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shaft construction

Thread Status: Hello , There was no answer in this thread for more than 60 days.
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IvarNelson

New Member
Mar 5, 2005
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Some of you have maybe seen photos of the mechanism im making...
Well, I have made 2 now and they seem to work very well, I will soon put it in a speargun and test it.
Although a problem have com up, I cant seem to find stainless spring steel in round bars with a diameter of about 7-8mm,I understand it is the steel commonly used for making shafts.
I have been told I can buy a steel called "SS 2331-06 (DIN 17224) from a big company called Sandvik but they only sell it in bulk loads of 260kg for over 1000€! And I only needed a few meters! :ko
The end of the shaft must look like this in order to fit my mechanism, the hole in spear must be 3mm wide. How thin a spear do you guys think I can use? One way to do it is to order regular spearshafts and modify them but that will sort of undo the meaning of the mechanism which is to optimize the length of the barrel and to apply the force at the back of the spear. If I buy a shaft it will have notches of fins so the shaft will be weakened. Maybe I can buy shafts for pneumatics and use?
I asked a spearfishing shop what type of steel it was and got the answer: "17-4PH stainless steel 44HRC". I am not an engineer so I dont really know what type of steel I am looking for, I guess it has got to be hard as hell and stainless!?

So the questions are: How thin can the spear be without becoming to weak in the end part and not damage the wishbone?
What type of steel should I use?
Where can I find the right kind of steel?

btw, I have access to a great machine shop so I can do all kind work on it, except heat treating it for stiffness.



Thanks!
Ivar Nelson
 
you could just buy an extra long spear and cut off the notched part then make the end suit your gun.
 
Don't even invest 2 cents in 304 stainless steel. It rusts in saltwater, and it doesn't have the memory required to make a shaft. It's very, very easy to bend, so don't get it

I don't know any material for shafts that doesn't require to be treated (hardened). Some europeans use titanium shaft, but it's very light, so you have to increase the diameter, and even there, it's too light, and very expensive.

The 17-4ph stainless need to be hardened at a given temperature, for a given time, in a space free of air...

Unless you know someone who can do this at low cost, buy shafts and work them to get the desired shape.
 
Hello there,
The grade of stainless steel that you are looking for is 17-4 ph900. It is the same grade the riffe and aimrite uses.Contact Sterling at Hana`paa hawaii.com they have 17/64,9/32,5/16 and 3/8 sizes.They also have a x-hard grade. Aloha
 
You are not posting where you are from, so it's difficult to tell you if I can be of any help.

I have just purchased 17-4PH SS to make over 50 shafts, both in 3/8 (US$18 per 6' bar) and 5/16 (US$19 per 6' bar). No minimum purchase was required.

The most labor intensive part was cutting and welding the fins to the shafts (3 on the 3/8 and 2 on the 5/16), both the machining of the back and front (I machined my tips so that the front is the back part of a slip tip) was easy to make.

Heat treatment (H900) was not expensive either, it ended up costing a little under US$3.00 per Kilo and the shafts turned out great, comparable or better to Alexander's, and I did not pay more than US$40.00 per shaft.

Hardness was tested after HT and I got a Rockwell scale of 43. I believe 40 is acceptable and 45 is maximum.

I live in Mexico City, and if I was able to find all I needed here, almost anyone can do it in first world countries. The labor intensive part must get more expensive though.
 
hi
one question: the 17-4PH SS don't it break more easly than the ASI 316 stainless steel? it's harder but more easy to break, doesn't it? i made my own shafts in ASI 316: hard enough, good memory and very cheap, about USD4,50/meter/8mm.
do you think is a good option?
 
316 is good stainless but isn't heat treatable.It will bend and not come back to shape like heat treated 17-4 ph.17-4PH will break if bent enough but a 316 shaft will would be permently bent with less force.Most shafts are heat treated stainless or steel.
 
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