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1. Goal

This vacuum pump I have built for vacuum bagging of composites. I have used the idea HERE, but used another, more robust, air compressor.

If you want to buy a pump, the best value for money is the ECVP425:

ECVP425 vacuum pump
ECVP425 vacuum pump

2. The used 12V air compressor

The 12V air compressor is sold under several names from €30:

  • Ningbo Lingsheng Electric Appliance LS4028
  • Mannesmann 12V compressor
  • Air compressor CTO28395
  • RING AUTOMOTIVE 12V Heavy Duty Air Compressor Kit

Used 12V air compressor
The used 12V air compressor

3. DIY vacuum pump facts

  • Vacuum: 0.1bar
  • Current consumption: 5A

Vacuum pump 0.1bar
Vacuum pump 0.1bar

The achieved vacuum is around 0.9 bar, professional vacuum pumps realize 0.9 to 0.999 bar (gauge pressure, 1 bar means absolute vacuum).
Here are the pictures of the vacuum pump. The heat sink provides extra cooling when the pump is wrapped in a duvet for noise reduction. This will prevent neighbors quarrel. To avoid loss of vacuum caused by small leaks, the pump can operate intermittent, with an optional timer.

DIY vacuum pump ready
Convert a 12V air compressor into a vacuum pump

Sound reduction by duvet
Sound reduction by duvet
Vacuum pump in operation
Vacuum pump in operation

DIY vacuum pump ready
Vacuum pump with timer
Crankshaft
Crank shaft and piston

4. Required parts

  • Extension nipple from Sclaverand to Dunlop valve:

Extension nipple

  • Flange screw M3 and M3 nut.

Flange screw M3
Flange screw M3

  • Reinforced PVC hose, 6 mm inner diameter. Special vacuum hose are too stiff, which can harm the extension nipple.
  • The vacuum pump timer is optional.

5. Modifications

  • Remove the valve plate and cylinder head.

Intake valve old
Cylinder with valve
Cylinder head old
Cylinder head
Exhaust valve old
Valve plate

  • Remove the valve of the cylinder; this will be the exhaust valve.
  • Seal the two holes of the cylinder with epoxy.

Piston holes sealed
Piston holes sealed

  • Remove the valve of the valve plate; this will be the intake valve.
  • Drill a 6mm hole in the valve plate for the exhaust valve. Drill a 2mm shallow hole for the valve lip:

Drill holes
Drill two holes

  • Flatten the valve plate with sandpaper (on the other side of the rubber ring).
  • Glue the extension nipple with epoxy into the intake valve hole (on the other side of the rubber ring).

Exhaust valve and glued nipple
Exhaust valve and glued nipple

  • File the M3 screw head down to 0.5mm thickness, see the image.
  • Mount both valves with the M3 screw. The intake valve comes at the original place again. The exhaust valve comes on the other side.

All parts
All parts
Intake valve
Intake valve
Intake valve
Intake valve

  • The screw head must sometimes be bent, to let fit the intake valve precisely to the rubber ring. The rubber ring may not leak and must keep the vacuum constant.

Intake valve
Bented screw head
Intake valve
The valve fits to the rubber ring

  • Put the valve plate and cylinder head back. Note: The valve plate is now reversed.
  • Mount a heat sink and use thermal grease. 

 

Heat sink
Heat sink

6. Soundproof vacuum pump enclosure

Because I use the vacuum pump sometimes all night long and don't want to have a war with my neighbors, I made a soundproof vacuum pump enclosure:

Soundproof vacuum pump enclosure
Soundproof vacuum pump enclosure

7. DIY vacuum desoldering iron

Cheap desoldering tools like desoldering pumps and rubber bulb desoldering irons work unsatisfactory. However, good desoldering stations are quite expensive. But if we have a vacuum pump, we can change a simple and cheap rubber bulb desoldering iron into a professional vacuum desoldering iron:

Rubber bulb desoldering iron
Rubber bulb desoldering iron
DIY vacuum desoldering iron
DIY vacuum desoldering iron

A vacuum filter is used to collect the solder tin. The vacuum pump is controlled by a footswitch.

My desoldering iron has a power of just 30W, each time after desoldering he has to warm up again, this is inconvenient. So more power is recommendable.

8. Avoid vibration during resin degasification

At resin degasification, the work table can vibrate due to the vacuum pump. This causes the resin splashes around in the vacuum chamber. A vibrating vacuum pump should be kept away from the work table.

9. Vacuum and the human being

  • A human being may survive a period of more than 1 minute in high vacuum, and will not explode!
  • The maximum vacuum that can be sucked by mouth is about 0.3bar.

Do you have any comments? Please let me know.
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