Using a Shapeoko3 to drill aluminum

Damin69 · Post by **Damin69** » Sat Jan 16, 2016 4:08 pm

maybe you could build a modified version of this with cnc base for doing what you want to. https://woodgears.ca/workshop/bill/drillpress.html

AnonymousPerson · Post by **AnonymousPerson** » Sat Jan 16, 2016 5:25 pm

krtwood wrote:The biggest annoyance trying to use drill bits is that the larger the bit the longer it is. I did the mod of attaching t-track to the z plate to stiffen it and that might be a viable way of mounting the drill with both a quick change (should be able to leave the stock spindle mount in place) while allowing you to move the drill up higher for longer bits. I don't think there's enough z travel on the Shapeoko to mount it in one fixed place.

Clearance seems to be a challenge with a mostly standard Shapeoko 3. Tried mounting my drill to my S3, with a 6mm drill bit in it:

: S3_with_drill_6mm_bit.jpg (252.67 KiB) Viewed 1208 times

Couldn't quite tighten the mount bolt enough to grip the drill. But, the photo still shows the clearance problem.

With a fairly long chuck, and the 6mm drill bit also being fairly long... there's literally no room left in the Z direction for the drill to move upwards.

It's possible to buy stub length 1/4" drill bits though, which could fix that. Also, locating a smaller drill would likely help too. (that one is kind of over kill for it)

Post by **twforeman** » Sat Jan 16, 2016 5:58 pm

Yes, clearance is currently an issue, but I have a fix for that.

I'm hoping to start building a torsion table for my S3 today. I plan on raising the whole machine about 2.5" when I do so. You can see in this photo how I accomplished that with my S1.

I'm ditching the stock waste board and cross bracing.

It doesn't give any more Z travel, but it increases the Z clearance, which is important to me since I use lots of jigs like the one in the photo.

There will be a build log and photos of this mod, along with the others I'm doing to stiffen up the Z carriage.

AlBorland · Post by **AlBorland** » Sun Jan 17, 2016 1:46 pm

I have used the DrillOko last year to drill some holes in aluminum. The result was not very good, due to the high z force the drill top was wandering to the -y direction.
I optimized my Shapeoko for smaller distance of the spindle center from the x axis, stock machines (Shapeoko 2 and 3) will have worse leverage.
While the Shapeoko 3 has a much stiffer structure, it still uses the same delrin wheels and bearings, so I would not expect much better accurray. I would also fear that the belt-driven z axis would loose steps when feeding with optimal parameters for aluminum.

I think you can't do much better than with drill press + jigs without spending a LOT of money.
I you have other reasons to use a Shapeoko, I'd use a smaller endmill and spiral down.

AnonymousPerson · Post by **AnonymousPerson** » Sun Jan 17, 2016 1:52 pm

AlBorland wrote:The result was not very good, due to the high z force the drill top was wandering to the -y direction.

Isn't the high Z force controllable by changing the plunge rate in software? So, reducing that, it shouldn't push off centre?

Note - just thinking out loud based on what I was trying in wood a while back. That seemed to work ok with drill bits, in a
Kress spindle, not a drill though.

Jimf · Post by **Jimf** » Sun Jan 17, 2016 2:46 pm

It takes a lot of vertical force to drill metal reliably. Most people have used a drill press before. The handles on them are around 8 to 12" long giving lots of mechanical advantage. I'm sure someone can figure out how much is actually required to drill metal with a 1/4" standard drill bit.

I have a small bench mill. The z axis is a 5tpi ballscrew. It was driven by a 276oz-in stepper motor, direct drive. It was never reliable enough for drilling anything larger than a 3/16" hole. The stepper would miss step once in awhile even with pecking turned on.

I ended up retrofitting the z axis with a servo with 5.5:1 pulley reduction (about 900oz-in equivalent peak torque). This gives me approximately 500 pounds vertical force. It has no problems drilling 3/8" holes now. If I plunge to fast, the spindle will even stall. That is another problem that needs to be upgraded soon.

I tried stopping my z axis with my entire weight pushing against the spindle, I can't.

AlBorland · Post by **AlBorland** » Sun Jan 17, 2016 3:20 pm

AnonymousPerson wrote:Isn't the high Z force controllable by changing the plunge rate in software? So, reducing that, it shouldn't push off centre?

This works only to some extent. Aluminum is much more picky in that respect than wood. If you go too slow, the drill would only rub on the surface and create heat, which melts the aluminum and destroys the bit.

I thought I had a link to speed & feed calculator also displays vertical cutting force, but I can't find it now. Anybody knows something like this?

AnonymousPerson · Post by **AnonymousPerson** » Sun Jan 17, 2016 3:33 pm

Interesting. I've drilled a few 3mm holes in aluminium (6082 T651) using peck drilling and a slow-ish plunge rate - turned out ok - but not anything 1/4" size (I don't have a 1/4" collet yet). Mostly I've done wood though, which is easy.

Jimf · Post by **Jimf** » Sun Jan 17, 2016 3:48 pm

AnonymousPerson wrote:Interesting. I've drilled a few 3mm holes in aluminium (6082 T651) using peck drilling and a slow-ish plunge rate - turned out ok - but not anything 1/4" size (I don't have a 1/4" collet yet). Mostly I've done wood though, which is easy.

Bigger drill bit, bigger chips. There always seems to be that one darn chip that gets stuck in a flute, even with oil lube. This causes the drill bit to bind and then you loose steps. It always seems to happen near the end of the job too. My solution, bigger servo motor!! Power it's way through!!!! Plus sharpen the drill often.

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