, but it is a lot closer now.

Trying to get the beat set with a clock that has been designed properly just requires it to be balanced properly. But, with my clock, I have to find the proper balance. I made it more difficult on myself by setting my escapement at an angle…


As a long run of thin acrylic will act just like a spring, why do you need gravity, Note how the drawing above uses a run of thin acrylic to hold the pin in place. The shape would be different, but the principle would be the same that would spring the pawls into place from any angle. :grin:


I had considered that. I was worried the stress would eventually break the acrylic, so I opted for gravity.

But maybe I should reconsider this. If I can get the right pawl/ratchet edge, maybe the acrylic spring would be more reliable. And I wouldn’t need as many since it wouldn’t require gravity.


The trick is to make the “spring area” long and even maybe even 4 spirals each halfway or more around and the force of the kickback perpendicular to the line of the spiral. I tried and did a horrid job of it and the ends should go one notch further around, and still they are lumpy but done evenly they could have an absolute minimum of pressure on any point and spread out so far as to almost eliminate strain.

I almost did not put this up it is so awful but has too much fiddling already, and gives the idea.


This is almost exactly what I was envisioning, but I planned a few differences to account for a few other things.

  • Peg holes to be able to hold the ring in place
  • Reduce the number of arms and make them longer

I just need more time to test these various ratchets, but I am very excited about these possibilities! (If I get time, I will post what I am envisioning and hoping to test for the spring-pawl.)