Beam Pin Vacuum Infusion Help Please

Hey Fanie

I've tried infusing some tubes, although not as big as yours, without any success. The last one was a 2 meter stern tube, 55mm dia. The vacuum compressed the stack to the point of choking off the flow. I did this vertically feeding from the bottom. It went well till about the half way point. I was using biaxial fabrics which I think might have been part of the problem.

I found http://www.solarcomposites.com/ who have a different method that I'm about to try. They recommend biaxial sleeves and shrink tubing in their method. This way you can hand lay up your tube on the mandrel and use the shrink tubing to give you the compression you need working from the center out. Here... they can describe it better than I.

Scroll down to "Professional Looking shafts....."

on this page

http://www.solarcomposites.com/composites/carbon fiber sleeves.html

They also have carbon fiber and basalt sleeves. I've got the basalt sleeves and they look like they'll work ok, cheaper than carbon and stronger than glass.

Just a thought.

 

I've made a decision to get something else.

If I get some 45 deg woven. Chances are 90% it's going to come out a lot better and in theory there shouldn't be any problems. Just one problem now is how do one roll it tight over the former ? or is it a matter of rolling it relative loosely and it expands sideways... Using a wider than required 45 deg glass and pulling it just enough to become the width required might make it. When you vacuum it will want to expand sideways.

Any one have an opinion on this ?

If I get some uni directional glass, how is it going to be different ? I've never seen it or used it.


Just for the sake of knowing I dismantled the current rolled glas's vacuum stuff and tried to wound it up tighter. I put a wedge pole through the former end and really cranked it. It worked, the ridges are almost non existent when I vacuum it.

 

Hi Rick,

The main consideration for vacuuming the glass is to minimise the weight without compromising the strength.

 

Ok I've made another few observations

Winding the glass on the former with the wedge pole makes the glass nearly as dense as when vacuuming it. When I switch the vacuum on the OD of the tightly reeled spool of glass reduces so little it's not going to make much difference.

I anyone considers doing their tubing the same way, that makes for quite a bit of forcefull cranking. The wider the glass obviously the more force you need to achieve the same density.

I'm going to use hand layup, it is going to rule a few questions out and reduce the risk of possible flaws, though more physical work and would probably take a bit longer.

The glass I have despooled from the former onto a 50mm pipe. I'm going to wet the glass on the former then tighten it, two layers at a time. The excess resin will squish out to the surface and help wet the next wound layers out.

One thing I noticed is that the woven does not despool when you've tighten it.

 

I haven't tried mine yet but I think, so I've been told, you'll get more compression of the stack from the shrink tubing than you would from a full vacuum pull. Just some thoughts. We need a materials engineer methinks!

 

Aye Rick, guys,

First pin DONE !!

Pic 1 is the first 2 layers wound on the plastic, ready to begin glassing. I phone one of my friends to come help, shame he worked today and was tired but he came never the less. He was going to restore a small cathedral hull before but gave up before he started, so had 50kg's of resin in his garage. I swapped it for one of my small anchors which I had a few exta made last time.

Pic 2 glassing in progress. Note my clothes how poor I am...
We'd glass 500ml of resin in at a time and then rotated the two reels oposite to squish the excess resin out. It worked quite well.

Pic 3 The completed pin. It took about two hours but it probably was like an hour and 15 mins worked on the pin itself. The pin is already hard, be ready tomorrow to pluck off with the block and tackle. The resin used wasn't measured exqactly and a little was left over, but I'd say I used about 3.6 kg's or resin. The peel ply was in the way so I draped it, it wasn't nesserary though.

Thickness is just over 17mm, will get cut to 16mm. One down five to go...

 

Fanie
It looks good and no doubt about the saturation of the cloth - more reliable than infusion.

From your explanation and photos I gather you did not vacuum bag it.

You could get a tighter layup if you bag the glass tube and pull a vacuum on it. The bagging can just be a plastic sheet wrap taped to the PVC tube. Having 15psi over the surface of the glass tube will force any air out of it once you pull the vacuum. It will also get rid of excess resin.

Would be something you could try on the next one and compare the result.

Rick W

 

Don't forget shrink tubing works for compaction and is simpler to use on tubes. I have some shrink tubing about that size in the shop right now.

