Science Buddies: "Ask an Expert"

Okay,so our bolts arrent magnetizing. we've tried a grade 5 w/ uninsulated copper wire &eletrical type around the core to insulate it, grade 5 w/insulated copper wire, grade 2 all-threaded w/ insulated wire, & a piece of rebar with insulated wire.All bolts were 5/8 except the rebar wich was 1/2.
we tried a 12v lantern battery, & at one time tied another 12v battery more to try to get magnatized. after that, we brought in a 12v car battery wich caused the bolts to magnatize. ( I should hope so w/ 300 amps!) But the instructions dont call for a car battery, and im afraid that since i have 4 hours of people pushing the switch, the wires will get to hot and the system may possibly overload. we have yet to attach the secondary coil, capacitors, and resistors to the core and primary winding, but we havent for fear of damaging the system & having to rebuild it.we had induction w/ the car battery of course with both insulated & uninsulated wire i dont know if these matter, but here are some other facts.

Bolt lengths:
Threaded-12"
Both grade 5- 6 1/2"
rebar- 11 1/4"

Winding length:
uninsulated: 3"
insulated- 2"

Number of windings:
uninsulated-12
insulated- 14


Some other questions:

Does the amount of space between the windings matter?
Does the size of the bolt matter?
does the length of the bolt matter?


please help! its due on monday and im on crisis manegment time

Please! any one answer!

so do the experts come on in the morning or what?

why does it need to magnatize to create an electro- magnetic field?and why is this project so difficult? just a randomn question that popped into my brain.....

Hi BlueRose,
Hang in there. Problem solving in this forum typically takes place over the course of days, not hours. That is especially for specialized projects like this one. If you find people are looking at your post but not responding, it probably means they don't have any useful advice to offer (that's the case with me).

Hopefully someone will come along soon who can help. Good luck!

Bluerose17 wrote:why does it need to magnatize to create an electro- magnetic field?and why is this project so difficult? just a randomn question that popped into my brain.....

Well, this was ranked one of the most difficult projects in the electricity section, so that part is kind of your fault for choosing it.

There is a lot of good advice on how to do this project on the forum. I suggest you search for this project, and read the threads.


Also, the way this board works it that each expert has a day to check (and we look in once or twice per day) and answer questions (I'm Sunday). Some of us may pop in at other times, but you could posted after the expert checked the forum for the day.

Anyway, I'm pretty sure that most of your questions have been answered.

You should be using insultated wire. The space between the windings doesn't matter, but the smaller/neater/tighter it is the better. Especially since you need to have a certain ratio between the primary and secondary coil, and if you aren't neat, it will be hard to do.

The bolt material should be magnetizable. Again, I think someone discussed this in the forum before.




Louise

Louise

okay... now will you answer my actuall question?

Bluerose17 wrote:okay... now will you answer my actuall question?

I thought I did. You asked about the windings (which I answered) and about why your bolt wasn't magentizing (which I answered- I said the material was important, and said that this had been covered before. I believe there is a list of appropriate materials for the carriage bolt in a post on the forum. Search for spark gap)

Is there something else I missed?

Louise

my problem isnt with the secondary winding... its first getting the bolt to magnatize with the primary coil witha lantern battery, not a car battery. that we have not been able to do

Bluerose17 wrote:my problem isnt with the secondary winding... its first getting the bolt to magnatize with the primary coil witha lantern battery, not a car battery. that we have not been able to do

Okay. Did you check on the material like I suggested? If it isn't magnetizable, it won't work. Also, in your first message you mentioned using both insulated and uninsulated wire. As I said, you do need insulated wire. I think the instructions say this, but the shopping list calls for uninsulated wire.

This is from another post on the forum (which I suggested you search and read):

What material did you use for the bolt?
Hard steel (bolts with hardness markings), stainless steel, and brass will not work! You need a soft or mild steel.

I don't really understand your bolt list in the first post, but it looks like you are using hard steel (grade 5 or 6)?

