Fender Rolling - The CUT method (questions, not answers)

KobaltBlau · 10:38 AM

I want to collect more information in a thread about the cut method of fender rolling. Here's a good post from 89turbocabmike from another thread, mike, can you give us more info on how you did yours? the aviation snips look hard to create good results with (without small ripples/bends), but the results look good!:

Quote:

Originally posted by 89turbocabmike
Alan, I went round on this a few months ago after lowering my car. I've use the rollers on other cars with some success but you just never know whether the paint is going to crack, heated or not. I finally decided to go with Bill Verburg's suggestion to use a 3 1/2 inch cut off wheel on my die grinder and use some wet towels to keep things cool as I went. But as I was removing the wheels and pulling tools from my tool box I spied my aviation snippers. It took about 10 minutes aside going very carfully and I touched up the edge with touch-up paint. This will work if you can live with a 1/4 inch lip to give it some strength. Just another idea

I think that bill verburg recommends using a cut-off wheel but I haven't found a detailed description of that method.

Any ideas, people? especially interested in feedback from 89turbocabmike on his process, and perhaps a better picture of the lip, it looks like the camera got fooled and focused on the background.

89turbocabmike · 10-03-2005, 10:58 AM

Andy, I will try and get a clearer pic.

The key is to take your time and take small bites, 1/4" inch, due to the radius. I used some sharp Wiss offset aviation snippers(available at most home improvement/hardware stores), a good quality tool makes a difference here. You can get by with either left hand or right hand offset. The fender is quite durable and the metal cuts easily. The only limitation with snips is that you probably can only trim the edge down to 3/16 safely. You could get down to 1/16" with the grinder method with some patience which is more than you can obtained rolling the fender due to the bend and metal thickness.

911pcars · 10-03-2005, 11:04 AM

I experimented and rolled the LF and cut the RF.

Rolling the lip can cause the paint to lift. In addition, it creates a nice trough for dirt and moisture to accumulate (NG).

I cut the RF with a grinding disc as Bill describes. Apply some masking tape along the edge, then mark the amount you wish to remove (only a small portion of the lip needs to be removed). Contour the cut so it blends in with the uncut portion. Lay wet shop towels on top of the fender and move the disk frequently so any one area doesn't overheat. Wear eye protection. Apply touch up paint on the bare metal edge.

Sherwood

RoninLB · 10-03-2005, 11:14 AM

Also

a pelicanhead posted that he used a fender rolling tool successfully.

Bill Verburg · Bill Verburg's Garage

Actually I used the cut off wheel the first time, and an air powered body saw the second. The body saw is sort of like a jig saw. The second method was much easier to control and didn't heat the fender at all.

Don't forget to seal the raw edge.

KobaltBlau · 10-03-2005, 11:58 AM

Mike, thanks for your speedy response. I didn't mean to criticize your photography, but I'm sure a few more pics would be instructive to others interested in this process.

I guess my #1 concern is, did the snips want to ripple the fender lip, as you took small bites?

you can only take 1/4" bites due to the radius of the fender itself?

I have found a local source for the exacct snippers you have, and will use that exact tool. Do you think it would help any to have both right and left offset available? if not, which would you choose for a right handed person? Also, are you especially skilled in working with sheetmetal?

mike, sorry for all the questions but I think this sounds like a really promising option and I want to try it

I think 3/16 or a 1/4" lip sounds perfect. As others have noted in the past, the lip is important for strength, and I doubt most rolled fenders have any smaller lip than what you can get with these snips. Do others with rolled fenders agree with this assessment?

For everybody who has clearanced fenders: where do you need to start and stop? Maybe this is easy to see by looking at where the tire will go.

Bill Verburg · Bill Verburg's Garage

Something like this gives max clearance

The shelf behind the fender/ bumper cap junction is also a prime candidate fro trimming

KobaltBlau · 10-03-2005, 12:12 PM

Very nice illustration, Bill. where do you stop on the side behind the tire? All the way down?

Bill, what do you think about this snips idea? I imagine it's very important to use the offset snips as they are made to cut curved metal like round duct pipes.

