Hole saws

[eggplant]

Hi all,

Great board I found here, spent ages reading and now its time for a question!
In the near future I need to make some holes in wood (not exactly sure of type but possibly 3/8 ply or similar) The holes need to be about 80mm. I have a set of holesaws which I got some time ago, they are the solid ones as agains the ones that are rather like a hacksaw blade bent round that fit into a sort of collar. The problem with the ones I have is that after every hole, I need to take the mandrel out to release the bit thats been cut out. The job I need to do needs 18 holes drilling in order to fit some fans (long story) Im not a DIY expert but pretty handy and would really like some advice on a decent tool for this job that doesnt require an "operation" after every hole, preferably not costing a fortune.

Thanks

 

[andy]

this is the main problm with holesaws. you can sometimes use a small screwdriver to push if out then the holes in the side of the holesaw, other than that its a case of remove and clear then re-assemble.

you can get holesaws that clip in/out and therefore take a second to pull pilot drill out so remove ****e


or, you could use a screw, screw into wood in saw and then pull out. altho this depends on how easy it is to get the screw in (works great for ceiling tiles etc)

 

[xerxes]

If you can drill from both sides, it's best to do so. Drill part way through; then use the pilot hole to drill from the other side. This avoids breakout; the offcut should protrude from the body of the hole saw, making it easier to remove.

 

[eggplant]

Thanks all, as it happens I was at the place that requires the work today. On closer inspection, it looks like the only option is to drill from both sides, one part is actually attatched, the back part is removable. I didnt realsise before that I needed to drill through the internal part. So now I have to drill through 3/4" or so MDF and 3/8 ply (this might actually be mdf, cant tell as its laminated in some fancy stuff)
Another question now, I have been looking for an SDS hole saw, figuring I could use my new Dewalt 005, I got it cheap(ish...) as I needed a decent tool for some hard drilling where I couldnt really get my mains SDS drill (cheapo but would have done, anyway an excese for a nice tool).
I have a hole saw set so would just need the arbour, that said, my set is a cheap set (yo know the ones, plastic grey box, half a dozen sizes of holesaw) and I have to drill 18 holes through the above mentioned material so was wondering if I oughtnt to buy a single size one specifically for the task - since if my existing one decided to get blunt part way through I would be in the poo!

Thanks

 

[Nestor_Kelebay]

How important is it that these holes be exactly 80 mm in diameter?

Instead of buying an 80 mm hole saw, would a laminate trimmer and a straight bit work?

What I'm thinking is that on Porter Cable laminate trimmers (and I expect Makita and Bosch are the same way), you can fit the same brass template guide collars that fit their larger routers.

So, if you start with any disk that's about 70 mm in diameter, you can use it to cut a hole in a piece of plywood that's about 85 mm in diameter using a laminate trimmer fitted with a 3/8 inch template guide and a 1/4 inch straight bit.

You could then use that plywood "template" with the 85 mm hole in it to cut as many 80 mm (approximately) holes as you wanted. Just run the laminate trimmer template guide around the ID of that 85 mm hole, and use the depth adjustment on the laminate trimmer to deepen the cut on each pass. The result will be an 80 mm hole (approximately) cut concentrically with the 85 mm hole in the template.

And, having a spare 1/4 inch straight bit or two on hand will ensure you don't get into deep poo (as you put it) if your 3 inch hole saw goes dull.

Besides, a good quality 3 inch hole saw and mandrel is gonna cost half as much as a good quality laminate trimmer, but you can use a laminate trimmer for 101 other things, too, not just cutting 3 inch holes. The versatility of a 3 inch hole saw is somewhat limited. Besides cutting 3 inch holes, you might be able to use it as an ashtray.

 

[eggplant]

I cant really use one of the machines you mention, I wont get it in, I appreciate what you are saying about me buying an expensive ashtray, but if I bought another fancy machine, I really dont think I'd use it often (might do though if I had one lol)

 

[Scrit]

Eggplant

In the UK you can get SDS arbors from Starrett which will take their hole saws as well as the Sandvik ones (about £17.50). They also do a spring ejector device for use with their arbors. Incidentally, Starrett list 76mm then 86mm.

If the work could be set in a horizontal plane I'd consider a router and trammel bar (which is what Nestor was probably trying to describe), but if you don't have the tools and you can't get a holesaw the size you need have you considered an adjustable tank cutter? These are really safest used in a brace and bit, but you can use them in a power drill if you pre-drill the centre hole and run them very, VERY slowly.

Scrit

 

[eggplant]

Thanks for the info. The holes dont need to be exactly, 76mm will be fine. I think the way forward is to either buy another cheapo incase one breaks/blunts or buy a decent one, I would have thought £20 for a decent one would be worth it even if I dont use it again.
Would you reccomend using the holesaw in an sds drill (dw005) or in a mains powered. My mains drill is a lot faster than the sds, but is too fast likely to blunt the tool quicker (not to mention that stink of burning wood)

Thanks

 

[Scrit]

Buy a decent bi-metallic or carbide-tipped one like Starrett, Sandvik, etc and you won't need a spare. I've tried the cheap ones and they burn out very quickly in MDF and plywood, etc. These saw drills soak-up power so a variable-speed mains drill would be a far better way to go than a cordless - you'll find a cordless drill may be prone to stalling, even the 18.8 volt ones can do that. For use in an SDS drill you'll need either the SDS arbor or a conversion chuck (i.e. a chuck to convert your SDS to use conventional drills - perhaps not a bad idea)

Scrit

 

[eggplant]

Thanks for that, I'll have a think about it, the cordless I have is 24v and has 3 batteries with it so I figured that should be enough, that said I suppose if I did get an sds hole saw, and the battereis did run out, I still have me el-cheapo with a normal mains drill to fall back on.

Thanks

 

[Hitachimad]

Screwfix do sds holesaw arbours
http://www.screwfix.com/app/sfd/cat/pro.jsp?id=10350&ts=69879


Whatever you do, steer clear or the Bosch quickhitch holesaws. Absoloute junk.

 

[Scrit]

The Starrett and Sandvik saws use the same arbor mountings

Scrit

 

[seaangler]

Whatever you do, steer clear or the Bosch quickhitch holesaws. Absoloute junk.

MORE INFO PLEASE

 

[eggplant]

Well,

it didnt go as planned ! I had so much work on I totally forgot about getting a new hole saw, so I ended up going along with my cheap ones, my dewalt 005 sds and my el cheapo b&q 36v piece of crap and my mains drill was left behind by mistake! about 4 holes later the smell of burning mdf filled the air where the holesaw was rubbing the mdf away rather than sawing it and my poor dewalt was starting to smell as well, I switched to the b&q spesh which actually coped better than my dewalt - its a standard hammer drill and seems to rotate a bit quicker than the sds. Anyway, after another 10 minutes the burning smell was too much so off to find a tool shop, the only one nearby was a machine mart from which I bought a hole saw and arbour for just over £20, and the rest as they say, is history. Im quite annoyed at myself actually, as an x mechanic I know that even for a one off job (the reason I bought the cheap set of hole saws) it pays to buy decent tackle as it WILL get used again sometime....