shaft heat treating, know a good place? [SOLVED]

[mud2005]

Hi, I bought a precision shaft from SDP/SI. Its stainless steel but not heat treated so the set screws tend to deform the metal more than I would like. Which brings me to my QUESTION
does anyone know of a good place to send stainless shaft for heat treating?
I've never had this done before and the idea of calling Industrial business and asking for one small piece heat treated doesnt sound like the best approach.
also I'm assuming I should file the flats on the ends before heat treating not after? I've heard there can be some warping which would be bad, but filing a hardened shaft is not an option.

edit: I live in Oregon USA. closer is better

 

[recumpence]

Your best option is to buy a hardened shaft. Then put the flats in. If the shaft is hardened, you cannot file it. But, you can use a die grinder or a Dremel to grind the flat.

Matt

 

[mud2005]

Excellent, thanks Matt that sounds doable. So where do I get an 8mm hardened shaft? SDP/SI only has the non-hardened and most of the other companies I know of only have inch/fraction sizes. damn, I wish USA would convert to metric

 

[Miles]

Drill blanks?
http://www.drillblanks.com/metric_sizes.html

 

[recumpence]

Yes drill blanks work. You can also go to McMaster Carr. They have more than SDP.

Matt

 

[etard]

I don't know how well this works, but it's worth a shot if you have a torch.

http://www.ehow.com/how_4579248_harden-steel-motor-oil.html

Then there is this article to give you a better idea of what is going on.

http://steel.keytometals.com/Articles/Art12.htm

Let me know how it goes.

 

[mud2005]

ok I just ordered 8mm hardened stainless steel shaft on SDP/SI I guess I was wrong about them not having the hardened shafts, I was just looking in the wrong place. Once they get here I'll figure out how to get the flats on.
while hardening steel sounds with a torch sounds like fun, I'd rather have a professionally hardened shaft on my bike

 

[mud2005]

I disassembled everything for a complete rebuild and discovered the motor pulley's set screw spun about 1/4 turn on the motor shaft and left a big gouge, bummer.
I'm entirely done with tightening set screws on shafts with no flat, it's just a bad idea.
The motor shaft has a hole in it, but it doesn't line up with the set screw
So I guess I should put some masking tape over the motor bearings to keep chips out and grind a flat onto the motor shaft? oy, I'm a bit worried about screwing up my precious motor.
Any alternatives?

edit: I'm now thinking about getting an aluminum pulley w/o hub and just drilling a hole through to line up with the hole on shaft.

 

[lawsonuw]

SDP-SI "fairlock" pulleys work VERY well on a smooth shaft. Otherwise, a loctite retaining compound can make a strong semi-permanent joint. (only recommended on outrunners where the shaft is easy to replace) Third, if you can replace the shaft of the motor, just mark where you need to grind the set screw flat then grind the flat after the shaft's been removed from the motor. Also, blue loctite thread locker and as much torque as possible is recommended to keep set screws in place. (a longer set screw with a more aggressive point can also help)

My two bits,
Lawson

 

[Miles]

Also, 2 set screws at 90 degrees is a lot better than one.

 

[mud2005]

I looked at the fairloc pulleys but the selection is very limited. In XL pitch .375 dia bore pulleys the only sizes with fairloc are 58, 60, and 72 teeth, and I need 14T
I'm not sure if the shaft on the motor is replaceable or not, I think I'll send astroflight an email and ask rather than taking apart the motor.
As far as the blue loctite on set screws, doesn't that also make them very difficult to loosen when you want to remove the pulley?

edit: I found a 14T XL fairloc pulley with .25 in bore, I wonder if I can drill it out to .375?

 

[lawsonuw]

Hm... looks like there is a small chance that .25 fairlock pulley could be bored out. If you have any access to machining, it easy to turn a set screw hub into a clamp hub. (sdp-si part #S1166Z-024A012 won't fit a timing belt but shows what a clamp hub looks like) A clamp collar goes over the thin fingers of the hub and it is quite secure.

Ah, you have an Astroflight motor I doubt the shaft is replaceable then.

Lawson

 

[mud2005]

well things are looking ok, after rebuilding my gearbox its possible to line up the motor pulley set screw w/ the hole in the motor shaft The pulley is farther down the shaft than it was, but I think its going to be fine. Also the hardened shafts should be here Monday and I got a high rpm drill and some grinding wheels from my father that look like they're from the 60's

 

[mud2005]

oy, I got the "hardened" shaft and I tried filing it to see how hard it was and to my surprise I could file it no problem
I asked someone and they said it's only case hardened not fully hardened. :? I'm going to go hit the used bookstore and get a machinist guide so I can figure this out.

btw, I liked the old emoticons better w/o the pointy chins

 

[buzzfirst]

Hello, If you can cut the shaft with a file it is not hardened. Case hardening, if you didnt know, is the process of just hardening the "skin" of the steel, usually not more than 2mm deep. Once you grind through the top layer you can easily file or machine the inside. I think case hardened metal may not be appropriate because once you ground a flat on the shaft you would be right back to soft metal for the set screws. I have actually never heard of a good hardened stainless. The presence of carbon in steel determines whether it can be hardened. I think your best bet would be to get some air hardening drill rod (not drill blank). It comes in lengths up to 8 feet, lots of times you can buy just a foot. It comes annealed (soft) and once you file it to the shape you want it is easy to harden. Just heat with a torch to the desired temperature(usually determined by the color) and then let it air cool. A quick google will tell you just how. There is also the oil hardening variety of drill rod. Air hardening is relatively new. asapsource or onlinemetals both carry drill rod.

