Help with failing Vacmaster VP115 ?

[Syzygies]

I'm hoping others here understand better than I do how chamber vacuum sealers work.

I have a two year old VacMaster VP115 (their current model is the VP120). The seal pad fell out. I ordered a replacement, but it turns out there were too many variants to count for the VP115, and they don't have replacement seal pads for my exact version. They kindly sent me a new lid.

Before the new lid arrived, I would simply line up the fallen seal pad, and the machine would usually work. When it didn't, the bag would still have air in it. I didn't understand why at the time.

With the new lid, this is an unavoidable problem: While the pump is running, the seal pad clamps the bag end so tightly against the sealing strip that some of the air can't escape the bag. It puffs up like the first Soviet space walk, and there's still air in the bag after the cycle finishes.

I am certain that I'm getting a good vacuum, as the pressure gauge shows the same performance as usual.

As one knows if one has such a machine, the lid pulls down with considerable force while the pump is running. So this is one of those things that one doesn't think about, while it works. Then, I wonder how the hell it ever worked? (I'm sure glad my career wasn't managing photocopier paper paths, I like engineering but I loathe this sort of poorly behaved problem.)

I can't imagine that any manufacturer would be stupid enough to leave this tolerance to chance. Therefore, I'm wondering if the two lid arms have a responsibility to resist the vacuum, enough to keep bags open during the pump cycle so air can escape.

If this is the case, then my arms are busted. Or at least in need of repair or a tuneup. The "elbow" bolt assemblies look pretty loose.

Hey, you put up with my speculation, so of course I'll humor anyone else's speculation. I'm hoping, as is so often the case on this forum, someone actually knows!

[egmiii]

I have the VP215, so I know what you mean about the incredible force exerted on the lid. Obviously the rubber pad is crushing the seal bar, to the point that air can't escape. The the thickness of the lid gasket and the height of the seal bar are two variables likely out of your control. The hinge fit and thickness of the rubber seal bar are variables you can control. I'd say get the hinges fixed, then shave the rubber seal bar to ease the pressure. There are plenty of Amazon reviews mentioning how the rubber seal bar needs to be installed by the consumer on that model. A little odd if you ask me, but if it came preinstalled, then it's possible they did it wrong. Especially considering it wasn't designed for your machine. 

[Syzygies]

I can now answer my own question. One can see how the sealing action works by removing the sealing bar, and watching the machine run empty.

The sealing bar rests on two brass piston rods (one is shown above, next to the underside of the sealing bar). These lift up the sealing bar when the time comes to seal. In theory, before this there is enough clearance for air to escape bags in the chamber.

The foam in my new lid stuck out an extra 1/8" further than the foam in my old lid. This removed the necessary clearance, so air wouldn't escape the bag, causing the machine to fail to work properly.

We ended up unscrewing the new sealing pad assembly, and sticking the old sealing pad into the recess. It stays in place without adhesive (so far!), and I get the needed extra clearance.

So why did I change lids? Dunno. Moving forward, it was enough of a nuisance swapping lids (the arms fell into the machine, and it was a dexterity challenge to reach them) that I'm happy not to have to swap the old lid back on.

[Syzygies]

Now that my chamber machine is working again, I'm going around the house looking for things to vacuum pack. (When Border Collies don't have work to do, they become bored and destructive.)

Who knew that shredded wheat crackles for minutes after you vacuum pack it?

[MacKenzie]

That is one way to crush your shredded wheat.