drilling holes

[Runner]

"Just wondering how thick of metal can be practically drilled with a bimetal hole saw."

I've cut holes in steel up to 1/2 inch thick with a hole saw without any problems. Takes some patience and a lot of lube, but it was easy and made a perfect hole.

 

[J_J]

I have been using a mixture like this for many years, but did not realize this is what CNC drilling use.

Quote

A typical CNC usually uses emulsified coolant, which consists of a small amount of oil emulsified into a larger amount of water through the use of a detergent.

So, maybe a 10 to 1 ratio of water to oil, and 2 tea spoonfuls of Dawn detergent. Shake the mixture p real good and you are good to go.

 

[JB4310]

I have been using a mixture like this for many years, but did not realize this is what CNC drilling use.

Quote

A typical CNC usually uses emulsified coolant, which consists of a small amount of oil emulsified into a larger amount of water through the use of a detergent.

So, maybe a 10 to 1 ratio of water to oil, and 2 tea spoonfuls of Dawn detergent. Shake the mixture p real good and you are good to go.

Interesting, thanks.

I would also add that you can blue the drill bits when sharpening them, I just use straight water in the water troth on the grinder to keep them cool.

JB.

 

[JoeL4330]

WD40 or any lubricant oil should never be used. You want to CUT not lubricate. The only benefit would be to cool the drill bit using lube oil. The down side is that lube oil has extreme pressure additives to prevent ware.

Not sure I completely agree: you want two things from the cutting fluid: coolant as described...and, friction reduction. Cutting is actually the use of that "inclined plane" we learned about long ago: that's how a chisel or a wood plane works and that's how your drill bit works. That's how a woodscrew works and using beeswax or soap on the screw dramatically reduces the effort to screw it in. Heat in the woodplane or screw is not typically a problem (but can be in a power saw), but in metal work it is a bigger problem: higher heat and the possibility of changing the temper of the bit and/or hardening the material to be drilled.

So, even WD40 can help, but there are much better, specially formulated products for the purpose; if getting the liquid to the site is a problem, there are also creams or waxlike products.

Now, a bit of cocktail party conversation: why is it more effective to "slice" with a knife, rather than just push straight down (think, tomato)? Because you are reducing the angle of the inclined plane ...just like zigzagging up a mountain ...(and, that's why some woodplanes permit the blade to be canted a bit.)

Sorry for the physics lesson, but the important take-away is the use of some fluid/cutting aid when drilling metal.

 

[Transit]

Joel, would you use cutting oil in your car or tractor?

 

[Iplayfarmer]

Just wondering how thick of metal can be practically drilled with a bimetal hole saw.

My experience is similar to Runner's... 1/2" is the max I can get with my small bench top Delta drill press. I wish mine would run slower.

I love the quality of the hole created by a hole saw, though. I've even sharpened a hole saw with a die grinder late at night when I only had a few more holes to cut. It's not near as good as a new one, but it gets through the metal and moves me on to the next step without having to wait another day and make another trip into town.

I have poor luck with the lifespan of a hole saw. If I get a dozen holes out of one, I'm lucky. I do use cutting fluid, but maybe not enough. I try to keep the "well" created by the kerf full of fluid. I am planning to try the putty pool trick in the near future, though.

 

[JoeL4330]

Joel, would you use cutting oil in your car or tractor?

only as a last resort ...

I probably didn't say it correctly but reducing friction is one of the objectives, second to cooling ...and, in fact, reducing friction reduces heating and thus...

Water can, by itself, can reduce friction: witness how ice skates work or why the slipperiest ice/snow is around 32F ...and, adding a surfactant (like a dish detergent) makes the water "wetter" so it works even better.

As I also tried to say, and as many of you said, there are specialty products which do the job best ...some choices dependent on the material being machined. ...I am partial to the products of Tap Magic Metal Cutting Fluids

But, I enjoyed your question of whether to use cutting fluids (or WD40) in an engine ...thnx, joe

 

[SandburRanch]

This link shows the RPM formula I was taught to use.
Calculating Cutting Speeds for Twist Drills

As for cutting fluids, I like to use products that were formulated for the job even if nothing more than Rigid thread cutting oil. An easy application method is to hold a small oil saturated brush against the drill bit as it rotates.

To avoid serious injury, clamp the work to the press table when using larger bits on some applications. You be the judge there.

 

[Transit]

Yes, use the right tool for the job. I always clamp the work to the table. All ways.

 

[wdchyd]

Just wondering how thick of metal can be practically drilled with a bimetal hole saw.

I have bored out 3.00" holes x 2" thick but it takes some doing.....Using a milling machine with coolant and a wet/dry vac to pull the chips out of the groove is the trick......if you don't pull the chips fairly often, then if a tooth breaks off it trashes the hole saw in about 2 seconds.....

It's doable but needs to be slow and cautious, and oh yes they need to be quality hole saws......