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Giant Wimshurst Machine - could use some guidance

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AwesomeMatt

Wed May 28 2014, 07:25AM

Registered Member #4454 Joined: Sun Feb 26 2012, 12:47AM
Location: Western Canada
Posts: 74

wrote ...
for sector design i used a program wimshurt machine designer (WMD for short)

I searched for, then found this. I was thinking "*This* is the guy I should be talking to!"

And then I found out it is Antonio. One of the people here who has been most helpful to me :)

Since by Friday I'm supposed to convince people that this can be done... this may help a lot.

I crunched the numbers I arrived at for my design... lo and behold it suggests that it's possible to do exactly what they want with what I am building.

Ash Small

Wed May 28 2014, 08:18AM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

AwesomeMatt wrote ...

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.

If you do have to use a hand drill, make sure you have at least one assistant to 'sight' the drill and tell you if it looks vertical. You may need two assistants if you are drilling vertically.

Another option (if I understand your design correctly) is to drill the holes in the plastic oversize, and then centre everything up when you attach the pulleys (I'd still use the above method for drilling the bolt holes).

EDIT: Another option is to use a 'MAG drill' (drill with magnetic base) if you have access to one. Lay a piece of heavy, flat steel on the disc and mount the MAG drill on that. You obviously need to take care not to scratch the disc, though (a second plastic sheet between disc and steel?). Once the drill is positioned you should be able to put some weight on it to hold everything in place while you drill (carefully). It's better to clamp the steel to the disc, but if you are careful, you may be able to get away with using an assistant to hold everything in place (maybe stand on it). Clamping would be safer!! (clamp everything to the bench, maybe, using extra plastic sheets to 'sandwich' the disc?)

AwesomeMatt

Wed May 28 2014, 07:04PM

Registered Member #4454 Joined: Sun Feb 26 2012, 12:47AM
Location: Western Canada
Posts: 74

wrote ...
If you do have to use a hand drill, make sure you have at least one assistant to 'sight' the drill and tell you if it looks vertical.

I was alone in the shop, worked until 11pm.

Fairly confident I could drill straight down if I just observed my posture, I've done this before when it was the only way and didn't do too bad.

Didn't matter, the drillbit was a little crooked and it wandered off side, wobbbled in the hole (oversizing it) and messed up a couple hundred dollars worth of acrylic.

My junior high shop teacher's motto: "Rushing ruins things"

Knew it was the wrong method, knew I was rushing, just didn't have time to think or plan a better one.

Bought more plastic today, going to try again I guess.

Frustrating and discouraging.

That's not even the hard part, the hard part is getting 4 holes in the side of the 1" pulley and trying to use a 2" wide face to steer a 48" disc.

I said last night my odds of finishing on time dropped to 50%. That was probably overly ambitious.

Ash Small

Wed May 28 2014, 08:50PM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

AwesomeMatt wrote ...

That's not even the hard part, the hard part is getting 4 holes in the side of the 1" pulley and trying to use a 2" wide face to steer a 48" disc.

Make a 'template' on a pillar drill. A disc of steel, maybe, narked out, centre-punched, and drilled accurately. Drill the centre hole undersize, drill a matching hole in the centre of the plastic sheet, and bolt the template to it, then drill the boltholes. Then mark out the disc itself, then drill out the centre hole in the template on the pillar drill again (you should be able to 'centre' it pretty easily, espacially if the drill bit has not been sharpened 'offcentre'-best to use a new bit here if possible, or turn up a 'point' on a lathe, for accurate centring), bolt it to the plastic using the boltholes, and drill out the centre hole, then cut the disc out (or, if you bolt the disc down to the table while cutting, cut it out before enlarging the centre hole).

Just my two cents worth

EDIT: I'd still advise arranging for an 'assistant' to 'sight' the drill for you, even using a drilling template.

