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Spring steel

General discussion on any topic which doesn't have a natural home on any of the other boards.
StephenB
Posts: 157
Joined: 26 Dec 2018, 08:45
Location: Hungary

Re: Spring steel

Post by StephenB »

Keith wrote:
18 Dec 2019, 15:44
If you let me know what size you want I'll have a look and see if I have the size.

Keith
Very kind of you Keith, I need to drill a clearance hole for a 2mm bolt, but you do know I'm in Hungary??

Is this the right approach: I should first heat the saw blade up and then allow it to cool naturally, fashion and drill it then re-heat and quench in water/oil to harden it. I'm going to have to get a blow torch before I can do this.

This is turning in to a lot of work for such a small component!

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Peter Balcombe
Posts: 1101
Joined: 18 Mar 2015, 10:13
Location: Clevedon, North Somerset, U.K.

Re: Spring steel

Post by Peter Balcombe »

Stephen,
As far as I can see, you have the right idea about the basic annealing/tempering method (what a friend did for me whilst heat treating my multi-leaf skid parts anyway).
I have annealed small parts, but we can usually get can pre-annealed material as the starting point in UK.

Presumably there is no-one to hand near you (another flyer?) who happens to have some kit/experience - especially power fliers who often need to fashion undercarriages/exhaust piping.

I have used a small butane type torch for the small parts - one which has a simple burner head that screws onto a standard gas cylinder roughly 80mm dia. (I used to use it for home plumbing DIY ;) )
It also helps if you can make a small hearth to reflect heat off bottom & rear to help get more even temperature over the whole part, but this really needs firebrick material ideally, but some solid concrete items may help (don’t use ordinary bricks as the heat is likely to cause then to fly apart as trapped air expands).

It’s a good idea to have the tempering colour chart in your mind when heating, as you can then follow the colour change progression & be ready to stop when the correct colour comes up.

As you say, it’s a lot of trouble for a small part, but there isn’t much alternative unless you can grind a small hole with a conical dremel or a drill which is harder than your strip material.

StephenB
Posts: 157
Joined: 26 Dec 2018, 08:45
Location: Hungary

Re: Spring steel

Post by StephenB »

Peter, I was going to buy a small blow torch as you described but your mention of firebricks/hearth has given me another idea. I wonder if I put the part in my log burner, left it in all day then allowed it to cool overnight before fishing it out the following morning and working on it. Then reverse the process to harden it only pulling it out whilst hot and quenching in water. Or is that too imprecise a method?

I've never come across another RC flyer around here, unless you count dr***es :lol:

Keith
Posts: 76
Joined: 07 Jan 2019, 18:18
Location: Lincolnshire

Re: Spring steel

Post by Keith »

Hi SteveB I have a couple of 2.2mm drills if you send me your address I'll send them to you.

Keith

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Peter Balcombe
Posts: 1101
Joined: 18 Mar 2015, 10:13
Location: Clevedon, North Somerset, U.K.

Re: Spring steel

Post by Peter Balcombe »

Stephen,
I think your on burner idea may be rather too imprecise as you suspect.
I asked my learned friend with heat treatment experienced if my thoughts on annealing & tempering were correct & it seems that I had missed out the intermediate re-hardening stage before tempering. See his reply below:

“Hi Peter, almost, to anneal do as you say and heat to dull cherry red and allow to cool, ideally in pre heated sand in a bucket which will allow the material to cool more slowly, drill with a sharp bit at slow speed with plenty of oil and firm down pressure. If the material work hardens then use a masonry bit with tungsten carbide tip. To re-treat heat to mid cherry red and quench in oil, this gives a slightly slower quench and allows grain structure to form more evenly. The material will now be very hard and consequently brittle, the hardness needs letting down by the tempering process. Clean the surface with emery cloth to a bright finish, then warm with a soft flame very slowly watching for the surface to start changing colour. Take it very slowly and have the oil bath ready below the workpiece, as the colour starts to show move the flame away, wait a few seconds, re-apply the flame by wafting it gently over the workpiece, watch the colour go from light straw though dark straw and making sure the colour is even across the whole surface quench immediately mid blue is seen. This is the correct colour for springs. Good luck, take it slowly! “

Hopefully, you find a way to make the skid one way or another.
Peter

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