Best jigsaw blade for cutting through roof

[DeanS]

Hello:)

 

I have to cut 3 holes through the roof of my widebeam (stove flue, gas heater flue, shower extractor)

The plan is to drill a lot of small holes, along the circumference of the circle, and then join the dots using a jig saw.

 

Which drillbits and blades are best for drilling/cutting through a boat roof?

Which blades are good for cutting chipboard, plyboard, and pine inside the boat

 

Appreciate the help. Thanks. If I bought this on my own, I'd buy junk.

Edited August 2, 2012 by DeanS

[ridders]

hss drill bits from a toolshop for drilling steel, drill slowly with weight on to prevrnt overheating, i think i would just get a mixed set of jigger blades from the likes of screwfix

[Timleech]

Hello:)

 

I have to cut 3 holes through the roof of my widebeam (stove flue, gas heater flue, shower extractor)

The plan is to drill a lot of small holes, along the circumference of the circle, and then join the dots using a jig saw.

 

Which drillbits and blades are best for drilling/cutting through a boat roof?

Which blades are good for cutting chipboard, plyboard, and pine inside the boat

 

Appreciate the help. Thanks. If I bought this on my own, I'd buy junk.

 

Bosch HSS metal cutting jigsaw blades for the steel, get the right tooth pitch for the thickness you are cutting (it'll be marked on the pack) and use a lubricant. Trefolex smeared underneath, or grease if you have nothing else, or a spray cutting oil regularly applied from above. Other good brands are available, but Bosch blades are good and easy to find. Use the lowest active orbital setting on the saw, assuming it has orbital action (usually marked something like 0, I, II, III. Use I, and a fairly low speed).

For the wood, the quality is less critical.

Drills, worth paying for a good brand if you have a lot of holes to drill in steel. Dormer, Presto, Guhring are all good. Again, use a lubricant.

 

Tim

Edited August 2, 2012 by Timleech

[stagedamager]

i'd use Bosch Progressor blades, and not bother with drilling holes, it will be quicker and cheaper. just drill one big one to start and off you go! They go through steel like butter.

Regards

Dan

[Ex- Member]

Hello:)

 

I have to cut 3 holes through the roof of my widebeam (stove flue, gas heater flue, shower extractor)

The plan is to drill a lot of small holes, along the circumference of the circle, and then join the dots using a jig saw.

 

Which drillbits and blades are best for drilling/cutting through a boat roof?

Which blades are good for cutting chipboard, plyboard, and pine inside the boat

 

Appreciate the help. Thanks. If I bought this on my own, I'd buy junk.

 

You'll need good quality Jig Saw blades for steel and a good quality jig saw. Don't run the Jig Saw too fast even using good quality blades you might need 2 blades for a 6 inch hole especially if you come across some ribbing.

 

With any metal cutting use quality bits, it will save you lots of time and money and fcuk ups. The same goes for any cutting tool really, but metal is a definite for good quality kit especially drills and Jigsaws. At the very minimum use Bosch professional quality or better.

 

 

 

 

 

[BEngo]

Hello:)

 

I have to cut 3 holes through the roof of my widebeam (stove flue, gas heater flue, shower extractor)

The plan is to drill a lot of small holes, along the circumference of the circle, and then join the dots using a jig saw.

 

Which drillbits and blades are best for drilling/cutting through a boat roof?

Which blades are good for cutting chipboard, plyboard, and pine inside the boat

 

Appreciate the help. Thanks. If I bought this on my own, I'd buy junk.

 

 

Any quality HSS or HSS Co (Cobalt) drill will do. Dormer are a good name as are Ruko. The gold-coated TiN covered ones are neither better nor worse for this sort of work IMHO. Use lubricant- the same stuff as for your hole saws- and don't forget to get a drill-bit that's big enough for the jigsaw blade. You will also need a centre punch to make the starting point for the drill holes and stop the drill skidding around.

 

Mark out where you want the outside of the hole to be. Mark out another circle on the same centre, but which has a diameter one drill-bit diameter less than the outside circle. This is the circle where you drill your holes. Make a series of centre punch marks one drill diamet apart all the way round. Drill alternate holes- it might be worth using something like a 3mm drill first then an 8 or 10mm drill. Once you have gone round the odd numbered holes, drill the even numbered ones. If you get it dead right the waste falls out as you drill the last hole and you can clean up to the outside line with a file or an angel grinder. Most likely some of the holes will join up and others won't.

 

 

For joining up the holes you will need a HSS jigsaw blade. I think its a T118A or T118B depending on how thick the metal is. Saw at medium speed on the jigsaw with lots of lubricant and do not force the balde or you WILL break either the blade or the saw..

 

Clean up to the outside line with a file or grinder- otherwise you will rip your knuckles on the projections that are left and it becomes very difficult to get it all clean enough to touch up the paint.

 

 

If all this marking out and drilling seems time consuming, it is, but it is better and quicker than the random drilling and sort it out later approach. Trust me!

N

[dor]

I've done this with drilling holes and joining up, but if you have a decent jig saw and blades it is much quicker and easier to just use the jig saw. No filing or grinding afterwards, just a nice round hole. Just take it steady and don't force the jig saw.

[system 4-50]

First drill a 3mm pilot hole in the middle of your circle. This is solely so that you can check that it is where you think it is on the other side!

