why do i get the feeling tha... ah forget it. insert smiley here
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Nick,
Been looking 3 years for a bit of Crumpton construction photo porn and here it all is in one thread, thanks for sharing. After trying plenty of different methods i've settled on something very similar to what you are doing which is good confirmation that i'm heading in the right direction. Are the chain stays you use standard enve assymetric or a Crumpton special order?
Bill
Go to heaven twice Nic. At some point I'll move this thread to framebuilders wiki where it belongs.
I spoke with Nick at NAHBS
and that chat
and this thread
just adds to my respect and admiration to this man's skills, craft and perseverence
to start from zero and journey to this level as an independent is fantastic
WTF would you go and get any other carbon bike but one of Nick's?
and I admire Nick's I got to do it this way, the correct way because it is to sate his desire for the purity in the build process.
Bravo!
so now we come to bagging the frame. the publication Vacuum Bagging Technique by the Gougeon Brothers was where i started. plenty of good info on the web but this is trusted complete source for $5.
the frame will go through a heat cure with a potential for 2 atmospheres clamping(~29psi). if doing heat cure, distortion can be factor. factors include the tubes and tacking Tg and the cure profile. and while its pretty easy to find a suitable cure profile, the dummy axle is an absolute necessity
http://farm5.static.flickr.com/4107/...5910a1d154.jpg
plug the threads or chase em out later. also, that tape adjacent to the laminate "flash breaker"
http://farm5.static.flickr.com/4152/...f0a267dcf0.jpg
thats a highly polished, release treated, honeymoon fitting aluminum tube keeping my HT ID nice and round.
http://farm2.static.flickr.com/1413/...57c7553f9d.jpg
pad hard points padded. a source of leeks.
http://farm2.static.flickr.com/1320/...ff60f140e6.jpg
joints covered in release ply, breather and bagging film. inserting the through bag connectors
http://farm2.static.flickr.com/1213/...42c1fd4f46.jpg
pulling vacuum then off to the oven.
http://farm5.static.flickr.com/4045/...6028a827dc.jpg
going to visit mom for a few days so updates to come later.
Hey Nick,
Don't forget to take it out of the oven before you go.
Hi Nick,
I was wondering, you mention with the BB sleeve and Headtube, that the tube is lined and faced with e-glass - is that a necessity considering you're bonding Titanium which is inert?
I'm guessing that with the dropouts because they're Aluminium there's some glass layer between them and the stays, but it wasn't obvious from the photos.
he mentions that the stay IDs are glass.
http://www.velocipedesalon.com/forum...tml#post244322
I should've mentioned I only get the Intarweb for the pictures.
Thanks Nick for posting this, the timing on this thread could not be better! I've been testing and developing carbon joint techniques and processes as well as building head tube and BB shells. Bagging the whole frame is interesting, I've been testing a joint based method so far.
http://img.photobucket.com/albums/v9...BBBagging1.jpg
Some of what I've been working on (both good and bad) can be found here.
back40 bicycleworks
I noticed you use fairly large fillets of epoxy at the joints. Does that make consolidating in the vacuum bag easier or more consistent? Have you thought of mixing the fillet epoxy with glass micro spheres?
Lots of work to do still...
http://img.photobucket.com/albums/v9...ng/BBTest2.jpg
Can't wait to see the rest of your process.
hey back40. i was checking out your blog. i am liking your recent results. man that bagging scheme on the bb cluster looks familiar. i do not miss that. i use a 36" wide LFT(lay flat tube) and just seal the ends. in wet layup days i would layup and bag individual joints, sealing the bag around the tubes just as you are doing there. the clock is ticking right? but with prepregs you can layup a bike on friday and bag it on monday. i do not miss making bags from scratch or sealing around tubes.
that fillet material i am using has properties just like i want at the moment. but i will say your fillet material looks like it tools nicely. is that quickfair? it is epoxy based yeah?
i like your test on shrink tape. its the nature of the tape. the joint radius would be fine but what is really going on is varied radii on the wraps themselves. the more varied the more pressure on smaller radii and less on larger. that means the broad stretch from HT to acute or obtuse side of the DT is a long no radius bit and we get zero compaction there, where we need it most.
