Vacuum bag press

[Mreagleeyes]

Hello all, been busy so only been browsing what's been going on.

Finally have a few coins in the bank and have started thinking about giving Bent Ply Furniture a go and on that note was wondering what peoples thought's where on the process of bending ply.

I've found the http://shop.instant-shop.com/bagpress/category80374.htm
web site and fairly happy with what ply to use.

My question is. Is it worth me buying a Bag Press to try and create something similar to this

Or would I be better of just creating a large MDF continuous former and clamping it to death.

In the picture the curves are quiet deep and I'm not sure a Bag Press will be able to 'Stretch' that deep.

I'm thinking of going along the Eames design of furniture with my own twist.

Here is the Bag Press I am considering.
http://www.axminster.co.uk/bagpress-pro ... rc=froogle

 

[Steve Maskery]

You could press that in a vac bag. Probably rather easier than using a pair of MDF formers and "clamping it to death" as you so aptly put it. Solid formers for that would weigh a tonne.

A good way to make a former for a job like this is to use that pink insulation foam. It's light and rigid and you don't get witness marks because there are no ribs. Cut the foam to profile, stack them on a piece of MDF and skin the top with 3mm MDF.

Depending on your former, you may need a 3m bag to accommodate the depth of the mould.

S

 

[Oryxdesign]

The amount of force you get with a vacuum press is incredible, much more than you could get even with an unending supply of clamps.

Si

 

[Sgian Dubh]

A bag press won't have any problem bending that-- we bend that and more severe in ours. For this you make a male former out of chipboard, MDF or out of polystyrene insulation board-- Celotex is one brand name. Whichever of those materials you use you need a release layer, eg, polish or a plastic barrier, eg, strips of shiny brown packing tape. This prevents the bent form sticking to the former.

If you don't use a bag press you will need to make a male and female mould that you clamp together to trap the layers of plywood. For this you can't use polystyrene insulation board.

Whichever route you go you almost certainly won't be able to get away with making your bending form out of a plywood skinned ribbed frame structure as the forces are too great and it will probably collapse. Slainte.

 

[Mreagleeyes]

Thanks guys, I was a little worried that I wouldn't get the pressure I required with a Bag but seems I'll get more than enough.

Any views on the Bag I'm thinking of getting.
http://www.axminster.co.uk/bagpress-pro ... rc=froogle

 

[Racers]

Hi, Mreagleeyes


Wow what a price! I got mine out of the skip at work!

A quick Ebay search came up with this http://cgi.ebay.co.uk/NEW-INDUSTRIAL-QU ... 48397d5828
and quite a few others at about the same price.


Pete

 

[Oryxdesign]

Hi, Mreagleeyes


Wow what a price! I got mine out of the skip at work!

A quick Ebay search came up with this http://cgi.ebay.co.uk/NEW-INDUSTRIAL-QU ... 48397d5828
and quite a few others at about the same price.


Pete

I don't think that sort of pump will stand up to running continuously, however I did buy my pump second hand off ebay for a couple of hundred quid which was 10% of the new cost.

I've got a 16m3/m job it evacuates very quickly and too quickly sometimes so that I have to slow it down by turning it on and off. I think you'll be fine with that sized pump.

I am very much looking forward to seeing what you achieve with it.

Oh yeah, if you buy some clamping pots it's good for clamping stuff to the bench especially whilst sanding and routing.

Si

 

[woodbloke]

I use the standard AirPress set up simply as the firm is local to me (about 20 mins from home) and gave me a 'deal' :wink: when I bought it.
Fantastic bit of kit...and it will run all day continuously. I recently ran it for around 14 hours non-stop - Rob

 

[CNC Paul]

Patrick,

I agree with Steve M in using the foam formers, I have used this method quite a lot but on deep forms like the chair I would not put the former in the bag as you will get distortion on the foam and the possibility of damaging the bag. I would just put the layers of foam in the bag and then clamp it to the former.

