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"Lempo" pneumatic ballistic knife

Built a miniature cannon? Then post it here! This section is for completed, finished cannons that you have built. Please include pictures and information.
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Unread postAuthor: jackssmirkingrevenge » Sun Nov 27, 2011 2:46 am

Thanks guys :) again it wouldn't have worked without jake's contribution.

Gun Freak wrote::cheers:


See what you can do with a proper lathe ;)

the blackening fits great with the hammer marks on the blade


My thoughts exactly :)

Awsome!
I envy your machining and now also your etching capabilities!


Cheers Brian. The etching really needs more patience and care than skill, I think it would definitely add an edge to your own wonderful projects so if you need any tips just ask :)

Will you be blackening the lows on the aluminium grip?


No no no, this has been stamped as "finished", no more!

Nice penetration in Señor Happy Face


It's not *that* dramatic to be honest, this was 350 psi and the actual air available is not that significant. It's so easy to trigger with the new collar that I'm guessing it would work at 850 psi, but I don't want to push my luck and/or risk damaging that awesome blade.
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Unread postAuthor: ramses » Sun Nov 27, 2011 10:37 am

jackssmirkingrevenge wrote:I don't want to push my luck and/or risk damaging that awesome blade.


Lies.

:D :D
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Unread postAuthor: Brian the brain » Mon Dec 05, 2011 1:49 pm

so if you need any tips just ask

Here we go:
I got the acid...so..

What do I use to mask off the highs? Will masking tape suffice?
Or will I need bees wax...or would vaseline do?
With what do I apply the acid? ( a few drops ,right?)

Will it work just as well on steel?

Lots of questions but you know I'm a newbie...

Newbs don't have google..... :D
Anyway, google only got me the official way of doing it....not the improvised version.
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Gun Freak wrote:
Oh my friggin god stop being so awesome, that thing is pure kick ass. Most innovative and creative pneumatic that the files have ever come by!

Can't ask for a better compliment!!
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Unread postAuthor: jackssmirkingrevenge » Mon Dec 05, 2011 2:31 pm

hehe, it worked :D

First, basic safety:

- MINIMUM protection of latex gloves and safety glasses, ideally no bare skin should be showing.
- Acid fumes are at best unpleasant, at worst deadly, so do it outside.
- An eyewash station nearby is useful just in case, at least a bucket of clean water
- always work with small quantities, don't prepare more acid than you need. I was woking with 5mL at a time.
- All containers used must be clearly labelled and disposed of correctly
- try out any technique on a scrap piece of equivalent material first.
- make sure the material is properly cleaned before starting, and once it's done rinse it off very well with water.

Brian the brain wrote:I got the acid...so..


What acid do you have, and at what concentration?

What do I use to mask off the highs? Will masking tape suffice?
Or will I need bees wax...or would vaseline do?


First I started with nail polish, then scratching a design with a pin.

The problem is that I was using concentrated nitric which removed the nail polish after a while. This is the wrong way to do it but I was impatient, dilute over a long period is better than concentrated over a short period

Masking tape on the other hand seemed to hold very well, the problem is that it is more difficult to create a detailed design.

I haven't tried with wax yet but it's a popular mask.

Vaseline will probably just be dissolved by the acid, I tried with grease - hey, it works for epoxy - but no luck...

With what do I apply the acid?


I was using a syringe but this can be dangerous, if you push too hard you can squirt it.

Ideally you need one of these:

Image

Probably you'll find them in a pharmacy for applying eye drops.

( a few drops ,right?)


That's what I did, a couple of drops, let it react, a couple more drops, let it react...

Will it work just as well on steel?


I haven't tried steel yet but there are plenty of formulas online, some examples below.

Anyway, google only got me the official way of doing it....not the improvised version.


Good place to find formulas though, for example:

Ferric chloride is normally mixed with water in equal parts to form hydrochloric acid in solution. It's more commonly used to etch copper, but it also works well to etch stainless steel. It also works with a wider range of resist materials than pure acids do; however, it can pit the surface if not attended to properly.

Copper sulfate is better suited to etching mild steels than stainless steel. It is best mixed in a 1 to 1 ratio with sodium chloride (NaCl - common table salt) to keep the copper sulfate from coating the steel with a deposit of copper that will stop the etching process. The blue solution gradually fades as the etching progresses and turns colorless when it's finished.

