bending 3/4 plywood

twisted · Post by **twisted** » Thu May 21, 2015 7:11 pm

hey guys, i am wanting to try some new stuff, do any of you guys have experience with actually bending and forming say 3/4" birch plywood? or is anything material wise (wood) better?

my idea is to build a center console for my truck and do a tight, heavy curve upwards into a rounded sub box, i would rather use wood than glass for structural integrity. this is something i have never done or thought about before.
so is it as easy as soaking it down then getting your bends, then covering it in resin to seal it or cutting several lines in the radius area at the bend points?

please share your experience with this type of wood working.

Post by **ttocs** » Thu May 21, 2015 9:24 pm

soaking will not do anthing. You need to kerf it and then glass it.

Renovatio · Post by **Renovatio** » Thu May 21, 2015 10:23 pm

i would fill some strengthen ant then bend it.

twisted · Post by **twisted** » Fri May 22, 2015 5:14 am

can you kerf it on the outside, or does it have to be on the inside? or does it really matter? and after filled and glassed will it have the strength for a sub box? also should i step up to 1" for the box instead of 3/4, i asked about wetting or steaming because i have used that method for thin plywood, but have never done anything this thick....

when you kerf it do you guys use a dato blade on your table saw or just your regular blade?

dwnrodeo · Post by **dwnrodeo** » Fri May 22, 2015 6:03 am

twisted wrote:can you kerf it on the outside, or does it have to be on the inside? or does it really matter? and after filled and glassed will it have the strength for a sub box? also should i step up to 1" for the box instead of 3/4, i asked about wetting or steaming because i have used that method for thin plywood, but have never done anything this thick....

when you kerf it do you guys use a dato blade on your table saw or just your regular blade?

The cuts have to be on the inside of the bend. Use a table saw with your regular blade and set the depth appropriately. The more cuts you make, the easier it is to bend. I've done this with MDF and found that I needed to wet the wood to prevent cracking. After you form it in the radius that you want and it dries, fiberglass the inside of the bend to seal it up and gain strength. See my door enclosures: http://www.phoenixphorum.com/viewtopic. ... 1&start=25

twisted · Post by **twisted** » Fri May 22, 2015 7:09 am

dwnrodeo wrote:
twisted wrote:can you kerf it on the outside, or does it have to be on the inside? or does it really matter? and after filled and glassed will it have the strength for a sub box? also should i step up to 1" for the box instead of 3/4, i asked about wetting or steaming because i have used that method for thin plywood, but have never done anything this thick....

when you kerf it do you guys use a dato blade on your table saw or just your regular blade?
The cuts have to be on the inside of the bend. Use a table saw with your regular blade and set the depth appropriately. The more cuts you make, the easier it is to bend. I've done this with MDF and found that I needed to wet the wood to prevent cracking. After you form it in the radius that you want and it dries, fiberglass the inside of the bend to seal it up and gain strength. See my door enclosures: http://www.phoenixphorum.com/viewtopic. ... 1&start=25

can you do the cuts and bend it the other direction than in the pic scott posted? and you have done this with mdf safely? nm i see you did this with mdf, how did it hold up?

and thanks for the advise guys

Weaklink · Post by **Weaklink** » Fri May 22, 2015 8:37 am

I usually fill the gaps with kitty hair right before you bend it. Fills the internal gaps. It squeezes out so be prepared for the mess

Post by **ttocs** » Fri May 22, 2015 3:39 pm

it will take a little practice to figure out how much to cut/leave. Be prepared to have a couple of them break on you. Steaming can help you make light bends like they do on a boats bow but if you want sharper bends it will crack. Once you pour the resin into the kerfed area and it dries it will be plenty strong enough.

twisted · Post by **twisted** » Fri May 22, 2015 5:50 pm

cool, thank you for the advice and replies

this will give me something to do over the weekend!

dwnrodeo · Post by **dwnrodeo** » Sat May 23, 2015 4:29 am

twisted wrote:
dwnrodeo wrote:
twisted wrote:can you kerf it on the outside, or does it have to be on the inside? or does it really matter? and after filled and glassed will it have the strength for a sub box? also should i step up to 1" for the box instead of 3/4, i asked about wetting or steaming because i have used that method for thin plywood, but have never done anything this thick....

when you kerf it do you guys use a dato blade on your table saw or just your regular blade?
The cuts have to be on the inside of the bend. Use a table saw with your regular blade and set the depth appropriately. The more cuts you make, the easier it is to bend. I've done this with MDF and found that I needed to wet the wood to prevent cracking. After you form it in the radius that you want and it dries, fiberglass the inside of the bend to seal it up and gain strength. See my door enclosures: http://www.phoenixphorum.com/viewtopic. ... 1&start=25

can you do the cuts and bend it the other direction than in the pic scott posted? and you have done this with mdf safely? nm i see you did this with mdf, how did it hold up?

and thanks for the advise guys

It has been holding strong for the last five years. Like ttocs said above, practice with it and see how it turns out. My first attempt without wetting it proved disastrous and I had to scrap it.

lukeman269 · Post by **lukeman269** » Fri May 29, 2015 2:19 pm

Be sure to bend with the grain on birch. I wasn't paying attention on my last box and wrecked a good chunk. I used construction adhesive in the seams and just used a 45 to relieve any pressure the kerf wall had. I did a kerf every half inch at about 12 cuts with this box.

