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Giant Wimshurst Machine - could use some guidance

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Antonio
Sun May 25 2014, 12:37PM
Antonio Registered Member #834 Joined: Tue Jun 12 2007, 10:57PM
Location: Brazil
Posts: 644
About the frame, the solution of increasing their separation seems simpler, but you can do this after testing the machine, if some obvious leak appears. This machine will be hard to turn when charged. You will probably not be able to turn it fast enough for vibration problems. Allow for some method of increasing the separation of the disks, as larger separation turns it easier to turn, at the expense of slower charge buildup. The methods for assembling the spheres seem good. The extra metal pulleys can be used later for a motor drive.
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AwesomeMatt
Tue May 27 2014, 08:56AM
AwesomeMatt Registered Member #4454 Joined: Sun Feb 26 2012, 12:47AM
Location: Western Canada
Posts: 74
I read most of R.A. Ford's "Homemade Lightning". Didn't answer most of the questions I had, scared me off of the stuff I thought I knew :(

It's becoming more and more obvious that this is the kind of machine that does not show fractional progress. Up until it's 99.5% done you get *nothing*, and then that 99.5-99.9% is where you progress through your entire results.

Intuitively, it would seem like "Well it works okay but not great, 60% spark distance until you go back and polish everything and make sure it's clean and joints are covered", etc etc. But that doesn't appear the be the case. It won't do a damned thing unless it's nearly perfect.

And, deadline looms, which adds stress to all decisions because there's not time to experiment or tinker.

Today's progress:

First, just because it feels like progress, I put the wheels on the upper axle. Was a waste of time and counter-productive (they have to come right back off), but, was satisfying to see anyway.

2014

It's fairly large and intimidating:

2015

The disks are 3/8" acrylic but I want to avoid as much wobble as possible, so I plan to buttressed them with 3/4" disks 21" in diameter.

2016

I got to the shop around closing time today, so, instead of having help with the Shopbot, I drilled a hole in the router table, mounted a screw and churned out the new circles myself. Not bad.

The assembly I have the least confidence with right now is how I will be driving the big wheels. Note the little 1" pulley below. I'm going to drill into the collar side of that, tap 4 holes, and... hopefully spin both the 21" buttressing shoulders and the 48" wheel off of that. The shoulders and the main wheel will also be bolted together with nylon bolts and either nuts or I"ll tap threads into one of the pieces of acrylic.

I'm just not confident spinning a 48" 100+ pound disk from 4 nylon bolts an inch and a half apart from each other. Maybe I"ll also silicone the pulley to the shoulder?

In the past I considered welding a flat disc to the 1" pulley itself and then bolting that to the shoulder, but, Homemade Lightning poo-poos the use of metal just about anywhere. Also, there were questions as to whether the plate could be balanced (I think a small issue, and, turn it on the lathe to make sure).

2017

Output terminals. I figured I'd solder (press fit for now) a T-joint onto the 1" copper pipe. It's nice and smooth, graceful curves. One piece of wood will handle the hinging action, the other will be the manipulable handle (though probably PVC to avoid conductivity to the user).

2018

A bunch more little T-joints for the 1/2" copper tubing (combs/neutralizers), I figure I can make most of the U-shapes out of these, as well as use them to connect to the leyden jars.

Also, bought some reducers, they're smooth tapered enough I hoped. This would help narrow down to the neutralizing bars or something I figured. Instead I'll probably just go buy some ball bearings or brass balls.

2019

Oh, and an action shot from cutting the shoulder disks.

2020


It's passed the point of being fun and interesting due to the time crunch, now everything I do has "#### I hope this works/I don't screw this up/It doesn't take that long" looming over it. Tomorrow lots of shopping for joining hardware and probably some sector cutting.

