bike_dummie Posted April 17, 2016 Report Share Posted April 17, 2016 (edited) Hi, Currently in the process of building a trials frame for work, but I know nothing about heat treating or what the numbers mean in reality. I will be sending the frame to be normalised but will it need to be tempered too? Thanks, Adam. Edited April 18, 2016 by bike_dummie Quote Link to comment Share on other sites More sharing options...
forteh Posted April 17, 2016 Report Share Posted April 17, 2016 (edited) As far as I'm aware, normalising afterwards is all that is required, just need to restructure the steel in the haz. Someone with more experience might advise further, I would speak to @aener as he's built his own frames Edited April 18, 2016 by forteh Quote Link to comment Share on other sites More sharing options...
Mark W Posted April 17, 2016 Report Share Posted April 17, 2016 There's no one way of doing the 'right' heat treatment, which a lot of BMX companies found out the hard way when making regular and 'HT' versions of your frames became a thing. The companies who'd spent a long, long time researching it did well (e.g. Odyssey/Sunday), while a lot of others who just rushed it didn't and ended up with heat treated frames that broke way faster than non-treated frames. I realise that's not really any help, but just wanted to say it's not that clear cut... Quote Link to comment Share on other sites More sharing options...
forteh Posted April 17, 2016 Report Share Posted April 17, 2016 (edited) Of course once normalised you can then temper the steel, as mark said the temper you use is dependent on the application. Or use a steel and/or manufacturing method that doesn't require further heat treatment, case in point standard and the ox platinum air hardening tubes If you're looking into furthering your heat treatment knowledge it might be worth dropping George French @ gsport a mail and see if he can offer any advice; I know he used t45 for his frames as it's stronger than 4130 but I suspect he would still be familiar with frame heat treatment in general. edit: upon further research it would appear that t45 doesn't require post fabrication heat treatment. I guess it would be a fair bit more expensive mind. Edited April 17, 2016 by forteh Quote Link to comment Share on other sites More sharing options...
bike_dummie Posted April 17, 2016 Author Report Share Posted April 17, 2016 Didn't think it would be so clear cut, I was hoping there was a rough ball park though. I think I will just normalise it and see how it goes as I don't want to make it brittle. In hindsight I would have chosen a different material. Quote Link to comment Share on other sites More sharing options...
Tony Harrison Posted April 18, 2016 Report Share Posted April 18, 2016 I think Curtis used T45 too. Quote Link to comment Share on other sites More sharing options...
forteh Posted April 18, 2016 Report Share Posted April 18, 2016 They did indeed, but they brazed rather than welded which I understand affects the grain structure less 1 Quote Link to comment Share on other sites More sharing options...
craigjames Posted April 18, 2016 Report Share Posted April 18, 2016 Less heat input with brazing, so doesn't cause as greater affect to the grain structure in the HAZ. Also allows a bit of flexibility in the joint when compared to welding, so gives the frame a very different feel. 1 Quote Link to comment Share on other sites More sharing options...
aener Posted April 18, 2016 Report Share Posted April 18, 2016 19 hours ago, forteh said: As far as I'm aware, normalising afterwards is all that is required, just need to restructure the steel in the haz. Someone with more experience might advise further, I would speak to @aener as he's built his own frames You honour me by assuming I'm so knowledgeable on the matter, but I actually just used plain-gauge mild steel tubes in whichever sizes were the cheapest. They weren't even seamless I just welded it all together and rode it - no heat treating. Maybe I got lucky and mild steel doesn't need treating or something like that, but I don't know anything about this type of stuff. That said, both of them lasted me nine months each, and the latter one is still in use (after having a few cracks welded over). 1 Quote Link to comment Share on other sites More sharing options...
bike_dummie Posted April 18, 2016 Author Report Share Posted April 18, 2016 Thanks for all the input guys! Appreciated. Simple thing but now it's come to doing it seems so hard to find out, what one is for these two measurements is correct? Quote Link to comment Share on other sites More sharing options...
forteh Posted April 18, 2016 Report Share Posted April 18, 2016 (edited) Neither are incorrect but both are incomplete, the 455 needs an angular dimension added and the 449.9 needs a vertical dimension added as a bare minimum. Depending on the frame jig, I would personally prefer to keep the dimensions purely in the x and y axis. In reality the 455 is easier to fabricate to but the angle could be hard to achieve, the 449.9 is more than likely outside of your fabricating tolerance so could be rounded to 450 and the 455 made a reference dimension. Remember that all vertices need to have both an x and y component (z if you're working in three dimensions) and all dimensions should come from a common datum, in the case off a frame the bottom bracket is ideal. Edited April 18, 2016 by forteh Quote Link to comment Share on other sites More sharing options...
bike_dummie Posted April 18, 2016 Author Report Share Posted April 18, 2016 (edited) Sorry I think I may have asked my question in the wrong way. The photo is not mine either but I am getting roughly half an inch difference between the two methods. To measure the chainstay length do I measure purely the X axis 350mm and then up 80mm in the Y axis. And that would give me - 350mm chainstay length with a bottom bracket rise of 80 mm. Like 449.9mm. Or Positive 80 mm bottom bracket with the most direct route (diagonally) down to the dropouts. Same path the connecting tube would take. Example 455mm. Edited April 18, 2016 by bike_dummie Quote Link to comment Share on other sites More sharing options...
forteh Posted April 18, 2016 Report Share Posted April 18, 2016 Chainstay length is measured directly between the bottom bracket and the rear axle, when designing the jig you will want to keep things as square and true as possible and hang the frame around it. Lay it out on cad and you can very quickly see where you need to be putting stuff. I can knock together a quick model for you if you want clarification Quote Link to comment Share on other sites More sharing options...
bike_dummie Posted April 21, 2016 Author Report Share Posted April 21, 2016 I had another look today at my jig and I must just have been having a thick moment. I was eyeing up rough positions using my current frame not realising the chainstay is 365 not 350! Thanks for all the help @forteh Quote Link to comment Share on other sites More sharing options...
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