Countersinking aluminum chassis - best method?

[amplifiednation]

Hmm, yeah so this is where I am lost. I was having better results with cheaper tools, (ryobi wood countersink) but the process wasn't efficient because the bit needed too much maintenance and cleaning.

I upgraded to the aircraft bit, reduced my speed, and added extra oil and its become a bit of a challenge. I'm obviously missing something. Its obviously operator error. I need these cuts to be perfect... I am getting rough circles that are questionably acceptable.

Zero flute countersink? That sounds intriguing. Nothing to clog up? How does it cut?

What makes something "aircraft grade"? The obvious???

I have a good drill press. What speed is best? I read slower speeds for soft metals.

SH- I am drilling the through hole first with the press, then countersinking. I'm getting lots of metal splinters. Are you saying the through hole needs to be the 'correct size' per the countersink diameter?

Thank you for your responses, I know this isn't the most exciting subject, but it is important!!!

[LeftyStrat]

I have sometimes found that higher speed with really slow feed works well.

The biggest issue is having the part clamped well, which is difficult to do with aluminum sheet.

I recently purchased some aluminum structural channel to try in an amp, simply because it is much more rigid and I can machine it on my milling machine.

http://www.onlinemetals.com/merchant.cf ... top_cat=60

[LeftyStrat]

I forgot to add one more method that might be suitable. Swivel deburring tools can do a moderate countersink:

http://www.amazon.com/General-482-Swive ... B00004T828

[amplifiednation]

I have sometimes found that higher speed with really slow feed works well.

The biggest issue is having the part clamped well, which is difficult to do with aluminum sheet.

I recently purchased some aluminum structural channel to try in an amp, simply because it is much more rigid and I can machine it on my milling machine.

http://www.onlinemetals.com/merchant.cf ... top_cat=60

What will you use that for?

Clamping is not something I can efficiently do unless it will fix my cleaner-cut issues. Sometimes I need to do 10-15 countersinks at a time so time is important

[LeftyStrat]

Then go for the deburring tool. It will be faster and you may be surprised at the results. It won't fix any holes damaged by chatter, but on a newly drilled hole, a couple of twists and you're done.

The aluminum channel replaces a bent aluminum plate chassis. 8x17x2.5 for about $40 makes it more expensive than the standard aluminum chassis, but I can get it faster, it's easier to machine (if you have a milling machine or CNC machine), and you can drive a car over it without any damage. Still need to shield three sides, but aluminum foil works fine.

The goal is to have something I can mount on a four-axis CNC milling machine with a tool changer, walk away from and come back to a finished chassis.

[amplifiednation]

Then go for the deburring tool. It will be faster and you may be surprised at the results. It won't fix any holes damaged by chatter, but on a newly drilled hole, a couple of twists and you're done.

The aluminum channel replaces a bent aluminum plate chassis. 8x17x2.5 for about $40 makes it more expensive than the standard aluminum chassis, but I can get it faster, it's easier to machine (if you have a milling machine or CNC machine), and you can drive a car over it without any damage. Still need to shield three sides, but aluminum foil works fine.

The goal is to have something I can mount on a four-axis CNC milling machine with a tool changer, walk away from and come back to a finished chassis.

That's cool! I gotta see one of these CNC machines

[patrick620]

I have sometimes found that higher speed with really slow feed works well.

The biggest issue is having the part clamped well.

Good advice there.

[amplifiednation]

I have sometimes found that higher speed with really slow feed works well.

The biggest issue is having the part clamped well.

Good advice there.

Appreciate it guys, I will give this a go today.

[Structo]

I used the one I showed to counter sink the screws on the aluminum trim on my head cab.
It is a Ceria cab so I'm not sure if it is the same alloy as what people are using in the USA.

I think it really depends on the alloy, how hard or soft it is which will dictate drill speed and feed.

[davent]

One size fits all with this one.

http://www.leevalley.com/en/hardware/pa ... 1306,41328

dave

[surfsup]

Leftystrat. How do you program your chassis? I am willing to offer free cnc programming for some machine time!

I did just find out a friend has a haas in his garage. I have been training him on programming on wknds and evenings. He said he'd "give me the keys to the garage, train me on the mill, and i can have at it".....nice!

If you come to IMTS, I'll be there working the show.

Taylor, if you can get some strong magnets, you can build a magnetic vice pinching the sheet btwn two opposing magnets, or more, which will be strong enough to hold it for this type of work. Or if its all corner work, get two channels cut at 45 and build a 90 degree channeled vice and use a clamp or two on the other sides to hold it rigid. By sliding the piece in a channel the same width as you sheet thickness that will hold it real well. Anyway, a couple ideas on a lazy sunday AM after finishing my redecking work and sippin a coffee outside enjoying this beautiful chicago morning!

[LeftyStrat]

Leftystrat. How do you program your chassis? I am willing to offer free cnc programming for some machine time!

I haven't finished my mill yet. Right now it is still manual. I have the steppers and the control board, I just need to make the mounts and get ball screws.

Call me old school, but for a lot of simple stuff I just write the g-code by hand. I started my career back in the days when we still punched paper tapes for machining.

But if it all goes well, I may offer custom cut chassis.

[surfsup]

Did you get a kit, or are you just building one? When i move i plan to get a kit. Those diy routers are plenty big for just about anything, 3x though. Having the 4th would be perfect.

[LeftyStrat]

Did you get a kit, or are you just building one? When i move i plan to get a kit. Those diy routers are plenty big for just about anything, 3x though. Having the 4th would be perfect.

I bought the mill from Harbor Freight and doing the upgrade myself. Here is a site dedicated to showing what can be done with this mill:

http://www.hossmachine.info/

[Cantplay]

OK, here's how I regrind drills and countersinks to not grab or chatter.

I'm reducing the cutting angle, makeing it more oblique.

The countersink has a straight neutral flute. I'm breaking the edge back at a slight angle with a hone stone.

The drill bit shows the same thing, and how the web of the drill is thinned.