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RAJEEV TUTEJA
Tue May 27 2014, 03:26PM
RAJEEV TUTEJA Registered Member #46265 Joined: Sun May 11 2014, 06:01PM
Location: AMBALA CANTT, INDIA
Posts: 9
i am also making one with 36" disks. instead of frame i had got some carpenter to turn me stands for mounting.
some pics attached
1401204334 46265 FT163022 Img 1551

1401204334 46265 FT163022 Img 1560

1401204334 46265 FT163022 Rajeev0832

1401204334 46265 FT163022 Rajeev0834

1401204334 46265 FT163022 Rajeev0843
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AwesomeMatt
Tue May 27 2014, 07:11PM
AwesomeMatt Registered Member #4454 Joined: Sun Feb 26 2012, 12:47AM
Location: Western Canada
Posts: 74

Neat. Thanks for sharing.

My plan is:

First make it work, then
Make it work better, then,
Make it pretty.
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Eleccentric
Tue May 27 2014, 09:48PM
Eleccentric Registered Member #33460 Joined: Tue Aug 27 2013, 06:23PM
Location: Seattle
Posts: 46
Don't let Homemade Lightning get you down - that book details how to built the BEST possible machines, and so focuses the finest details. It also is for sectorless machines, which are much more finicky. A machine with sectors will give you something even if it is built poorly.
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AwesomeMatt
Tue May 27 2014, 11:50PM
AwesomeMatt Registered Member #4454 Joined: Sun Feb 26 2012, 12:47AM
Location: Western Canada
Posts: 74
wrote ...
A machine with sectors will give you something even if it is built poorly.

That made my day, thanks :)
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Antonio
Wed May 28 2014, 01:07AM
Antonio Registered Member #834 Joined: Tue Jun 12 2007, 10:57PM
Location: Brazil
Posts: 644
AwesomeMatt wrote ...

It's becoming more and more obvious that this is the kind of machine that does not show fractional progress. Up until it's 99.5% done you get *nothing*, and then that 99.5-99.9% is where you progress through your entire results.

First, just because it feels like progress, I put the wheels on the upper axle. Was a waste of time and counter-productive (they have to come right back off), but, was satisfying to see anyway.
The disks are 3/8" acrylic but I want to avoid as much wobble as possible, so I plan to buttressed them with 3/4" disks 21" in diameter.

The assembly I have the least confidence with right now is how I will be driving the big wheels. Note the little 1" pulley below. I'm going to drill into the collar side of that, tap 4 holes, and... hopefully spin both the 21" buttressing shoulders and the 48" wheel off of that. The shoulders and the main wheel will also be bolted together with nylon bolts and either nuts or I"ll tap threads into one of the pieces of acrylic.

I'm just not confident spinning a 48" 100+ pound disk from 4 nylon bolts an inch and a half apart from each other. Maybe I"ll also silicone the pulley to the shoulder?

Output terminals. I figured I'd solder (press fit for now) a T-joint onto the 1" copper pipe. It's nice and smooth, graceful curves. One piece of wood will handle the hinging action, the other will be the manipulable handle (though probably PVC to avoid conductivity to the user).

Oh, and an action shot from cutting the shoulder disks.

You can test the machine after the neutralizers are in place, before mounting the terminals. You will see the disks charging and the cranking become difficult.

The frame could be smaller. The disks can come quite close to the lower pulleys without leakage, since the voltages at the bottom are small.

The reinforcing disks are a good idea. No problem in fixing them with nylon screws, but keep their holes distant from the sectors.

The small pulleys fixed to the disks shall have two bearings each, or a long metal tube forming a journal bearing over the axle. They also can't be too small, or the driving belts will slip. No problem in fixing the disks to them with metal screws from inside. Read what the book says about the precision required on the bosses. As they essentially control the parallelism of the disks their construction is critical.

Avoid silicone glue, or any glue. Glues are useless in blocking electricity and are ugly.

Use plastic for the handles. Wood is useless as insulator. PVC tubes are ok.

Be careful to not scratch the acrylic when making these disks. Keep the protective covers.

