thanks, Nick! - Garro.
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thanks, Nick! - Garro.
Nick,
This is really awesome! Thanks for sharing this. You used the term "bondline" in your post showing the Ti insert going into the carbon bb tube. Were you referring to clearance between the ID of the carbon and OD of the Ti or something else?
Thanks,
Tom
Great thread. Thanks! Keep going!
back for another round. so we got the drops all bonded up and the Ti BB insert bonded into the carbon shell. once those were set, alignment is checked on the drops. brake mount height is checked to the drops. ready to proceed.
tubes all laid out, labeled for angles and lengths.
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diamond grit saws spinning at a good 2k rpm. 2k to 3k is the range for the average frame tube dia. a water flood would be really great here to control dust but i am not interested in trashing my mill. so dust collection gets 90% of it.
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it throws a burr. in fact if the tube hangs out more than an inch or so from the block, the saw will throw the tube in that direction and cut off center. sorry but the damn iPhoney wont focus on the focal point.
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burr easily trimmed with by warn out fiskers from the layup room.
http://farm2.static.flickr.com/1109/...90c5a6c035.jpg
this will do just fine. also been hit with the file and some emery. more sanding later.
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if you are lucky enough to have an early anvil chainstay miter fixture, it works really well with a monobox stay once you shift the numbers 4cm forward. like my new cardboard & sharpie witness?
http://farm5.static.flickr.com/4112/...96c24b0ae3.jpg
someone asked about vent holes. i do them on all 3 tubes of the bb. but thats it. i actually only do that for drainage on the road. i like step drills, sorry Don but no Walker here.
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So the tubes are all mitered and ready for bottle boss holes. i have a nice fixture for that. i use nutserts so no fudging on location and alignment. sometimes i put the serts in now, other times i do it after tube assy. this time its after tube assy. but the holes go in now.
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i use really sharp brand new short jobbers for this. but you can still get tear out. this isn't good. so i us an old scrap tube with the correct OD to slip in for backing. works like a champ. looks like the swiss cheese i didn't have at lunch.
http://farm5.static.flickr.com/4002/...27bf64075c.jpg
vroom vroom. a custom diamond grit bit with plunge guide would be sweet and save all those .49c bits i toss. oh well.
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nice clean holes regardless. what, you cant see the black hole in the black tube?
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dry run. check it all. make sure it all fits. nothing forced, nothing dangling. nothing worse that trying to make an adjustment to the end of a tube with glue all over it.
http://farm5.static.flickr.com/4058/...b3b67b239f.jpg
for my money, tube-to-tube isn't right if the tubes don't mate fully. the wrap we put on later is an "overlap" and works with the substrate underneath. if there is a gap, there is no substrate at that point and the joint is severely compromised unless wrapped with enough material to make up for the missing. do a good job here and you wont have to overdo later.
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that last bit brings many of you to ask "how much wrap anyways?" that comes later. and the answer isn't easy. for now i acetone wipe all tube ends and the entire BB shell and HT. at this point i am submersing and wiping down.
http://farm2.static.flickr.com/1123/...f8c850b833.jpghttp://farm2.static.flickr.com/1374/...ed26767c1d.jpg
abrade. clean out any remaining burrs. i also, using 80grit, do a bit of abrading where all the wraps will go. it will get cleaned up again later pre-wrap but its easy to give it its tooth(maximize surface area) now. not too aggressively. you don't want to see fiber destruction. these roll wrapped tubes are ground to about 1500g and too slick for me as is. its a grip and twist action for me.
btw, if your tubes are from columbus or dedacciai, they are likely clear coated. same for their stays. you need to remove all clearcoat where the wraps will land. do it now. its a lot easier. you don't want any of that polyU mucking up your co=molding. and it will. it MUST go.
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and another wipe.
http://farm2.static.flickr.com/1167/...bda52ecd16.jpg
i like to dope the ends of the tubes. probably not needed but if there is surface area, i wanna exploit it. i load the BB and HT into the fixture, work around the BB leaving the HT/TT followed by the SS. the order you load is all not very important. note those extra large holes, makes for no fuss Di2 internal on this one.
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next
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next
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all loaded with tube ends doped, this is just tacking. i'll add a mass of adhesive later and sand a nice fillet into it. this will sit in the fixture for a min of 4hr (when warm) or longer. in winter i heat the area to get it done. no room for a walk in oven. if it were important to rush, there are other ways of speeding it along.
http://farm5.static.flickr.com/4128/...74098fb23a.jpg
give me a few more days for the next installment.
Cool pix, thanks!
It looks like you apply your pattern of 'patches' onto the tubes prior to building up the frame?
Cheers,
RG
that random pattern cosmetic, it is applied by the tube maker as part of my spec. i then do the same thing on the joints. it is instead of PW or nothing. i like it. it is unique and funky. the bonus is that its scrap from the cutting room that would normally go into the trash bin.
Nick, this is awesome. Is the blue colored epoxy you are using to tack the frame different than the black 420 you use to bond in the BB sleeve and the dropouts?
Many thanks!
Zank my fellow Italian American, its plain ol off white DP420. and i am glad you asked because there are a few thoughts i didn't include in the last couple posts.
1. what you tack with had better be able to survive well beyond your chosen process for lamination/heat/compaction lest you build crooked frames. what we are talking about is the "service temp" of the adhesive. and that means in service which includes funky loading by vacuum or whatever type of clamping you come up with... at whatever temp you choose. *edit* or plan on fixturing the frame during cure.
2. if you are vacuum bagging, and this is real important, that tack and/or your fillet should seal the entire joint air tight. if not, under vacuum you can/will get dry porous stupid results right where you need best result. can you kinda picture air passing though the leak and taking resin with it?
