Steel sheet suppliers 4130 / T45

[mike425]

Hi all, I am a hobby builder of bike frames and various other bits.

Recently I have been making an electric bike frame which involved making a motor mount out of steel sheet. As this was effectively a test frame I made the mount out of mild steel and probably over did it on thickness at 4mm.

I am looking to build a second frame now and would like to take some weight out of the bracket by using a higher grade steel and going down on the thickness.

Ideally I would like to use 4130 or T45 but the prices of these in the UK seem to be so high when in reality I only need a very small piece.

Does anyone have any suppliers for either of these that will sell in small quantities, or is there another sheet metal variant that would be suitable?

Thanks in advance

Mike

 

[ronan]

I'd just use 5 or 6 mm aluminium or dural plate. Plenty strong enough, doesn't rust and easy to get.

 

[Maker]

I'd just use 5 or 6 mm aluminium or dural plate. Plenty strong enough, doesn't rust and easy to get.

Hard to weld to a 4130 frame though.

 

[ronan]

Sorry, i thought it was being bolted in. I'd go with mild steel then, it would easily cope with the output of an electric motor.

 

[mike425]

Hi, thanks for the response. If I have to use mild then I will, I would have just been more comfortable with 4130 or such like if the thickness was 2mm.

The motor is pretty big, its rated at 160nm of torque and on the the current bike there is some twist when running it on maximum power.

Its really annoying when you see how cheap 4130 is in the states!

 

[ronan]

Have you tried Steelexpress in Sheffield ? You could do what people have traditionally done when they wanted to shed weight, drill holes. You could also use one of the 300 series of stainless, its stronger than mild and weldable, easily available too, 2mm of stainless would be pretty strong.

 

[bletchmonster]

Is it feasible to use 2mm mild and fold a lip, eg 12mm, around the edge which will massively reinforce the mount plate

 

[mike425]

That's a good shout actually, I have a home made metal brake that will probably just about do it. I have bit the bullet and ordered 2.5mm mild. Its worked out so much cheaper than any of the 4130 quotes I had that it it just makes sense to see how it lasts.

I am pretty sure even if it were to fail it would be long enough down the road that I will already be onto mk3 of the frame anyway!

 

[hotponyshoes]

Bit of tube and cut it and flatten it out?
Or could you not just make a mounting frame from tube, drill the motor mount holes over size and weld some more tube through them to stop them crushing?