what kind of welding?

[dotdies]

guys i' ve searched the whole forum and i' ve seen a hundred times that you weld stuff (i' m interested in welding engine mounts to a steel frame) but you don't tell what kind of welding you use. is an electric (arc) welder sufficient for the task? Or will i need to have a professional do the job? (the engine is going to be -VERY! - heavy (considering a 2000cc mitsubishi one but still looking around car engines are so much cheaper here than smaller ones)

[IgorVigor]

any form of welding should be fine...

MMA is still used for farm repairs, on big tractors so a mitsi 2L engine isnt a problem...

MIG/MAG is quicker, cleaner, easier (personally)

TIG is very good, but slow and expensive

and gas welding is possible (never done it myself)


Any type of welding is fine, just make sure you get good penetration...

I presume when you say ARC welder you mean a stick MMA (Manual Metal Arc) welder?
it will do the job, but it might be worth you getting a few bits of scrap steel (pipe and plate) and practise welding them together...
Personally, I would recommend a MIG welder as you dont need to keep changing the sticks all the time...

Good luck with your project though

[Henk]

Hello , my name is Henk Verleg , I am Dutch and building a dieselbike .
Motorcycleframe's are considdered as dynamic constructions and the best welding is a full penetration welding to my opinion.

[OilyPhil]

The type of welding is not as important as carefully considered mount design, they need to be designed to minimise localised stress which could lead to failure. Another important factor is the quality of the weld, correctly welded MMA could be better than badly performed TIG which should be theoretically better. Therefore I suggest you do what ever you can do best!
For a few basic ideas on bracket design etc have a look at Phil Irving's book Motorcycle Engineering (ISBN 0-85113-075-5), Its an old book, Phil was the designer of the Vincent motorcycle, but the principles are still relevant.

Phil

[Henk]

Hello Oilyphil,
quality is always important.
I consider a normal welding as imperfect because there is always a build in crack.
A low stress connection is favourable but in combination with dynamic forces the shape of the weld will be very important, because of possible fatigue problems.
Most of the damage I have seen isn't stress overload but fatigue wich occurred by far lower stress.

[DieselFly]

I'm kind of lucky that I have MIG, Tig, Oxygen/Acetylene and Stick welders available to me. I remember from the Hughes 269 helicopter structural repair manual that the main tube frame structure was not to be TIG welded. Their concern was the built up stress from the intense local heating of the TIG process. The wanted good old O/A torch to be used. I TIG welded my frme togeather and when it was finished took a rosebud tip and heated each cluster to a dull red and then let it air cool to remove the stress created from the TIG welding. The FAA in the states publishes a guide book to aircraft repair called AC43.13 that has a good section on repairing tube structures and is a great start for design for one that is starting with little or no knowlage. Always think triangles and remeber gussets go on the outside of the tubing not on the inside centreline. There is a reason I call my bike Shaken not Stirred. It does have a high level of vibration as the engine is soild mounted. I did a complete teardown and stripped all the paint last winter and inspected the frame and all was good. Here is a good little read on frame design http://www.tonyfoale.com/Articles/Frame ... waMods.htm

Sean
Thoughts of turbos dancing in my head

[XLerate]

Well apologies because I wrote a reply before reading Diesel Fly's excellent post! I'll go ahead & post what I wrote in case it might help but he pretty much said it all...

Important to note that the EAA as Experimental Aircraft Association suggests Oxy/Acetylene for all airframe construction! Hey, who has to depend 100%, life & death, on the quality of their welds?

Most of these airframes are steel alloy tubing, either DOM mild carbon steel or Chrome Moly steel, same as our bikes. Proper temperatures, tip & welding filler rod will result in a weld that's as strong or even stronger than the parent metal tubing. However one wants care that the filler rod isn't considerably harder than parent metal or else this can induce cracks & tearing under flex & stress.

It's necessary to 'normalize' the airframe welds & airframe tubing, by heat treating with a rosebud type torch to relieve all stress risers that could develop cracks. Some are even able to toss whole sections of airframe into ovens constructed to normalize large pieces all at once. Not that hard to build such a thing with bricks and use a propane - natural gas burner to heat it up. Exact temperature is important within about 100 degrees so a thermostat or thermometer is used to monitor temperature.

Heating to 1,500 degress followed by air cooling, then reheating to 800 degrees & air cooling is good. Even reheated to 800* alone without the former 1,500* will get things good, but some web research is suggested rather than my word. Many will reheat to medium to cherry red over large areas then air cool.

The EAA info can also be sourced through their website but you have to join to get access to tech articles.

[henneberg]

The temperatures are Fahrenheit values, I presume

[XLerate]

Yes, farenheit. If Celsius you'd probably have a melted blob where your frame used to be.