Nick this is an incredibly generous thread. Thank you so much for documenting the process.
This is probably completely ridiculous, but what kind of control do you have over tube selection? Is diameter and wall thickness correlate to steel tubes? Is there much variety in wall thickness from suppliers, or is tube diameter the main variable in tuning the ride quality given the customer size? I understand that most tubes are wrapped or wound, would it be possible to vary the wall thickness on a single tube? Is there a correlation to butted steel tubes?
Thanks,
Matt
Matt, the main tubes i use are roll wrapped. the ID is set by the mandrel while the ~OD/wall is the addition of what ever plays are stacked. the final OD is done by minimal grinding(centerless grinder) to remove texture from the compacting cello wrap. The stays follow similar principal but without the grinding. i get what i spec.
Carl at edge has good stock profiles as well.
Nick,
I noticed the bb and ht have a weave pattern while the main tubes and stays have a patch pattern. What is the difference between the two? Is it purely cosmetic or is there a function to that finish? Why the different pattern at the bb and ht? Thanks again for posting all of this. Can't wait to see some pics of the joint wrapping process.
Thanks,
Tom
hey Tom, my reasonings for that are driven by observations in bench testing. how i have seen co-molded joints(what we do in t-2-t)taken to failure on my bench. in some cases i see interlaminar failure of the substrate, some uni might peel. i like how the weave is interlocked and self arrests. just another subtlety like doping tube ends thats probably not really important.
about things like this, driven by bench testing. YMMV so do not take what i am doing for granted. i'm gonna be driving this message home a few times so i might as well start now. i will never tell you "use this material" or "your wrap should be this thick or this # of these plys". the rational is everyones process will have varying results. even if we follow the same recipe. so the answer to "how many plys of what kind?" should only be answered by your own testing with the tubes and process you intend to build your frame with. or just 5x over build the damn thing.
i'd talked about putting the bottle bosses in, here goes. i use to use the fancy aero space torque wrenchable tool but realized the simple lever works really great. i mix up a bit of black.
http://farm2.static.flickr.com/1404/...b500c30ca3.jpg
i like to dope up the backside of the hole. the bonding is an extra step not proven to be needed.
http://farm2.static.flickr.com/1319/...1e92be7a60.jpg
at this point i wipe off any excess adhesive and use compressed air to blow out the threads just in case i drug some adhesive out with the tool
http://farm5.static.flickr.com/4019/...d7a24f819c.jpg
the extra adhesive added for fillet. notice its wet out pretty good, not just a cold blob. akin to getting your brass fillets wetted out, makes for much nicer transitions/ easier sanding and blending.
http://farm2.static.flickr.com/1428/...872ccfe5bd.jpg
fillet sanded and cleaned up. ready for layup. the better the results in layup and bagging, the more important this step. if you have researched vacuum bagging composites you will know that they always demonstrate the laminate against a tool. they talk about the tool side of the part and the bag side. in the case of T-2-T building, the substrate of tube and fillet are the tool. and while the crux of the job is getting a good looking finish on the bag side, as good as you can get that will only be as good as the substrate.
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and the whole thing ready for final wipe and layup.
http://farm2.static.flickr.com/1423/...145a8e7656.jpg
i have a small area of the shop framed off and covered with insulated foam board. a small window AC in the wall. this is for a couple reasons. it gets hot here in the summer and generally kinda humid. some prepregs can be very tacky in higher temps and generally do not respond well to humidity. as tough as it is, i find working with the stuff in the mid 60's f is a luxury i can live with. in the winter when temps in the room are below 60f, i use a heat gun and or an electric space heater to develop some tack lest it all wind up on the floor.
here we have pulled prepregs from the freezer and they are stabilizing to room temp. they remain sealed until they re stable and condensation is gone. now i have been told by many industry experts that this is unnecessary but i am a stickler for the datasheet. i only store in freezers in a sealed bag and only open at room temp after a few hours stabilization.
got everything i need here. acetone, wipe, sharp blade, sharp scissor, sharp-ie, measuring and straight edge. oh and a nice cutting matt. and a cool 63f.
http://farm5.static.flickr.com/4062/...b2a4597711.jpg
i'm not going to go into laminate schedules or any of that as i believe those are best arrived at in one own setup. what i will share with you is how i work with ply's on the frame. i don't tend to work with complicated precise patterns. given every bike is unique, i prefer to work with a couple less refined shapes that can be trimmed on the frame as well as strips of strategic fiber angles and widths. some of them seen here.
http://farm5.static.flickr.com/4090/...12f538fdc3.jpg
some bulky base going down on the BB area. but first a good acetone wipe on each area just before the 1st ply goes down. no more greasy fingers anywhere on the surfaces till its all laid and cooked.
http://farm5.static.flickr.com/4040/...0ab92637bc.jpg
kinda see what is going on? make it fit, trim excess. its kind of important that the seams of subsequent layers offset or alternate.
http://farm2.static.flickr.com/1240/...37361445a3.jpg
the bulk of it is uni. here it begins to build. so why that PW underneath? good bulk that drapes well. the BB area is an odd shape, it helps set the foundation.
http://farm5.static.flickr.com/4026/...da59e7143d.jpg
and the BB area complete. there are 27 individual pieces on that joint. but that doesn't really mean much given the variety of fiber weight out there as well as a whole host of other reasons. but it sounds cool.
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the HT area complete. ready for bagging. its even got the cosmetics on it. there are over 30 pieces here minus cosmetics.
http://farm5.static.flickr.com/4006/...0706802537.jpg
incredible stuff.
nice...thanks for the update.