New Guy From Oregon USA

First Stop Introductions
#1

Hi…

I’m retired for about the fourth time and love to tinker. Over the last 40 years I’ve owned a half dozen companies that started out in my basement or garage, which turned into successful businesses. I’ve also done consulting for other companies in a market and product development capacity.

My industry experience relates to laminating multiple layers of thin veneers into 3D shapes for the fenestration industry, and later on in supplying the military with armor laminated out of Spectra, Kevlar, S-2 Glass and other high performance materials using a variety of resins and binders.

My avocation is woodworking and I’m a guitar builder. Many of the instruments I’ve built use a myriad of material combinations that include veneer and composites in areas like the neck and body to give them both flexibility and strength, using vacuum bag and flat laminating technology.

Other than in a hobby setting building guitars, I have no hands-on production experience at all when it comes to laminating veneers or composites, as the work I’ve done has been in an administration capacity, so my knowledge is limited when it comes to processes and technique.

Most recently, I’ve been dabbling with composites making RTV silicon molds to inject hot wax for plugs used to make investment cast parts out of 4130 – 4149 steel, stainless, and aluminum that I have a foundry cast for me then sell the components online.

I have some product ideas using veneers and composites formed into 3D shapes I’d like to pursue that would complement the investment cast components I’m making and selling on line, which would be a culmination of everything I know to date about these processes and materials.

I have a 20’ X 60’ shop and about 6 months ago I bought a used hospital sterilizer I’ve begun converting an into a lab / production autoclave, which has a working chamber of 20” X 20” X 48” that will allow me form the veneers and composite materials under vacuum, heat, and pressure.

I’ve attached some pictures so you can see where I’m at with the project. I stripped it of the steam generator and related components, as I’m going to use heat from a convection oven I’ve cannibalized that is going to be mounted inside at the back of the chamber.

This autoclave has an inner and outer chamber with an air space of 1 ½” between them, which I’m going to put under vacuum to isolated the heat inside the inner chamber. Heat won’t pass through a vacuum, so in theory I should be able to heat the inner chamber up to 550F without heating the outer chamber.

I bought a used Welch Scientific 1376 vacuum pump http://welchvacuum.com/products/duoseal-1376 I’ve mounted on a 35 gallon tank for my vacuum source. Addition to vacuum I’m going to be able to pressurize the working chamber as well, which if I’m not mistaken will aid in compressive force outside the vacuum bag.

The three part video tutorials from Easy Composites showing how to make the plug and mold for a carbon fiber airbox has been very informative! Using these instructions I’ve begun the process of making molds for a couple carbon fiber components I want to introduce to the market.

I’ve also got a male mold / mandrel I’ve poured using Vac Cast into an existing 3D part produced out of 8 layers of birch veneer. I’m going to reproduce these parts by forming veneers in a vacuum bag over the mandrel in the autoclave under vacuum, pressure, and heat, and do the secondary trimming on a CNC.

I’m at the point where I need folks I can talk to directly through these processes and this forum will give me a platform to do that. I look forward to getting to know you all and look forward to the comradery and fellowship as I make friends through this adventure.

#2

Welcome,

sounds like you’ve got some great experience that you want to apply to some new ideas.

What pressure can that autoclave reach? Also, do you plan on going to 550 degrees?

Welcome, and you’ll find some very smart and helpful folks on this forum.

-=Sam=-

#3

Hey Sam thanks for the quick response!

I’ve attached a photo of the serial plate showing max pressure at 33 lbs at 278° F.

I tend to push the envelope on things like this, as they’ve typically been tested in manufacturing at pressures and temperatures that exceed the rating by double whats listed.

I certainly don’t want to create a meltdown and blow it up, as I might not live the experience, but I should be able to use working pressures at 50 lbs, and temperatures at 350 with no problems.

I’m new to this, but I think my 1st carbon fiber project is going to require a four part split mold, with a male mandrel coming in from the top to form a completely closed mold using pre preg.

I think molding 3D veneer consolidations should be fine using the prescribed ratings, but if you’ve got knowledge of what type of pressures and temperatures I’ll need for something like CF in this mold I’d be really grateful for your help!

