Does anyone know something about drilling into aluminum? DIY tonearm fail!!

[Retrovert]

it also says that ideal surface feet per minute for aluminum is 350-500 sfm, Mild steel is 100-150 sfpm, so basically aluminum cuts at 3-4x the speed of steel. Surface feet per minute isn't rpm though, and it varies with tool diameter. 1/4" bit at 400 sfm is 6100 rpm. 1/2" at 400 sfm is 3050 rpm. 1" is 1500 rpm. Most likely as fast as you can make that drill press go is how fast you want it running.

That's an important point, and one I made in No. 25 but without specific numbers. Both the feed rate, aka SFM (Surface Feet per Minute), and RPM (speed of the bit) must change with the material. Being harder, steel and cast iron are 25% of the SFM and RPM for aluminum. Any faster overheats the bit. So, yes, in this case the RPM should be set appropriate to the bit diameter and the material. Machining books often have tables for this.

Lower SFM has no drawbacks. If one periodically backs out when drilling aluminum the curls will better break, which reduces jamming of the flutes. I'll also stop the press and clean out the bit if I'm doing a number of holes. Prevents broken bits.

A drill bit sharpener is also handy to have around even when the bits don't break.

 

[Grenadeslio]

Most machine shop cutting fluids are water based. And notice, they're cutting aluminum lol.

View attachment 1448767

A bandsaw using water based coolant

View attachment 1448777

Cutting concrete with water as a coolant.

View attachment 1448771

Such tools are stainless steel being specifically designed for constant water exposure.

Most older tools are not.

Try it with a 1950s Bridgeport or 1970s Stanley drill press and tell me about how the rust worked out for you.

Water and machine tools are generally considered to be incompatible, and water and electrically powered machine tools are typically deemed to be super-duper incompatible

Sigh, this was your response to my post also quoted, notice where I said "water based" in the very first line, then again in the second line? Then read again your response. And I'll add again, no special bit is required for drilling aluminum as you erroneously stated, and stainless steel machines are not required for the use of water/water based coolant.

I've also added a statement concerning using water/water based coolant with cutting equipment from another post to the quote above as the pictures I've posted clearly show this statement in error.

Since this was brought up, I've never seen a lathe, mill, drill press, hammer drill etc etc that was made entirely from stainless steel lol.

Misinformation does no-one any service.

 

[Grenadeslio]

That's an important point, and one I made in No. 25 but without specific numbers. Both the feed rate, aka SFM (Surface Feet per Minute), and RPM (speed of the bit) must change with the material. Being harder, steel and cast iron are 25% of the SFM and RPM for aluminum. Any faster overheats the bit. So, yes, in this case the RPM should be set appropriate to the bit diameter and the material. Machining books often have tables for this.

Lower SFM has no drawbacks. If one periodically backs out when drilling aluminum the curls will better break, which reduces jamming of the flutes. I'll also stop the press and clean out the bit if I'm doing a number of holes. Prevents broken bits.

A drill bit sharpener is also handy to have around even when the bits don't break.

Only in this case lol?

 

[EngineerNate]

Looking at the pic I'm wondering if his drill bit isn't ground on center. A poorly ground bit could work fine-ish on wood and other very soft materials but jump all over the place when trying to drill anything metallic.

Anchoring the vise to the press is always a good idea.

 

[toxcrusadr]

Starting smaller and stepping up to the final size should result in cutting less with the largest bit, just around its outer circumference, so if it's a funky bit it should alleviate that.

 

[gadget73]

The feeds and speeds in the Handbook are generally aimed at max material removal rates for production purposes. It can run slower, it just takes longer to get the job done. One guy making a thing in the garage is not a production shop knocking a widget a minute.

 

[Binkman]

WD-40 is a near useless product save for two things- removing gum and stickers

I never use it and I've worked in shops that would not allow it on the premises.

 

[Ohighway]

First and foremost..... clamp the piece in a vice and make sure vise is clamped or bolted down to table of drill press. (Or depending upon your equipment you may be able to clamp the piece directly to the table) Under no circumstances try and hold the work piece down by hand.
Drill a smaller starter hole, maybe 1/4' . Then move up to your 1" drill (or whatever size that is) 1000 rpm +/- should work fine. You can adjust speed to see what works best but if it's chattering then you're going too fast. Use whatever oil you have available for lubricant. Motor oil is fine...... WD40 isn't great but better than nothing. Hell you could use canola oil or candle wax if you wanted. I wouldn't use water. Try and maintain a constant downward feed. (meaning don't try and jam it through,nor just barely push down at all) You want to pull nice consistent chips off the piece.

