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Mar 21st 2016, 12:05 PM   #1
 holypiston's Avatar
 
  Jan 2016
  Vancouver, WA

Non Magnetic metric bolt for ignition rotor

Hello all,

What I am looking for is a non-magnetic bolt that basically holds the rotating magnet that sits atop my ignition rotor for my RD400 modified DYNA-S ignition.

If someone could point out exactly what type of bolt (series/strength/etc) to look for that would be great. Trying to eliminate the possibility of the bolt interfering w/ the magnet @ low rpms (sub 1600 rpm). Next will be a battery swap and then coil wiring check.

Any ideas for a bolt ? typically w/ the old ignition the bolt would magnetize when the power is turned on.

Not quite sure of the bolt size but economy cycle sells a replacement that is M7 X 60mm, thinking the thread pitch would be odd like 1.25, but not really sure. Any RD gurus can speak up now.
Attached Thumbnails
Non Magnetic metric bolt for ignition rotor-dyna-ignition-2.jpg  

Edited by holypiston on Mar 21st 2016 at 12:09 PM
Mar 21st 2016, 01:57 PM   #2
 
  Jan 2016
  Seattle

Stainless, aluminum, or titanium are all nonmagnetic
dragracer1951 likes this.
Mar 21st 2016, 02:00 PM   #3
 MMcN49's Avatar
 
  Jan 2016
  Small Island Surrounded by Puget Sound

  07 Buell XB12STT, (Two) 12 Suzuki DR650 SE 72BMWR75/5 KIA @ 243K
Not sure why you need a nonmagnetic bolt but that limits your choice to nonferrous, (aluminum, brass, nylon and SS). Forget about the first three but 304 & 316 SS are non magnetic. 18-8 and 303 may or may not be. 304 is stronger and probably your better bet. 316 is expensive but hey you're only getting one fastener.

Tacoma Screw is your friend here. Take the original bolt to them and have them match it. Their Portland store is the closest to Vancouver.
Mar 21st 2016, 02:25 PM   #4
 holypiston's Avatar
 
  Jan 2016
  Vancouver, WA

Thanks for the replies guys. I also read that T316? would probably be the way to go, I'm guessing that might also be a marine quality bolt, so that might be an added plus against corrosion. AS a test I went and turned on the key and applied a magnet to the bolt. I believe this bolt to be stainless, as I didn't feel magnetism w/ key on (usually happens w/ stock ign rotor bolt, which this is not). HOwever, my machinist is going to look at it and can make me a custom bolt if necessary. So I just might have the right bolt...guess i should have checked it before posting, 8) but anyway, at least I know what series of bolt i do need.

Thank you for the Tacoma Screw plug...i'll look them up and see if they do indeed have a store in this area.
Mar 21st 2016, 03:02 PM   #5
 holypiston's Avatar
 
  Jan 2016
  Vancouver, WA

ok it looks like the bolt i have in there now is F593C which turns out to be 304 Stainless steel. Only the bolt head is slightly magnetic (more magnetic than the threads and right where the rotor is) and i read this can happen in the forming process of the hex cap "head" and threads on the bolt.

Edited by holypiston on Mar 21st 2016 at 04:14 PM
Mar 21st 2016, 06:41 PM   #6
 liberpolly's Avatar
 
  Jan 2016
  Seattle

  Triumph Street Twin
Stainless steel can be magnetic. It depends on its quantum state. I kid you not.
Thumperpilot likes this.
Mar 21st 2016, 07:58 PM   #7
 
  Jan 2016
  Seattle

Quote:
Originally Posted by liberpolly
Stainless steel can be magnetic. It depends on its quantum state. I kid you not.
If you went into Tacoma Screw and bought a ss bolt, I guarantee you it wouldn't be magnetic. There's always exceptions, but in general, stainless isn't magnetic
Mar 21st 2016, 08:04 PM   #8
 Thumperpilot's Avatar
 
  Jan 2016
  Rome

  SV650S, CRF450R, and others

You need an austenitic stainless steel bolt. No, I didn't know this but just learned it here: Why dont magnets work on some stainless steels? - Scientific American

Edited by Thumperpilot on Mar 22nd 2016 at 12:28 AM
Mar 21st 2016, 10:03 PM   #9
 liberpolly's Avatar
 
  Jan 2016
  Seattle

  Triumph Street Twin
Quote:
Originally Posted by Thumperpilot
You need an austenitic stainless steel bolt. No, I didn't know this but just learned it here: Why dont magnets work on some stainless steels? - Scientific American
Oh, yes, good explanation. Saved me lots of typing.

