26 March 1999

GET TO PLACES WHERE

OTHERS CANNOT REACH

A neat unit borrowed from the

car repair world can extend

your workshop options, as

Andrew Pearce discovers

THERE cant be many farms without an angle grinder. Big or small, its an agricultural standard thats hard to do without. But what happens when room is tight or a delicate touch is needed? Even a 4in grinder needs a fair bit of space to poke its blunt nose into, and there are times metal comes off faster than youd perhaps like.

Changing to an abrasive disc slows the rate of cut and improves finish, though that doesnt make the unit any smaller. Whats needed is something with a mini-motor and a more compact head – and the car bodywork boys have it. Tipped with either a bristle brush or an abrasive disc, an air-powered paint surfacing tool chivvies off metal or strips surfaces. And itll dive into crevices where an angle grinder can never fit.

Such tools are relatively new to the UK, with orient-sourced versions more affordable than the American originals. One such is Universal Air Tools model UT8777.

&#42 What you get

£65 buys a short aluminium-bodied device weighing 0.6kg (1.3lb) and measuring 155mm (6.1in) overall. The working bits are about as simple as they can be: a soft disc holder mounts directly on to a four-vane air motors shaft, with a safety-interlock trigger controlling airflow. In the handle, a threaded valve can be screwed in and out to adjust maximum speed. Direct drive means no right-angle gearbox, so reliability is potentially improved and the tool can run right up 25,000rpm. More revs means speedier material removal and (all other things being equal) a finer finish.

Theres something a little different about the abrasives, too. Small, 50mm (2in) consumable discs mount with 3Ms Roloc system (careful how you say that). Two options are on offer: conventional abrasive pre-mounted on a plastic backing pad, or 3Ms bristle discs. The former come in various grits and are for aggressive material removal. The latter scour away light rust, paint and general crud without harming underlying metal.

&#42 In use

The tools air requirement is a modest 90psi/4cfm, though youll still need a reasonable-size compressor to run it continuously.

Given that, what can it do? Just about anything that an angle grinder can (short of cutting) and some more besides, all within the limits of small-motor power. Handiness is this tools strongest point: the small head lets it winkle into tight spots and when grinding, its light weight and featherable trigger let material be skimmed off very controllably. Given a coarse disc the UT8777 can remove fair volumes of metal, so pre-weld preparation of small or limited-access joints is no problem. If you need to blend a finished weld into the parent plate, this tool provides the control needed. Or if youve make a complete cobblers of the job, itll let you tidy up before anyone happens along.

Still using conventional abrasives, the UT8777 is a hit when rescuing damaged surfaces on shafts, casings, etc. Working much faster than a file, itll produce a finish right down to a light polish. Again, handiness and controllability is the key.

Swapping discs takes a quick, quarter-turn twist. With the bristle variety in place a new set of possibilities opens up: for while the heads flexible fingers cant chew away steel, they work like tiny vertical strimmers to scour and clean. Again its small jobs that benefit, like taking off surface corrosion before repairing or joining items with MIG, bronze or solder.

On the maintenance side, old gaskets are whipped off without surface damage, with a speed bonus over handwork thats worthwhile in itself. And if youre into machinery refurbishment, items can be cleaned to a standard that approaches beadblasting – albeit slowly, and without that techniques neat matt finish and ability to reach into every pocket and radius.

Everything happens to a soundtrack thats part-banshee, part-dentists drill. But as exhaled air is piped away by an exhaust that sleeves the supply tube, the operators ears dont suffer. As with any power tool, eye protection is advisable – not least because the bristle discs can shed the odd quill.

Two things would improve the package. If the standard arbor could be swapped for a properly guarded cut-off wheel – not easy to arrange – the possibilities would be extended even further. Potentially easier to organise would be an insulating sleeve for the handgrip, which can get quite chilly in use.

&#42 Running costs

Conventional discs last pretty well but need changing as soon as the circumference is shredded, else the tools soft backing cup suffers. Replacements average £5.50 for a pack of 10.

Bristle discs lose their tips quickly but attrition then slows, as bristles are tapered. New ones are not cheap at around £3.50 a throw. Service life can be prolonged by using the tools throttle valve to slow rpm, suggest the suppliers.

&#42 Sum-up

Able to do much more than its paint-surfacer name implies, this is one of those tools that suddenly finds all sorts of jobs. If light repair and machinery rebuilds are your speciality, give one a whirl.

Supplier: Universal Air Tool Company Ltd (01494-883300)