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I have a rather large the veneer job coming up. An architect has designed a fancy roof to go at the rear of our house and it has rather complicated curved beams cut out of LVL beam material. I want to edge each beam and solid timber and apply a 3 mm shop sawn veneer. I think I have worked out a system for setting up the bag but I have no vacuum pump.
Some years back I did a small veneer in job for some plywood draw bottoms and I just used a vacuum storage bag from the grocery store, a large and very powerful Mile?vacuum cleaner rigged up to a timer switch so it cycled on and off. It worked out really well and after 15 years there is no sign of any problems.
This time around I don't want to use the vacuum cleaner, but purpose made vacuum press pumps are hugely expensive. You can get much cheaper vacuum pumps designed for removing refrigerant gas and many of these produce more than enough vacuum for the purpose. I did a bit of research on the Internet and there was plenty of people claiming success? veneering with these pumps. There were however a couple of issues that they noted.?I know nothing about these refrigerant pumps but it would seem that they must use a thick film of oil between the piston and the cylinder to achieve the vacuum and as a result they consume quite a bit of oil and exhaust a fine oilly mist. Furthermore it would seem that when the system cycles off if there is any leakage in the bag oil can be sucked up towards the workpiece. The suggested solutions are to fit and non-return valve and try and place the pump outside. I'll be doing the job outside anyway so this shouldn't be an issue.
Another possible cheaper option is using a venturi valve system, they seem to work well for small jobs but I'm concerned they may not be up to the task of the large beams that I am attempting to veneer.
I was just wondering if anyone has had any experience with these pumps or any suggestions or comments on the above.
Thanks in advance
Murray