So it indeed depends on the quantum state of Tacoma Screw. Which sounds... intriguing.
Mar 22nd 2016, 03:48 AM   #10
 MMcN49's Avatar
 
  Jan 2016
  Small Island Surrounded by Puget Sound

  07 Buell XB12STT, (Two) 12 Suzuki DR650 SE 72BMWR75/5 KIA @ 243K
Here's a list of Austenitic Stainless Steel types. 304 is not on the list. 316 is the most expensive but may be the best choice to meet your needs. Its considered non-magnetic. Titanium according to google is lightly magnetic.

• Type 305 (Chromium and Nickel alloys) – This alloy is very dependable due to a high nickel content that allows for easier forming and cold heading.
• Type 384 (Chromium, Nickel and Carbon alloys) – Especially developed for cold heading, this type has a high nickel content (between 17 and 19 percent) that increases the cost of raw materials considerably.
• Type 303 & 303Se (Chromium and Nickel alloys) – This type is good for hot forging, although should be avoided when cold heading processes are required. Used for large nuts that will be machined heavily.
• Type XM7 (Chromium, Nickel and Copper alloys) – Modified from type 302, this type is excellent for cold heading and costs less than the popular 305 and 384 varieties.
• Type 316 (Chromium, Nickel, Molybdenum and Carbon alloys) – The addition of molybdenum makes this type resistant to surface pitting. It also has a higher tensile strength in extreme temperatures than other austentitic types.
Mar 22nd 2016, 09:23 AM   #11
 holypiston's Avatar
 
  Jan 2016
  Vancouver, WA

I've read that although 304 is the most common and stronger, the 316 is less magnetic, but slightly weaker.

I talked w/ RB and it looks like one of his modified non metric bolts as F593C is "imperial" or household hardware style bolt, but i believe the threads were cut metric?

In any event, he doesn't think this bolt should affect it much, but still, if the 316 series is even more less magnetic, I'd want that choice. What's a couple more bucks?

I also heard the how the material is cooled or is that annealed? can be a factor (besides the forming process) also and confirming what all you have said about SS, it is a myth that it is non-magnetic...it is a lot less non-magnetic, but the magnetism is strongest on the bolt head and less so on the threads, the virgin shaft (hehe) body doesn't have any magnetism...so depending on where you put the magnet, you either do or don't get the magnetism.

In summary: does a non magnetic bolt even exist? I mean one that is truly non-magnetic?

Where are our alien friends when we need them!! Maybe it is really the flouride in our toothpaste blocking our mind antennas or something?

I know that if you want to reuse a copper head gasket, you anneal it w/ a torch and quench as it realigns the atoms and allows it to be reused.

Edited by holypiston on Mar 22nd 2016 at 09:37 AM Reason: fire & ice
Mar 22nd 2016, 09:38 AM   #12
 holypiston's Avatar
 
  Jan 2016
  Vancouver, WA

I'm really surpised @dragracer1951 hasn't chimed in. He did a unique custom manifold bolt for me that you couldn't find in ANY bolt store. Worked until i ran out of bores.

So what do you think DR?
Mar 22nd 2016, 10:18 AM   #13
 MMcN49's Avatar
 
  Jan 2016
  Small Island Surrounded by Puget Sound

  07 Buell XB12STT, (Two) 12 Suzuki DR650 SE 72BMWR75/5 KIA @ 243K
Quote:
Originally Posted by holypiston
In summary: does a non magnetic bolt even exist? I mean one that is truly non-magnetic?
Bronze, Brass, Copper, Aluminum, Nylon

Many years ago in Subic I did a little work on an old post WW2 era wooden minesweeper. The hull and beams were held together with large, very hard brass or bronze bolts. It might have been naval brass but I don't really know. I do know that all these bolts were totally non-magnetic. The vessel had Waukesha engines with stainless blocks. I think, but don't know for certain that the con rods were titanium.

This boat made its living blowing up magnetic and other marine mines. Almost everything on it, including tools were made of non ferrous materials.

If you really need total non-magnetic do some research and find out the alloy of these bolts, order some stock and have one made. One of the vessel's engineers told me this stuff was a bitch to machine. If you go this route you'll probably pay far more than 316.
Mar 22nd 2016, 12:46 PM   #14
 holypiston's Avatar
 
  Jan 2016
  Vancouver, WA

MMcn49 thanks for all your help. I decided to try local Vancouver Bolt and the guy there was real knowledgeable. I basically picked a size bigger T316 Imperial bolt AND washer (5/6-18 X 2-1/2 hex cap screw 316SS) as both the old washer and bolt (304) had magnetism to it w/ the rare earth magnet. This new bolt and washer don't. yeah!! I'm sur eit can handle 10 ft-lbs torque easily. Hope Ron can machine this as he was able to machine T304. X-fingers.

So I've e-mailed my machinist to see if he can cut it down to size (see image for original smaller T304 bolt).
Attached Thumbnails
Non Magnetic metric bolt for ignition rotor-t316_replacement-bolt.jpg  

Edited by holypiston on Mar 22nd 2016 at 12:51 PM
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