Hardening non hardened steel gears....??

[vidio1]

I'll bow out of this one after a few points.......... Don't try to depend on "color" to get a temp reading. Use a non-contact thermometer, temp crayons, or a preset oven. The material needs to be "heat soaked" not just heated with a torch and dunked. There are formulas depending on temp and mass/shape of the material. I understand the prototyping element of it, but If this does turn into a production run have the gears professionally treated. It will save a lot of grieve from end users abusing your product if you can produce a document stating the gears of a known material were treated using X process to X test standards. Just my 2 cents............

[fabr]

+1------mostly.I prefer to HT in house though as I have the proper equipment  so I'm responsible for QC. I don't like relying on others.

[Hammerworks]

I agree

[Whiplash]

Thanks guys! I will likely be doing it myself to save on cost since my profit is not going to be huge on these bikes after the parts involved, but I will invest in a good non contact thermometer and experiment with it till I get it perfect. For now I will just use the magnetic trick to get my first set done, I trust that Fabr will get me at the very least 99% of the way on this, I have never seen him give advise that he is not sure of. Hopefully they will not get brittle... Thanks! I will document the process for show and tell if you guys like. I need to get the torch from a friend to do it. Hey will MAPP gas get hot enough? That would save some hassle..

[fabr]

You will not like the price of a non contact thermo as the ones that will read high enough are pricey. Be cheaper to just have a small batch heat treater do it for you. Why not investigate a trade/tech school in your area that has the capability to do small runs of custom parts as part of the curriculum? I'm thinking that is best bet for you to get a quality part-cheap. The reason I say this is because it is unlikely that you will find a production shop doing any runs of 1144 of similar size/mass as your gears. The actual process of heating times/temp and quench technique they use may result in less than desired results. Maybe. Maybe not.

[fabr]

Now for the good part. How are you planning on heating it and how are you going to prevent/minimize scale and how are you going to prevent carbon loss?

[Whiplash]

I was thinking just a torch with a nice even heating approach and doing it as slowly as I can. As for the carbon buildup, can't that just be wire wheeled off or something? I saw on youtube, where they just brushed it off, is that not OK? What is carbon loss?

[fabr]

You CAN do it that wat if you wish. Problem is that you will likely end up with a brittle part. It needs tempering after hardening. 1145 is not the best choice of material IMO. Personally I'd have started out with maybe 1018 or 8620 and case hardened it. The high carbon in the 1145 will allow easy hardening but will lack the tough core that a 1018 or 8620 case hardened part would have had.  Hardening the 1145 is easy the way you described  but tempering it requires a tighter control of the heating to add toughness to it. Did you make the gears or are they off the shelf parts?

[Whiplash]

They are off the shelf... I saw on Youtube a guy tempering at 400* in his home oven. He baked the items for a few hours @ 400* and had good success, I was planning on trying this method if you recommend it? I think it kind of normalizes the material right? I am fairly familiar with cryo treating stuff, as I used it in my engines and such over the years, but I never did it myself. I DO know they bake the parts and slowly bring down the temperature after they cryo it to normalize the part.

[Whiplash]

Hey also, when you are setting up the spacing on the gears, the "pitch diameter is the number you use correct? so that if I have a pitch diameter of .800" and 2.400" I would set the center line of the axles they ride on at 1.600" apart correct? Or do I need to add the gear lash clearance to that?

[fabr]

They are off the shelf... I saw on Youtube a guy tempering at 400* in his home oven. He baked the items for a few hours @ 400* and had good success, I was planning on trying this method if you recommend it? I think it kind of normalizes the material right? I am fairly familiar with cryo treating stuff, as I used it in my engines and such over the years, but I never did it myself. I DO know they bake the parts and slowly bring down the temperature after they cryo it to normalize the part.

400 won't temper or normalize it. That's the trouble with you boob. It's actually easy to get good info if you'll stay away from goof ball sites like uboob. Do some googling of heat treating forums. Bear in mind they will be modern techniques discussed but the info is still spot on as to temps and times to achieve desired results.   I actually had to "teach" some of the modern HT guys some of the old ways since all modern HT use various gasses being injected into the furnaces instead of using stuff like kasenit(if needed for low carbon steels) to add carbon to steels. Your 1145 does not need any carbon added to harden. It will tho need very careful tempering. Can you get the gears in 8620? Be a much better alloy to start with. All you need do is case harden that and still have a tough core .

[fabr]

Hey also, when you are setting up the spacing on the gears, the "pitch diameter is the number you use correct? so that if I have a pitch diameter of .800" and 2.400" I would set the center line of the axles they ride on at 1.600" apart correct? Or do I need to add the gear lash clearance to that?

You need to allow for backlash clearance. Only add enough backlash to allow lube to flow tho. IMO that is.

[Whiplash]

OK that is all I needed! Thanks!

[Whiplash]

I got the gears all machined, except for the final drive gear that needs to be drilled for the half inch shaft it will have coming out of the box to drive the cranks on the bike.... All came out within .0015-.002" so pretty good considering I have not done any machining for about 10 years now! LOL!



Here is the assy. the way it will fit in the box...

[Reidy02]

You will not like the price of a non contact thermo as the ones that will read high enough are pricey. Be cheaper to just have a small batch heat treater do it for you. Why not investigate a trade/tech school in your area that has the capability to do small runs of custom parts as part of the curriculum? I'm thinking that is best bet for you to get a quality part-cheap. The reason I say this is because it is unlikely that you will find a production shop doing any runs of 1144 of similar size/mass as your gears. The actual process of heating times/temp and quench technique they use may result in less than desired results. Maybe. Maybe not.

Actually Fabr I bought a laser thermo gun off ebay it was pretty cheap and works well I'll dig it out and post some details if you like.