Vacuum hold down?

[Alex]

Hi, I'm pretty new to cabinetery so what do you all think of vacuum hold downs? I've got a lot of niggles this seems to solve them, examples.
1. I've got a formica gloss kitchen top (recycle,recycle) as a work bench no bench dogs so either drill 19mm holes and Veritas puppy vs vacuum hold down.
2. Router and sanding again nothing to hold it to work bench.
3. Router templates, no more double sided tape.
4. Feather board clamping to my table saw/maxi26 so pressed thick steel top no mitre slot.
5. Maybe in the future a bit of veneering?

Now i've got a small 1 1/2hp 7cfm compressor and i've been researching vacuum venturi generators, anyone got any points on this angle? or maybe an old fridge compressor.
I've also found this http://www.toolpost.co.uk/pages/Woodwor ... lding.html
What do you think?

Any info or past experiences would be appreciated.
Alex

 

[Scrit]

Hi Alex

How do you intend to "dam" the vacuum hold-down? I've used closed cell soft rubber gasketing in the past using 8mm diameter cord in a 6.3mm square groove and that worked fine, although your vacuum pods do need to be of an airtight material such as well sealed birch plywood or plastics - MDF or chipboard simply won't work. Double sided pods on a high gloss worktop are likely to slip if there is any contamination or the vacuum isn't high enough (a minimum of 15in Hg is required for safe commercial operation, 20in+ is better)

As for usefulness, I'm convinced. Vacuum is a great way to hold stuff which you are machining without pinning or marking delicate pieces (I used to run a big CNC router and pin routers) but it isn't really suitable for very small components where you have to adopt solutions like onion skinning

My first vacuum pump (for veneering) was an old fridge compressor where the pipe had been punctured and the freon had all escaped and it worked OK, but I wouldn't go that way unless you can get hold of a properly drained unit.

Take a look a Joe Woodworker for some more ideas

Scrit

 

[Alex]

Hi Scrit,
I been on Joe woodworkers web site a exellent reference site. I only wish he was based in the uk. I was thinking about building one of those vacuum storage kits with automated control either running of my compressor ,vacuum venturi generated or ?
That foam your talking about where did you resource it from? The link has the materials to build 'The Big Mach' hold down that works of a plain old vacuum which i have my doubts about how much hold down force it will have, but it maybe viable to buy and build with a proper venturi 20Hg vacuum.What do you think?

I was plaining a double sided hold downs to hold on to the formica gloss top.

How well did the fridge compressor work,i mean did it produce enough pressure? Festo do vacuum venturi genrators with controller and solenoid build in but i can't find any online prices yet.

I'm getting pretty excited about building one of these now :lol:

 

[Scrit]

Hi Alex

In the UK one source of supply is BagPress. They do their own stuff, not JoeWoodworker's, but much of the stuff you'll need is also available from compressed air tool suppliers, such as Thorite. For example rigid nylon/ABS/PVC pipe, joiners, elbows, stop valves, mainfolds, etc are available in plastic or plated metal under the brand names Ennotts (IMI, British) from Thorite, although the other well-known brands are Festo (German) and Camozzi (Italian). Sizes are generally expressed in exterior diameter sizes (6, 8, 10mm) and the fittinga you want to go for are are push fit. Bags can be made up from PVCsheet, although as this can be difficult to source in small quantities BagPress ready-made bags may be a better solution. PVC cement used to make bags is available from many industrial supply houses, such as the local engineering merchants, as is closed-cell neoprene cord. I got my last cord from a company called Ernie Platts in Bury, but there are other rubber companies out there who can oblige. For a try-out grey self-adhesive draught-proofing strip can be used providing it is closed cell (i.e. the rubber must be non-porous) - the main downside ir that the stuff has "memory" and compresses down over time, but hey for a first jig it's easy to find and cheap

How well did the fridge compressor work, I mean did it produce enough pressure? Festo do vacuum venturi genrators with controller and solenoid build in but I can't find any online prices yet.

The compressor pump wasn't brilliant, to be honest, it was only about 1 cfm so emptying a bag took forever, however the way to speed that up is to use a vacuum cleaner to suck most of the air out, then connect the pump. For veneering you don't need a huge amount of pressure - for work holding you need lots more, in part depending on how porous the material you are holding happens to be.

Scrit

 

[Johnboy]

another source for the neoprene closed cell foam is CIS direct. they do sheet and strip. website here http://www.cisdirect.co.uk/categories.asp?cat=120

 

[Alex]

Thanks all for the replies,links and info. I'll defently be checking out all the suppliers and hopefully be posting the reproduction in progress soon.
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Alex