Member postings for Izack Madd

Thanks for those that were adding helpful comments. All the others sorry you wasted your time.

I'm now considering this subject closed as I'll deal with it the hard way. Experimenting and learning not criticism.

With high hopes

Big deal. Check the name. Sanity doesn't come into it

That's nice to know know deal with the question

Not relevant

So what...

?...

This is approximately how it was envisaged with the gears between the pullies and the drum. And as the drum onlyhas to turn at a speed of 1rpm and the weight has a potential speed of 32 feet per second even reducing that by a factor of five still gives me 6rpm. And a pulley ratio of 4:1 so I'd have four times the travel and enough speed. And by gearing down as with a cars gear box I'd increase the force enough to turn the other gears in the clock. Or so I thought.

I don't know about using breeze block but it would be a very unusual clock with the weights like that

The lead I've got 75% fills a box 300 x 250 x 450 mm and that only weight 9.5kg. So I must have been sold a pup and it's not lead. But it looks like lead and it weighs the same and melts the same. So...

Hi Neil

I realise that I can't get back all the energy hence the reference to torque not speed. As I would be sacrificing speed to balance the equation and so it's not a perpetual motion device. Yes Harrison used Lignum Vitae for his bushings as well as some very complicated gear construction to compensate for humidity. Such as putting odd shaped pieces of different wood at angle to the growth rings. The original plans that have it running for just 1.5 days uses bearings and such likebut to still at its limit of power input to torque output. Once the power has gone through all the gears as they have to gear down the power as it's the number of teeth that's important. Not the torque as with a normal gear box.

My thought was as the speed is regulated by the mechanism not the drive force then the speed of the primary drive wouldn't matter so long as its faster than the minimum rpm the clock creates. Rather than the drive setting the speed.

I'm still baffled as to why gear can't compensate the loss of torque. As they seem to increase in power when geared up but loose speed. Which is fine. And would negate the problem of the loss of power of the increased travel of the weight on the pullies.

Since a "multi purchase" block n tackle trades long pull at low force for short pull at high force...
You want a weight to fall say 4feet at 2.5 kg.
But really want 16 feet at 2.5 kg
thus a ten kg weight would in an ideal world suffice..
I would make the blocks allowing for say a 12 kg weight but adjustable down
A fourne purchase is modest...
Bear in mind the support doesn't need to be part of the clock...
Imagine hanging a weight on the wall from a block 'n' tackle ..with simple pully under clock redirecting fall end of cord....

The down side might mean a very large winfing drum in the clock.

Hi,

Your right about the idea of the pullies not needing to be attached but the problem is the size of the said weight as even with lead I'm looking at a block around a 300m cubed. I am hopeful of using a block and tackle that's what will give me the 4:1 ratio. But the torque I'd loose, 3/4 means the clock wouldn't have enough power to run. More like a breeze block than a sleek timepiece. I assume then that I can't use a gear train to compensate? As for the drum that's not a big issues as the design is such that there is plenty of space to show off all the gears so a big drum would be hidden.

My main confusion is clocks such as longcase clocks can run for up to a month. Yet they only have small weights perhaps 3kg and a drop of four feet. And I know they use pullies. So how do they do it. As John Harris made his clocks totally from wood even the shafts. So it's not friction that's the issue but some archaic secret it seems.

From when I was at uni we were told that up 20% of the book can be copied but only for personal educational use. As you are only saving the original from getting dirty. SillyOldDuffer is right the publisher is the one to give permission but will probably not even responded as it none commercial. One way around it is to photograph the pages and print the photos. You could even do that at the library as they will have no idea where you got the pictures. As for the library not having the right licence. Surely the copier is there for that very purpose.

Also Not done it yet, I live alone so no one else to wind it and the friction isn't a big issue it's just why I need a ratio of 4.5:1. On the gear train. To compensate. But I'm ok with pullies just not gears. As that's more of an engineering thing. As you don't get many gears trains in a chest of drawers... just gear changes.

Hi,

I like your thinking and a deep hole would allow the weight to travel for longer but the house half buried below mine might get a bit miffed with a hole in their ceiling and a weight slowly descending once a week.

I'm already thinking of using pullies but that means a loss of three quarters of the torque and so not enough to drive the clock. Hence the need to regain the torque hopefully by a gear train.

Hi, yes it's the weekend and daft questions abound.

I'm trying to work out a problem with a clock I'm making. At the moment it requires 2.5kg to run for 1.5 days.

Now that's fine but I'm lazy. I want it to run for at least a week. There are two options mount the clock so high of the floor it would need to be upstairs with a hole in the floor. Not practical as I live in a bungalow.

Or use pullies to increase the distance the weight travels.

But that means I'd need a pulley ratio of 4:1 and at least 12.5kg of weight. Now as the clock is wooden anyway. To give me enough torque. That's a no go.

But and this is the big question. If I use a gear train with a ratio of at least 4.5:1. Would I get back the torque lost because of the pullies?

I realise some torque will be lost through friction etc. And normally the speed would be so slow as to be useless but the speed will be regulated from the clock not the weights. And so as long as the torque doesn't exceed the original tolerances would it work?

And if so what gearing should I use. A simple two gear train or more? And if not is there any other way of increasing the time between windings without needing steel reinforcement in the walls?

Sorry if my terminology or anything else is wrong but I'm just a daft old wooden top.

Thanks

Izack

If anyone reads this silly question

As I can get hold of the right sort of pullies I think I want. But they have teeth. And so do the belts which are flat.

But apart from the reduced friction side would it be possible to run a toothed belt inside out. That is with the smooth side contacting the pulley?

That way I'd relive the issue of over friction and allow the belts to slip if needed. Or would they just slip completely without excessive tension?

Sorry that should have read I have a small 300mm centre Unimat style lathe. Works great if it wasn't for the nutter using it.