GCinDC's Giant DH Comp

[jonescg]

keyne's got a pretty darn appealing post on his fiberglass box.

e-cannon's got another:

Zoot Katz did a good job in his fiberglass battery box too. Part of his build from about 2009 or thereabouts.

 

[GCinDC]

guess i'm gonna try something new.

seems like a good idea to cut out a piece the shape of the frame:

better yet, let's make it only as big sa the widest part of the tubes, and then tapered from there:

let's see how things will lay out:

if i lay the lipo sideways, i can just put two blocks in the middle to keep the width consistent:

oops, forgot to add the controller hood like keyne did, to protect the wires.

it's ok, there's a lot to work out before we get messy.

suggestions are welcome, btw.

 

[Trackman417]

Where did you get the resin and fiber glass?
I was thinking of doing the same thing with my bike, but got too lazy to get around to it
Good luck and make sure you have some windows open when using that stuff. I don't think it's too good for your health :wink:

 

[GCinDC]

a lot of little details to work through before i start laying up fiberglass. i'm debating wrapping the fiberglass around the frame, but imagine it will be difficult to trim whereever it ends on the frame. i like the idea of it strengthening the frame, esp if i fiberglass the inside around the tubes too, but it's such a commitment! and if it fails, it could be a total mess.

i'm also worried about how the rear brake hose will travel thru/passed the enclosure...

i've been living on keyne's thread. a lot of challenges, but am exciting about trying this material...

in the meantime, i came home yesterday and found this scene on the front yard. the kids always play rough, but i was surprised to see charlie going down the hill backwards!
[youtube]DY6wIDBmTYs[/youtube]

 

[pendragon8000]

Greg thats awsome, fibreglass box! my only sugestion is add a little room in desighn for foam padding under the cells, especially the vertical ones. and space for the wires to snake around. i have made 2 battery boxes now and i under estimated room for wire on both, still works but inconveniently tight.
good luck with it.

 

[dbaker]

I can see Charlie needs a Down Hill bike

 

[Thud]

Hi greg,
Is your resin epoxy or polyester based? (polyester dosent play well with foam) not a big deal though. the work around is to use a spray glue compatible with foam, & laminate some tin foil to your shaped foam plug....then glass over that. (same thing ive done with your other GT battery box)

I have some lovely snap closures also you may want to look at:
http://www.mcmaster.com/#cadinlnord/1891a48/=mr0kw3
these are coming on the big GT's battery box to keep it closed...still looking at a qwick release set up for the whole mess to come off the bike with a single hand nut.

Stanly sure forms are fantastic for roughing out foam shapes...& some decent hard sanding blocks will get you the rest of the way home.

I guess I am over due for a update in the other thread 8)

catch you in a bit.

 

[GCinDC]

wow, i was just thinking about you, thud!

you've obviously been swamped. the bikes are Giants, not GTs.

i've been dying to talk to you about all this nonsense...

thanks for the snap closure links. i started thinking more of a mold-based design so that i could remove it easily...

epoxy or polyester? hmm.. i got it from home depot, so i guess i'm automatically fracked. it's this: Bondo® Home Solutions™ All Purpose Fiberglass Resin, 20124, 1 Gallon (US), 2 per case
i searched the data sheet for epoxy with no hits, but found this when searching on polyester: Ingredient POLYESTER POLYMER

 

[speedmd]

Looking to build a battery box soon also. Most Bondo uses polyester. I have normally wrapped foam in a thin poly bag if it needs to be unfinished and dimensions are needed. If it needs to be tight fit, I use the vacuum cleaner to help pull most of air out. I have clear gel /coated the foam molds also to keep the resin attack of the foam down, but unless you are painting the mold with the bondo resin directly it should stay reasonably well if your laying up just impregnated fiberglass. It is temperature/ hardener and foam dependent so it will vary a bit.

