DIY Strong Linear EM accelerator with 150mm stroke

Thread Starter

Buster710

Joined Feb 18, 2023
64
Hi folks - looking for some opinions on how best to build a simple and effective Linear EM accelerator for a design I am currently working on. (Sorry if the question is a bit jumbled)

Strictly speaking, a powerful solenoid capable of moving about 5kg and with a large 150mm stroke.

I realize a normal solenoid has very limited stroke up to 35mm ish due to their design characteristics.
Iron is normally used due to the high permeability and low magnetic retention. Rod centered on coil and is repelled by a spring in "off" state.

In coilguns / other magnetic accelerators I have seen, a series of coils is fired in sequence. I want to avoid this complexity if possible.

I would like to avoid the use of iron if possible, due to the hysteresis losses, and use copper on magnets if possible.
I'm then stuck with the strength of the magnets iinm? which should be fine as they are n52's and quite strong, although would it be better to use a sample piece of 99.99% pure iron as the "projectile" given it's 20,000 permeability (+ a longer coil for it to center in)? or are neo's better for this, seeing as they will accelerate to the end of the coil and out if unrestrained? (doing so seemingly under their own force)

Were I to fit a stack of neodymium ring magnets on a brass rod with a shaft collar & compression spring, could I then place that stack inside of a coil wound on aluminium tube and have the coil fire in opposite poles to the mag stack, pulling it through forcefully?

I will attach a steel cable to both ends (rod sat in 2x linear bearing blocks) on with a counterweight, one with a spring.

Do I need a ferrous "core" or "liner" for the coil bobbin or is air (aluminium) core OK given the magnets conduct the flux inside more efficiently than outside?

Will it work as I imagine?
Many thanks in advance for any suggestions.
 

Sensacell

Joined Jun 19, 2012
3,432
Always start by asking yourself:
"Where have you ever seen anything that works like this?"
Probably nowhere, this is not a viable scheme for a linear actuator.
 

Thread Starter

Buster710

Joined Feb 18, 2023
64
Always start by asking yourself:
"Where have you ever seen anything that works like this?"
Probably nowhere, this is not a viable scheme for a linear actuator.
Could you kindly suggest something that would work in a similar fashion?
Or explain why it won't work so I may amend the plan?
Also have you built one of these? That is to say who knows what it'll do if no one's tried it - just saying
 

wayneh

Joined Sep 9, 2010
17,496
Why not use a simple lever to convert a short stroke into a longer one? You need more force on the solenoid side of the lever, but that's less a problem than such a long throw.
I think a motor turning a wheel would be better still.
 

Thread Starter

Buster710

Joined Feb 18, 2023
64
Why not use a simple lever to convert a short stroke into a longer one? You need more force on the solenoid side of the lever, but that's less a problem than such a long throw.
I think a motor turning a wheel would be better still.
Great idea, I'll try it out. thanks
 

LowQCab

Joined Nov 6, 2012
4,023
If You would simply explain what it is that You are trying to accomplish,
You would probably get some much more useful answers.
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