Wednesday, 22 June 2011
More progress on number five.
I'm making good progress on putting Ben's frame together. Here's a photo of the front triangle and chainstays in the jig. The XL tube sizes are a tight fit, but it all goes in okay. The top tube isn't brazed in yet - it's just jigged up so I can mitre the seat stays and work out what to do with the skirt section on the seat lug.
Here's a nice macro photo of the lower head lug. I used 56% silver filler with this, and dropped back to a number 12 tip, using the system 48 flux. I'm quite pleased with how it turned out - the amount of filler is good, and I got full penetration without much encouragement. Also shown is one of the ergo cable adjusters. These are quite a challenge to hold on the downtube. These were brazed in with 56% silver filler, using the stainless light flux.
Here's the progress on the bottom bracket. As you can see, I'm yet to mitre or braze in the chainstays. The BB-downtube join was done with system 48 filler, and system 48 flux. I went up to a number 20 tip for this one (I modified my largest acetylene tip for LPG by drilling a counterbore in the end). I really liked using this tip - it let me get very even heating.
The system 48 filler is a little gummier than 56%. I don't get the minimalist shoreline fillets I'm used to with 56%, so there's a little more shoreline cleanup needed. That said, it pulls through really well and fills bigger gaps than 56%. Just the ticket for bottom brackets. I can see myself using quite a lot of this filler.
Finally one of the dropouts. I've got a standard recipe now that works a treat for stainless. 56% filler with grey stainless light flux. I used a number 12 tip here, as the dropout tends to act as a bit of a heatsink. I overdid the filler a little, as evidenced by the excessive fillet in the cutout. Contrast that with the really nice fillet I got on the cutouts on the lower head lug.