#4

well using an old autoclave over pressure that it’s rated for could be dangerous. Autoclaves, for composites, are rated and then have to be checked and are re certified through out their lives. If it were me, I wouldn’t use something like this. Seems too risky for my taste. There were a few other guys on here doing similar things though, not sure how it turned out. I just rember being taught that autoclaves use nitrogen to avoid fire risk. I don’t know how great that risk is when using compressed air?

As far as the part your thinking about. If it’s a closed mold with a mandrel, then you won’t need to clave it probaly? Autoclave process is for open mold vacuum bagged parts. You need the bag for the pressure to be applied to the part. The clave heat cycle and vacuum cycle vary from one resin system to another. I don’t really know the recipe, as I never really commited it to memory since I didn’t figure I’d be using an autoclave. There might be some information out there on the web? Though again, with a closed mold, it’s generally not the process used but, I could be wrong… surely some one, some where does this? Though a mold of this sort starts to get tricky, as you need to keep thickness of the laminate under control to ensure that it closes up and that you get good compaction. The molds we do at work that are closed, generally use silicone to provide compaction. I don’t know what the actual PSI is, as it also varies, but it can exceed that of an autoclave; which is generally in the 50-100 PSI range.

I think that’s about the extent of my autoclave knoweldge… lol

what do you mean by 3d veneers? What kind of parts are you planning to make? Sounds interesting.

#5

Sam,

I want to produce a mold that will allow me to have finished molded surfaces both inside and out on the component I’m producing, which will have a high degree of structural definition both sides.

The exposed outer surface of the finished part needs to be a cosmetically perfect twill weave pattern and the only way I can figure out how to orient the fiber do this is pre preg on the 1st layer.

The subsequent layers don’t need the cosmetics, so do they need to be pre preg, or can they be vacuum infused with wet resin in the same mold then baked in the autoclave?

I’ve attached some images of the parts I’m currently having injection molded out of 35% fiberglass filled high temp nylon using permanent CNC aluminum tooling I own, and I’m wanting to do these in carbon fiber as an alternative.

It’s important that the internal structural definition of the parts be as well defined as the outside, which includes both ends, so my thinking is the only way to achieve this is to vacuum infuse a closed mold with resin so I don’t get any voids.

I’d actually prefer pre preg as it’s easier to work with, and money isn’t the issue. My concern is that due to the varying thickness in certain locations inside both ends, it may be difficult to get both fiber and resin to properly fill those areas adequately using pre preg.

In the following picture I’ve shown arrows where there are exposed edges that are seen, so this top edge needs to be cosmetically perfect both visually and dimensionally on the lower hand guard.

In these next two pictures of the lower hand guard you can see where there are critical surfaces on the front that need to be formed dimensionally to within +/- .030”. There are similar critical surfaces on the back end, as well on the inside on both ends.

In the next three CAD renderings you can see arrows pointing to an upside down isometric view of the upper hand guard where there are also similar critical surfaces on the back and front end, as well as inside.

I’m about half way through making the plugs for these two parts and my next step is doing the split molds.

I’m using rapid prototypes on the plugs, as I find they are dimensionally more stable in terms of twist, bow and warping than production injection molded parts. And they are of a material that lends itself to making changes using body putty and accept gel coat nicely. I’m also making these where the vents in the sides will be CNC machined in afterward and then be clear coated on the finished production parts.

I sincerely appreciate your input here, as I have no real clue what I’m doing, other than what I’ve seen watching videos!

#6

Sam,

You’ll see some pictures below of one of the components I’m producing using 7 plys of .023” birch veneer that is 0°/90° cross banded, then has an 8th ply of exotic hard for the face veneer. This is formed over a mandrel using urea-formaldehyde adhesive in a vacuum bag.

Once formed, they are put into a vacuum chamber and infused with liquid acrylic then baked to cure the acrylic. This plasticizes the wood making extremely durable and the only finishing required is with a buffing wheel and polishing compound. Trimming for the outer edges and ends, along with the vents are then machined on a CNC router.

The advantage of using veneers is it makes a wood component that has great dimensional stability, with no warp, twist or bow, without spiting or cracking.