Thread: Protool Surface Grinders

Dear Justin,

I don't have either of those Protool units that you have mentioned, but I thought it would be worth telling you nonetheless that the difference that a Dust Shroud can make to an Angle Grinder with a Diamond-Cup disc on concrete is simply massive. It really is Chalk and Cheese.

Anyhow, here are my two setups:

These first two photos are of my small 5" setup which I use for getting into tight spaces, and going along walls - courtesy of a detachable front toe on the Shroud. The Grinder is a 1200w variable-speed GMC unit that I picked up for $60, and the Shroud is an aftermarket Bosch unit designed for their own grinders, but which I was able to "shoehorn" onto the GMC using some sheetmetal and an Arc Welder. The Diamond Cup disk was a generic brand unit from Trade Tools which set me back about $78...

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The next two photos are of my larger 7" setup, which comes into its own on floor areas proper. The Grinder is a 2300w 9" Ozito that cost about $79 at the time, and the Shroud was an aftermarket unit by specialist manufacturer Holer, which cost just under $200. Its 73mm collar was designed to fit onto large Bosch grinders, but it was a perfect fit straight out of the box onto the Ozito. The Diamond Cup disc is a Husqvarna Mizer-series, and cost about $120 I seem to recall...

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I take it that you know about this purpose-made Bosch unit which retails for about $600 or so:
Bosch Power Tools - Concrete Grinder GBR 14 CA
The only problem is that it's only 5", which means that you'll be grinding away for quite a while if the floor is of any size. Makita do one too; its only about the same size as the Bosch, but I don't think you can even buy it in Australia. Having said that, both of them are still larger than those Protools that you mentioned. On that basis alone, my own recommendation would be to avoid buying the Protools you have nominated. Too dear, too small...

If you don't want to be grinding forever, you're going to need something bigger than what you've got in mind. You'll even find the 5" Bosch to be frustrating, but the problem is - nobody does a 7" purpose-made Concrete Grinder straight off the shelf down here in Oz. You'll have to knock one up yourself by laying your hands on a decent aftermarket Shroud if you've already got a large Grinder, or going to a specialist Concrete-grinding shop (they do exist...), and they will set you straight with probably either a large Metabo or a Makita, fitted with a Shroud and a 7" Cup. Your biggest problem then will be making sure that your Workshop-Vac will hook up to the Dust-Extraction Port on the Shroud...

Good Luck,
Batpig.

P.S. Just noticed that you are on the Gold Coast Justin. If you did want something larger and cheaper than the Protools, try these guys at Coorparoo, not too far from Carbatec: http://www.archquip.com.au/

Mate! Why couldn't you simply use a Kangol?? Or a hammer and cold chisel?

Mate and I stripped about 150sq.M of tiles off a floor. Started with a Kangol and did most of the rest with a suare mouthed shovel, Only us the Kangol on the obnoxious bits.

thanks for the replies guys.

batpig, that lools like an awesome setup you have there.
i have used the metabo grinder with shroud to grind a whole house. the vibration from the metabo was not good for me, as i have poor blood circulation to my arms as it is.
i tried to convince the builder to use the push along grinder with a dust extractor, but some of these old school builders think they know best.

i would never use a 9 inch grinder again, i would use the push along models with an extractor dragging behind me. i would use the small grinders for the hard to get areas.
that is why i am looking at these smaller grinders, i like the protool grinders as they are well balanced and vibration is kept to a minimum.

i will have to bring my 5 inch grinder to the tool shop and see if i can get that bosch shroud.
that will be a quick fix for now.
thanks again batpig for the photos and advice.

regards, justin.

Dear Justin,

A couple more things are worth pointing out about the Bosch accessory Shroud: Firstly, it is mainly just made of plastic (except for a metal centre where it fits around the Grinder's collar - it was a bugger to weld onto without melting the plastic..), but it was also only about $30. Secondly, they actually do two slightly different versions; one of them has a flange at the top of its neck with little indentations, a'la the same way that Bosch do the tops of the necks on their "tool-lessly adjustable" conventional spark-guards. In other words, it's set up specifically for certain small Bosch grinders. The other one (ie. the one I've got) has a straight up and down collar, which will probably be a better proposition for a non-Bosch grinder (although you might have to "slit" it in a couple of places, and then put a decent hose-clamp around it to pull it back into the actual size of your Grinder's neck...

Just another thought too - Artme might well and truly be on to something with what he said. If the adhesive has "let go" up at the underside of the tile, rather than down near the slab, a Kanga - or as he also suggested - a big stand-up style manual Scraper (like a shovel or one of those specialised hardened dedicated-tile-removing long-handle Scrapers that you can get at some toolshops - see photo below...), could be very, very handy, and save you a lot of time. Sometimes, especially if it's straight out cement-style (rather than acrylic and/or rubber modified) adhesive, it can just take a good sharp sideways wedgey-whack to get it to let go of the slab and come up whollus bollus. But you're the man on the spot, so you obviously know what you're up against...

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Good Luck!
Batpig.