back for a quicky to finish up pre paint. the rest will be post paint prep and that may take a bit.
easy enough pulling it out of the bag. remove all the flash tape. then deflash and any other sanding for the painter. best to take care of any porosity issues now lest you get. pinhole riddled bikes back from paint. i don't care how good one is, cosmetic porosity is the crux of working with carbon.
http://farm5.static.flickr.com/4087/...a3742a291c.jpg
most issues should be where the two side of the bag met or on tube ends.
http://farm6.static.flickr.com/5207/...ab8898b1dc.jpg
a word of warning, that epoxy flash can be razor sharp. blood stains raw carbon.
http://farm5.static.flickr.com/4132/...a49dbec155.jpg
clean threads
http://farm2.static.flickr.com/1210/...8501877fc0.jpg
this is what i am after
http://farm2.static.flickr.com/1347/...00ed4d8c63.jpg
nice drill guide for cable stops. again, new sharp jobbers. 135d point if i didnt call that out earlier. i thin the point makes a difference. i put stops on after paint. just my preference.
http://farm5.static.flickr.com/4153/...860d5ed641.jpg
i bond the head tube cups in now. these are made for a final milling and facing to remove material and insure concentricity and all that. i do em with a thread like pattern with a narrow flat peak and wide flat bottom. the peak is a honeymoon fit and the bottom is the bond gap. makes it a total lathe job and a twist to install.
same as it ever was, both the ID of the tube and the OD of the cup. wipe/abrade/wipe
http://farm6.static.flickr.com/5164/...4ee3ca2696.jpg
cup is in there with just enough excess to face nice and clean.
http://farm5.static.flickr.com/4133/...e06691a6e7.jpg
this is all the pics i have to date. when i found some adhesive on my phone from doing these cups... you get the point. i don't think the rest will be all that remarkable but i'll post em when i have em.
Thanks Nick,
Been a great thread, surprising the little things you pick up from looking at someone else work, your product is and has been inspirational.Thanks
Bill
I had not thought of bagging the whole frame before. When I get to that point I'll give it a try I think. Have you ever tried folding the bag back on itself between the stays to avoid needing the dummy axle? My shop is about 50F so I could leave the pre-preg out there for more than a few days before bagging. The Stretchlon bag is really easy to get to pull into the joints...500% elongation.
I'm trying fairing compound, it's Aeropoxy Light epoxy based. I'll probably try DP420 and microspheres next.
The shrink tape experiment was more out of impatience, I did not have all the bagging supplies yet and wanted to try baking something. It does a fantastic job on straight head tubes and BB shells I made. Along with the UHWW mandrels I can make nice compacted accurate tubes. The latest head tube came out at 43.96mm ID, perfect for the press fit Inset cups. I can wrap support rings of 90deg fiber where the cups go and it still slides straight off the mandrel. More experiments to go...
Thanks for the feedback and for the thread, your timing is impeccable.
Hey guys, my name is Dimitri Harris and I am new to the forum and have only been building frames for about 3 yrs. now under the brand MEECH. Just wanted to introduce myself and like eveyone else find this thread with Nick Crumpton very interesting.
I have been playing with wet carbon layup in the past but have never tried vacuum bagging and I was wondering about what type of vacuum pump is needed. I have been looking at all kinds and recently spoke to a rep. from Gast but what he recommends
seems much larger than the pumps at say Aircraft Spruce. Just looking for the basics but something that has some lasting quality. Any ideas?
Hey Dimitri, i honestly would get the biggest sucking machine you can afford(within reason) ideal is 29.5Hg on whatever size bag you plan top use. several CFM is in order. you can also use a simple venturi device on your air compressor. this is where i started.
If you just want to try without spending much cash get a compressor off an old refrigerator. They pull about as good a vacuum as you can get, just not in volume. Use a vacuum cleaner to get the bulk out. The one I have runs fine for 24 hours nonstop without issue.
I would love to see the oven. Great thread, thanks!