Thread: Auto-cycling vacuum pump for vaccum bagging veneers and vacuum clamping.

The hose I'm running from the pump is 3/8" reinforced, and one of the issues I was struggling to solve, was some sort of connection to the bag, that didn't restrict airflow. I had bought some tyre valves from ebay (only cost me $1), but when they arrived, I realised that the connection to them would be 1/4" maximum. I know some will say "what does it matter? It'll only take a bit longer to evacuate the bag" but having gone to all the trouble of building this setup, I didn't want to restrict it in the final stages. So I tossed the tyre valve idea out the window and set about trying to find some sort of bag connection that was 3/8" minimum.

A big thanks to Shane for pointing me in the right direction here (and John Samuel for the original idea, or whoever he got the idea from ).

I ended up going with 0.75mm thick PVC for the bag. I looked at the 1.0mm, and whilst it might be more durable, it's not as flexible.
It was 1370mm wide, so I started with 1m length. This will make a small bag, and allow me to validate the valve fitting before stepping up to a larger bag. And see how flexible it is and whether a bigger bag should be made out of 0.75mm or 1.0mm.

The fitting to go through the bag is this one: https://www.bunnings.com.au/philmac-...utlet_p4814051. Cost $11.28
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I was trying to find a way to connect a 3/8 reinforced hose to it, when I thought of garden hose fittings. They are either 3/4" or 1" BSP threads. For a total cost of $1.97 I got one suitable for 12mm garden hose.
I knew I wouldn't be able to fit the 3/8" reinforced hose over it but being plastic, and fairly thick, it was nothing I couldn't solve with 5 mins on the lathe )
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For the tank outlet, I cut the nut section off with the hacksaw, and smoothed it out on the lathe. Then I used the router to cut some channels in it to allow air flow out if it sits flush on anything in the bag.
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Here's the final fitting. All that is needed now is some thread tape on the threads, and to be attached to the vinyl.
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I've got to glue/tape the vinyl edge to make the bag. From what I read most are using HH-66 vinyl cement, or VHB tape.
Does anyone have any info on either, and whether one would be better than the other? Is gluing more likely to reduce chances of leaks, or be more durable? It seems like the process of gluing isn't easy (without assistance), to ensure a good seal. I've got to source either the glue or the tape now, so any info re one or the other would be appreciated.

Many posts I've seen talk positively of the VHB tape. Its is in my Amazon cart.

As far as ensuring a seal, I've seen pictures of where people have made two cauls that are clamped together. The same method is also used for the "open" end.

With the plastic, did you end up using the Bunnings flooring PVC?

yes I just got the Bunnings vinyl. https://www.bunnings.com.au/vinyl-ta...-wide_p6640034 $21.45 per meter.

I've already made the cauls for the ends of the bag, from 20mm and 25mm pvc that I had lying around. They should do the trick for closing both ends of the bag. Now it's just rolling the vinyl into a cylinder and then gluing/taping it in place. Hence the question re the glue & tape ;-)

I sent a request to Blue Nautilus Marine for a price for some HH66 (237 ml can).
They came back with "The price is $35.00 and around $20.00 freight depending on how far out of Sydney you are."

$20 postage for a single can, really?? I got stuff posted from China for less than half of that (admittedly non-flammable though). I don't know if this is what is being reflected in the high postage cost.
Does anyone know of any suppliers in Sydney that might be cheaper than that?

Originally Posted by TimberNut

$20 postage for a single can, really?? I got stuff posted from China for less than half of that (admittedly non-flammable though). I don't know if this is what is being reflected in the high postage cost.

Most folks don't realise the reason local charges are so high is because of free or cheap shipping from China.
Because of the international postal agreements, shipping items from China that are delivered in Australia by Australia Post costs AP millions of $ a year so they make up the difference by raising charges on internal postage.

I've only just noticed this thread. Many of the issues you are trying to solve are the same as those in resin infusion/vacuum bagging for boatbuilding.

You might consider searching resin infusion and reading some threads.

There is "tacky tape" specifically for sealing vacuum bags and around the standard fittings for getting the vacuum and resin lines into the bags. The fittings are cheap, some just a few $ some fancier ones about $35ish. Tacky tape is somewhat expensive but works well. Talk to good fiberglass consumable suppliers and they will know what you need. Unfortunately not all fiberglass retailers are good, some are pretty hopeless.

You can buy bagging film that comes as a tube, so you only need seal the ends. Newer bagging film is often multi layered to avoid pin hole leaks. Infusion often means keeping the vacuum on the part for 24 hours and striving for the best vacuum you can pull and testing it, all of which takes time. Unless you are doing many large panels the cost of good quality consumables should not be prohibitive.

Good luck whichever way you decide to go.

I did find a place in Western Sydney that sold HH-66. Can't remember the exact place but think it was a place that dealt with pools.

After much searching, I've been unable to source a Sydney-based supplier of HH-66, so ended up ordering it from these guys - PCM Distributors - Marine Distributors, Boat Paint, Antifouling

I got the 2nd smallest tin (around 500mL ?? I think it was).
It cost me $45 + $20 courier to Sydney. I'm guessing due to it being flammable, they couldn't use Aus Post. The suppliers couldn't give me expected shelf-life of the stuff, but googling indicates it should last a while. I expect to have a fair bit left over after I make a couple of bags, so if any forumite is in Sydney, looking to source this stuff, they might want to go halves with me or something (assuming I haven't used it already). Hopefully it'll arrive before Easter and I can get a bag glued up over the long weekend.