AwesomeMatt

Wed May 28 2014, 10:53PM

Registered Member #4454 Joined: Sun Feb 26 2012, 12:47AM
Location: Western Canada
Posts: 74

wrote ...
Make a 'template' on a pillar drill. A disc of steel, maybe, narked out, centre-punched, and drilled accurately.

This is basically what I did last night.

I cut one piece of 1/2" acrylic with a 1/2" axle hole, and then one 7/64" hole the right distance away.

Then, I took another piece of acrylic and drew a precisely square X on it, scribed lines fairly deep. I drilled out the center on t drill press to 1/2" when I was done.

Then I put a 1/2" bolt through the pair to secure them axially. I took the 7/64" drillbit in the drill press and plunged it through the first plate into the second plate where it lined up with 1 of the lines in the X. Then spun it to the next X, drilled again. Then a third time, then a fourth.

This made sure that my holes in the second template were all the exact same distance away from the center... and I had a jig I could place over the pulley to drill. I could also use the same jig to place over the acrylic.

But.. since I guiding myself through acrylic into steel, the steel shavings kinda abraded away the walls of the template a bit. So, makes it a bit of a moot point as a super-precise template.

Pulleys are now drilled and tapped. Once the acrylic shoulders are re-cut I can drill and tap them, put it all together, make up a belt and test the mechanical assembly.

Then, I have one day to make all the electrical assembly, diagnose it, etc.

Sorry it's been a boring read lately, I'll try to get some more pictures up tonight.

...

Questions:

1 -I have a question about the neutralizer bars. can they be shorted to each other? I.E. ... I won't do it purposefully, but if they're mounted basically to the axle, and the axle is metal, I figure there's not enough insulation there to prevent any voltage from arcing from one bar to the opposing bar through the axle.

2 - Antonio's WMD [

<-- search/scan for WMD] has a variable of "boss size" that, at some point, limits the length of the arc. Does this presume that the boss is made of a conductor? Or is it based on the fact that the screws (even if nylon) will puncture the discs? Or some other variable I have not considered?

*deep breath*

Monday or Tuesday is new deadline.

Whew.

Breathing room.

"Progress" of the last couple days:

Here's the "Center + 1 hole" jig I talked about earlier:

2021

And here is the jig I used the other jig to make, to ensure all holes were equidistant from the axle. Also, there are the small pulleys that I drilled, tapped, and pressed bushings into:

2022

Here is yesterday's ruining of a couple hundred dollars in acrylic. These are the 21" shoudlering discs. Holes are different sizes, and both are off center. Throw 'em away, cutting new ones tomorrow.

2023

Also holesawed out a 2x4 base for the output supports (what the electrode arms will hinge on), and cut 2" PVC to length:

2024

Will grow up to be leyden jars I hope. Take 4" PVC pipe (not shown), throw end caps on the bottom, screw caps on the top, and the screw in lids themselves will have the conductor in them.

I can cut them to be 24" tall or whatever they would need to be:

2025

Chain, to connect the inside of the jars and the base of the jars to each other.

2026

1/2" copper elbows for bends, and 3/4" vinyl tubing I probably won't use (wanted to sleave some 1/2" tubing over the copper, but it got stuck after about 3", so I bought 3/4" instead... which obviously looks terrible and saggy):

2027

Some brass shim stock. Couldn't get phosphor bronze.

2028

And the final result as of today (doesn't look much different, just the 2" PVC pillars added).

2029

Rod-on

Thu May 29 2014, 06:54AM

Registered Member #6541 Joined: Sun Sept 09 2012, 05:01AM
Location: Melbourne Australia
Posts: 16

Fantastic project, you might want to take a look at a series of youtube video's made by Mr. Teslonian on how to make a huge Whimshurst machine from easy to find bits and pieces. Here is a link:

AwesomeMatt

Thu May 29 2014, 07:22AM

Registered Member #4454 Joined: Sun Feb 26 2012, 12:47AM
Location: Western Canada
Posts: 74

wrote ...
you might want to take a look at a series of youtube video's made by Mr. Teslonian

I'm familiar with his project.

