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Old 07-02-2011, 15:42   #16
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Iused a worm drive with a standard carbide blade and had no trouble at all. The cutting of the top laminate was the easiest part of the whole job!
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Old 07-02-2011, 15:45   #17
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Look at a Bosch PMF180E.
regards
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Old 07-02-2011, 15:54   #18
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Harbor freight tool's knock off of the fein multimaster is good where precision is paramount, but the expensive blades and short lifespan of same would suggest using something like an angle grinder with a heavy carbide saw blade. I have used a dremel tool to do this kind of work, but it is far to labor intensive and the little motor generally packs up on the first day! Good luck!
Please, Please only use tools with appropriate guards. An angle grinder is NOT designed to be used freehand with a SAW BLADE. A receipe for disaster in the hands of of a DIYer.
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Old 07-02-2011, 16:10   #19
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I redid the deck on my boat and used a skill saw with a plywood blade for the straighter cuts and a air powered die grinder with a cut off wheel for the tight spots.
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Old 09-02-2011, 00:30   #20
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Having cut way too many linear yards of 'glass over the years, the last tool you want to use, particularly if you're a DIY'er is a rotary anything. You're just tossing bits of 'glass all over the place and making a huge mess. What you want is a reciprocating saw, either a jig, which generally lacks power and the ability to steer or the "saws-all" reciprocating saw. All other tools will spit out microscopic size and up pieces of 'glass everywhere and lots of it. A slow running reciprocating saw with a fairly aggressive blade will limit the dust and bits to a bare minimum, making for easy clean up.

A shop vac hook up is handy, though often unwieldy and difficult to get into tight spots. Most back yard guys don't have this option.

For really fine "carving" work use a metal cutting blade. It's slowish, but precise. For just plowing through and straight cuts, a tooth count that is half the thickness of the outer skin is very fast cutting and nearly dust free if you move quickly. Check the length of the stroke on your tool and break the blade off as required, so you don't punch through the inner skin. Trust me on this, you don't want a circular saw, Roto-Zip, disk or angle grinder tossing crap all over the place, you're just going to regret it when it comes time to clean up, especially yourself.
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Old 09-02-2011, 04:31   #21
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im in the process of doin this now, replaceing the deck on my dive boat, I used a 4.5 in grinder with a diamond blade and it worked like a charm
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Old 09-02-2011, 04:55   #22
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I've been building Megayachts for decades.

The tool of choice is a circular saw. Router bits will last about 2-4 feet. I do this daily. Prefer a wormdrive, if you are concerned about brushes in the saw, affix a mesh screen over the intakes. After completion of project, blow out the motor with compressed air. Saw will last 2-3 years if used daily.
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Old 09-02-2011, 06:43   #23
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I've been building Megayachts for decades.

The tool of choice is a circular saw. Router bits will last about 2-4 feet. I do this daily. Prefer a wormdrive, if you are concerned about brushes in the saw, affix a mesh screen over the intakes. After completion of project, blow out the motor with compressed air. Saw will last 2-3 years if used daily.
What do you wear when you do this? I've not found something that keeps the dust off.
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Old 09-02-2011, 07:32   #24
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Have done a lot of this. Here's a partial list of tools:
-A small 3" rechargeable circular saw works very well.
-Long recipro saw blade for digging under to get rotten core. These seem to work best.
-a sharp chisel to peel up balsa that's still attached.
-6" grinder with #60 stiff epoxy sanding disk for tapering 12:1 edge.
-A good aromatic fume mask.
-Weights of some sort and wax paper to compress edges where needed.
-Plenty of mixing and measuring pots. (Volume of epoxy is too much for doing with pumps. It's easy to maintain West system 3:1 with wax coated, disposable cups.)
-Squeegees
-Lots of disposable chip brushes
-large box of nitrile gloves (better than latex)
-Good scissors for cutting new glass.
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Old 09-02-2011, 07:36   #25
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If you want to control depth you need either a circular saw or router. If you want precise straight cuts you need to be able to position and clamp a guide. If you want a very fine kerf with minimal dust, high precision and control by "feel", and ability to follow gradual curves, and ability to cut flush to an edge or surface, the Fein Multi-master is the way to go.

Don't cheap-out on grade of tools, blades or protective-wear. Better quality tools allow you to do a better quality job with less effort, last longer, and operate smoother making the entire job less fatiguing. Change blades frequently, as dull blades lead to forcing the tool and that leads to tool slippage and snapped blades -- mistakes/injuries result. A Tyvek suite, with gloves, Tyvek hood, eye protection and proper mask should be worn until you can get the dust blown-off.

One more thing - reciprocating saws and jigsaws are only good if you cut all the way through. reciprocating saws in particular lack precision, and are difficult to control -- likely to result in "collateral damage".
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Old 09-02-2011, 09:34   #26
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im in the process of doin this now, replaceing the deck on my dive boat, I used a 4.5 in grinder with a diamond blade and it worked like a charm


I absolutely can second Ram's advice here from plenty of experience - did my first deck core repair in the mid 80s. The diamond blade in the "knee grinder" (4.5" angle grinder) is the only way I'd do it today for the majority of the cuts.

