Re: Wimshurst machines (fwd)

[Steven Roys <sroys@xxxxxxxx>]

---------- Forwarded message ----------
Date: Sat, 15 Nov 2003 16:18:34 +0100
From: Finn Hammer <f-h@xxxx>
To: High Voltage list <hvlist@xxxxxxxxxx>
Subject: Re: Wimshurst machines (fwd)

all,

I have just uploaded a rendering of the layout of the drive belt for a
Wimshurst Machine using only one belt, but still operating the machine
facing the discs, and with the benefit of having the same ratio of
revolutions btwn. the large driving pulley and the smaller pulley`s on
the disk bosses.
By rendering the drive pulleys as transparent, it is possible to
visualize the complete path of the belt, something that is difficult
with real world materials. ( Well, of course the parts could be made
from polished acryllic...but then there would be optic abberations.)

http://home5.inet.tele.dk/f-hammer/TRANSWIM.JPG

All pulleys, except the one in the front of the machine, with the crank
handle (not shown), are idlers.

Anyway, as you will see, the layout follows that of :
http://www.coe.ufrj.br/~acmq/rovc1.jpg
and
http://www.coe.ufrj.br/~acmq/rovc2.jpg
Which was built by Paul Hendriksen


With the added convenience of ratio and operating position. By the
latter I mean "where the crank is situated, and hence where the operator
stands, ie. in front of the machine".


High Voltage list wrote:
> Original poster: Steven Roys <sroys@xxxxxxxx>
>
>
>
> ---------- Forwarded message ----------
> Date: Fri, 14 Nov 2003 08:38:26 +0100
> From: Finn Hammer <f-h@xxxx>
> To: High Voltage list <hvlist@xxxxxxxxxx>
> Subject: Re: Wimshurst machines (fwd)
>
>
>
> High Voltage list wrote:
>
>
>>>Makes it easy to have 48 exactly placed sectors. The neutralizing points
>>>were small roundheaded screws,
>>
>>
>>Screws? Wouldn't they scratch the disks? I use brushes as light as I
>>can.
>>The current is very small.
>
>
> I use very soft and thin wire for the brushes too. But it annoys me if
> these wires drag marks around the disk, by touching the disk itself, so
> i had holes drilled in the narrow end of the sectors, threaded them, and
> put small screws in them, so that the brushes touch them, not the disk.
> It is just another way of making the small bump that is often made on
> sectors, if they are made from foil, and glued or waxed on to the disks.
>
> I have a picture of one spare disk here, without screws, but with holes.
>
> http://home5.inet.tele.dk/f-hammer/wimshurstdisk.jpg
> Battery in the center is a AA for size.
>
>>
>>>and although they promoted interdisk spark
>>>formation at the low voltage end of the machine,
>>
>>
>>Sparking close to the neutralizers always happens. The only way to avoid
>>it is to mount the sectors inside the disks, accessed through small
>>buttons, as in the old Wehrsen/Wommelsdorf machines. Maybe you can make
>>a machine using a multilayer PCB with internal sectors using a standard
>>professional PCB construction method. It's even possible then to mount
>>the sectors as two interleaved sets in two plates for greater
>>insulation:
>>http://www.coe.ufrj.br/~acmq/wehrsec.jpg
>>http://www.coe.ufrj.br/~acmq/wermov.jpg
>>Made the access buttons flush with the disk surface, or they break
>>the brushes too easily. PC boards seem a good method for this.
>
>
> I think that if the disks run true, then it is ok to have the buttons
> protrude a bit.
> I worry that the marks on the disk could form a conductive path that
> would, in time, short out the machine.
>
> snip
>
>
>>>I also deviced a drive layout with only one long belt, which does not have
>>>to be crossed at one of the disks. This saves the machine from becoming
>>>covered vith rubber dust in time.
>>
>>
>>Don't use rubber belts. You know the effect. Ozone destroys rubber.
>>A classic method of using a single belt is to pass the belt through
>>two pulleys at 90 degrees with the pulleys in the disk bosses, one
>>fixed to an axle and another free to rotate over it:
>>http://www.coe.ufrj.br/~acmq/rovc1.jpg
>
>
> That picture reminds me of how much I have to learn: That is one very
> beautifull machine. But I am not able to imagine the drive belt`s path
> from the picture and your description. Have you got other pictures? Or
> could you spend a few more words? I see that they are using timing belt(s)?
>
> How big is that machine, anyway?
>
> Making pictures of these belt systems is not easy, I am currently trying
> to make a 3D rendering of my own system ( based on the work of others)
> that shows how it is done. It uses a round polyurethane belt, that I get
> on a reel, like magnet wire,  and join by welding the ends together.
>
>
>>The thread is here now.
>>
>>Antonio Carlos M. de Queiroz
>>
>
> Cheers, Finn Hammer
>
>
>
>