[fudd]

i'd use Bosch Progressor blades, and not bother with drilling holes, it will be quicker and cheaper. just drill one big one to start and off you go! They go through steel like butter.

Regards

Dan

 

Seconded. Make sure you have a good jigsaw. Bosh are the best. Go slowly and it will take only a minute. Make sure you don't cut through a spar. Could open up a can of worms. Whatever that means.

Steve P

[smileypete]

Which drillbits and blades are best for drilling/cutting through a boat roof?

Which blades are good for cutting chipboard, plyboard, and pine inside the boat

 

Appreciate the help. Thanks. If I bought this on my own, I'd buy junk.

Agree with comments about the metal blades, the cleanest cut for wood comes with a taper ground blade as opposed to the normal side set ones. Best practice on some offcuts or waste before going for the money shot.

 

A look at all the different blades in the Bosch range gives an good idea of what's available.

 

cheers, Pete.

~smpt~

[David Mack]

First drill a 3mm pilot hole in the middle of your circle. This is solely so that you can check that it is where you think it is on the other side!

The adjustable fence on my jigsaw has a hole in the opposite end to the fence part. Insert the fence upside down, put a bolt through this hole and the pilot hole in the roof (at the exact centre of the circle), and it will guide you round and give a nice circular hole.

[Mike Jordan]

As smileypete says the more expensive blades make a great job of cutting timber. I suggest the Bosch T308B which gives a smooth cut with no tear out on the top surface. Its sometimes a good idea to reduce the length of the blade to enable you to cut the inside linings from below without the blade hitting the steelwork.

Mike

[Chalky]

I used a cheap £12 jigsaw from B&Q and the blades that came with it. Cut holes for 4 mushroom vents and the chimney using the original blade - cut dry with no lubricant. The jigsaw was 750W with speed control and a footplate? made of tinfoil. No problems with the motor or speed control however the footplate needed severely straightening several times.

[ditchcrawler]

I used a hole saw and a very big slow speed electric drill, O and Rocol

[GSer]

I use either the DeWalt cobalt or Bosche blue bi metal jobbies, both tough little blighters that get the job done

[nb Innisfree]

Wrong thread edit.

Edited August 2, 2012 by nb Innisfree

[NBMike]

i'd use Bosch Progressor blades, and not bother with drilling holes, it will be quicker and cheaper. just drill one big one to start and off you go! They go through steel like butter.

Regards

Dan

I'd agree with that but get them on EBay, not in your local DIY shop. Much cheaper! If you find a roof brace in the way, they'll slice through that too. Don't ask me how I know this

Mike

Edited August 2, 2012 by NBMike

[bargemast]

i'd use Bosch Progressor blades, and not bother with drilling holes, it will be quicker and cheaper. just drill one big one to start and off you go! They go through steel like butter.

Regards

Dan

 

 

That's exactly how I've always done this too, with my old Makita jig-saw, never bothered drilling any holes apart from the one to get my jig-saw in to start the cutting.

 

Peter.

[Ex- Member]

That's exactly how I've always done this too, with my old Makita jig-saw, never bothered drilling any holes apart from the one to get my jig-saw in to start the cutting.

 

Peter.

 

Hi Peter

 

Mine's a Hitachi, I've had it 18 years now and it hasn't missed a beat, and been used a lot as jigsaws seem to do. The older Bosch ones though are probably even better.

 

I did the same BTW one pilot hole and good jig blade, job done, drilling loads of holes is a total bore, forgive the pun

 

 

 

[fudd]

I'd agree with that but get them on EBay, not in your local DIY shop. Much cheaper! If you find a roof brace in the way, they'll slice through that too. Don't ask me how I know this

Mike

 

That's the can of worms I was talking about?!

[DeanS]

I'm going to go for the one hole, long cut approach

[Batavia]

One important thing, which I don't think has been mentioned to date, is to keep the jigsaw pressed very firmly against the roof of the boat - if you allow it to come up and them slam down, you will almost certainly break the blade.

 

Also, cover the surround area with something, otherwise the hot metal "chips" embed themselves in the paint and act as excellent starter points for rust.

 

 

Chris G

[dave moore]

Hi

 

A friend of mine fitted roof prisms to his boat earlier this year. He was advised by Glynne at Norton Canes Boatbuilders to use the progressor blades and borrowed my Bosch jigsaw to do the job. Easy peasy, apparently. He knidly left me a couple, but I've not tried them on metal yet. Hope this helps.

 

Dave

[bizzard]

I don't think i'd recommend a newbe to making big holes in a roof which is likely to be 4mm or so thick in one jigsaw swoop with no ring of pilot holes, its not easy without practice to keep on line without running out and once that happens trying to get back so sharply on line will almost certainly snap the blade, then you have to stick it back into the hole and chase around in the opposite direction hoping to meet up which you probably will do because that cut might also run out.

Any holes in that sort of thickness smaller than say 4'' dia i wouldn't attempt that method at all.

Anything 4 1/2'' and small i cut with bi-metal hole saws with a large ultra slow speed drill. This is just my opinion, people can of course do as they wish with their own boats. If you do do it like that Dean, concentrate deeply.

Edited August 4, 2012 by bizzard

[Graham Bowers]

Lots of valid points.

All I have to add, is consider getting a piece of steel of the same thickness to practice on, to get the feel of it.

Oh, and the old adage, measure twice, cut once.

Graham