vacuum bagging forms

[marcros]

When vacuum bagging, what do people make the forms from, particularly for one offs? Is there something cheap and readily available?

I have an idea for a laminated bent item but it is quite tall- 600 ish x 600ish deep and 100mm wide- that is a lot of plywood!

 

[adidat]

Make a softwood frame and clad it with mdf?

Adidat

 

[Steve Maskery]

Celotex.
Make an MDF template of your curve, bandsaw and flush-trim the celotex. Bond together until you have the right thicknes. Skin with thin MDF. Varnish and wax, or cover with parcel tape to prevent glue sticking..
S

 

[custard]

I'm suspicious of hollow forms. I know lots of makers are successful with hollow pressing forms but I've had a couple of not so good experiences so I try to avoid them. Consequently for smaller forms, say something like a curved drawer front or a chair back splat, I'll usually make them myself from MDF. But with bigger forms the weight becomes an issue and I'll often sub the job out to someone like Bagpress,

http://www.bagpress.com/Styromoulds.html

Because so many workshops are now getting CNC equipment it's getting cheaper and cheaper to have an MDF master template CNC'd in a local workshop, which you can then copy yourself to build up the required width or have the CNC workshop make multiple copies. This is having quite a big impact on workshop practices. For example, if you need a perfectly fitting male and female curve for a job, or a very large curve with a precise but shallow radius, then those used to be fiddly and time consuming jobs, but with CNC it's fast, accurate, and getting cheaper all the time.

 

[flanajb]

In the past I have had great success from a pink insulation foam from B&Q. Denser that celotex and can be easily cut and sanded.

If you do make a frame and clad it, make sure the frame is really strong, otherwise, you'll just destroy it when you turn on the vac pump. I have experienced this first hand and watched in desperation as the 18mm mdf ribs I had spent ages making where crushed like balsa wood :-(

 

[n0legs]

http://www.bagpress.com/Styromoulds.html

I've just had a little look here as vacuum pressing is something I may be having a go at for some veneering.
What do you guys use as your vacuum source?
I've got air compressors with good capacity and those Venturi Vacuum Generators caught my eye, any thoughts?

 

[marcros]

i have a small vacuum pump. i need to get a closer for the bag system, but i have everything else ready to go I think.

I can't see the foam insulation on the B and Q website, so I will have to have a ride over there one day. failing that, it may be a solid form. I want to make something like this http://www.matthewwernerfurniture.com/c ... tands.html (without the marquetry!). I was going to do it 4" wide, so I had a second one to practice on.

 

[Steve Maskery]

I'm currently building a replacement for my Airpress system that some other blighter has now.
I bought a Zensen pump off eBay, but the one he sent was not the one he described, a very different model. So I got a very good refund and the result is that I have a nominally 4cfm pump for £11.56, delivered.

I then spent a few pennies short of £40 at alocal valve company, for a vac gauge, a hose tail , elbow, hose and quick connector. I probably paid top whack, but it was worth it to be able to walk in with the pump and make sure that everything fitted together.

The only part they couldn't supply was the breach valve, but there is a company near to my Mum who could, so again I went in with my hose and I could make sure that everything was compatible. That was another £35-odd.

So I have good change out of £100, which, in the grand scheme of things is pretty good, given the cost of a kit.

I still have one of my bags, although I don't know which one as it is still wrapped up in cling film. It's either the 8' that came with the kit, or the 10' one I bought subsequently for a wardrobe job.

I've also bought a fuel filter from China for the princely sum of 71p, delivered. It arrived yesterday and it is not the size I ordered- 6mm instead of 8mm. But apart from that I am now good to go. I'm making a case for it, a bit like a sewing machine case, wooden base with a detachable cover.

I'm looking forward to using it.

This is work in progress:

 

[custard]

If you do make a frame and clad it, make sure the frame is really strong, otherwise, you'll just destroy it when you turn on the vac pump.

I've never had a hollow form collapse, but the problem you can encounter is the supporting ribs telegraphing through onto the workpiece. It's often just very faint witness lines, but if you're picky then any witness line is too much!

 

[Steve Maskery]

I've finished the box for my new pump.

The top comes completely off, revealing everything except the bag itself, safely stored inside.