You could use an epoxy resin for your infusion. Choose a BPF resin like Epon 862 or 863, then thin it further with Heloxy 62 or 68, about 10%. The resulting resin will be around the viscosity of the typical polyester resin. Use Emi-24 cat at about 5% . Do your infusion and take your time as this resin takes about 5 days at ISO std (25C). When you are ready to cure just heat to 120*F (just nice and warm, really) for 4-6 hours and you're done. Post cure as necessary if you need high temp service

Jimbo

 

Hi Rick, not so easy ! I tested the tight wound layup and compared with the vacuumed of it while wound so tight, made little difference. That pin you see there was pulled tight with force rotating the jig, so much so the red pin you see in the pictures got bent. I can hang on it ok without bending, but we extended it with a piece of sqr tubing to add some leverage. That did it

I also used normal resin since I have it, the inner layers were probably gelled by the time we finished the outer layers, so vacuuming would not have made much difference.

It is currently a very pleasing temperature to touch. I ripped the peel ply and the glass is stone hard already. It looks good...

 

Jimbo and the other Rick

Will the scrink tube provide enough crimp force ? I wonder. Usually crimp sleeve does make a bit of pressure, but not nearly as much as vacuum or even close to the way I did it above, unless your crimp sleeve is really something else... ? I did have a look at the link, but I still wonder. It may let it look really good and give an excellent finish, but remember the pins will not be visible, they will be enclosed into the structure they will live in.

This reminds me. When the pins are cut in the lathe and polished to very smooth, I have to give it a varnish layer. What to use ?

I would also like to put something like a pollish or grease on it so the beam housing that gets glasses around it doesn't want to stick to it firstly and secondly should act as a lubricant for the pins so they won't rotate dry. Preferably something that is water resistant or water repellant... Any ideas ?

I could add a grease nipple

 

Thanks everyone for your help, comments, advice etc etc. I pulled the first pin off the former today, and it looks really good. It is un be friggin lievable hard.

The two trees is all I have to pull it apart with

 

Fanie,

I'm sorry I missed all the excitement.

The way you did this one really looks nice.

For all practical purposes, the weight of any extra resin is entirely wasted. Any stiffness you get from the resin is going to be there with the "minimum use" strategy of vacuum infusion. On the other hand, I'm not sure if you're losing much with your rig.

If you decide to try infusion, I like Rick's idea of putting the pin on its end and pulling resin from the bottom, but with one modification:

Instead of trying to pull resin through the entire pin, put several feeds on it. One on the bottom, one 6" or so higher, and one more 6" higher than that until you get to the top. The feeds are rings. All feeds start clamped shut, except the bottom one. When the level gets as high as it will get, you clamp off the bottom feed and turn on the one just below the current epoxy level.

The first pin you do this way will tell you how far apart you can make your feed rings. The biggest cause of failed parts in infusion, from my reading, is failure to get the entire part saturated. It won't hurt you to have too many feeds, but it will hurt to not have enough. You never know until too late how well the part will allow resin to flow.

If you wanted an inside mold, you can sometimes find clear acrylic tubing for not much money. You could put the channels on the inside, vacuum bag using whatever and then just break the mold off the part.

 

Hi Ken,

Not much excitement however, just donkey work.

Tbh, I'm a bit scared to try and vacuum infuse this thick a layup. The method of rolling and tightning the layup works very well. Winding the supply reel and the layup opposite directions makes for quite a tight layup.

Initially I thought the resin content is too high, using about 4kg of resin per pin, then I weighed them. The pins weigh about 10kg as is, so there is 6kg's of glass and 4kg's of resin. Not perfect but ok.

I think I will use this method again to make round things. I must say, the pins are fairly rigit Good exercise winding them too.

Pin #2 done. I got another friend to come help me this time. I better give them all a chance to help with one pin before the word goes around

You can see the resin squish through when you wind it up some.

 

Since I plan another boat similar to this one just smaller (8m for daysailing and fishing) I can just as well make it's pins as well. With all these pins I hope I remember to do the rest of the boat

Since we're kind of on the topic of wetting glass and layups and vacuuming.

I was thinking of a glass wet out bin. The idea would be to wet all the layers out as it gets feed through the bin, in one go. The bin hangs over the hull and can be moved backwards, either from a beam or a trolley extending both sides of the hull.

If you then precut and lay all the layers and stitch or glue them together (somehow), as the glass goes through the wet out bin it gets layed on the hull former. Once all the glass is on the hull and in place. you pull a bag over the hull and vacuum it in one go. Any excess resin will be sucked out and you may have less problems with resin not flowing where it should.

What do you think ?

 

The problem with that IMO is that the vacuum won't really squeeze anything out, at least not a lot of it. Chances are your resin will have started to heat, and you will get minimal resin out.

One of the main attractions of infusion is that you never mix a drop until after the bag is turned on and at a hard vacuum. Another attraction is that you never even draw resin unless you need it.

Every document I've read so far concerning infusion, they focus on getting the feed channels set up properly so that resin can flow properly.

I think that if you put the layers of feed channel close enough together, you will be able to use infusion properly without too much trouble.