Saturday, 30 March 2013

DIY Sping Compressor



 In the past if i ever needed to compress a spring for one of my air rifles i would use the wood lathe, it was one of those jobs where you would clamp a drill in the headstock. The tailstock would adjust by sliding along a round bar then lock in place, it had a live centre which would wind in about four inches. By placing a wooden bed above the round bar and a block of wood over the hole for the drill in the headstock, i could then secure the spring and piston cylinder to the bed at the right height for it to be in line with the centre on the head stock. This worked fine unless there was a lot of preload on the spring but i usually found some way around that. However i had other plans for the wood lathe, and that was to convert it to a rudimentary metal lathe which i did. Unfortunately the conversion made it impractical to use it as a spring compressor anymore, and besides i really needed a bit more than four inches of movement when taking a spring out.

Makeshift metal lathe from old wood lathe

Having seen other DIY spring compressors on you tube and various airgun websites i decided i would have a go myself, and the sooner i did it the sooner i could get on with tuning up the glut of air rifles i was given. Not only that but its bloody freezing in the shed sometimes, and it would be a lot warmer to work on the kitchen table with some thing a little bit more portable with easier access to to the kettle

Cylinder bed
Framework for nuts and threaded bar

There was a load of various offcuts of wood in the shed, and instead of using an old G clamp i would use some 12mm threaded bar and nuts surrounded by a plywood frame and secured with metal putty. An old piece of wooden shelf was used for the base, the end block was very hard wood in which i cut a slot in for barrels to fit through. This was butted against three lengths of wood that ran part length up the base, the middle piece being a tad lower so an air rifle cylinder would sit comfortably.

Threaded bar clamped for cutting

Handy homemade disc cutter attachment for the drill

Bar lined up, washers and nuts in place for metal putty to be packed in

As the most pressure is pushed outwards against the two end blocks i decided i would strenthen and support them with metal brackets bolted to the bed, i then made a trough for a piece of hardwood to slide without slipping when the threaded bar is wound against the back of the rifle. When i tuned the Norica Quick the cylinder was held in place with strong tape, though later i drilled two holes in the bed and popped a couple of coach bolts through them. Now i could clamp a piece of wood strengthened by aluminium to act as a clamp.

Nuts held tight, metal bracket for extra support
Plastic strip for support trough

Admittedly it did not like the five inches of preload from the Norica's mainspring, but after a little settling in it did the job fine. This one will do for now but i have a load of metal frame and sqare section that will make a more permanent compressor, and this one should be able to handle a lot more pressure. But the odd jobs keep mounting and there is no telling when that will get done, let alone the tuning of my other springers and the Weihrauch HW35 most definitely needs a good check up as it's not as accurate as it used to be.

Just needs a few finishing touches


  1. Thank you for posting this. I do need to build a spring compressor and you build looks good.

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    It is an excellent site. Good information and under the "Related" tab you can see who they think is similar (sometimes I disagree) and also who the artists were influenced by and who were influenced by them.

    The site used to have a lineage chart that let you see graphically how different subgroups of music came about. I miss that. ~Ken

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    I can already see where the compressor can be inproved upon but the basic design works a treat. TTFN

    Sir Nigel Tetlington-Smythe