vacuum pressing

[RogerS]

Has anyone bought/built one of these from Joewoodworker ?

One of the attractions is the degree of control it seems to give rather than being on all the time like some of the other makes.

And at the other extreme is this from Roarockit. Not sure that I'm convinced on the degree of vacuum one can achieve.

 

[RobertMP]

there is a 'h' missing from your first link - ttp:// not http:// and firefox is not clever enough to work it out

 

[woodbloke]

Rog - Interesting. If you look at the roarockit system he doesn't quote the pressure per sq ft, so although he talks about 3000lbs that could be over quite a big area. I use the Air Press system (the pump pulls a vacuum right down the zero) which is very good and as they build the stuff just down the road from Salisbury, its convenient for spares and also advice from the guys there, which is very useful - Rob

 

[Roger]

Here's your link Rog .....

Joes Woodworking

And no I haven't made one from his site, although seen the results. 'Interesting' but didn't have the time / inclination to go that route. I use a BagPress bag and extras with a pump I bought specifically.

 

[Scrit]

I tend to use the shop vacuum (cheap LIDL one) to remove the bulk of the air and get the bag pretty flat before switching over to the 10cfm Gast vacuum pump installed in one of my pin routers because the 10cfm rate of the vacuum pump makes it a bit slow to exhaust a big bag, however, but it will happily pull down to about 21 or 22in Hg. Beyond that and you can start to find out where all the leaks in your bag and connectors are! I've found the Joe Woodworker site to be an excellent source of information and a vacuum pump makes a lot more sense than a water venturi or compressed air venturi - the former being wasteful of water whilst the latter is extremely energy hungry. If you are just looking for a vacuum pump there are several good makes on the market notably Gast (American) and Becker (German) both of whom produce pumps used in many woodworking machines - for suppliers try compressed air specialists such as Thomas Wright (Thorite) in Bradford and with branches over the North of England. Look for oil-less compressors - oil-lubricated units require extra filtration to avoid contamination and will leak oil if accidentally tipped over.

From experience for vacuum veneering you don't need a 27in Hg pump, 20in is more than adequate. If buying secondhand on eBay, etc. be aware that vacuum pumps are very heavy items, carbon vane kits are expensive (a set of vanes for my little Gast would set you back £60, the bihgger 100cfm Becker I had on our CNC was £32 per tip - all prices plus VAT) and ex-lab or industrial equipment may be contaminated with something nasty or have worn-out tips or seals.

If you are looking for stuff in the UK the supplier I'd recommend here is BagPress in Letchworth - they do kits from about £225 upwards.

Scrit

 

[Nick W]

Roger,

You missed the leading 'h' off your first link, here it is corrected.

I wonder why you want to go to the US when we have two home grown companies Airpress and Bagpress?

I have an Airpress system, but would probably go for Bagpress if starting again as their bags are PU rather than Vinyl and therefore more flexible, and, more importantly, more puncture resistant.

EDIT: Oh the delights of posts that cross. :lol:

 

[Scrit]

....would probably go for Bagpress if starting again as their bags are PU rather than Vinyl and therefore more flexible, and, more importantly, more puncture resistant.

The best material of all is silicone rubber, which is not only extremely flexible, but will withstand heat as well - ideal for use in combined low-voltage heat/vacuum pressing applications. The downside is that it is opaque.

Scrit

 

[Roger]

Yup - BagPress do the best bags I find and a decent Gast Pump does everything you need. If you hunt around you may well find a good second-hand one that hasn't been hard done to. Check with Gast UK however that it will pull against a Vacuum once created - most will but some won't.

I tried the Rubber once but not being able to see what's happening inside and adjust if necessary, is just too much of a downside as you say Scrit.

The bigger bags can also be reduced down to size with additional end clamps placed halfway if you're only using a small section for the job in hand. Whatever you do, get the biggest bag you can afford ...... you'll probably need it one day and they aren't cheap!

 

[Jake]

I've just bought one of the Joe kits, but I haven't put it together yet. Why? It cost me about £200, (to which I need to add the price of a bag) for a system that is (supposed to be) as or more powerful than the £500+ Bagpress and Airpress stuff. This is one of the venturi systems, so it was dead light (and thus cheap) to air freight.

