vacuum bag press/equipment

[m_dex1]

hello everyone, my name is Miles and I design and make small furniture and related 3 dimensional objects, intro over

I have read a few threads on here regarding vacuum bag pumps, bags etc etc, so apologies if I'm going over the same ground. I'm looking at investing in a small set up for now, I've done plenty of forming/bending using different techniques and now want to add a different dimension to my designs.

Ok, first question, is this pump any good, should I be worried about oil ? (I don't have permission to post links apparently, so it's the pump that East Coast Fibreglass supplies do)

Also, does anyone know where to get polyurethane (PU) sheet to make bags, I have sourced vinyl (PVC) sheets, but have heard PU is better, so I want to make my own bags, I'm trying to keep costs down to a minimum, I don't mind spending around £300 all in on a decent basic set up. Any other info or tips would also be appreciated, cheers, Miles

 

[Job and Knock]

does anyone know where to get polyurethane (PU) sheet to make bags, I have sourced vinyl (PVC) sheets, but have heard PU is better, so I want to make my own bags

Hi Miles. You may want to try rubber sheeting suppliers as PU sheet and neoprene are both sold by rubber suppliers, although one firm I've come across in the past who sell PU sheet is Dataroll in Weston SM. Personally I'd consider silicone rubber instead of PU because it's possible to use it in conjunction with heating elements for faster throughput. I used to have a contact in Bradford who made silicone rubber bags (as well as selling the sheet). If I can find them I'll post a link

Incidentally I can't see the vacuum pump you refer to - the link is missing - but basically most of the pumps in use are 1 to 10 cfm. the bigger the bag, the bigger the pump you'll need

 

[m_dex1]

thanks for the tips on sourcing PU sheet, re the vacuum pump, I think because I'm new on here the site won't let me post links to websites, I guess you gotta earn that privilege, and not spam with advertising links etc !! If you go on East Coast Fibreglass Supplies, they have 1 vacuum pump, I'm unsure if it will be ok for vacuum bag forming and pressing, and whether its an oil or dry pump ?? cheers

 

[m_dex1]

ok, it seems there's a 3 post rule until you can add links to the discussion, this is my 3rd post

 

[m_dex1]

does anyone know where to get polyurethane (PU) sheet to make bags, I have sourced vinyl (PVC) sheets, but have heard PU is better, so I want to make my own bags

Hi Miles. You may want to try rubber sheeting suppliers as PU sheet and neoprene are both sold by rubber suppliers, although one firm I've come across in the past who sell PU sheet is Dataroll in Weston SM. Personally I'd consider silicone rubber instead of PU because it's possible to use it in conjunction with heating elements for faster throughput. I used to have a contact in Bradford who made silicone rubber bags (as well as selling the sheet). If I can find them I'll post a link

Incidentally I can't see the vacuum pump you refer to - the link is missing - but basically most of the pumps in use are 1 to 10 cfm. the bigger the bag, the bigger the pump you'll need

here is the link to it, any thoughts if it would be anygood and work simply ? http://www.ecfibreglasssupplies.co.uk/p ... -pump.aspx

 

[Job and Knock]

This is the pump, a Javac CC-31 1.4cfm pump. The references I found elsewhere state that it is an oil sealed vacuum pump which I don't think is suitable. Dry pumps are generally advised for woodworking tasks because of the dust. Dust contaminates the oil and can cause all sorts of issues with the seals

The other thing is that 1.4cfm will take its time to evacuate a large bag unless you give it a hand with your shop vacuum cleaner first (to get the majority of the air out)

In the past I've had success with Gast oil-free rotary vane pumps, which were the type supplied by Wadkin for use on their pin and CNC routers. The pin routers used to come with a 5 or 10cfm vacuum pump, from, memory. but they were production machines where a high throughput was required, hence the larger pumps. The equivalent model to that 1.4cfm Javac would something like a Gast model 1532-101-G288X (although I'd enquire first). They are a little bit more expensive, but are almost maintainence free apart from the periodic need to replace the solid carbon vanes in the pump (probably only every 4 to 5 years on small scale use)

 

[RogerM]

Miles - Welcome to the forum. I faced the same dilemma as you when I was looking for a vacuum system. I bought the East Coast Fibreglass supplies kit for a bookcase project, but the full rationale behind my purchase is contained in this extract.

