Vacuum bagging vs. Press Machine Assembly

MJTennison · Post by **MJTennison** » Tue Sep 11, 2012 8:12 pm

Hey All,

I'm the new guy on here...so at the risk of asking a previous question (haven't found the discussion on here yet if it exists), I'm hoping I can get some initial insight from some of the experts on here...if a similar post exists I'd appreciate a link?

I'm starting my first board construction project...going through the design and analysis of the board right now (materials selection, epoxy/fiber ratios, etc.) but have some manufacturing questions:

1. Vacuum mold vs. Pressing (hydraulic, pneumatic, etc.): Assuming the mold is structurally sound, and a tapered wood core (~7mm in center, ~2 mm on ends), will a vacuum bagging technique also produce favorable results? Perhaps preforming the core (separate vacuum pull process, or CNC the core from laminated wood strips) and then vacuum bagging the room temp epoxy, 22oz triaxial glass, base layer, top sheet and other components concurrently?

2. If anyone has used a vacuum bagging process, what is the max psi you pulled with your pump setup?

Any thoughts are much appreciated. Thanks all-

deepskis · Post by **deepskis** » Wed Sep 12, 2012 5:16 am

Hi MJT!
I use a vacuum setup for both skis and snowboards. Easy to learn and it works fine.

1. Use tipspacers. Yes, you can use epoxy that cures in room temp, like west system or similar.
2. 0.95 atmosphere wich is enough to press a board.

twizzstyle · Post by **twizzstyle** » Wed Sep 12, 2012 7:35 am

Tons of people do vacuum bagging.

Max pressure you can get is atmospheric pressure, roughly 14.7psi at sea level on a standard day.

For a pneumatic press, people press anywhere from 50-100psi, and everything in between. I've only seen one guy on here do hydraulic, seems like more hassle than air to me.

ClayWheeler · Post by **ClayWheeler** » Wed Sep 12, 2012 4:18 pm

Yeah, I agree I don't really see a difference Twizz. But thats pretty cool.

MJTennison · Post by **MJTennison** » Wed Sep 12, 2012 6:38 pm

Great feedback fellas, thanks! I've done some vacuum bagging before, but it was a flat carbon fiber panel, nothing with camber so I wanted to confirm.

deepskis- Just so I'm clear, are you suggesting using solely tipspacers on the nose/tail and using wood core in between? Is this a ptex material, or comparable?

Thanks again for the quick feedback-

M

twizzstyle · Post by **twizzstyle** » Wed Sep 12, 2012 7:06 pm

The tip spacers that most people on here use, and is sold by the few materials suppliers, is 2mm thick ptex. I have 6" worth of tip spacer on each end of all of my skis, no wood extends into my tips at all.

MJTennison · Post by **MJTennison** » Wed Sep 12, 2012 7:21 pm

Thanks twizzstyle for clearing that up for me.

Do you use a glue joint, miter joint, or some variation join the ptex to the core? Or just slot the wood core and overlay the ptex?

-M

deepskis · Post by **deepskis** » Wed Sep 12, 2012 9:42 pm

You can also use base material as tipspacers. Glue two pieces together. Use tape, hot glue or similar to attach to core edge to edge.

Found this old pic...

twizzstyle · Post by **twizzstyle** » Thu Sep 13, 2012 7:12 am

Yeah I just do edge-to-edge just like deepskis. I don't even attach it with anything, I just set the tip spacers in during the layup, and I've been lucky I haven't had any slipping/gaps.

There's lots of options for temporarily holding it in place - super glue, hot glue, staples (on the outer edge where it'll get cut off after pressing)

deepskis · Post by **deepskis** » Thu Sep 13, 2012 10:34 am

twizzstyle wrote:Yeah I just do edge-to-edge just like deepskis. I don't even attach it with anything, I just set the tip spacers in during the layup, and I've been lucky I haven't had any slipping/gaps.

I have not been so lucky... I just use som small pieces of tape on the bottom side. Easy and it works!

hegan · Post by **hegan** » Thu Oct 04, 2012 6:13 pm

deepskis wrote:

1. Use tipspacers.

Would thinning the core in the tips and tails down to a smaller dimension work? Say 2mm to 1mm.

sammer · Post by **sammer** » Thu Oct 04, 2012 9:46 pm

hegan wrote:
deepskis wrote:

1. Use tipspacers.
Would thinning the core in the tips and tails down to a smaller dimension work? Say 2mm to 1mm.

Ya, you can do full wood core but it's a pain as it sits above your mold unless you prebend you tip and tail.

I tried steam but it softened up the glue and made the individual wood pieces splay.
Read thru the logs, you'll see some pretty ingenious wood benders.

Tip spacer is a million times easier.

sam

skidesmond · Post by **skidesmond** » Fri Oct 05, 2012 2:44 am

Use wood tip spacers. I buy 1/16" (about 1.5mm) poplar and ash veneer. I use 2 layers in the tip for a very strong and torsionally rigid tip. I guess 1 layer will work too as long as you have a decent weight FG or CF.

hegan · Post by **hegan** » Fri Oct 05, 2012 6:37 pm

skidesmond wrote:Use wood tip spacers. I buy 1/16" (about 1.5mm) poplar and ash veneer. I use 2 layers in the tip for a very strong and torsionally rigid tip. I guess 1 layer will work too as long as you have a decent weight FG or CF.

Good idea right there.

hegan · Post by **hegan** » Sat Oct 06, 2012 8:26 am

Been thinking about this, what do you do when you have a long low profile rocker? Do you just make the tip spacer really long? I'm working on a pair right now they will be my first pair with a long rocker and in SnoCad they have a huge tip spacer length at 358mm. Has anyone else come across this problem?

Ski Builders Forum

Ski Builders Forum

Vacuum bagging vs. Press Machine Assembly

Vacuum bagging vs. Press Machine Assembly