View Full Version : Drilling aluminum

10-09-2015, 03:19 PM
I just finished drilling a number of holes in some 1/2' aluminum flat bar.
I had laid out the parts I was making with tool makers blue ink and found out the hard way before that WD40 will wash that stuff right off.
So to drill these holes without washing my layout off I had to put some WD40 on a rag and wipe the drill bit before every hole.
This made for a very tedious job when there was a couple of dozen holes to drill.
Does anyone have a better idea? Is there something else I could use to stop the aluminum from sticking to the drill but not remove the ink from the aluminum?

Paul Alciatore
10-09-2015, 03:29 PM
I ...

1. Mark it up with layout fluid

2. Punch the hole centers

3. Drill using the punch marks.

By punching the holes first, you increase the accuracy of the hole location. I use a magnifier or a visor to aid me while doing this.

Also, the lines should still be visible after the layout fluid is washed off. You just have to look closer.

Another technique, if you do not need the accuracy of a traditional layout technique, is to paste some label stock on the work and layout with a sharp pencil. The WD will remove the paper, but it takes longer and you can usually finish the job first. I do this a lot with sheet metal work. And I spray with a lot of WD to remove the adhesive paper. You can use spray on adhesive on plain paper if you prefer. And you can create the layouts in a CAD program and just print them at full size for use.

10-09-2015, 04:59 PM
Ditto on what Paul said and use a real tool coolant. I like Cool Tool II- it's UPS-able and works well with different metals and operations. Won't attack layout dye.

10-09-2015, 10:14 PM
Thanks for the feedback guys. I did center punch the holes first using an optical punch devise. Gets a pretty accurate mark if you are careful.
The reason I wanted to keep the layout ink intact was that I want to mill the pieces to shape after I have sawed them out, which I have now done.
With my older eyes a little extra help to keep the lines really visible is good.
I will have to try and find some of that Cool Tool and see how that works.

Paul Alciatore
10-09-2015, 10:42 PM
Another thought: When I make a part that requires both milling and drilling I use a manual, vertical mill/drill. I use the hand wheel scales on that mill to locate all features. I do layout the locations, using layout fluid and scribing the lines in it. But I do not punch the hole locations. If I need to, I first finish two adjacent sides so I have a reference corner. I determine the corner I want to use by studying the drawing for the part. Once that is done, I use that corner to locate the rest of the features. The layout is done either first or just after that initial corner is machined: this is determined by the part and the condition of the stock.

The order for cutting the remaining features depends on the part, but generally I do the milling work first.

I drill the holes again using that corner as my origin. The scribed layout helps to avoid stupid errors, like being one complete rotation of the hand wheel off. I drill a hole with a sequence of drills: first a spotting drill or center drill because they are very short and will not "walk" off position. Then, if the hole is small I use the final size drill. If larger, like 3/4" or more, I will use a drill the size of the final drill's web or slightly less. Then a final sized drill. Finally, I use a countersink to deburr the entrance and exit of that hole.

I do not punch the hole locations because it may be a bit off and the mill's scales will provide a very accurate location for everything. A punch mark may pull the hole off center. As I said, the layout lines are only used as a reality check to avoid gross errors. If I am just a bit off of a layout line, I do not worry about it.

The same technique can be used with a mill with DROs and they will be as accurate as or more accurate than the hand wheel scales.

10-09-2015, 10:54 PM
Does anyone have a better idea?

don't use wd40. a few squirts of regular soluble oil will work fine.

btw, centre punch the hole with a proper centre punch after the optical, only tap the optical enough to make a mark to centre punch. another btw, if not using something like an optical punch, the correct way is to first prick punch first then centre punch. The sharp end of the prick punch makes it easier to find scribed lines by feel and it raise the material...then the centre sets up the cone the drill will follow

10-10-2015, 07:51 AM
I must be the odd one. I drill all aluminum all the time dry.

10-10-2015, 08:44 AM
I must be the odd one. I drill all aluminum all the time dry.

I started drilling and milling dry or with small amounts of kerosene rather than with WD40 since I had a severe reaction to the fumes from the WD40.
Works just as well, maybe better and the layout dye stays longer.

10-10-2015, 09:30 AM
On Aluminum I try it dry first, if the dril and I are both happy the I do them all dry. If it, the drill, is not happy I use A9 for the rest of the holes. If the depth of the hole will allow me, I use screw machine length drills with a 135 degree split point.

Paul Alciatore
10-10-2015, 03:25 PM
When using WD or other cutting fluids, a drop or three is often enough if it is applied directly to the drill. I make small dispensing bottles from Wal-Mart brand nasal spray bottles and those "straws" that come with many spray cans of lubricant. I never throw the old straws away.

http://img.photobucket.com/albums/v55/EPAIII/Photos%20for%20Tips/P23Crop_zps1fe84101.jpg (http://smg.photobucket.com/user/EPAIII/media/Photos%20for%20Tips/P23Crop_zps1fe84101.jpg.html)

You have to remove the original labels and sand the smooth plastic to allow a Sharpie marker to be used to label them. I drill the original, very small opening out with a drill that is about the size of the straw and bell out the opening a bit with an awl to allow me to insert the straw. The plastic is resilient so friction holds it in place with no leaks.

With just a drop or two on the drill itself, there is not much to remove the markings. This also helps to conserve the product. I find that one fill-up lasts a very long time. You just can't squirt out too much.