 

[GCinDC]

...use a spray glue compatible with foam, & laminate some tin foil to your shaped foam plug....then glass over that.

thanks, but what do you guys think about glassing the FRAME as well as a foam plug in the triangle that i'd later cut out? would the epoxy/polyester adhere to aluminum? if not, a layer could be added inside around the tubes...

benefits would be:
- pack epoxied to frame! (no extra mounting method nec, just an access panel) :wink:
- fewer steps, much less work
- strengthens frame (if only a little?)
- waterproof

disadvantages:
- non removable battery for winter charging? (or need for larger access door to remove entire pack) :|
- messy join where glass meets frame
- nightmare/messy to remove/change.
- limited options for cable routing (but i suppose the glands could be put on edge of door so cable easily be removed for servicing..

i'm sure there are like 10 other variables.. and if i could think through them all, i might go for it.

but IF i were to build a removable enclosure, i'd like a scooped on the bottom so i can set it on the bottom tube, lean it in so it snugs under toptube with a simple strap that velcros or snaps on opposite side, like so:

seems like expanding foam would be best way to get form of inner tubes. i can't imagine how else... but am i correct that i'd then need to:
- glass the plug
- cut it open, wax the inside for the mold
- glass each side?

but where to cut to make two halves? at the equator, or top, not the meridian, since that would ruin the support, and create a seam that would cut into lipos..
and how to latch? is this what you've done thud? made a tackle box? sure you don't have any more pics handy?

 

[Trackman417]

If you think you would want to remove the fiberglass, put something in between the frame and the epoxy. When I wanted to do something like this, I found the wrapping seran wrap around the places you didnt want it to stick. If you want something a little sturdier getting some play dough and wrapping it in serran wrap would be good as well and may not shift as much.

Can't wait to see what you come with.

 

[speedmd]

If you are looking to remove it, I would wrap the frame in poly or wax it heavy. I would make it in one piece. Removable, you would wrap the foam mold with the composite and compress it with a air bag (vacuum) on the out side and melt out the foam when done. If your looking to make it a permanent part of the frame, you would want to make a outer mold and air bag the interior of the box once you wrap and insert the inner foam mold with a air bag. 15 psi is enough to give you a good smooth finish but your will need to hold the outer mold closed while pressurizing the internal bag. Something like 3/4"plywood with a few Bessie clamps will work. If you can not hold it closed even a few pounds of pressure will improve the finish greatly.

 

[mushymelon]

Good progress on the rebuild

I just recently built a custom fibreglass box using pink foam and yes the common fibreglass resin will eat the pink foam.

I used plumbers putty on all the gaps and seams, then waxed. The wax and putty worked, but It was a mess to clean out afterwords maybe modelling clay works better.

The mould was a too complicated to just brush the resin on, it kept lifting the glass up at the tricky bits. With a lot of extra effort it worked out but I would use more wax and a vacuum form if I had to do it again.

 

[Thud]

thanks, but what do you guys think about glassing the FRAME as well as a foam plug in the triangle that i'd later cut out?(sounds like a lot of redundanty for the finished effect) would the epoxy/polyester adhere to aluminum?Yes...very much if not, a layer could be added inside around the tubes...


but IF i were to build a removable enclosure, i'd like a scooped on the bottom so i can set it on the bottom tube, lean it in so it snugs under toptube with a simple strap that velcros or snaps on opposite side, like so:

seems like expanding foam would be best way to get form of inner tubes. this is a nice senario.i can't imagine how else... but am i correct that i'd then need to:
- glass the plug
- cut it open, wax the inside for the mold
- glass each side?
What you describe is a plug-to make a mold construction....total overkill for a one off...I'll list the step below
but where to cut to make two halves? at the equator, or top, not the meridian, since that would ruin the support, and create a seam that would cut into lipos..this is an age old question...findng the suitable parting line & keep the shells aligned once seperated..I typicly just fasion a lip inside 1/2 the shell & let the cover slip fit directly onto it. its easy to do once you see it done once