Before diamond blades were commonly available (cheap), I used the thin brown composite cut-off blades, meant for metal, which are a brown resin/grit compound in a fiberglass matrix. There are some wheels for _grinding_ metal and masonry that are maybe 1/4" thick, and some for _cutting_ that are maybe 1/8" thick, or less - the point isn't the exact thickness, but that there do exist thinner ones that work much better for cutting than the thicker ones. Don’t sink a thin composite blade deep into the cut then stress it sideways or it might fracture and send shards flying. But if at all possible, bypass the composite blades in favor of the diamond blades...

Full safety gear, including heavy leather gloves, full face protection, full filter respirator is a must for me using tools like this. Also, ALWAYS be aware of where the tool will go if it binds and kicks out of the work. Be careful to position your body so as not to take a nasty gash - a "knee grinder" is not for grinding your knee!! These tools will often cut flesh and bone faster than wood or glass, and a knee grinder will nip a finger to the bone, or deeper, before you even know that you allowed yourself to be bitten.

The safety guards that come with knee grinders are included by the manufacturer on the advice of lawyers, not the people that use them daily. I've never seen a "pro" using a knee grinder with a safety guard in place as most of what these tools are commonly used for cannot be done with the guard in place. My safety guard is between my ears...

For the record, I am NOT recommending the use of any tool without all safety guards in place. Better yet, just forget doing any kind of manual work yourself - its much too dangerous. Just stay in your home, preferably in the living room, one of the safest rooms in the house, sit on your couch, pick up the phone, and hire a "pro" to do it. Caution: never try to walk around while using a phone - its too dangerous:
Should We Ban Walking While Wired?

The 5" angle grinder is the do-all and can get in most places, and so is the "one-tool solution". But for straight cuts where there is clearance on the sides, nothing beats the circular saw (it can also cut long curves if set for a very shallow cut). The same type of cutting blades/disks (diamond & thin composite) are available for circular saws, and these work great because they control the depth, have better power, and overall better tool control.

As for wearing out the tools - blow them out good when done and they will last OK. My own take on this is that tools are cheap and skilled labor is expensive. If you are worried about a fine Bosch, Milwaukee or other commercial grade tool, buy cheap ones from Harbor Freight... I think the 4.5" angle grinder was on sale for $17 recently... I'd still use the better tool, though, as part of what makes it "better" is that its also plenty durable.
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Old 09-02-2011, 10:22   #27
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There is a right-angle circular saw attachment for the roto-zip that could work for you, but I worry about glass dust packing up the innards. With some skill you can cut a fairly tight curve with it. Alternatively, a roto-zip can be used as a router with a ver small plate, allowing you to get closer to a lip that you would want if you are going to reglass the gap later.

Serious eye and mouth protection are an absolute must; I would urge you to work with an assistant holding a vacuum hose near the work; it will save you days of nasty clean up.
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Old 09-02-2011, 11:15   #28
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Thanks for all the replies, I'm amazed to were they have come from. All around the world.
I have two angle grinders and a sawsall, so I will use those.
I have found two great new blades for the sawsall, one is a chisel which will be great to remove the old rotten core, and the other is a carbide grout removal blade.
There is a really nice small circular saw available, the Matika 4200, but it's not cheap and not easy to find!
Baz
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Old 09-02-2011, 15:13   #29
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As I mentioned above, if you can find an old 3" Makita rechargeable saw with a carbide blade, it really does a great job on this. These have to be available pretty cheap now. You can set the depth of cut and get in close. It also throws up very little dust. Add a Tyvek suit (and probably two or three) to my list above and lots of stirrers for epoxy. Have also used small diameter rollers for large areas but these are pretty expensive if you need a lot of them. The safety sheets on epoxy resin indicate it is fairly safe but I have my doubts. Fumes give me a throbbing headache, even if using for a short time and it can't be good getting this stuff on your hands or soaking through your at your knees. I replace mask filters often. This is a really messy job from start to finish but you can usually substantially improve what was there before, The main reason for the core rot is that most companies like Pearson, etc. produced these boats very quickly and did not saturate the balsa with enough resin. If the balsa is saturated so that water can't soak in, it precludes rot when the water gets in, which it eventually will. The balsa core is a super material for the job and results in a 40+ year job if done right. Also, consider glassing solid around any thru-bolted fittings, especially at winches and blocks. You can pretty well slide/pack wet glass in and under edges after digging out old core.
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Old 09-02-2011, 15:45   #30
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Those new "oscillating" tools are great. Just bought one and you'd be surprised what it can do. Used one down at the marina and I was sold. I bought a Dremel, but Bosch, Milwaukee, and others make them.....LL
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