- but I just couldn’t justify spending over £600 on a Bag Press. After lots of hunting around I settled on a system from East Coast Fibreglass Supplies. The people there are very friendly and helpful, and provided much valuable advice on putting together a budget system without any "hard sell". They provided a 50 micron poly tube and some malleable doublesided sealing tape. The concept is that you seal one end of the tube, and then once the work piece is inside, using the same tape you seal up the other end, simply wrapping a piece of the sealing tape around the tube from the vacuum pump. Once the glue has set, you just cut of the end of the vacuum bag, and so the bag gradually gets smaller with use - but at only £3.95 per metre for a 1500 mm wide bag, it’s no big issue. I bought a bag 3 metres long so given that you lose about 2 – 3 cms each time you use it, it will be some time until it is too small for even quite large projects. A complete kit of a 3metre bag 1500 mm wide, a 2 metre bag 600 mm wide, breather fabric, tape and 2 stage vacuum pump set me back another £275. Gulp - this had better work!

I decided that my first attempt with the vacuum bag would be to veneer the rear of the back, thus providing a balancing veneer as well as a valuable training exercise. Overall I was happy with the result. Here is the back under vacuum. I used cascamite to prolong the working time. The veneers were about 4 x 160cms long by 20 cms wide on a 6 mm ply base.

Notice the careful use of breather fabric. And just imagine how cascamite squeeze out sticks to it like s*** to a blanket! Another valuable lesson learnt.

Next I turned to the front. 7 x 3mm veneers, each about 100mm wide. To mimic a t&g effect I took a 2mm bevel off each edge. Having learned the hard way, this time I wrapped the edges in plastic to keep any squeeze out off the breather fabric.

Then wrap the breather around it .....

... and press.

End result seems quite satisfactory and achieves the effect I was looking for.

In practise, I have found that the tube seals down really well, and in fact a few days ago I ran the pump in the early evening, switching it off before i went to bed, and the bag was still more or less under full vacuum when I came down in the morning to take the workpiece out. Whilst it won't be as robust as a purpose made bag, the tube is sufficiently cheap that you don't have to be precious about it. I just seal up the end of the tube, roll it back onto the cardboard core again, and then just unroll sufficient to contain the piece I'm working on. The pump is fine and will pull down to a vacuum of just 0.005 atomospheres - which is quite good enough. It doesn't mind being left running and pulling against a vacuum, but if I start doing more veneering i'll buy/build a switching mechanism. However, the fact that the vacuum held for over 10 hours overnight makes me wonder whether it's worth the expense and hassle of doing that.

HTH.

 

[m_dex1]

This is the pump, a Javac CC-31 1.4cfm pump. The references I found elsewhere state that it is an oil sealed vacuum pump which I don't think is suitable. Dry pumps are generally advised for woodworking tasks because of the dust. Dust contaminates the oil and can cause all sorts of issues with the seals

The other thing is that 1.4cfm will take its time to evacuate a large bag unless you give it a hand with your shop vacuum cleaner first (to get the majority of the air out)

In the past I've had success with Gast oil-free rotary vane pumps, which were the type supplied by Wadkin for use on their pin and CNC routers. The pin routers used to come with a 5 or 10cfm vacuum pump, from, memory. but they were production machines where a high throughput was required, hence the larger pumps. The equivalent model to that 1.4cfm Javac would something like a Gast model 1532-101-G288X (although I'd enquire first). They are a little bit more expensive, but are almost maintainence free apart from the periodic need to replace the solid carbon vanes in the pump (probably only every 4 to 5 years on small scale use)

