How do you cut a straight line with a cutoff wheel?

zachj · Mar 23, 2003

I've been trying to cut my steel case for about two weeks now and every time I make a cut, it goes all crazy and my cuts aren't straight. I've been lucky enough not to cut outside where I want to cut, but it's all jagged and slanted. How do I cut a STRAIGHT line ALONG the EDGE of what I want to cut? That Tungsten Carbide bit that looks like a drill bit will cut through it like butter, but it goes all over the place and there are a few scrathes that I'm gonna' have to sand out, now. What the heck do I do, here? The only thing I've seen so far is to just cut inside where I want to cut and then grind down to the edge of where I wanted to cut . . . Tell me there's another way?

Thanks

Z

NiTrO bOiE · Mar 23, 2003

Try a lower RPM setting, and make sure you have a firm grip on it.

SlowChemical · Mar 23, 2003

what nitro boie said and TAKE YOUR TIME! If you start to feel like you are f*cking up or something is wrong turn the saw off step back and take a breather. SLOW AND STEADY SWINGS THE SWORD...

CSaddict · Mar 23, 2003

Also make sure the wheel is perpendicular to the metal and straight up as possible.

DaveSauce · Mar 23, 2003

Well, make sure you have a line drawn on what you're going to cut. That will help a lot. Use a pencil so you can wash off any messed up lines

When you say cut inside and then grind it out, you are on the right path. It's better to have to cut out more than it is to have cut off too much.

Use the carbide bit for smoothing. Or, if you can, set up a straight piece of wood and use the router head on the dremel. not the router table...the router head. However, this is not advised, because clamping a piece of wood down against the case panel might cause it to bend or warp..... but it will get you a straight cut.

And BTW, the way I did it was like this....I would cut as close to the line as possible....but at times I would veer off. What I would do afterwards was take the cutoff wheel to it again. It works very well....much better than trying to use a de-burring bit.

ptwearnhardtfan · Mar 23, 2003

Here's a little tip that might help. Clamp a straight edge to your side panel, like a piece of wood or something. Space it at a distance from where you want to cut (parallel) so that you can rest one of you hands on it and guide your cuts. This should give you better stability. Don't cut all the way through on the first cut. Use the wheel to score a straight line, and just keep going over the line a few times until you cut through.

Yodums · Mar 23, 2003

Definitely turn down the RPM. When cutting stuff I only use an RPM of 3K. Not only will it be more precise but at high RPMs, your cutting wheels will be worn out FAST.

I also do what ptwearnhardtfan mentioned. I do a very light outline (Meaning, I apply no pressure) and then I just keep on going over and over till it is deep enough that I can apply more pressure.

Yodums

stool · Mar 23, 2003

I use a straight piece of flat aluminum stock as a straightedge. Anything off will be to the side I am eliminating, thus easily fixed.

Daemonfly · Mar 24, 2003

Sounds like it's a big cut, window??

If so, do you have access to a Jigsaw? Works a lot better for larger cuts than a Dremel.

If you don't have access to jigsaw, Carbide bit? Should be using Fiberglas reinforced cutting discs for better straight cuts.

seamadan000 · Mar 24, 2003

like has been said, make a guide that you cut out from a piece of wood (or whatever you have lying around), then score it with the first pass, and then cut all the way through.
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zachj · Mar 24, 2003

Okay . . .

It's not a window, but I'm cutting out that much material. It's a Mac, though, so I can't take the panel off to cut it, which has been a real pain.

The reason I haven't been using a guide is because I can't attach anything to the dremel while using the cutoff wheel, so a guide is useless.

I had been just cutting until I got off course, and then finding a new line to cut and just repeated that until I got through, but this wore out the wheel very rapidly and it resulted in VERY jagged cuts.

I've been cutting on 10k RPM because that's what the manual for the dremel says to do. Guess that explains why a fiberglass wheel only lasts about 1.5 feet?

The carbide bit just drew all over my case, so that has to be sanded out. I'd appreciate not having to use that anymore. I guess I'll try the scoring method and just do that 'till I'm through . . .

Thanks for the help

Z

LittlePiggie · Mar 26, 2003

whoa whoa. you need to drill a hole for the carbide bit to start in. then it will work like a charm.

zachj · Mar 26, 2003

Well, that's what I thought too. So at Home Depot, I asked how to go about that, and the guy said that it would drill a hole for me. I looked at the thing, and I'm like "how in the he** will THAT drill a hole?" Well, I went home and tried it, thinking that an employee of Home Depot would know more than myself about tools. He was wrong, of course, which would explain the vast damage to my case . . . BAH!

Z

four4875 · Mar 26, 2003

mac=bad, but i dont want to get into that. i find that if you go in the direction that the wheel is rubbing, it's easier. so if you're holding the dremel with wheel facing away from you, you'll be moving your hands left. and get a firm, steady grip on the dremel.

use a drawn line, too. and get a old AT case to practice on.... pick up one at any comp repair place, and just anhilate it, getting the feel for your dremel. this is what i did. got the case for free. just draw paralell lines on the panels, and have at it. practice makes perfect. hope this helps some

zachj · Mar 27, 2003

THis mac= good . . . You'll like it. There'll be a story on it on the front page when it's done, I promise

Z

four4875 · Mar 28, 2003

well... if it has mac guts.... its bad lol

Mark Larson · Mar 28, 2003

I use a few tricks to get the straightest lines -

1. Draw a straight, dark line.
2. Use a speed of 35k rpm.
3. Lightly score a line first - continously but lightly. Move your hand with the dremel so the wheel doesn't change angle.
4. Cut in little sections - don't do it like a saw.
5. Use the deburring bit sparingly - it has the potential to turn a straight line into a not-so-straight one very easily. Rather use a hand file.

zachj · Mar 28, 2003

35,00 or 3,000 to 5,000? My dremel does 10k, so 35 isn't an option if that's what you meant. Somebody above said use 3000 . . .?

The Mac? Trust me, you'll like it. Make no assumptions. Read my sig . . .

Z

Captain Slug · Mar 29, 2003

Daemonfly said:
Sounds like it's a big cut, window??

If so, do you have access to a Jigsaw? Works a lot better for larger cuts than a Dremel.

Ditto. Rotary tools are not meant for large cutting jobs (hence why they're small). I use a jigsaw with a smooth finish metal blade. You'll still need to mask off the entire side panel to prevent scratches. And make sure to drill a large starting hole and smaller holes at each corner.

It's always safer and easier to use the RIGHT tool for the job at hand.

zachj · Mar 29, 2003

Firstly, I don't have a jigsaw. Second, I'm 17, so I can't buy one. Third, the case is riveted together, so it's not just a side panel that would be on the table to cut. It's the whole case. I don't really see any alternatives to a dremel right now. I'm not un-doing the rivets . . .

Z

How do you cut a straight line with a cutoff wheel?

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