Nitric acid is commonly mixed in a ratio of 1 part nitric acid to 3 parts water. It can also be mixed with acetic acid (vinegar), in a 1 to 1 ratio, or with hydrochloric acid.

Sulfuric acid should be used only in concentrations from 10 to 25 percent. Generally, dilute solutions are more effective than concentrated ones. Acids generally take longer to etch steel than do chemicals that form acids in water, however.


I think I covered everything, good luck :)
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Unread postAuthor: Brian the brain » Mon Dec 05, 2011 3:57 pm

Hmmm..I'm trying HCl at just 10% with a drop of Hydroperoxide...
Read a Dutch website and they recommended adding some.

Me too is impatient.
Started before your reply.

I used a thick layer of vaseline and drew a design in it with a steel pin.
Applied the acid with a brush.. :D

dilute over a long period is better than concentrated over a short period



The process seems to be very slow...not even sure if it's working...

Oh well...I'll see in an hour or so.
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Gun Freak wrote:
Oh my friggin god stop being so awesome, that thing is pure kick ass. Most innovative and creative pneumatic that the files have ever come by!

Can't ask for a better compliment!!
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Unread postAuthor: jackssmirkingrevenge » Mon Dec 05, 2011 4:11 pm

:D

Brian the brain wrote:The process seems to be very slow...not even sure if it's working...

Oh well...I'll see in an hour or so.


Patience is key, it will take more than that to be deep enough to be clearly defined.

Just remember that as you are putting acid on rather than dipping it in a bath, it's important to re-apply acid at regular intervals to make sure the reaction continues.
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Unread postAuthor: Brian the brain » Mon Dec 05, 2011 4:24 pm

Clogging your thread here butta..

I just checked the testpiece...whiped the grease and acid off and saw a pattern emerge...very shallow though..
The lines looked very fine.

It is definately working.

just applied it to the gun and will wait out the night...
Those regular intervals would disturb my sleep..
Not good for a fybromialgic.

I'll see in the morning if it was good enough...and I'll post the results in my thread...if they are good enough that is..
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Oh my friggin god stop being so awesome, that thing is pure kick ass. Most innovative and creative pneumatic that the files have ever come by!

Can't ask for a better compliment!!
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Unread postAuthor: jackssmirkingrevenge » Tue Dec 06, 2011 12:40 am

Image

Come on, let's see the result ;)
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Unread postAuthor: Brian the brain » Tue Dec 06, 2011 12:37 pm

Hey!

Just done working, dining and doing the groceries!


This morning I went to my workshop in anticipation...only to find ...the acid did NOTHING!
I mean..DAMN! :shock:

Nothing happened...weird...I'm starting to wonder how I got the earlier result....

Maybe I'll go get 30% HCl and good grade hydroperoxide....pff..what an anticlimax...

Ruined my day. :roll:
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Gun Freak wrote:
Oh my friggin god stop being so awesome, that thing is pure kick ass. Most innovative and creative pneumatic that the files have ever come by!

Can't ask for a better compliment!!
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Unread postAuthor: Heimo » Tue Dec 06, 2011 1:04 pm

BTB, have a look at the technique used HERE to etch PC boards, you can apply the same idea to etch whatever design you wish... the only issue I can see is if your surface ain't flat, you might have a little trouble...
also if someone else posted this or similar before, I must have missed it...
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Unread postAuthor: jackssmirkingrevenge » Tue Dec 06, 2011 1:15 pm

I think the critical fact is that you applied drops as opposed to dipping it in a bath. Unless you re-apply acid over time, once the thin layer has reacted there won't be any progress no matter how much time you leave it.
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Unread postAuthor: Brian the brain » Tue Dec 06, 2011 2:29 pm

Ah yes..that's why they keep the stuff moving...add fresh acid all the time...
I'll keep at it this time.

Let's hope this works...!!
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Gun Freak wrote:
Oh my friggin god stop being so awesome, that thing is pure kick ass. Most innovative and creative pneumatic that the files have ever come by!

Can't ask for a better compliment!!
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Unread postAuthor: jackssmirkingrevenge » Sat Dec 24, 2011 4:04 am

I took the Mk.2 collar and some more turning and polishing later, voila. Merry Christmas darling, I'm an awful human being :)
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Unread postAuthor: jakethebeast » Sat Dec 24, 2011 4:18 am

HAHA :D

I made this for my darling

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Unread postAuthor: jackssmirkingrevenge » Sat Dec 24, 2011 4:21 am

Just don't make her angry :)
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