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Newton Brawn
Wed May 28 2014, 02:38AM
Newton Brawn Registered Member #3343 Joined: Thu Oct 21 2010, 04:06PM
Location: Toronto
Posts: 311
Hi Rajeev ,

I like the two posts supporting the disks, the style follows the time when the machines begining the generation of the electrical generation...
Conratulations, keep posting the pictures.
Newton
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AwesomeMatt
Wed May 28 2014, 03:07AM
AwesomeMatt Registered Member #4454 Joined: Sun Feb 26 2012, 12:47AM
Location: Western Canada
Posts: 74
wrote ...
No problem in fixing them with nylon screws, but keep their holes distant from the sectors.

Hrm, was about to do that now.

How distant is "distant"? 48" wheels, 21" reinforcing discs, so there is 13.5" of space around the reinforcing discs. That has to be shared by sectors and any isolation gap I need.

I haven't even thought about how tall my metal sectors would be.

If anyone wouldn't mind giving this a stupid-proofing, here's my logic:

If max voltage is from the left side to the right side of the big wheels (where the combs are), and I have 40 total sectors, that means 20 total sectors per half. That means the space between sectors must be greater than t size of the arc I want to achieve (18"). Call it 20" so the math is easier. That means I need 1" separation between each sector (20" total across 1/2 the disc).

I don't want the sectors ending in sharp points, so there's no purpose in having them dagger down all the way, so, call it... half inch min width near the bottom of their rounded-trapezoid shape. So... 20x 0.5" = 10", plus 20" of separation... = 30"

Since that's across a half disc, my circumference needs to be doubled to account for the whole wheel (60" minimum).

Circumference = 2 * pi * radius
So,
Radius = Circumference / 2 * Pi
Radius = 60' / 2 * pi
Radius = 9.55" away from the center.

Well, my reinforcing discs are already 10.5" away, so, I will be trimming the metal sectors much less long than they could be.

Same math using 1" sector min width and 1" separation = 12.75" min radius.

Anyway, suppose it's something around there. What would be the necessary amount of separation? (The measurement marked "???")

201

wrote ...
The small pulleys fixed to the disks shall have two bearings each, or a long metal tube forming a journal bearing over the axle.

I couldn't figure out a way to make bearings work, so I used phosphor bronze bushings instead. They seem to be okay so far. Per side, I am using 1 on the pulley and one for the two discs (4 total).

wrote ...
No problem in fixing the disks to them with metal screws from inside.

Whew. Good. I was scared with the nylon here. Metal it is!


wrote ...
Read what the book says about the precision required on the bosses. As they essentially control the parallelism of the disks their construction is critical.

The trouble is also that I do not have a drill press with a 24" long arm, so I can't be sure I am drilling the axle/bushings holes 90'. I have to use a hand drill.

If they end up crooked, I will have to shim where they attach to the pulley, or, use the lathe to "face" the side of the pulleys.

wrote ...
Avoid silicone glue, or any glue. Glues are useless in blocking electricity and are ugly.

Oh? Hrm. Are they conductive, or is the issue the difficulty in applying them consistently?

For example, if I apply silicone to the two discs prior to screwing them together with nylon bolts, then squish the faces together, I think they will seal up just fine (not that they need to).

wrote ...
Be careful to not scratch the acrylic when making these disks. Keep the protective covers.

Yep, they're coming off when I have the sectors cut, and not before.

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RAJEEV TUTEJA
Wed May 28 2014, 03:51AM
RAJEEV TUTEJA Registered Member #46265 Joined: Sun May 11 2014, 06:01PM
Location: AMBALA CANTT, INDIA
Posts: 9
for sector design i used a program wimshurt machine designer (WMD for short) and then i had a screen shot of the same which i imported into coreldraw and made the template for my size of disk.
photo attached
1401249075 46265 FT163022 Rajeev0842
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