 

[recumpence]

Buzz,

I did not know air cooling hardens steel. Quick cooling hardens. The shaft needs to be quenched in water or oil to harden it. Slow cooling softens steel. Or am I missing something?

I used to harden my RC car shafts by heating and quenching them.

Of course, I am not a professional in this, so I may be wrong.

Matt

 

[Miles]

But the quenching is the fun bit

http://www.engnetglobal.com/tips/glossary.aspx?word=Air-Hardening+Steel

 

[lawsonuw]

Buzz,

I did not know air cooling hardens steel. Quick cooling hardens. The shaft needs to be quenched in water or oil to harden it. Slow cooling softens steel. Or am I missing something?

I used to harden my RC car shafts by heating and quenching them.

Of course, I am not a professional in this, so I may be wrong.

Matt

Cooling rate to reach full hardness depends on the steel you're trying to harden. Most steels need to be quenched in water or oil, but some alloys will reach full hardness just from air cooling. These "air hardening" steels are usually used when quenching a part in water or oil would distort the part too much. (RC parts are usually so small that distortion from quenching is a non-issue)

And now you know,
Marty

 

[recumpence]

Buzz,

I did not know air cooling hardens steel. Quick cooling hardens. The shaft needs to be quenched in water or oil to harden it. Slow cooling softens steel. Or am I missing something?

I used to harden my RC car shafts by heating and quenching them.

Of course, I am not a professional in this, so I may be wrong.

Matt

Cooling rate to reach full hardness depends on the steel you're trying to harden. Most steels need to be quenched in water or oil, but some alloys will reach full hardness just from air cooling. These "air hardening" steels are usually used when quenching a part in water or oil would distort the part too much. (RC parts are usually so small that distortion from quenching is a non-issue)

And now you know,
Marty

Ahh, thank you Master!

Now, I can say I know it all.

Matt

 

[mud2005]

I'm making slow and steady progress on this issue. I just got back from the used book store, I got "strength of materials" 1945 and "modern steels" 1958, very modern
not sure if these books will tell me anything, but I may learn something anyway :|
I also sent an email to Edwards heat treating service as their site said free consultation so I'm taking advantage. They replied saying

SO MANY questions!! Lots of variables when it comes to your project. Is it possible to call me on Monday? I have a couple of questions for you. Thanks Lee Edwards Edwards Heat Treating

so I guess I overdid all the questions in my email, but I'll give them a call monday and see what they say.

 

[mud2005]

Well I just got off the phone with Edwards heat treating and it went very well. I spoke to Lee Edwards who was very helpful, he recommended buying some 8620 steel (not sure what that is yet)
then filing the flats and sending it to them for case hardening. He said that way the shaft will have a hard surface and a tough core.
They have a minimum charge of $75, but thats for 25lbs of steel. If anyone else here needs some stuff heat treated maybe we can send it together to save a few $$ as I only have a couple lbs. of stuff I need treated.

 

[mud2005]

ok, I finally figured out what I was doing wrong here

stainless shafts are bad.

I was buying shafts from SDP that were stainless and having nothing but problems. I ordered a hardened steel shaft from MSC and filed flats with a diamond file and now when I tighten the set screws they barely leave a mark at all in the steel.

 

[Almasi]

ok, I finally figured out what I was doing wrong here

stainless shafts are bad.

I was buying shafts from SDP that were stainless and having nothing but problems. I ordered a hardened steel shaft from MSC and filed flats with a diamond file and now when I tighten the set screws they barely leave a mark at all in the steel.

So hardened steel is 'much' stronger than stainless right? (By a factor of what?)

Robin

 

[lawsonuw]

In this case the important factor is 'surface hardness'. This is one of those engineering measurements that everybody has there own favorite units for, I can think of at least 10 different scales off the top of my head. (blech, it's really a pain it the rear) Most scales are based on taking a hard point of a specific size and pushing it into the material under test with a specific force and then measuring the dent made. Rockwell C ("RC") is the hardness scale I've seen used most often in the US to measure the hardness of steel. (btw this is NOT a linear scale) A Rockwell C of <20 is usual for soft steels. Rockwell C of 30-40 means it's fairly hard and strong, but still machinable with the right tools. A Rockwell C of 55+ is really hard, and steels peak out at a Rockwell C of 60-65. Get a shaft hardened to 60+ Rockwell C from any vendor and a steel file will be hard pressed to scratch it.

Lawson

 

[mud2005]

right on lawsonuw, the shaft I got from MSC is advertised as rockwell 60-65C and a file just glides over it. I found some diamond cutting wheels and files at harbour freight that work great though.