It’s been a while and was wondering how the system is going?

Especially the garden hose fittings in the pipe connections.

Starting to gather the ingredients to put my system together.

Cheers
shane

Hi Shane,
yes it's been a while, so it's probably time to provide a detailed update for all interested, and anyone researching their own vacuum solutions. I'll try to keep the comments brief, but just let me know if you want more detail on any of the below:


I absolutely love the vacuum setup I made. 2 years on I've gotten over the high $$ to purchase the pump. I've been able to use my setup anywhere in the shed at any time I want, and the auto-cycling works an absolute treat. Bugger all noise so I can leave going at night and it happily auto-cycles away, and given how long it can be between cycles, this thing will outlast my grandkids.


I've read all my original comments and they are all still valid.


Things I'd change if I did it over again:
- The PVC from Bunnings - in summer it's fine, but as it cools in winter time, the bag can be a little stiff in a cold shed. That's not a problem once the pump gets going and evacuates the bag, but clamping the ends to seal them is a bit more of a pain as the bag isn't as flexible when cold so it takes a bit of wrangling to get it clamped. It probably only adds another 15-20 seconds so not a deal breaker at all (more of a first world problem), but if I were sourcing more PVC I'd look for something thinner. The HH-66 cement makes it so simple to make bags I'm no longer worried about durability of the bag - if I need to make another one, it'd take me about 20 minutes. So bag durability is far less of an issue than I originally thought. Bag flexibility is quite important, so I'd aim for a thinner bag where possible.


As part of a business we run from home, I use this setup every second day, so it gets a regular workout.
I haven't had to change anything from the original build, with 1 exception - how I seal the bag ends.
On one end I've glued the bag closed so it's permanently sealed.
The open end - I originally used 2 lengths of 1 inch PVC pipe snapping one over the other with the bag sandwiched between - whilst this worked, it lead to leakage and the bag would lose vacuum. The pump cycling was easily able to keep up with it, but having invested so much time into this solution, I didn't like a half-solved solution for sealing the open end of the bag, so I changed it. Now I use this method:


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It only takes about 30-40 seconds to clamp the bag between the 2 bits of timber. I've still got a very minor leak somewhere so the pump cycles now about once every 5-10 minutes. If I had nothing better to do I'd track down that source of the leak. I know it's in 1 of 3 spots:
- the clamping of the open end
- a pinhole in the bag itself somewhere (can be fixed with a dab of HH-66 cement if I find it)
- the hose fittings from the manifold to the bag.


I'm sure it's not in the pump/pressure vessel part, so I'm not worried about it. Having the pump cycling every 10 minutes vs once per hour is really nothing to stress about, so for now I've put up with it, but one day I'll track it down and sort it, just because I'm like that )


I've added one item - a TP-link smart switch - that is linked to my phone. You can see it in the photo. I use google home and say 'Hey Google, turn on vacuum pump" and voila! it kicks in. I can also turn off with voice commands, but most jobs I do with it I need it running for about 2 hours, so I just go into the Kasa app on my phone, and set the timer for 2 hours, and walk away. 2 hours later my phone shuts down the switch and turns off the whole setup.
I have also linked it into my Samsung Smartthings hub so I can write rules to sms/email/notify me based on any criteria I want. For example I can have a rule that says 'if pump is running for more than 3 hours for ANY reason, shut it off, and send me a message'. Flexibility like that means I'll get the maximum longevity of my setup, so my grandkids can use it one day (or perhaps say their granddad always over-engineered solutions )

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Anyone in Sydney investigating building their own that would like to see mine in action before they get underway is more than happy to come and check it out.

Thanks for the update.
I might have to revisit my plan. I was going to just take the simple Fridge vacuum pump plan but you've got me thinking now.

Hi Shane,
there are pros and cons to both approaches. By the time I completed my vacuum build the price ended up over $1k, which I know will be a roadblock for a lot of woodworkers. I hadn't set out to spend that much but after investigating all the options, the idea of atomised oil in the environment didn't appeal to me so this is the path I chose.

The intent of this post was to provide everyone with all the options that I was aware of, and my reasons for either choosing, or avoiding, at each step. It took me months and months to do all the investigation, and sourcing of materials required so I figured I'd give others the benefit of my hard-earned experience.

I know there are a lot out there for whom a < $100 refrigeration pump is more than suitable, and I'm certainly not going to try to dissuade them from choosing that path, but rather I'm just outlining the reasons why I built what I did, so others can make their own informed decisions as to what works best for them.

Regardless of which solution you choose, I can say that having the flexibility to use vacuum pressure as a clamping method has made so many clamping jobs much more easily managed, with more consistent results. I'd recommend anyone to add it to their 'toolbox' of options to make woodwork that much more fun.

Good luck with your build. Keep us posted on what option you choose, and how well it works for you.

Great video here from NSW maker Darren Oates on how he set up his vacuum system for veneering. Very detailed video including bag construction.

Make A Two Stage Vacuum Press For Woodworking - YouTube

@timbernut Ive got a lot of information from this topic - thank you.

I'm building a vacuum clamp only with a venturi with an air compressor. It wont be the same as yours but your information of titbits has made it easier.

A few questions I have:
The yellow gauge - what model is it? - is this the vacuum controller (or just gauge)? (part of next question)
The grey box with 71.1 - 84.6 - whats in there?
In one of your photos you show to controllers...not sure which one is which

Some close up photos of the components showing models etc would be great (or just writing them)

Cheers