 

[Tronk]

I didn't realize the size of the bit until I went back and looked at the image of it. Wouldn't it be better to go up in steps before drilling to final size? If the pilot hole at the moment is 1/4", a pilot bit for a holesaw it 1/4" and he could say use a 3/4" holesaw next and then step up to the final size?

I mean sure the larger you step the hole up the less of the cutting edge of the final size you'll use, but that may be a good thing because it will be taking less material away as it goes through.

 

[Retrovert]

I never use it and I've worked in shops that would not allow it on the premises.

3-In-1 is the other shop-banned product which doesn't work as a cutting fluid. Wax and solvent.

 

[EngineerNate]

I've always been told that aluminum cutting is one if the few things WD40 is actually good for. We used to use it on our metal cut saws when we cut aluminum extrusion.

 

[Binkman]

shop-banned product which doesn't work as a cutting fluid.

I wasn't referring to cutting fluid. A.) it's corrosive if not rinsed B.) it gets in the air and can screw up finishing. C.) it contaminates wash bath cleaner systems solvents or water based wash systems..

 

[maxhifi]

I never use it and I've worked in shops that would not allow it on the premises.

When I worked in a shop, we got it in gallon tins, to spray onto recently machined parts, so they wouldn't corrode.

I have a chart showing twist drill speeds in different materials on the wall near my drill press, I'm sure if could be easily found online.

The advice to clamp the material being drilled is excellent. Another thing you want to do visually is check the drill for runout. If the bit is bent, or the drill press has been damaged, it could have excessive runout at the end of the bit, which makes accuracy all but impossible.

For cutting oil I have a bottle of non detergent sae 30 beside my drill press, and I just dip the bit in it before getting going. It does the job just fine, the main jobs of the cutting oil are cooling and lubricating. Keeping the cutting edge submerged in oil is ideal.

 

[EngineerNate]

It's pretty common for job-shops to give uncoated steel parts a spray of WD40 or something similar before throwing them into a plastic bag for shipping so that they don't get surface rust prior to reaching the customer.

 

[Retrovert]

I wasn't referring to cutting fluid. A.) it's corrosive if not rinsed B.) it gets in the air and can screw up finishing. C.) it contaminates wash bath cleaner systems solvents or water based wash systems..

Didn't meant to imply it was exclusively banned for use as a cutting fluid.

It's just Stoddard solvent, some petroleum oil, and a corrosion inhibitor like EDTA. I'm surprised it facilitates corrosion,but, then again, I don't use it.

I'm not surprised it makes a mess out of everything, including the liver.

 

[Retrovert]

It's pretty common for job-shops to give uncoated steel parts a spray of WD40 or something similar before throwing them into a plastic bag for shipping so that they don't get surface rust prior to reaching the customer.

Sure. Given that the protection is from mineral oil plus an anti-corrosion additive like EDTA or benzotriazole, or something else equally benign and inexpensive, it's possible to use pretty much anything for that purpose.

I used to wipe down parts with a lightweight oil to seal the surface until coating. The coating shops usually first dip everything into a solvent bath. I wonder about their livers. Actually, I don't wonder...

 

[Grenadeslio]

T

The feeds and speeds in the Handbook are generally aimed at max material removal rates for production purposes. It can run slower, it just takes longer to get the job done. One guy making a thing in the garage is not a production shop knocking a widget a minute.

This is only partially true, it is possible to go too slow, and doing so will induce chatter. The correct speed and feed will also produce the cleanest cut reducing time being deburred.

 

[Binkman]

I did find another product launch.. NO BS... Note I'm not responsible for the link content.
http://costaricaconfidential.com/2016/08/wd-40-launches-mens-fragrance/

 

[Tronk]

I did find another product launch.. NO BS... Note I'm not responsible for the link content.
http://costaricaconfidential.com/2016/08/wd-40-launches-mens-fragrance/

 

[Binkman]

I'm still laughing my ass off.