Auto-cycling vacuum pump for vaccum bagging veneers and vacuum clamping.
I've finally finished construction of my new auto-cycling vacuum system, so I thought I'd share the journey.
The original goal - to build a vacuum system to be used for vacuum pressing veneers, vacuum clamping stuff to the bench for sanding and routing, and also to connect to a vacuum clamp setup on the lathe.
When I starting researching how to go about it, these were the options I found I had:
- just buy a cheap refrigeration vacuum pump, to connect directly to a vacuum bag (bought or made), that would have to run continuously whilst clamping, till the glue dried (usually overnight).
- Buy a more expensive vacuum pump, that didn't disperse oil to the atmosphere (the problem with the refrigeration pump option). Use this pump, as above, to run continuously till the glue dried.
- Buy a ready made solution (vacupress)
- Build my own from parts sourced wherever.
When considering what path to take, each has pluses and minuses:
- Refrigeration pump
- PLUS - cheap
- PLUS - one purchase, and you're up and running
- MINUS - the pump atomises oil into the atmosphere, which means you either use it outside to protect your lungs, or you risk health issues if using indoors
- MINUS - the atomised oil will settle on everything in your shed, which is bad for many reasons.
- Oilless rocking piston pump (standalone)
- PLUS - no atomised oil
- PLUS - continuous rated - you can leave it running without it breaking, or voiding any warranty.
- MINUS - cost - a good one (continuous rated, with flow rate of ~5CFM) will cost you in the range of $800 - $1000
- MINUS - if used standalone it will run continuously, and whilst not excessively noisy, I don't really want any machinery noise all night that could upset neighbours
- MINUS - difficult to control vacuum pressure, and keep within a specified range.
- MINUS - if it doesn't auto-cycle on/off, you are limiting the life of the pump. The more it runs, the quicker it wears out.
- ready made solution
- PLUS - one purchase, and you're up and running
- MINUS - limited choice. There really is only 1 suitable solution out there that I could find - vacupress.
- MINUS - cost. I got a quote for a 5CFM model, and including postage was approximately $1500 AUD.
- MINUS - all internals are NPT thread as it is made in USA, so when sourcing spares, parts etc, you need to factor in that this is not a standard thread gauge readily available in Australia
- self-built solution
- PLUS - I could make it suit my requirements, without compromise
- MINUS - sourcing parts would take time, and total cost might creep up as I went along, depending on how elaborate I decided to be.
- MINUS - I didn't know much about vacuum pumps, regulators, relays, thread variations, brass fittings, filter options, etc etc etc.
- PLUS - There is good information available on joewoodworker.com about similar setups.
I quickly ruled out option 1 (refrigeration pump standalone). I value my health too much, and given what I ultimately hope to use my setup for, this just wouldn't cut it.
I ruled out option 2 (oilless rocking pump standalone). I can't risk upsetting my neighbours having machinery run all night whilst glue dries, and I just don't like the idea of it running all the time, wearing out quicker, even if it is continuously rated. Sooner or later it'll wear out. Also, not being able to easily keep vaccum pressure in a specified range, whilst not a massive issue when vacuum bagging veneers (as the more pressure the better), but would be a big issue when vacuum clamping on the lathe. This needs carefully controlled vaccum so you don't collapse the walls of thin pieces.
I ruled out option 3 (vacupress) for 2 reasons. Firstly, cost. I nearly died when I got the quote. Secondly, the issue of everything being NPT thread didn't appeal to me. I'd begun investigating a self-build solution, and was having lots of difficulty finding suppliers of brass fittings in BSP thread (which is the Australian standard), let alone trying to find NPT, which is standard in US, but not AUS.
I settled on option 4 - and set about researching everything I'd need to know to build my own solution. At that time I had no idea just how big an undertaking this would turn out to be. It's taken me 2 months to source everything I ended up needing, and many, many nights struggling to get my head around everything I didn't know. Silly little things like 'can I use a 40micron filter designed for air compressors and rated for 150PSI positive pressue, in a vaccum setup?'. The questions were many, and varied, and it's taken me 2 months to answer every question, and source every part. I'm not going to call myself an expert on vacuum pump setups now (that would be egotistical) but I will say I know so much more than I ever thought I'd need to when I started down this path. To quote a famous TV personality - "How hard can it be?" The answer - a hell of a lot harder than you think.
Am I sorry I chose this option - No. It's been a good learning experience (and you're never to old to learn something new, right?). But I do wish there were more options available here in Aus, because a self-build isn't for everyone, but the scope of what I'll be able to use this for I'm only just beginning to understand.