 

[Anonymous]

The best material of all is silicone rubber, which is not only extremely flexible, but will withstand heat as well - ideal for use in combined low-voltage heat/vacuum pressing applications. The downside is that it is opaque.

When I worked in the motorway sign industry we used huge vacuum presses with row's of big light bulbs inside to apply preessure and heat to get the cut DoT letter's to stick to the ally plates. They had silicone rubber mat's that were virtually indestructible even after being used day after day in extreme heat and rough industrial use.

It might sound like an ignorant question but if theres all that atmospehric pressure why doesnt it cave our bodies in?

 

[Roger]

Because we have that same atmospheric pressure inside us. Take a quick pop out into space and you'd see what happens - or a dip into the ocean w/o a diving suit. Pop (and crackle and crunch) being the operative word there!

It works in a Vacuum Press as the vacuum is created inside the bag, allowing the full outside pressure to act on the wood and veneer inside, w/o any 'interference' of the equal pressure inside.

 

[RogerS]

Thanks guys for the information and apologies for the duff link

The reason for considering the EVS system from Joewoodworker is that my impression with the Airpress or Bagpress units was that they were permanently on...but this could be my own misconception. I'd not discounted either...just curious about the EVS from Joewoodworker as it seemed to be 'the biz'.

 

[Roger]

The BagPress and AirPress and all the others (I know of), are on as long as the pump is running. If the bag itself has no leaks and the sealing rods at each end are positioned correctly, then you can switch of the pump and that's it. The the vacuum will hold and the job completed. Most veneering is only left in a Vacuum Press for 45 minutes - an hour in any case.

 

[ivan]

A vac. press is something I fancy trying one day, if I find a vac pump at the right price. I read somewhere that butyl pond liner works quite well - obviously it has to be strong / puncture resistant to work as a pond liner, I presume it must be glueable (if you have to line a very big pond) it is opaque, though. Anyone tried this?

 

[Roger]

As Scrit mentioned - it's opaque and you can't see what's happening inside, if you need to adjust or move something as the vacuum builds

 

[woodbloke]

Roger - the guys at Air Press told me to leave it on all the time when pressing, doesn't do the pump any harm and the vacuum is maintained. It can be switched off if need be but I just leave mine running, go and have a brew and browse the forum :lol: - Rob

 

[Scrit]

A vac. press is something I fancy trying one day, if I find a vac pump at the right price

Almost anything that can suck air will work - my first vacuum pump was actually an old fridge compressor motor which had been drained of coolant and I set it up to suck air out of the bag. It didn't last long (a few weeks), it was slow (hence the tip about using the shop vac to exhaust the bag first), it was noisy and the only way to cycle it on and off was to switch the power. It also wouldn't give me that much vacuum, but even a small amount of vacuum is better than none. All the air line fittings were cadged secondhand compressed air fittings and the initial bags were clear polythene builders sacks with nylon tarpaulin eyelets drilled and tapped as connectors. Whilst not brilliant it was a really cheap starting point.

Instead of thinking about what you'd like to have, a bit of "kitchen table engineering" will often provide you with an introduction to something new and potentially very useful like vacuum veneering.

Scrit

 

[RogerS]

What glues do folks use if the pump/press only needs to be on for 45-60 minutes. I seem to be misunderstanding something as others suggest Titebond II but the spec says 24 hours. I've also asked this question here in this other thread

 

[jasonB]

Lable on Titebond II says

"Clamp for 30mins. Do not stress joint for 24hrs"

You don't need to leave it in the press for long when veneering but if you are laminating curved work it needs longer as the wood trying to spring back can stress the joint.

Jason

 

[RogerS]

Thanks for the glue update, Jason

I've just bought one of the Joe kits, but I haven't put it together yet. Why? It cost me about £200, (to which I need to add the price of a bag) for a system that is (supposed to be) as or more powerful than the £500+ Bagpress and Airpress stuff. This is one of the venturi systems, so it was dead light (and thus cheap) to air freight.

Jake - what compressor are you using to power it? Which kit from Joe did you get and have you managed to source a bag yet with the right connector to interface to Joe's kit?

Many thanks

Roger