Dremel and bit recommendation

Hey everyone,

I'm going to be milling out a chassis on my brother in law's mill, but I only have two weeks to do it (it's in another province, so I only get access to it when we head out on vacation). I envision there being some additional touch-ups to do afterwards. I know some people have used a Dremel and milling bits, so I'm looking for recommendations on which Dremel and which bits to buy (a mini-mill isn't in the budget...yet!). This is for 3/16" 6061 aluminum.

Thanks!

Chris

[JThiessen]

All you will really need are the abrasive metal cutting blades. They also make a new quick lock collet bit for them - if your doing much consecutive cutting and going through blades, its really convenient.

Maybe a wire brush for cleaning up an area.

The only drill bits you will need are 3 and 4mm, or just get the ANSI equivelents.

in my opinion abrasive blades are not ideal for aluminium cutting as the oxide tends to coat the blade making it no longer abrasive.

aluminium is so soft that a standard metal file will make quick work of removing metal burs on your milled chassis.

[BrianG]

^ +1. I usually use a hacksaw to make the rough cut and then files to do the fine work.

[suicideneil]

Agreed. A small flat and round metal file is perfect. That will remove 99% of the rough areas, then just go town with the wet & dry sandpaper for a beautifully smooth finish. A Dremel has its uses, but one slip and you'll have a nasty scratch that wont polish out running half the length of your new chassis.

[What's_nitro?]

Can you afford a bandsaw? Even a small one will do aluminum just fine. I've never tried to "Dremel mill" something before but it sounds like it would take a while. Plus you would need a guide of some sort. Unless your hand is bionic so it can withstand all the torque from cutting and is also perfectly stable for those straight cuts. As far as which attachment to use, a milling bit any larger that 1/8 woud require a very strong and steady hand and none of the bits I've seen for sale with the Dremels are made for metals so they wouldn't last long. I have had some success with the fiber-backed disks as opposed to the aluminum oxide ones. They don't seem to get caked up as much when cutting soft metals.

If you are just cleaning up after milling, I'd just get a set of good files and a perhaps a jig saw (the manual one).

What are you making a chassis for? I might rethink the choice of material. You're talking about making a chassis that will be almost 5mm thick.

I'd consider something along the lines of 3mm or 4mm 7075 (depending on the application), which is a lot stronger than 6061. I, often times, find myself wishing that I had gone with 7075, rather than 6061.

If you look at the specs of many models of rc cars and trucks, you will find that 6061 is what they use in the cheaper RTR version and 7075 is what they use in the Pro version. 7075, is much more rigid than 6061.

Once you have the chassis done up, you might also want to consider having it type III anodized. The anodizing will put an abrasion resistant coating on the chassis to help to keep it from getting buggered up by the screws and bottoming out.

Thanks for all the tips guys. I may look into getting a bandsaw. A lot faster than a hacksaw anyways. We'll see, this is just something I'm trying out at this point.

As for why I'm going with 6061, a few reasons. 1) It's cheaper than 7075, so if I screw it up, I won't be out of pocket too much!, 2) From what I've been told, it's easier (at least for a beginner) to work with than 7075, and 3) 7075 seems to be a special order item only around here, while 6061 is much more readily available. I would definitely like to use 7075, but not until I'm more confident in my skills.

I was definitely thinking of anodizing as well. Thanks for the lead on what type I should go with. I wonder if anyone has ever tried powder coating? I've done this extensively with my bikes, and it produces a very strong finish, although my bikes don't go through the abuse my r/c vehicles do.

Thanks!

Chris

ecoli,

I too have used the 6061 for the same reasons that you stated, but as I said, I almost invariably wind up wishing that I had used 7075.

I just might find out how easy it is to tweak a 6061 chassis. It would just suck to put all of that work into the chassis and then wreck it because it wasn't strong enough.

As for the powder coating, it is nice; but will chip at the screw holes and actually make tightening the screws more of a chore. The anodizing will be much more abrasion resistant.

I actually have a tool handle that I made out of 6061 and knurled it at the grip portion and had it anodized type III mil spec (green). Although I can knock it against a piece of metal and ding it, because of the relatively weak 6061; I have also used the knurled part to saw through wrought iron without damage to the finish.