Hole saw lifespan

[bean438]

How long do these things last? I have drilled about 50 or so holes, and due to screw ups I have about 50-60 more to do.

Should I buy a couple more? The holes seem to be taking a real long time to drill and the teeth are not as sharp.

[AntonZ]

The biggest problem with wear & tear on hole saws is the sawdust that builds up and clogs the saw. It heats up (smoke), then burns the teeth. If you drill a few small holes with a regular drill (like 1/4"-3/8") right on the circle, you will allow the sawdust to fall down through. Cuts the holes a lot faster, and your hole saw will last a good bit longer.

[bean438]

I tried the holes trick and didnt seem to work that great. I just saw for a few seconds and periodically blow the dust out of the hole.

[LelandCrooks]

Did you buy bimetal saws? If not, you're probably done.

[bean438]

My saws are bi metal. I bought 2 new ones just in case.

[Ron K]

OK understand this as best you can. The saw is made of metal and has a high temp point where the metal when heated quickly will begin to anneal (soften). This softening point is where the blade will wear quickly. Now you may not see this because the very tip of the blade is so small the heat buildup is rapid and quickly the blade tips wear down.

Slow down you blade speed! The larger the diameter the more you should turn down the speed! Making HSS Tooling last is simply a matter of feed and speed! The biggest problems associated with hole saws is when running at slower speeds it becomes difficult to secure the work piece.

I use a 8" machine vise bolted to my Drill press table. Then with some small screws I can attach a 7" wide strip of scrap wood to the work piece from underneath and place it securely into the vise. Now with the proper slow speed I can slowly lower my quill without burning up my blades.

One other thing.Carbide hole saws are available as well. They cost more but last a really long time in metal or wood.

[bean438]

I am thinking it is probably my technique, not the saw.

I can only drill 1 hole 3-3/4" and have to stop because the drill will burn my hand. I am guessing the drill should not get this hot?

I dont know how much pressure to put, or how fast.

As a guideline how long should it take to drill through 3/4" baltic?

[Ron K]

If the drill is getting hot then either the speed is too fast or the feed is too fast.If the speed is non adjustable then lowering the feed will help. Keep in mind with a larger bore the outside lineal speed of the blade increases quite a bit compared to the actual lineal speed of say a 1/4" bit! The RMP stays equal but the surface speed is higher.

Lower your feed to keep the blades from getting hot.

Remember the more the blade heats up the faster the wear. If they are already worn a good bit then you will get hot even faster as now friction heat begins to build because wood or saw dust is not expelled.

Chipping or the escape of the wood dust helps remove some of the heat.

If you must you can get a piece of 1/8" steel rod and mount that to the drill press. Drill 1/8" hole in side of the table and drill and tap another hole 90 degrees to that hole. Install the rod and place a set screw in the side to hold it firm. Then make a loop and install an air nozzle and QD fitting to it. Braze it in place if need be. Attach a 3/8" air line with a flow control valve in series with the air nozzle.Aim at the work piece and the blade. Air cooling will help keep the blade cool for you and help remove the chips/dust!

It's all about feed and speed and either can be increased if you increase cooling!

Time through a 3/4" piece around 1 minute 1.5 minutes per hole.faster with carbide and cooling.

Nothing will help if the blades are already worn. get new ones and start fresh!

100-200 RPM should be plenty. 100 up around 4" diameter and 200 down around 2" diameter.

If you really are going to need to cut a whole bunch of holes i would highly recommend a carbide tipped hole saw blade. It will last a whole bunch longer but they cost a whole lot more as well.With them it really takes a lot of heat to destroy the tips.

[bean438]

So what is the correct speed, and feed?

[Tom O'Shea]

Slow as your drill press will go. Hole saws are the subwoofers of drills--they eat up loads of power. Need lots of torque.

Feed rate--slooow. I back out the hole saw frequently, and drill about halfway through, then flip the workpiece over and drill through from the other side. Keeps the saw much cooler.

[bean438]

I do not have a drill press, I am using a hand held drill. I tried a new saw. It seems to cut better, but when keeping slow the drill still gets too hot to hold. I can only drill maybe 1 hole before I have to stop and let it cool.

Maybe my drill is on it's last legs?

[Tom O'Shea]

It might be your drill, but hand-drilling with a hole saw's not just hard work for you--unless you've got awesome steady hands and can drill at true right angles, you're making your hole saw work harder than it ought.

For big holes, use a jig saw or even a coping saw, and save hole saws for smaller (<2") holes.

[Ron K]

I do not have a drill press, I am using a hand held drill. I tried a new saw. It seems to cut better, but when keeping slow the drill still gets too hot to hold. I can only drill maybe 1 hole before I have to stop and let it cool.

Maybe my drill is on it's last legs?

Unless you're strong as an ox hand drilling large holes with a hole saw is pretty rough.I wont ask but I'll bet more then just me are wondering how many times you took the hand-drill for a ride??

With a hand drill positioning is everything. I would recommend placing the work piece in a table mounted vise and cradling the drill and doing horizontal plunges instead of trying to go vertical.You can get a pretty good grip when you cradle a drill with your left arm and guide/run the trigger with your right.Lots easier to steady using your body weight.

Maybe put a drill press on your Christmas wish list??

Even plunge Router with a Jasper jig. They make pretty holes especially speaker and port cutouts!

I'd suggest you be a good boy and leave Santa some Rum and Cookies! Hold the Milk the old boy is lactose intolerant!

[bean438]

I am drilling 3-3/4" for the goldwood mid basses. These are the tough ones. I am going slow, and trying to keep the level bubble in the middle. Very hard to do.

The tweeter holes are easy. I do have a plungerouter so i may take a look at this jasper jig The plans call for hole saws and made no mention of a jig saw or router.

I did notice that the jasper jig is not compatible with any Milaukee router.

[Radian]

+1 on the router

Anything over 1/2" and it really becomes prudent to use a drill press for safe, precise work. Some can pull it off without, others aren't so fortunate. That and unless you've got a really sharp set of Fostner bits, there really isn't much boring over 1" that a plunge router with collars and a hole jig can't accomplish just as easily, as far as millwork is concerned.