It's basically a "How-NOT-to" series. He doesn't seem to understand how a Wimshurst works, so he copies without context and made a lot of mistakes, resulting in a very sub-par machine.

He's also nuts. He believes the pyramids were giant tesla coils and the water channels in them are conductors. He believes energy "flows" inside water from the atmosphere down to the oceans (electrically, not as moving water) and we could all have free limitless energy if we built giant tesla coils.

Poor reasoning in general surfaces in all decisions people make :(.

Thanks for the support though.

RAJEEV TUTEJA

Thu May 29 2014, 08:40AM

Registered Member #46265 Joined: Sun May 11 2014, 06:01PM
Location: AMBALA CANTT, INDIA
Posts: 9

QUOTE BY AwesomeMatt
"Here is yesterday's ruining of a couple hundred dollars in acrylic. These are the 21" shoudlering discs. Holes are different sizes, and both are off center. Throw 'em away, cutting new ones tomorrow."
well I also MADE THE SAME MISTAKE. then what i did was screwed in a nut with plastic washers to protect the acrylic to both of the disks and mounted on a big lathe at my friends workshop and turned the outer rim to make it concentric with the holes. sure the disks were left a few mm small but what the ????, will not make any difference at all.

Antonio

Thu May 29 2014, 12:18PM

Registered Member #834 Joined: Tue Jun 12 2007, 10:57PM
Location: Brazil
Posts: 644

Several random comments:
In the WMD program it's assumed that the center bosses are conductive, so it looks at their distance from the sectors.
About aligning disks with bosses and centering holes: I make the disks by first making the central hole with the exact size of the axle and then cut the disks by turning them around a similar axle. I use a template with the same central hole for the screw holes in the disks and bosses, and once everything is fixed in place and aligned around the axle I enlarge a bit the center holes in the disks. The disks can be fixed to the bosses with flat-head screws from inside, with a thin metal plate between the screw heads and the disks to avoid excessive stress. Screws with protuding heads can be used too in a large machine, but this limits the spacing of the disks. I place a spacer of soft material between the disks and bosses, to allow adjustments on the verticality of the disks with the pressure of the screws.
Use a lathe to align face and hole in the bosses.
Note that the neutralizers shorten the distance for a spark jumping across the disks. With the neutralizers at 60 degrees the distance is 1/3 of the sum of the distances between pairs of sectors across an entire disk.
The problem with holes in the disks is that they may short-circuit the machine at the top and bottom quadrants. Not a big problem, since the voltage there is low.
Glues usually don't resist high voltage and are easily perforated by sparks. And they turn maintenance difficult.
Verify if the tubes used as insulators are stiff enough, since they will support the heavy terminals and the charge collectors, that may touch the disks if they are not solidly fixed in place. You can add arms (horizontal tubes or acrylic bars) fixing them to the frame too.

AwesomeMatt

Thu May 29 2014, 07:19PM

Registered Member #4454 Joined: Sun Feb 26 2012, 12:47AM
Location: Western Canada
Posts: 74

wrote ...
sure the disks were left a few mm small but what the ????, will not make any difference at all.

My issue is that the drillbit itself was bent, and thus drill oversized the hole.

I don't know anyone with a 48" (well, 24") lathe, but I do have a big routing table. That was going to be my plan too, but, I can't add material back.

wrote ...
In the WMD program it's assumed that the center bosses are conductive

Fantastic. I couldn't think of a way this wasn't true, but, I'm glad I reasoned it out myself.

wrote ...
I place a spacer of soft material between the disks and bosses, to allow adjustments on the verticality of the disks with the pressure of the screws.

Interesting... I may try that method. What is "softer" material to you? HDPE/PVC, wood, or much softer like foam or cardboard?

wrote ...
You can add arms (horizontal tubes or acrylic bars) fixing them to the frame too.

Yes, acrylic bars were my plan.

Thank you all again for all your help. I would be far more discouraged without everyone's guidance.

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