Gerlach Posted June 15, 2015 Posted June 15, 2015 So this is my first topic...I've been toying with the idea to build my own frame and maybe some other custom bits. I've got experience in metal works, composites, plastics and product design....even built a variety of race cars from the ground up Inspiration:Trek, PYGA, Morewood and Momsen to mention a few Reasons:I like the challenge; I looooooove mtbiking; I have some tweaks I feel will make the manufacturers' above bikes suit my ride style a little bit more, like a custom fit (for my type of riding)........and I have some tooling that might help. Let me just say that I love Trek bikes, their little details just make all the difference. Makes you feel like you're on a real special machine, almost boutique like. The abp system and the floating rear end really makes an accurate race bred feel when bombing down trails. PYGA and Morewood have taken some inspiration from these and Momsen has taken some brave leaps too. I love the fact that mtbiking has come to this stage where we have such a huge range of race bred machines to choose from, almost like looking at Lotus, Porsche, Ferrari, Koeniggsegg etc. I will be posting my ideas, designs and progress in here. Feel free to comment, criticize and add suggestions.Burner, ons ken mekaar al tydjie. Moet laat nooit iemand vir jou se jy kan dit nie doen nie. Die ouens wat al uit die 90's en vroe 2000' down hill ry wat my ken, sal weet wat ek en my pa gedoen het, en ek sit nog met die raam . Ons het n down hill raam van niks af gebou, op die Orange 222 se specs. Sal kyk waar ek fotos het. Net na dit het Morewood die mark in getree ook.
Burner Posted June 15, 2015 Author Posted June 15, 2015 Hi Gerlach! Thanks for the motivation, it feels good to have more and more support for this project. Please post those photos of your Dh build, I'd love to see it.
nolipoli Posted June 15, 2015 Posted June 15, 2015 Hahaha, Mitres are a great test of patience. Luckily I have Rhino which allows you to flatten surfaces to print on paper. I have done this "old school". The frame material is Chromoly, although it looks like I will have to settle for Mild steel on a couple of the parts due to a lack of availability in SA.
Burner Posted June 15, 2015 Author Posted June 15, 2015 Nice, I just love Rhino and it's versatility. Where did you manage to get chromoly? I struggled to find a supplier and went with stainless Steel on another project. Try stainless on some sections, except where you are going to add threads because it tends to bind
Burner Posted June 17, 2015 Author Posted June 17, 2015 I've taken the comments regarding the seating position into consideration and moved it 30mm back. It might improve the reach, and position the rider better for wheelies and manuals. Lets see how it works when I add in a 3D scan of myself ;D
nolipoli Posted June 17, 2015 Posted June 17, 2015 Nice, I just love Rhino and it's versatility. Where did you manage to get chromoly? I struggled to find a supplier and went with stainless Steel on another project. Try stainless on some sections, except where you are going to add threads because it tends to bind I will have a look at Stainless as an alternative to Mild Steel - thanks! http://www.cycle-frames.com/bicycle-frame-tubing/home.php It worked out pretty expensive though (this is what I ordered - check the shipping cost):
Burner Posted June 18, 2015 Author Posted June 18, 2015 I will have a look at Stainless as an alternative to Mild Steel - thanks! http://www.cycle-frames.com/bicycle-frame-tubing/home.php It worked out pretty expensive though (this is what I ordered - check the shipping cost): NOVA Order.jpgHave you estimated your completed frame cost yet? I remember building my first car from scratch in 2008 and some guys from UK were telling me that whatever I thought I was going to spend I should multiply that by 3!!! I can't believe how accurate their estimation was for first time builders. I'm not saying you going to spend a fortune, just saying accept it and enjoy the ride ;D This will be my first time building something this complex in carbon with inserts etc, so I'm not going to set a budget, just try to make it as good as I can.
nolipoli Posted June 18, 2015 Posted June 18, 2015 Luckily a steel bike frame is a lot more simple than a car! So far, including the frame jig and all associated costs like shipping, I guess I am on about R10k. I would guess that the balance of small parts, which will require some laser cutting and machining will be another couple of grand. I have decided to ask a friend of mine to weld it, as he is well practiced, and I am not. Hopefully this won't cost too much more than a case of beer. All in, I expect about 14-15K for this one including a 2nd hand shock, but the next one will cost less than 10K. Now a carbon frame - I couldn't begin to guess what goes into that. I am a simple guy, kind of like a blacksmith.
