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beanbag
12-16-2010, 05:47 PM
In a lot of bike applications, I see a bolt with an unthreaded section that also serves as an axle, for a pulley or cog, for example. I'm assuming this unthreaded section is hardened and polished smooth. The hardened bolts I usually see are either some golden color or matte black, but in neither case are they polished. Where can I get this kind of polished bolt, or how can I make my own out of a bolt? Obviously, I'd need to make it perfectly round and smooth.

CCWKen
12-16-2010, 06:00 PM
They're called Shoulder Bolts (Screws). McMaster-Carr has a pretty good selection although you may have to do your own "polishing" or plating.

http://www.mcmaster.com/#shoulder-screws/=a6dgc8

Ken_Shea
12-16-2010, 06:06 PM
Beanbag,
This place has about every imaginable fancy bolt for motorcycles or whatever you can think of.
Even Gold plated ones :D


http://www.gardner-westcott.com/

beanbag
12-16-2010, 06:41 PM
Thanks for letting me know what those darn things are. Is that bright silvery color the natural result of polishing, or are the typically plated?

Evan
12-16-2010, 08:40 PM
Decent quality grade eight bolts polish up real nice. They are zinc electroplated and chromate passivated. The polishing removes the chromate which is the yellow colour but unless you get really carried away the zinc will stay on. Here is a good sized bolt that I had lying around that I polished for something but didn't end up using. They are very round, good enough for most purposes.

http://ixian.ca/pics8/polishedbolt.jpg

BigMike782
12-16-2010, 09:29 PM
If you want polished for looks you can use hardware store grade stainless.I then take a wooden dowel and drill a hole in the end put a saw kerf cross ways add a hose clamp and you have a good way to hold it while you polish.

Black_Moons
12-16-2010, 10:41 PM
Ahh so its chromate that makes them yellow. I just assumed it was some kinda heat treatment that turned the zinc yellow, since it seemed rather exclusive to grade 8 hardware. I guess i'll stop assuming hardware is grade 8 because of the yellow tint, if its just another coating.

(I was wondering why the nice yellow screws on my moped striped as easily as every other crap grade 3 chinese screw)

JoeFin
12-16-2010, 11:45 PM
If you want polished for looks you can use hardware store grade stainless.

I was going suggest the same thing. Stainless can be polished to a "near" chrome appearance. Additionally stainless can be quench hardened to a narly tough hardness if need be too

gmatov
12-17-2010, 12:40 AM
About 30 years ago, they were Sheradized, or Cad plated. I don't think they use that anymore. It's all we did use. (That was the brassy color of them.)

Even in HD, if you buy a bolt, look for the markings on the head, count the pips, add 2. 3, grade 5, 6, Grade 8. No pips, it is a "stove bolt", worthless except for holding panels together IN a stove.

There is MUCH more to fasteners than that.

Cheers,

George

Evan
12-17-2010, 12:53 AM
You should be careful where you use stainless steel and what type it is. 300 series is not very strong material. 303 austenitic hard cold drawn bar has a yield strength of about the same as mild steel (60 ksi) and if in the annealed easy machining temper it is way down to only around 35 ksi. 304 is even worse with a yield of around 31 ksi.

Generally 300 series shouldn't be used for axles on motorcycles or similar applications. The martensitic 400 series is much better in that respect. 403 tempered bar has a yield of 85 ksi which is much more suitable for highly loaded applications.

Cad plated and chromate passivated George. It's the chromate that makes them yellow. They still use cad plating on aircraft fasteners.

beanbag
12-17-2010, 12:59 AM
Why is it that every time I say "bike" on this forum, people think motorcycle? :confused:

gmatov
12-18-2010, 12:28 AM
Beanbag,
I haven't had a motorsickle for over 40 years. We got bike, as in bicycle, builders on here. I assume, unless you get into how big the engine is, that you are speaking bicycle.

We don't ALL assume you are into Choppers..

Cheers,

George

Circlip
12-18-2010, 05:23 AM
The shoulder bolts from big Mac are known on our side of the pond as stripper plate bolts. The shanks are a specific ground size and slide in reamed holes in the spring plate.

Regards Ian.

JoeFin
12-18-2010, 08:12 AM
You should be careful where you use stainless steel and what type it is. 300 series is not very strong material. 303 austenitic hard cold drawn bar has a yield strength of about the same as mild steel (60 ksi) and if in the annealed easy machining temper it is way down to only around 35 ksi. 304 is even worse with a yield of around 31 ksi.

Generally 300 series shouldn't be used for axles on motorcycles or similar applications. The martensitic 400 series is much better in that respect. 403 tempered bar has a yield of 85 ksi which is much more suitable for highly loaded applications.

Stainless Steel bolts are Grade 8

Plenty strong enough for bike applications. The hardened/tempered variety run 95-135 Ksi yeild

JCHannum
12-18-2010, 10:22 AM
You cannot broadly state that stainless steel fasteners equal Grade 8 standards. There are many alloys of stainless. The most commonly available stainless steel hex bolts are 18-8, which approximate a Grade 5 bolt. 316 is a bit closer to Grade 8.

http://www.tessco.com/yts/customerservice/techsupport/whitepapers/pdf/bolt_grade.pdf

When you go to the hardenable alloys, you sacrifice some of the corrosion resistance.

Evan
12-18-2010, 01:12 PM
Stainless Steel bolts are Grade 8


No, they are not. The standard grade designations don't apply to stainless steel bolts, only carbon steel. Stainless steel bolts are weaker than equivalent size grade 8 bolts by quite a margin. 300 series are much weaker. There is a big difference between the austenitic stainless steels and the martensitic (ferritic) stainless steels also.

http://ixian.ca/pics8/boltgrade.jpg

jkilroy
12-18-2010, 01:21 PM
Man I WISH stainless steel bolts were grade 8. I have to use stainless bolts as I do water quality work and put out a lot of product in and around salt water. I upsize all the hardware one size, learned the hard way after having costly instrumentation lost due to failing hardware. Oh, and only use 316, titanium, or other costly nickel based alloys in salt water, 18-8 is below marginal, and 304 is right out crap.