I'm only planning on making 2 small bags, 1m x 1.5m & 1m x 1m for now, so I'm thinking the pump would be adequate, but I understand what you mean about dust getting into it, to be honest I am not constantly working with wood, I would maybe only use the piece of kit a few times a month, so I think dust contamination would not be an issue, it would also be stored away when not in use. I will check out the Gast link though, thanks for that, I was thinking of using this bag connector with the pump, http://www.ecfibreglasssupplies.co.uk/p ... t-kit.aspx

cheers, Miles

 

[m_dex1]

Miles - Welcome to the forum. I faced the same dilemma as you when I was looking for a vacuum system. I bought the East Coast Fibreglass supplies kit for a bookcase project, but the full rationale behind my purchase is contained in this extract.

- but I just couldn’t justify spending over £600 on a Bag Press. After lots of hunting around I settled on a system from East Coast Fibreglass Supplies. The people there are very friendly and helpful, and provided much valuable advice on putting together a budget system without any "hard sell". They provided a 50 micron poly tube and some malleable doublesided sealing tape. The concept is that you seal one end of the tube, and then once the work piece is inside, using the same tape you seal up the other end, simply wrapping a piece of the sealing tape around the tube from the vacuum pump. Once the glue has set, you just cut of the end of the vacuum bag, and so the bag gradually gets smaller with use - but at only £3.95 per metre for a 1500 mm wide bag, it’s no big issue. I bought a bag 3 metres long so given that you lose about 2 – 3 cms each time you use it, it will be some time until it is too small for even quite large projects. A complete kit of a 3metre bag 1500 mm wide, a 2 metre bag 600 mm wide, breather fabric, tape and 2 stage vacuum pump set me back another £275. Gulp - this had better work!

I decided that my first attempt with the vacuum bag would be to veneer the rear of the back, thus providing a balancing veneer as well as a valuable training exercise. Overall I was happy with the result. Here is the back under vacuum. I used cascamite to prolong the working time. The veneers were about 4 x 160cms long by 20 cms wide on a 6 mm ply base.

Notice the careful use of breather fabric. And just imagine how cascamite squeeze out sticks to it like s*** to a blanket! Another valuable lesson learnt.

Next I turned to the front. 7 x 3mm veneers, each about 100mm wide. To mimic a t&g effect I took a 2mm bevel off each edge. Having learned the hard way, this time I wrapped the edges in plastic to keep any squeeze out off the breather fabric.

Then wrap the breather around it .....

... and press.

End result seems quite satisfactory and achieves the effect I was looking for.

In practise, I have found that the tube seals down really well, and in fact a few days ago I ran the pump in the early evening, switching it off before i went to bed, and the bag was still more or less under full vacuum when I came down in the morning to take the workpiece out. Whilst it won't be as robust as a purpose made bag, the tube is sufficiently cheap that you don't have to be precious about it. I just seal up the end of the tube, roll it back onto the cardboard core again, and then just unroll sufficient to contain the piece I'm working on. The pump is fine and will pull down to a vacuum of just 0.005 atomospheres - which is quite good enough. It doesn't mind being left running and pulling against a vacuum, but if I start doing more veneering i'll buy/build a switching mechanism. However, the fact that the vacuum held for over 10 hours overnight makes me wonder whether it's worth the expense and hassle of doing that.

HTH.