Hi all,

to chip off the tiles themselves, i agree with Artme. A chisel or small electric hammer is the most efficient way to do that. I use a Makita HK1800. Agile thing, packs a lot of punch for its size, yet with moderate vibration. If the adhesive is chalk-and-sand-based, a chisel or hammer can also chip away much of the remnants underneath the broken-off tiles. With a bit of practice, you can leave a surprisingly clean and flat surface with a seemingly coarse tool like a chisel. When the surface is not too large and if chiseling is enough, i prefer it to grinding. The dust generated while grinding is enormous and i hate cleaning the tools (especially the stone dust vac) afterwards. The debris from chipping often just takes a broom and a gathering tin.

If the finish must be perfectly smooth or if the adhesive is latex or butyl or epoxy based, than grinding with a diamond cup wheel is the most effective way. Michael (Batpig) has a lot of practice with that, and has done some very worthwhile experiments in developing his own kit. I've had a lovely topic discussion with him about a diamond wheel grinder on a dolly to relieve a user of the machine's weight, but when applied to a wall there is alas no such solution. As for the discussion, the ball's in my court now, Michael! I have yet to round off the findings about lateral and torsion forces and i have to make good on presenting my own results thus far, haha!

Back to this topic. Concrete grinders with diamond cup wheels have special arbour bearing dust seals. When you provide similar measures yourself, the machines used on top of the shrouds could be replaced by ordinary angle grinders, provided they have abrasion resistant copper wire insulation. Apart from that, here's not much special about a concrete grinder, the factor that ultimately kills them or lets them survive, is proper dust suction. Furthermore there is a surprisingly large choice of diamond wheel types. The types to flatten away bonded-sand residues tend to have diamond particle elements with lots of contact surface. Usually they are just rectangular slabs. Discs to remove epoxy or butyl or latex based adhesives, encounter much more friction heat and tend to have thinner curves diamond elements, which double as cooling vanes like in a centrifugal fan. The Thermojet discs by Flex are brilliant examples, but are very expensive (more than 400 Euros for a 180 mm disc).

The Protool grinder in the left pic in the opening post is a copy of the Festo SAF750E renovating grinder, which was developed and made for Festo by Flex, which also carries a similar tool. The fact that Protool should have an exact copy of this Festo tool is locigal, since the brand name Protool was a result of the cooperation between Festo and the Czech firm Narex. The SAF 750E wasn't originally fitted with a diamond disc, but rather had an array of spiked TCT wheels, mounted on four arms stuck inside a central hub. This hub is mounted on the arbour through a rubber shock absorber, which relieves the gear case bearings and the user of intense shock loads, since the TCT spike wheels do their chipping work by bouncing and rattling over the surface. Fortunately there is no such vibration caused by a diamond element grinding disc. Something of a rubber shock absorber between a grinder arbour and the diamond cup disc is even a bad idea, since it suspends the disc in a slightly flexible way, making any perfectly plane smoothing effect nearly impossible or at least very unreliable and unpredictable. But if a user should fear adverse vibration effects from a diamond cup grinder, fit the machine with a dampening front handle grip (widely available from Metabo, Bosch and Flex) and choose a grinder with a rubber dampened rear handle grip as well.

the pics underneath show the HK1800 and the SAF750E

regards

gerhard

Forgot to comment on the right Protool pic. This machine seems the have three rotating elements. It reminds me of my Philips electric razor, which also has three rotating shaving heads. This is indeed done the reach better under the nose, and all heads adjust themselves to curves in all directions. Though the three discs in this renovating grinder will probably not adjust themselves in a 3D-way (there would be a big chance in leaving deep cut marks in the surface if the discs would snag for some reason and be cantilevered).

So this machine would seem to be a precise device. But how many times do you encounter corners in every single job? In most cases i only meet four, with the ones in the corners near the floor giving the most extra work. As for the rest of the surface, it's just straight going until you covered everything, just like mowing a lawn, really.

For the bonus of more agility in corners, there are the disadvantages of complexer gears, three arbour dust seals prone to failure instead of only one, and three small discs lacking the advantage of the high circumference speed and efficiency of a large disc. I.m.h.o. i would consider this machine to be very handy on stucco near staircases or near roof beams (lots of corners) or to have as a second machine for details, but not to use as a main machine for large surfaces.

greetings

gerhard

As for the spots in the corners where single large disc machines don't reach: i just chip or scrape those off by hand. Sometimes problems are smaller than the solutions that manufacturers would let us lead to believe are necessary for solving them.

Here is a quick summary of the new Protool masonry renovators:

RGP3 (not actually new, just a few minor upgrades) Three disc delta design for getting close to edges and around uprights and penetrations, steps and small spaces.

RGP 80 (not new either, but upgraded to 1100W) suitable for diamond discs and scabbling heads. Use for concrete, mortar, pre-cured/cured concrete, paint and coating removals.

RGP 130 (new) very cool and easy to use with minimal user fatigue. Takes diamond/carbide discs, no scabbling wheels for this machine.

RGP 150 (major upgrade of the old RGP150) for bigger jobs, optional handle, takes diamond/carbide discs and scabbling wheels.

Dust extraction (with an extractor) on all of the machines is excellent, but that is to be expected.

See this page for a bit more info.