Burner Posted June 18, 2015 Author Posted June 18, 2015 It is simpler yes. R15k is not bad knowing your have a good jig to build more. I'm guessing the carbon build will be about double with the mould .....will be able to pop out about 20 frames, hopefully I can pay back the moulds and machining.
Werner van Aardt Posted June 18, 2015 Posted June 18, 2015 @Burner: Are you going to do strength calculations to optimize your carbon layup accordingly or what is your approach in terms of material thickness? What fabric will you be using? I have an idea for the manufacturing of moulds. Use machinable wax, it machines easily and then you do not need any kind of mould release. (This wil obviously not works if you plan to cure your frame in an oven) Also, you can melt your moulds and reuse the wax afterwards. It will be a lot less expensive experiment.
Burner Posted June 18, 2015 Author Posted June 18, 2015 @Burner: Are you going to do strength calculations to optimize your carbon layup accordingly or what is your approach in terms of material thickness? What fabric will you be using? I have an idea for the manufacturing of moulds. Use machinable wax, it machines easily and then you do not need any kind of mould release. (This wil obviously not works if you plan to cure your frame in an oven) Also, you can melt your moulds and reuse the wax afterwards. It will be a lot less expensive experiment.Hey Werner, I'm not 100% sure on the lay-up yet, must still get to that. I do know that I want to cure it to get the most out of the matt-epoxy/ prepreg combination. I want to use kevlar/aramid near the BB and head tube to improve stiffness. The wax is a brilliant idea if it was just being laid up, I'm just concerned of the strength if the frame isn't cured, the epoxy might still be "green"
Werner van Aardt Posted June 18, 2015 Posted June 18, 2015 There are epoxies which are made to be cured at room temperature with a cure cycle of about 24 hours. The cure temp does not affect the strength, only the cure time. Once out of the mould the frame can be post cured at a higher temperature. Vist amt composites' website and contact them of you feel the need. They are always helpful.
Burner Posted June 18, 2015 Author Posted June 18, 2015 If that product is available then it will help bring costs down tremendously. I'll go around there soon
nolipoli Posted June 22, 2015 Posted June 22, 2015 I think I have the rear end finalised... concept is inspired by the Funk Cycles Titanium bike
Burner Posted June 23, 2015 Author Posted June 23, 2015 I think I have the rear end finalised... concept is inspired by the Funk Cycles Titanium bikeFS-Simple rear 3 quarter.jpgLooks like it'll have very little flex at the rear. How are you going to make those linkage sections above the BB?
nolipoli Posted June 24, 2015 Posted June 24, 2015 Looks like it'll have very little flex at the rear. How are you going to make those linkage sections above the BB?At this point it looks like I will laser cut from 10mm thick Mild steel and then machine out the bearing cups as well as gusset areas to reduce material. The mild steel won't be as hard to machine, will warp less while welding to the chainstays, and is easier to come by. I have designed in pinch bolts for easier tolerance allowance. What is not shown in my model is the joint in the seat stays. This will be an inline cylindrical anti-vibration mount, close to the dropouts. The purpose will be to provide a controlled flex in the seat stays which allows the rigid shock mount, but also to help smooth out trail buzz. There is an Enduro bike somewhere that they have been messing with a rubber shock mount, and I figured it looked interesting. The Funk Cycles La Ruta below has a thinned Titanium piece in the seat stay for flex. Their earlier models didn't have this and I suspect they had a problem with cracking at the joint to the dropout
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