Hi Roger, thanks for sharing this and your experience of using the Javac pump, firstly I've got to say, love the photo of your set-up in what looks like your living room, made me smile :lol:
I'm not sure whether that kind of bag set-up is what I'm looking for, although it obviously works for you, nice work, think I'll go down the route of making either 500micron vinyl, or 300micron PU bags, I will only be needing relatively small bags too for gentle curved work and some flat pressing.
It seems you're getting great results from the Javac pump though, and to be able to leave it off overnight and it still keeps good pressure/vacuum sounds a real bonus !! cheers, Miles

 

[fluffflinger]

Cheaper here;

http://aircontradesupplies.co.uk/javac-vacuum-pump-cc-31-jav22.html

 

[m_dex1]

Cheaper here;

http://aircontradesupplies.co.uk/javac-vacuum-pump-cc-31-jav22.html

thanks for the link, yes much cheaper =P~

 

[worn thumbs]

This is a topic I know a bit about.There are several approaches to making bags and they all work.I have seen the various silicone/rubber bags that stretch over the workpiece and they are fine within the range of stretch that the material allows and ideal for applying veneer to flat sheets.You can also use rugged polythene with the interlocking plastic seal strips or you can use adhesive mastic tape and gain from the flexibility of adding tucks to wrap a bag round some large and bulky objects.I once showed a cabinet maker the technique and he betrayed his narrow range of experience by commenting that it was nearly as good as a proper vacuum bag,meaning the type with the interlocking plastic extrusions his employer used.

The breather cloth helps the air reach the extraction point,but on most timber there is sufficient porosity to get by without and I have used old towels on occasion.For composites it is normal to use release film (rather than carrier bags ;-) ) and again there is a substitute in most households as clingfilm works nicely.

Quick connect fittings are nice to have but not essential,you can get away with just a reinforced plastic hose passed through the mastic seal and with a breather "wick" inserted into the tube .On a larger job it helps to have more than one vacuum point as it can take time for the full evacuation to reach the extremities of the bag.

The pump,whether oiled or oil-less can get a bit warm on longer cure cycles and the nicest system I have known had a huge reservoir and upper and lower limit switches, so that like an air compressor,it could cut in when necessary and switch off when the correct vacuum level was reached.


In short there are lots of ways of making a vacuum system work for you and none of them are wrong or right.

 

[m_dex1]

This is a topic I know a bit about.There are several approaches to making bags and they all work.I have seen the various silicone/rubber bags that stretch over the workpiece and they are fine within the range of stretch that the material allows and ideal for applying veneer to flat sheets.You can also use rugged polythene with the interlocking plastic seal strips or you can use adhesive mastic tape and gain from the flexibility of adding tucks to wrap a bag round some large and bulky objects.I once showed a cabinet maker the technique and he betrayed his narrow range of experience by commenting that it was nearly as good as a proper vacuum bag,meaning the type with the interlocking plastic extrusions his employer used.

The breather cloth helps the air reach the extraction point,but on most timber there is sufficient porosity to get by without and I have used old towels on occasion.For composites it is normal to use release film (rather than carrier bags ;-) ) and again there is a substitute in most households as clingfilm works nicely.

Quick connect fittings are nice to have but not essential,you can get away with just a reinforced plastic hose passed through the mastic seal and with a breather "wick" inserted into the tube .On a larger job it helps to have more than one vacuum point as it can take time for the full evacuation to reach the extremities of the bag.

The pump,whether oiled or oil-less can get a bit warm on longer cure cycles and the nicest system I have known had a huge reservoir and upper and lower limit switches, so that like an air compressor,it could cut in when necessary and switch off when the correct vacuum level was reached.


In short there are lots of ways of making a vacuum system work for you and none of them are wrong or right.

interesting point of view, thanks for the input, cheers

 

[m_dex1]

any thoughts on this pump anyone ??

http://www.ebay.co.uk/itm/Double-Stage- ... 9250&rt=nc

looks a bit on the cheap side, would it be adequate and reliable is the question ?

 

[Myfordman]

Should be fine especially if you control it as Worn Thumbs has suggested to avoid over heating.

They say it is for HVAC applications which would normally not run for more than 30 mins per job

 

[m_dex1]

Should be fine especially if you control it as Worn Thumbs has suggested to avoid over heating.