I think rebar is generally made with mild steel, but yous should probably verify your rebar material for your self.

So, I would focus on using the insulated wire and the rebar and not mess around with the other bolts.

Since posts don't get answered quickly, I highly recommend that you use the "search" function and see what advice has been given about this project in the past.

Also, how do you know it isn't magnetizing? Are you trying to attract the switch or a nail or something?
You may want to look at the "build an electromagnet' project since that is the component you are stuck on.

https://www.sciencebuddies.org/mentorin ... ?from=Home


When I was looking around, I also found this comment from another expert:

The relay is shown incorrectly. The normally closed contacts should be oriented away from the bolt head so that when current flows, the primary and bolt act like an electro magnet and open the contact. The normally closed contacts should be wired as shown, it is just the mechanical orientation that is wrong.

The description of the building of the apparatus should indicate that the Neef vibrator should be constructed and tested and be in good working order BEFORE winding the secondary! This should be done to allow working with the circuit without the high voltage danger!

Louise

i just realized a mistake on the list....

the all threaded is grade 2.... and the rebar is 1/2 thick, unlike the other bolts wich were 5/8 and we were using the uninsulted wire just to see if it would work. the problem is just getting the 12v lantern battery to magnatize the bolts. we tried all of them and none of them worked

and we have already searched all topics realting to spark- spark gaps- and the project create your own spark

Bluerose17 wrote:and we have already searched all topics realting to spark- spark gaps- and the project create your own spark

The advice I quoted said that steel bolts with any hardness number was unusuable.

My best advice at this point is what I suggested in the previous post. Use the rebar. Look at the electromagnet project for ideas. And again, how are you testing that it is an electromagnetic.

Oh, and you did scrape of the insulation where you connected it to the battery, right?

Louise

yes we scraped it off, and we r using a screws and nails to check if it gets magnetized. all bolts r magnatizable, its just they wont magnetize with so little amperage

Louise wrote:

Bluerose17 wrote:and we have already searched all topics realting to spark- spark gaps- and the project create your own spark

The advice I quoted said that steel bolts with any hardness number was unusuable.

My best advice at this point is what I suggested in the previous post. Use the rebar. Look at the electromagnet project for ideas. And again, how are you testing that it is an electromagnetic.

Oh, and you did scrape of the insulation where you connected it to the battery, right?

Louise

Sorry, I misread your first post. You did get this to work with the car battery? I'd use that setup and test your three bolts. See which one is the best electromagnet for a set number of coils. Count how many paper clips it can pick up or something. Which ever one is best is the lowest carbon steel, and will make the best electromagnet of the materials you have. (The amount of carbon in the steel determines the hardness and the magnetic properties. Higher carbon steel is very hard, but not magnetic. Low carbon steels is soft, but magnetic. You probably can make an electromagnet out of any type of steel, assuming enough current, which I guess is what you proved.)

The magnetic field induced will be related to the number of coils. That is why neatly wrapping is better, so you can fit more in.

Louise

If you read the instructions they always talk about the "iron core", so I think the person who did this project description was using iron, not steel bolt, so this is probably why the single lantern battery worked.

Also, the original instructions (see the bizarre labs link in the bibliogrpahy) uses an iron core.

You may be able to get one of your bolts to work with the lattern batteries, but maybe not. I agree the car battery may be problematic at the science fair, so if you can get a chunk of iron quickly, I'd try that.

Louise

okay, thank you

Bluerose17 wrote:okay, thank you

I hope you got this project to work, since I think you said it was due today. Good luck!

Either way, could you post back here with what your findings were? Did you get this to work with a lattern battery and the rebar? Or did you have to work with the car battery? Or did you find a chunk of iron? Or was something else wrong.

Thanks so much.

Louise

actually, we tore apart an inductor coil from a tractor and used that for the iron

Bluerose17 wrote:actually, we tore apart an inductor coil from a tractor and used that for the iron

Cool. You got everything else to work okay?

Louise