Drilling with Shapeoko

[samc99us]

Not sure if this belongs here or in general discussion...

I was drilling some holes at work in aluminum with the Bridgeport clone. We have a chuck that looks like a regular drill press chuck, so loading up different bit sizes isn't an issue. I was wondering if loading up something similar in my Dewalt 611 chuck would work? Such as this: http://www.amazon.com/gp/aw/d/B004HAA22 ... ref=plSrch

The reason I ask is drill bits with 1/4" or 1/8" shafts to use a regular collet are near impossible to find (precise bits have them but they are expensive and they 160deg point isn't always ideal). My concern is the square edges on that chuck may not be good for my collet. Also, total runout will be higher, but the ability to use stub length drill bits for precise centering work sounds pretty nice. Thoughts?

[madhatter]

I have one of those chucks tht I have had for ~8 years ro so. I bought it for drilling small holes using an inexpensive screw gun. I can tell you that it will most likely not do what you want. It is not the same chuck as a regular drill chuck. This uses the hex post on the back - that is actually threaded with what looks like ~#10-24UNC threads for half of its length - to push a plate up inside that causes the jaws to close on the bit. It has a hard time with holding a bit from slipping while drilling into wood, so I don't think drilling into metal would work well. Also, it likes to work itself loose while being used. My suggestion is to not waste your time on this.

Sorry for the letdown.

EDIT: Maybe this will be better if you have the clearance under the gantry?

[samc99us]

Yeah, something like your link could work. Maybe. Has anyone tried it? How else are folks drilling holes that aren't 1/8" or 1/4" on their Shapeoko?

[WillAdams]

I just mill most holes.

Once or twice I've used the 1/8" hole as a pilot hole and worked up through a series of index drill sizes in a drill press.

[twforeman]

I'd love to be able to chuck up some drill bits in my Shapeoko, but the main issue is the spindle speed. 10,000 RPM is still way too fast for most drill sizes.

I'd really like to be able to chuck up a 1/2" Forstner bit but you need to run those around 1300 RPM.

[Estlcam]

Hex shafts are not a good idea to put into a regular collet and spindle speed will most likely be too high for drilling anyways, especially in aluminum.
Just mill the holes with a smaller endmill - this will usually work much better.

[samc99us]

Yep, I'm aware of the spindle speed issue.

I'm quite sure the 1/4" hex shaft won't be GREAT, but I have the stock collet the Dewalt 611 came with to try. I might give it a whirl.

I'm really not planning on doing a lot of holes. Maybe it makes more sense to mill them, but I don't think so. I think the best plan is to use a spotting bit on the mill (which really wants to turn fast anyway) and then a drill press to walk this up in size.

FYI, I used these tools to drill 60 #21 holes in 3/8" aluminum plate at 2 in/min a few weeks ago, worked out great, had the Dewalt set to 2 on the knob so about 10x as fast as the bit wants to run (2,000 rpm). So certainly not ideal but it worked.

http://precisebits.com/products/carbide ... ts!!!#Tabs

http://precisebits.com/Reference/drillfeedspeed.asp

[RobCee]

I would imagine that the biggest problem you would face with this type of drill chuck is the accuracy, specifically the runout once a drill bit is held in it.
The stacking of different work holding methods will always introduce runout and it will be exaggerated by holding multiple items. If the workholding method allows for compensating then you may have a good solution.
The biggest issue (assuming you are using a small drill bit) will be the overall runout + too high speed will tend to want to snap your drill.

I have found that hex shank tooling is great for hand held power tools, but once you start to introduce machine rigidity to the system, it can fail spectacularly.

[samc99us]

Roger that RobCee. I think reducing spindle speed will be key. All I can say is the runout will be far far better than the craptastic drill presses I used today. My home press is far more accurate, and I think a good idea will be to use a center bit in the Shapeoko and then the drill press after to enlarge the holes.

Curious, which 800watt spindle did you go with? I'm debating between that and a 1.5kw unit, the latter seem a little cheaper at times but in reality the 800watt is plenty unless I'm milling aluminum (rare). Just being able to turn the bits slower and maybe drive a little deeper with the stiffer machine will be a godsend on tooling costs.

[RobCee]

I went with an ebay spindle/inverter package so nothing special. The biggest thing to worry about is the weight of the spindle, as that causes you the most problems.
You will need to think about twist around the X axis, deflection in the Z plane and acceleration issues if you use a larger spindle. The spindle I am running weighs 2.4kg (5.3lbs) and I do see some deflection issues.

Here is a link to the info on my spindle.