I usually machine the formers in layers to suit the thickness of foam

 

[seanybaby]

Whichever route you go you almost certainly won't be able to get away with making your bending form out of a plywood skinned ribbed frame structure as the forces are too great and it will probably collapse. Slainte.

Instead of using a bag, you could make up a ribbed former with a laminate on top. The laminate ensures the work doesn't stick, but putty does stick. Then using special throw away bag material and a roll of putty stuff stick it on the jig, put a tube in and suck away.

I haven't explained that very well at all sorry :roll:

 

[rileytoolworks]

Mr Eagleeyes.
Yes, as has been said, a vacuum setup is ideal for this job. I agree with all that has been said regarding the formers.

I use that very pump at work on a daily basis and whilst it will run continuously, it will take an age to evacuate the bag. At home I use a pump which draws 40m3 /H. Sometimes this is too fast, but I simply turn this down till I'm sure the bag is sat 'right', then crank it right up.
Also, at home, I have my bag setup with a non return valve so I can turn off the pump and the bag maintains vacuum.
One problem you will have to overcome is the bag being sucked between the lamina and former. A second pair of hands stretching the bag is helpful here.
I would love to hear how others tackle this problem on large bent laminations.
Sorry for such a long post.

Good luck, and remember we need pictures!!!


Adam.

 

[rileytoolworks]

I've got a 16m3/m job it evacuates very quickly and too quickly sometimes so that I have to slow it down by turning it on and off. I think you'll be fine with that sized pump.

Si

16m3/m? Really? Thats 960 m3/H. That's a mother fu£$er of a pump!!!


Adam.

 

[wizer]

I've got a 16m3/m job it evacuates very quickly and too quickly sometimes so that I have to slow it down by turning it on and off. I think you'll be fine with that sized pump.

Si

16m3/m? Really? Thats 960 m3/H. That's a mother fu£$er of a pump!!!


Adam.

:lol: and I've got it's 'little' brother

 

[Oryxdesign]

Sorry per hour not per minute.

 

[rileytoolworks]

What does yours draw per minute/hour Wizer. And before some smart buttocks pipes up and says that the draw rate is less important than vacuum level - I know. I just want to be able to say 'Mine's bigger than yours', but if Simon's does actaully draw 16m3/M then he's got the king of pumps and should offer it to BP for their problem on the Gulf Coast... :shock: :shock: :wink:

 

[rileytoolworks]

Simon, it seems our posts crossed. What kind of stuff do you do with your setup?
As an aside, has anyone got any maintenance tips for the bags themselves?

Adam.

 

[Oryxdesign]

I've not had it that long. I've done a little bit of veneering as a test really. I've used it to clamp a load of panels to an unusual sliding door I made for an interior designer. I use it all the time for work holding but it's a bit of an overkill for that.

I think I'll be able to suck start my Harley with it when I have a mid crisis.

 

[wizer]

I bought mine 2nd hand on here last year. It's an Elmo Rietschle V-VLT 8 I can never find the spec for it when I search, I think it's a discontinued model. I think it was something like 9m3/h. Means nothing to me. It's been sitting under my bench for the past 6months :lol:

 

[rileytoolworks]

I bought mine 2nd hand on here last year. It's an Elmo Rietschle V-VLT 8 I can never find the spec for it when I search, I think it's a discontinued model. I think it was something like 9m3/h. Means nothing to me. It's been sitting under my bench for the past 6months :lol:

Get yourself a bag and start using it mate. Once you do, you'll be looking at everything thinking 'I wonder if I could vacuum that?'!
How're you feeling now, by the way?

Adam.

 

[wizer]

Yeh, we had a little demo at Rob's place last weekend and it really opened my eyes to what can be done. My workshop is a state of total inhalation atm. Trying to focus on one thing at a time, but that never works with me :roll: :lol:

I'm feeling much better thanks. Pain is still there, significantly. But I'm generally coping much better. Keeping busy. Thanks for asking.