knightrider358 · Post by **knightrider358** » Fri May 29, 2015 7:27 pm

Thats some box skills there

lukeman269 · Post by **lukeman269** » Fri May 29, 2015 8:42 pm

Thanks man! The guy I built it for ended up staining and varnishing it. Turned out really nice. He also won a couple trophies in a comp. First place in one category and second in another. Not sure if the kerfed port had anything to do with it, but I was happy he won.

twisted · Post by **twisted** » Sun May 31, 2015 6:32 pm

damn thats a bad ass box!!!! nice work!
i see you braced the kerf internally too., i wondered if that was required. thanks for the tips.
i have not had a chance to play with it any yet, but i was building a box for 3 10's today and put a phillips bit through my thumb.....holy hell that hurt like a bitch, it deflected off my thumb nail and sank right next to the nail......

Post by **ttocs** » Sun May 31, 2015 7:17 pm

dayum! ya should have warned those of us that are squeamish.... Gotta love those. last year sometime I did something similar but with a really sharp pic instead of a Phillips. It was one of those things that really hurt when I felt it hit the bone, and yet was still pushing. I also use to have a voltage probe/test light that had a sharp tip on it and that thing has drawn blood on me more then a few times.

lukeman269 · Post by **lukeman269** » Sun May 31, 2015 7:46 pm

OMG! That's nasty. I can't imagine how bad that feels. Thanks for the compliments! Hope your thumb heals ok.

twisted · Post by **twisted** » Sun May 31, 2015 8:22 pm

after i soaked it in some iodine for a bit, i found where it almost made an exit......it was only skin thickness keeping it from exiting.....lol
i bled all over the box and there is 1 helluva trail into the house and the steps into the back door while waiting on my wife to bring me a towel is mostly red from blood.....this thing bled like a bitch!!!!!!!!

twisted · Post by **twisted** » Mon Jun 01, 2015 7:29 am

ttocs wrote:dayum! ya should have warned those of us that are squeamish.... Gotta love those. last year sometime I did something similar but with a really sharp pic instead of a Phillips. It was one of those things that really hurt when I felt it hit the bone, and yet was still pushing. I also use to have a voltage probe/test light that had a sharp tip on it and that thing has drawn blood on me more then a few times.

dont you hate it when your brain doesnt tell your body to stop!?!? lol
i have stuck myself with a probe more time than i care to count!!! those are sharp lil bastards

quickrip · Post by **quickrip** » Tue Jun 02, 2015 7:15 pm

Hey lukeman, did you use any nails or screws to secure this box, or rely only on wood glue? I like twisted am about to make a center console birch box for my two elite 12d's. I was also going to stain it like your buddy did. Now i will for sure. it turned out great!
Sorry for thread jacking twisted. I've been back and forth on using nails or not.

lukeman269 · Post by **lukeman269** » Tue Jun 02, 2015 7:37 pm

I use 2" brad nails on all my boxes. Never had any issues will joints coming apart. Much cleaner than screws in my opinion and quicker! Just make sure you have a decent nail gun.

Post by **ttocs** » Tue Jun 02, 2015 8:20 pm

there needs to be some kind of mechanical fastener besides the glue for it to be really strong enough. If you want a no-fastener look you can also use a biscuit joiner. You make a cut in each side of the joint with a special saw that allows you to align the cuts and then insert a wooden (biscuit)fastener and a bunch of glue into the cut and the biscuit will expand as it glue soaks in. Its a common joint used in furniture that is very strong and yet shows no joint at all. I personally also used 2" brads and an air gun to shoot them and it makes for quick/easy work with some glue.

quickrip · Post by **quickrip** » Thu Jun 04, 2015 4:57 pm

Damn, looks like Ill be buying an air gun. I want to make sure it is strong enough to last.
Thanks.

Post by **ttocs** » Thu Jun 04, 2015 5:39 pm

they are not cheap and you can even just use a small portable compressor for them but they will save you time.

twisted · Post by **twisted** » Fri Jun 05, 2015 8:17 am

quickrip wrote:Damn, looks like Ill be buying an air gun. I want to make sure it is strong enough to last.
Thanks.

i have a harbor freight nail gun, been using it since 2007 and still going strong......i just make sure i have plenty of air pressure.

bending 3/4 plywood

bending 3/4 plywood

Re: bending 3/4 plywood

Re: bending 3/4 plywood

Re: bending 3/4 plywood

Re: bending 3/4 plywood

Re: bending 3/4 plywood

Re: bending 3/4 plywood

Re: bending 3/4 plywood

Re: bending 3/4 plywood

Re: bending 3/4 plywood

Re: bending 3/4 plywood

Re: bending 3/4 plywood

Re: bending 3/4 plywood

Re: bending 3/4 plywood

Re: bending 3/4 plywood

Re: bending 3/4 plywood

Re: bending 3/4 plywood

Re: bending 3/4 plywood

Re: bending 3/4 plywood

Re: bending 3/4 plywood

Re: bending 3/4 plywood

Re: bending 3/4 plywood

Re: bending 3/4 plywood

Re: bending 3/4 plywood