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Discussion Starter #21
With the small quantites that I have of the tubes it would be impossible to use weight as a definitive way of working out what is and is not Chromolly steel. I have used a series of crude tests to come to the conclussion along with the NZ Ducati agents verifying our conclussions as well, though they could not tell me exactly what grade of Cromoly steel they were manufactured from. I have the actual material spec listed down some where but at the moment I seem to have miss placed it.
For the purpose of this repair I am going to proceed with the belief that it is Chromemolly 4130 (or an equivalent there of. To that end and having spoken to our Aeronautical metal workers and welders in the Royal New Zealand Airforce they have recomended that i use MESSER MG600 tig welding rods. This rod is designed for maxmium strength and is the best rod to use for joining disimilar metals if you are not 100% sure what the metals actually are. Apparently the RNZAF use alot of this for various welding jobs for some of the historic aircraft that we still fly.
As far as not MIG welding Chromemolly steel - have a look at the robitic welding of the KTM frames - manufactured useing Chromemolly steel and MIG welded.
 

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Apparently the RNZAF use alot of this for various welding jobs for some of the historic aircraft that we still fly.

That has to be one of the best walk up start to have a jab at a Kiwi statements I've seen in a while. But it might be prudent to wait till after the One Day Cricket finals this weekend (assuming Australia actually make it past India)


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Discussion Starter #24
The piece of 3.2mm plate 4130 for the gusset has turned up and I am just waiting on the welding rods and the tube to follow suit. Have been practising my welding on some heavy tube sections and I am grogessively using thinner wall section tube and getting tighter and smaller with the welds just to get familiar with welding plain steel - its been a while since I had to do any.
Yes it will be good to see the Black Caps win the World cricket cup - the last match was certainly a cliff hanger to watch.
Yes most of our aircraft are old - we still have a Havard in use and it is only just in the last couple of years that we retired the Soiux helecopter. The Iroquois are been taken out of service within the next month or two - just shy of the 50 years in service within the RNZAF I believe. The Hercules has just hit 50 years in service as well.
 

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Something out of the blue here.
Could it be that your type of tank brace mount stresses the frame more and causes it to crack?

Being solid from left to right, it can't flex as much and causes the cracking.

The frame on my '92 SL and my trackbike have a tank brace mount like this one

I think a setup like this tolerates more flexing, so less prone to cracking.
Knock on wood: no cracks spotted yet.
 

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There seems to be several variations of reinforcements over the years and they still cracked.
Here's my `95 before I had it repaired / welded at FrameCrafters in Union IL.
In this case the crack began at the weld and propogated around the base of the weld blob where a stress riser was created.

 

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That has to be one of the best walk up start to have a jab at a Kiwi statements I've seen in a while. But it might be prudent to wait till after the One Day Cricket finals this weekend (assuming Australia actually make it past India)
Sorry to interrupt, but the Aussies actually thumped the Indians and will now roll the Kiwis convincingly. :)

But I am surprised that anyone from California knows anything of such exotic sports - are you an ex-pat Dave-G?
 

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Discussion Starter #31
Now, now boys, I am only to aware that NZ has snatched defeat from the jaws of victory many times before - will have to wait and see.

But back to the frame - my thinking is that the way the weld is finished for such a high stressed area is 90% of the issue. Just about every frame that has cracked seems to start from the welds. On my frame one side is better finished off than the other and hasn't cracked. But the side that has cracked has a very noticeable, blunt finish of the weld.
Still it s all off now so I can right the wrongs of the past. Just waiting for the tube and welding rods to show up.
 

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Discussion Starter #32
To take my mind of matters to do with the frame I have been looking at all the fairings and body work to see what the issues will be with making a full set of carbon body work. The fairings are going to need to be repainted any way and I had thought of up dating the side panels to the later version so I can run some additional ducting to the rear cylinder s now that I am going to put a big bore kit in the bike. To that end the fairings them selves are in pretty good condition apart from one which has got a series of cracks around the mounting holes and a mas of stone chips in the lower fairings. I am looking at also building some light weight ducting for the side panels as well as the possibility of making up a new airbox which will allow me to put a tube across the top frame tube the same as the early model 750 F1 frames. I have found a company in Australia that does all the other bits at a reasonable price including the cam belt covers but they don't do a rear hugger at all - weird.
Have also taken a heap of photos of the version 3 exhaust pipe that has been forwarded to a company that is going to do the bulk of the tube bending for me. The goal this time around is to try and reduce the amount of welding that I have to do. I am still waiting to hear from the other company about the collector, I have just about given up on them to be honest after all the promises in the world that they made about getting it made.
Have contacted J precision about getting the head worked but they have not returned my emails as well. At the moment I have two sets of cylinder heads that are destined to head there if they ever get in contact with me.
 

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i'd replace the fuel tank hold down mount with one coming up from the steering head tube, like an ssie. they share the frame forward of the rear engine mount with the carby bikes, but don't crack. I was going to slice the tank mount bosses from my 93 frame (like the white frame shown) on the frame rail. that way, they won't try stop the top tubes flexing, being mounted only to the steering head tube.

interestingly, the monster is much the same, but it has a stamped metal bracket for the ignition switch welded on in much the same place, but they don't crack either. that metal bracket will flex due to the style of construction.

which is not to say that the frame wouldn't work better with an sbk like cross tube there, because anecdotal evidence from the desmodue series is that they indeed do feel better with a brace.
 

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Discussion Starter #35
Thats not entirely true Pajazo - have been shown a frame off a 1000DS that has what appears to be a crack in the frame around the welds. I hope that this is not a sign of things to come for these bikes as well........Time will tell.
 

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Thats not entirely true Pajazo - have been shown a frame off a 1000DS that has what appears to be a crack in the frame around the welds. I hope that this is not a sign of things to come for these bikes as well........Time will tell.

You would have to know a bit of history about the frame to know if the crack was the result of a structural issue or the poor thing being thrown down the road. You can crack anything if you go at it hard enough unless your a Kiwi trying to crack a ton in a one day final!


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Discussion Starter #39
To get back to reality - I have found a company in Auckland (Kendals Distributors) that is closing down which supplies NZ with an amazing range of the welding rods and various bits and pieces. Managed to secure a 2.5kg lot of MG 600 x 1.2mm Tig rods from them for the same price as it was going to cost to get the 1 kg lot. Score. Still waiting to hear back about the tube though, which has got me concerned as I wanted to get the frame sorted by the end of Easter. Have settled on using 5/8" x 0.083" tube to replace the old 1/2" x 0.083 support tubes. For tube to go over the frame tubes as a load spreader, I found that 1 1/8" x 0.083 fits perfectly over the outside.

Have also got my painter buddies reaserching the frame color as well which will be in gold again. I have decided to stick with the red paint work and have exposed carbon fibre in selected areas, specifically around the edgers and on the belly pan area as well.

Have managed to find a reasonable supplier of the carbon cloth and all the other composite bits that i want to make up. Someone has suggested that I do a carbon fibre fork legs using the old tubes as the internal bearing surface, turn the outside down to remove the corrosion, get them reanodised and then wrap a carbon fibre cloth around the outside of it before finishing it off with a carbon tube finish. Not sure about this one but might give it a try and test it when I have replaced the fork legs later this year.
 

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Hmmm - the only negative that I can think of, is stone chips hitting the CF on the fork legs, and 'starring' the resin. I know I've had that problem with my CF front guard. :(
 
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