and how to latch? is this what you've done thud? made a tackle box? sure you don't have any more pics handy?nothing of the latches...but many of the composit proccess. I'll have to dig though my photobucket account is out of whack/hacked(?) I lost a bunch of pictures I had..any posts of mine missing photos are the victoms

to keep the reply form getting too long (I know...too late :lol: ) the method I use for a 1-off is "moldless" construction.
#1 make a nice fitting box of the desired shape in styrofoam...
Make the bulk of the box a monolithic unit & add the fancy details last (like your frame wrapping photo above) you can make it fit odd frame tubes by wrapping a frame tube with sandpaper & grind the shape into a foam block. find a tin can that has a radius your looking for. sure forms are great for roughing foam as are small drywall detail saws. Let your imagination be your limit.
You can glue the detail sections to the main box with some spray glue...any odd fillets blending is easy to do with drywall spackel (i try to keep it to a minimum)
#2 I am a big advocate of wrapping the sacraficial pattern in tin foil...the same Elmers spray Craft glue holds it perfectly. It works as a decent release agent when your cutting the fiberglass shell off the mold...prolly saves you a thimble of resin also. do not worry if looks perfect...the micro wrinkles are smoother than the the 1st layer of glass you'll coat the pattern with.
#3 1st layer of glass- i recomend chopped strand matting for the base layer....it conforms to all the compound curves & will be easy to squeedgie out entrapped ari bubbles.
Polyester resin: for your project...I'll let it sit till the 1st layer is dry...(over night) then rough sand out any imperfections & then the entire surface to remove any wax (that is in the resin when you bought it) after that you can cut some cloth into the shapes that will allow you to wrap the box in another 4 layers of cloth (I typicly use 4oz....but home depot stuff is prolly 6oz) I shoot for 1/16" thick in the un-stressed sections & add a layer or 2 where you may need some stiffness.

Epoxy is nice because it can be worked a little quicker than polyester...& has nearly a zero shrink rate....& stinks less (no styrene fumes) with epoxy I'll let the base coat dry to a tacky state & add the final layers of galss at that time.

keep in a ventialted area with any resins you use & protect your skin...I use a barirer cream & disosable vinyl gloves...I know too many guys who became hyper sensitive to epoxy's over the years

the perfect tool for cutting the shell off the pattern is a occilating cutter...i have a Fein from way back when no one knew what they were..but you can get one from harbor freight for $30 these days....& they are damn handy just to have.
http://www.harborfreight.com/power-tools/oscillating-tools.html

stopping here for now....I'll make it a point to get a tutorial together. AFTER i finish your bike.
there is a crap ton of fiberglass videos on youtube showing mold making & one off construction...
freeman supply has all the modlemakers tricks available for a looky lue also
http://www.freemansupply.com/video.htm
scroll down & you'll see some fiberglass specific videos.
Catch you later

 

[GCinDC]

thud, awesome tips. i'm sure that took a minute. thanks.

i'm hung up thinking about the access panel now. i loved my velcro'd fabric cover, so easy to rip up to reveal all the connectors that were firmly anchored.

with a fiberglass enclosure, how to design a water resistant panel big enough to man handle the 4mm bullet plugs and centronix connectors, with a hidden hinge and push latch... :lol:

in other news, i've almost all the parts, so i am the only one stopping me from getting this build back together, and believe me, duct tape has crossed my mind.

new shop:

beloved fork:

new half grips:

old handlebars, kinda wimpy half twist (w/ regen button that might be better put to use for horn!) and of course the stokers. i freaked when i saw how big the pistons are on the brakes:

but thankfully the motor side had plenty of room! phew!!
wires and electrical. note the led voltage monitors, scruff.

these will need a quick glance cover so i don't look like a christmas tree. not sure if i'll try to stretch them to the bar or where to mount yet..

done with db25's. trying these out for top off balancing and led monitors:

finally, i think i'll swap stators so i don't have to splice on extensions just yet:

i freaked out when i saw how big the pistons were on the hayes stoker:

 

[dnmun]

that led thingy must consume around 100-200mA the leds are so bright. that would be a good way to drain the battery.

