Suds Pump
Home Up Lathe Tools Gear Repairs Suds Pump


Home made 'Suds' Pump (lathe cutting fluid):
All scrap, Cost $0.50

Made from an old plastic box with lid, old evaporative air-conditioner water pump (an alternative would be a washing machine pump), assorted scrap PVC tubing (various sources), old brass needle valve from an LPG tank, copper tube from a refrigerator, old printer shaft, old retort stand clamp, magnets out of VCR's & speaker, plastic funnel, acrylic wadding, laddered stocking, tea strainer & bath plug.

Pump mounted in box, Large pipe is outlet from pump & circulates excess fluid flow in the box.  The final outlet is a small 'bleed' off of the main pipe (the small blue pipe) via a tee-piece.
The visible upright bar has a magnet at its base for attachment. The thin blue tubing enters the needle valve which controls fluid flow out via the nozzle (copper pipe held in retort stand clamp).

The cutting fluid return path is:  The lathe tray, with a hole cut in its base, the right size for a stainless steel tea strainer to sit in.  Beneath the tray is a plastic funnel to collect the fluid, with a pipe returning it to the plastic box reservoir.

Inside the funnel is a primitive filtration system to minimise particles entering the reservoir.  Into the funnel I first places some acrylic wadding. over this (& the funnel) is stretched the foot of an old laddered stocking.  On top of the stocking is a round magnet from an old speaker - this holds the stocking down & collects all the iron swarf, the filters mentioned collecting the rest.

The plastic reservoir also contains a couple of magnets (from VCR head units) near the return inlet as a double safety measure.

I often use an old plastic bath plug sitting over the tea strainer to reduce swarf entering the filter.  Because the tea strainer isn't a tight fit, it doesn't impede the fluid flow, but means I have to clean it out less often.  This is especially the case when machining cast iron or machining without the need of cutting fluid.

It works beautifully, can run all day & cost about $0.50 for the plastic funnel.

Aeration of the cutting fluid will minimise the risk of it 'going off'' & smelling foul (I guess the problem is anaerobic bacteria) - A solution to this is to aerate it using a small fish-tank aeration pump, set up as a fish tank would be, with an 'air stone' at the end of the pipe - this creates many small bubbles instead of just a few large ones.