They say it is for HVAC applications which would normally not run for more than 30 mins per job

yes I suppose just keep an eye on it and turn it off every now and then, any thoughts on this one from Rutlands, I can't seem to find any reviews on it, it's only a small set up, but the bag sizes supplied would suit my needs for now,and I won't be using the pump daily, more like a few times a month, cheers, Miles

http://www.rutlands.co.uk/sp+vacuum-cla ... 135?tyah=y

 

[Myfordman]

Should be fine especially if you control it as Worn Thumbs has suggested to avoid over heating.

They say it is for HVAC applications which would normally not run for more than 30 mins per job

yes I suppose just keep an eye on it and turn it off every now and then, any thoughts on this one from Rutlands, I can't seem to find any reviews on it, it's only a small set up, but the bag sizes supplied would suit my needs for now,and I won't be using the pump daily, more like a few times a month, cheers, Miles

http://www.rutlands.co.uk/sp+vacuum-cla ... 135?tyah=y

No don't rely on turning it on and off - do it properly with a vacuum switch with adjustable hysteresis then you can safely leave it set up for an overnight cure. Adding a vacuum vessel ( old gas bottle or a vacuum brake tank from a truck) will make it even better.

I don't tend to trust Rutlands for anything important. You may have a different opinion.

 

[Keith 66]

I just bought a two stage vac pump from Airtech UK of ebay, 4.5cfm 1/2hp motor. Its virtually identical to the Javac but at £142 rather cheaper. I have bought it for vacuum bagging GRP laminates, resin infusion & veneering mainly on boat parts. The size is ok for doing quite sizable mouldings or panels.
I also just built a large Vacuum tank for use as a vacuum reservoir & degassing chamber. It started life as a large steam Autoclave used for sterelising laboratory equipment. Finally failed its pat test & was scrapped by the college where i worked. Cost about £30 for gauge & fittings.
Removed safety valve & pressure gauge & replaced them with vac gauge & screwed in ports to take hose tails. Fired the system up last night & it pulled 29" Hg & on shutting the valves held it for 2 hrs with no leaks. Happy days!

 

[RogerM]

I just bought a two stage vac pump from Airtech UK of ebay, 4.5cfm 1/2hp motor. Its virtually identical to the Javac but at £142 rather cheaper. I have bought it for vacuum bagging GRP laminates, resin infusion & veneering mainly on boat parts. The size is ok for doing quite sizable mouldings or panels.
I also just built a large Vacuum tank for use as a vacuum reservoir & degassing chamber. It started life as a large steam Autoclave used for sterelising laboratory equipment. Finally failed its pat test & was scrapped by the college where i worked. Cost about £30 for gauge & fittings.
Removed safety valve & pressure gauge & replaced them with vac gauge & screwed in ports to take hose tails. Fired the system up last night & it pulled 29" Hg & on shutting the valves held it for 2 hrs with no leaks. Happy days!

Nice one Keith. How about some photos please?

 

[m_dex1]

I just bought a two stage vac pump from Airtech UK of ebay, 4.5cfm 1/2hp motor. Its virtually identical to the Javac but at £142 rather cheaper. I have bought it for vacuum bagging GRP laminates, resin infusion & veneering mainly on boat parts. The size is ok for doing quite sizable mouldings or panels.
I also just built a large Vacuum tank for use as a vacuum reservoir & degassing chamber. It started life as a large steam Autoclave used for sterelising laboratory equipment. Finally failed its pat test & was scrapped by the college where i worked. Cost about £30 for gauge & fittings.
Removed safety valve & pressure gauge & replaced them with vac gauge & screwed in ports to take hose tails. Fired the system up last night & it pulled 29" Hg & on shutting the valves held it for 2 hrs with no leaks. Happy days!

thanks for the input Keith, good to hear its working well for you, I will be mainly using the set-up for small curved work using thin plys, 3mm, 6mm, and I also use a lot of construction veneers in my work, 1.5mm and 2.5mm, do you think this kind of pump would be sufficient ? cheers, Miles