 

[GCinDC]

good point. rather than cover it and accidentally forget to disconnect it, i could use a tinted cover of some sort..

wrapped the frame:

made a box:

used two cans but ran out!

of course i forgot to wrap the box sides in plastic, so it'll be fun to try to slice them off tomorrow.

i have no idea what i'm doing but i'm having fun. much more fun than sanding!

we'll see who's laughing when it comes to sanding the fiberglass tho... :lol:

 

[GCinDC]

two cans of this btw;

 

[dnmun]

"forgot to wrap the... in plastic"

been there, done that

 

[kfong]

Haha, Greg you just glued your bike to the box You might have luck cutting it with very thin steel fishing line.

 

[Thud]

We are about to have a learning moment
That spray urethane foam is tough! Nix a wire for sawing it & it produces noxious fumes if hotwiring it.

My suggestion it a 26" hand saw...you can kep it flat against the mdf panel you used for the mold.

My favorite tool for carving this type of foam is a power carving knife used for slicing meat.
http://www.amazon.com/Black-Decker-EK700-Electric-Carving/dp/B0000DAR49/ref=sr_1_2?ie=UTF8&qid=1368878686&sr=8-2&keywords=electric+carving+knife
These also work well on foam rubber.
After its roughed out you can use the sure form or some course sandpaper to shape it....

now for the bad news...or at least a word of caution from experiance.
That spray foam is a muther-scratcher to remove from inside a fiberglassed shell......you will want to ues the foil method to create a mold for the fibeglass & lay it up 1 side at a time......to make foam accesseable for removal with the panels removed.
Feel free to give me a ring if you want to chat in real time about this kind of project.
Its really easy & i encourage every one to release the maker within...& I am happy to let any experiance i have save you some time.

 

[GCinDC]

yeah I figured it was time to start making some mistakes so I could get some learning!

thanks for the offer but maybe you can answer one of my 50 email begging for your phone number!. Lol. Just kidding.

anyway I was all excited to cut the foam out this morning with a wire or string or something and found that a drywall knife works very well except that the inside is still wet!

good thing I bought the acetone yesterday too because otherwise the drywall knife would be ruined!

nothing like playing with acetone before breakfast.

the frame is properly wrap in plastic by the way it's only thing and yes and that side bar that I forgot to wrap..

more later thanks for the help guys.

 

[GCinDC]

attached a fishing line to a vice and tried sawing it side by side. made little progress.

considered the saw, but cleanup woulda been tough.

found something else i thought would clean up nice enough afterwards, a square:

surprised, 14 hours later to find the center hollow and churning like hell:

i thought it would be hard to do something more disgusting than the oil cooling mod, but perhaps i was wrong.

spent the morning at soccer games, everything had hardened by afterwards. picked up a new can and filled the gaps.

now to wait till it all hardens up.

if i had to redo it, i think i'd cut a triangle to fit perfectly inside, then make the detail pieces, just ripping some angled strips to craft glue around the tube, as someone else suggested.

might not need a perfect curve on the bottom channel anyway!

i suppose i gotta start thinking ahead to once i've got a perfectly shaped foam form. if i glass around it, it'll be too big to fit, so i'll just have to use it for a shell..

 

[dnmun]

you thought you had problems with security in the fed building before, wait until they see all the C4 you packed into the frame.!

try riding it like that down Pennsylvania ave.

 

[GCinDC]

mmm, sniffers gonna like those keywords.

those are the kinda words they hunt for! alas, i imagine whoever parses the data knows me by now. :lol:

i often think how glad i am the fire happened at home than at work. notta been good for the old career!

i've learned there are a couple very touchy spots in this town, and others you won't get picked up unless you begged.. still, stealth is good.