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View Full Version : Learning Dremel Case Surgery. Could use some advice on bits?



Judaeus Apella
02-08-2006, 12:52 PM
I just started getting into case surgery, and I'm having fun with it. :)

I got me a Dremel 400 XPR and I love it! It’s comfortable to use, and it’s just like using a sketching pencil. So far I’m doing pretty damn well with it, considering I’m new, but I have some questions about bits.

For example, I’ll use a simple project. The first project I attempted was cutting away the metal from an existing fan vent, size is 120mm. The stock grill cut into the stock case is just a bunch of holes, drilled out to form the shape a circle, which severely decreases the amount of airflow and increases the dBa.

Keep in mind I favor steel cases for their durability, so the case I’m using is constructed from 0.8mm SECC.

1. Cut out the large portion of metal using the small cut off wheels, the ones that come in a pack of 20, and was happy with the cut I made. I’m not used to the flex shaft, so it got away from me a few times until I became comfortable with it. A couple of times, it jerked from my grip and scratched the immediate area around the hole. Luckily this is the intake vent, behind the front door of the case which is under lock and key about 99% of the time, so it’s not in plain view. You can only see it when I open the door for maintenance. Towards the end of the project, I had much more control over it and slipping became almost non-existent.

2. Shaping the circle and touching up the edges using light to moderate pressure, on higher settings. The first bit I tried for shaping the circle this was the 8175 Aluminum Oxide Grinding Stone, which I found to be very unproductive and annoying. It's progress was agonizingly slow, so I tried the 85602 Silicon Carbide Grinding Stone, which was described as a bit for grinding non-ferrous metals, among other things. I gave it a try with the same results. The kit didn't really offer anything else for this task, so I tried stacking four of the cut off wheels together to form a thicker grinding bit, and sure enough it worked great! I was able to very precisely shape the circle using light touches, like sketching with a pencil. After shaping the entire circle, the cut off wheels had only lost about 1/4 of their circumference.

3. Smoothing the edges to get rid of razor sharp edges, splinters, and overhangs. I really haven't done much in this area, accept remove some of the splinters and what look like "lips", you know where the metal starts to widen at the edge, where it was ground.

What should I use for the final step? Is this what I should use?
Abrasive Buffs (http://www.dremel.com/en-us/attachments-and-accessories/attachment-accessory-group.htm?H=188569&G=66429)

I thought about using the sanding wheels/bands, but I was afraid they'd have a mind of their own and rather grind away the perfect cuts I made.
Sanding Bands (http://www.dremel.com/en-us/attachments-and-accessories/attachment-accessory-group.htm?H=188569&G=66408)

As for grinding and shaping, is there anything better than that 20 count tube of cut off wheels? They wear down to quickly, which can get costly. Would any of these last longer? What about their effectiveness? Do they cut as well? Better?
Dremel Accessory Directory (http://www.dremel.com/en-us/attachments-and-accessories/attachment-accessory-category.htm?H=188532)

Perhaps just a fine sanding sponge?

DFI pit bull
02-09-2006, 02:55 PM
I love dremel. Sorry I have no advice.

SlackerXL
02-09-2006, 04:30 PM
first of all you should use masking tape to cover all the surrounding area
on both sides of your cut lines

then i suggest you use an angle grinder rather than a dremel
for those long lines that need to be straight and clean cut..
(ex. side windows)
it costs far less and has a better result

as for the finishing touch
i use the following method
first you remove the large splinters with a chisel
then you smooth the rough spots with the fine sanding bands
and the finishing step is to just use fine sanding paper manually
(no matter what you do, your hand is always more responsive and controllable than a tool)

a dremel can be a powerfull tool for your mods
but can't always achieve the best possible results...

anyway
i believe that through practice
(all relatives/ friends will gradually obtain cases with side windows and blowholes )
you'll find your own style of dremel-work and probably come up with some method of your own...

good luck and enjoy your new toy :)

Judaeus Apella
02-09-2006, 06:06 PM
I don't have an angle grinder.... nor the money for one....

Coroner Kyle
02-09-2006, 06:49 PM
Sanding bands. I use cutting wheels to cut whatever I'm cutting then I use it to sand things down and get the shape I want then I use the sanding bands to smooth the edges. It's metal and you're using a dremel so don't expect a perfect finish, but you can get it smooth and safe.

Celeron Gamer
02-09-2006, 10:34 PM
Seems like you're getting way too ahead with your new toys.

Like others said above, later the side with masking tape, 3-5 layer preferably. And don't be afraid of it. Put your arm on the cutting piece, and make the most contact on the steel, so you can have good grip on it.

It seems like you had some money, and bought the XPR 400, and a flex shaft. I suggest getting used to the dremel itself before using the flex-shaft

Sanding bands are fine btw, just let it run along the ridges themselves, and avoid putting anything more than a bit of pressure on it. "The mind of it's own" is what you should follow, rather than force, then it should not dent anything.

SlackerXL
02-10-2006, 11:29 AM
I don't have an angle grinder.... nor the money for one....
the cheap ones (400w) cost less than 10€....
and have no problem at all, cutting computer cases...
trust me...
the dremel disks required for the same ammount of job will cost you more

Dngrsone
02-10-2006, 11:50 AM
You definately want to use the fiber-reinforced disks-- they last longer. I save the disks when they fall below half-diameter for cutting in close-quarters, that way I don't waste my metal bits.

The sanding bands work very effectively, sometimes too much, you need a light hand. The ferrous stones are good for touch-ups.

Bevel the edges at a 45 degree angle and then flatten the cut edge again, that takes care of the sharps and the rest is dressing.

Like SlackerXL said, hand-sanding the last is best.

Judaeus Apella
02-10-2006, 12:17 PM
Thanks for the great advice guys. I'll keep practicing and adopt the advice you gave me. :)

BTW, I didn't buy it myself. I did some work on my parents house and Im currently restoring their Lawn Tractor. The Dremel happened to be the best thing for all the jobs, and they bought it for me as a way to pay me for most of the work. It worked out cause I've always wanted a Dremel, and it was on sale... so thats how I got it.