I don't have an air powered body saw, though I guess I could buy one. Did you use something like this?:

Bill Verburg · Bill Verburg's Garage

Quote:

where do you stop on the side behind the tire?

There is more room in the back, roughly down to the top of the hub

Quote:

Did you use something like this?:

Yes, They are very precise and quick cutting

KobaltBlau · 10-03-2005, 12:46 PM

Thanks again. Any opinion on the snips approach 89turbocabmike used?

Bill Verburg · Bill Verburg's Garage

Quote:

Originally posted by KobaltBlau
Thanks again. Any opinion on the snips approach 89turbocabmike used?

I wouldn't want to do it that way

KobaltBlau · 01:28 PM

Fair enough. What reciprocating blade did you use? Also, what do you use to seal the cut lip? Boy, am I full of questions today.

I'm wondering if that air tool is equivalent to this electrical reciprocating saw, I have one of these somewhere:

juanbenae · juanbenae's Garage

i would bet the sawzall has a longer throw and is less precise.

911pcars · 10-03-2005, 02:08 PM

Hey guys,
We're not demo'ing a construction site. If you're doing this for the first time, I'd take it slow and easy. The recip. saw is not as precise as other methods discussed. One slip and the term, "faster than a knife through butter" will come true. Remember, you're doing this on your back, looking upward. Besides, you'll have a ragged edge to clean up with a sanding disk anyway.

Sherwood

KobaltBlau · 02:32 PM

so sherwood, what is your favorite method? I agree that the recip. is too long of a throw; maybe a jig saw like the below picture would be better, though the shape of it isn't great. I have one of these too.

Sherwood, since you tried a couple of methods, what do you think is the best? The reason a reciprocating saw appeals more than a cutting wheel to me is the heat, but maybe I'm making too much of that.

you say "only a small part of the lip needs to be removed" How much would you say you cut off? I'm fitting a 225/50-16 front tire, but I know the cars vary.

911pcars · 10-03-2005, 03:41 PM

Andy,
As per my first post, I suggest using a sanding disk. It removes material slower, thus it provides more control at the expense of generating heat which can be managed by applying wet towels to the area and moving the disk around (not sanding one spot too long).

Years ago, I used a 7" flexible disk sander on some rear fender lips. That removed metal quite nicely, but it was heavy and a little awkward controlling it overhead. I think the 4-4.5" elec. grinders are very controllable.

I forget what specific areas of the LF/RF wheel well pose the most interference. That would depend on how high (or low) you set the ride height and, of course, the tire size, wheel width and offset. In my case, I just observed where the tire rubbed up against the lip and used that as a guide. As you state, the clearance varies from car to car. I do know the entire lip does not have to be trimmed. A rough guess; R/F: from 10 o'clock to around 2 o'clock and L/F 2 to 10.

I would stay away from reciprocating blades as they might tend to catch the material and distort the metal. In addition, the cut is a ragged, unfinished edge which should be cleaned up with some sort of electricl sander anyway.

However, YMMV. There's usually more than one way to do it.

Hope this helps,
Sherwood

KobaltBlau · 03:52 PM

Thanks for contributing your experience, Sherwood. what type of sanding disc did you use? A "metal" grinding wheel? (for grinding metal, not sure they are made out of metal. If you put 178490 into the search field on www.homedepot.com you'll see what I'm looking at) They seem to come in 24 grit. I take it the grinder doesn't interfere with the tape that is marked with the cut-back line and that it doesn't damage the paint as long as it is kept cool enough, i.e. the edge that has been ground is not too rough.

Bill, when you say "cut off wheel" I assume you mean a thin cutting disc rather than a grinding wheel like sherwood is referring to. Does the body saw just cut so easily that it's more controllable?

Much appreciated,

911pcars · 10-03-2005, 04:00 PM

Andy,
Off the top of my head, I'd suggest a 4-4.5" segmented sanding disk, about 120 grit should be fine. 24 grit is fairly rough. Rigid cutting wheels tend to want to cut in a straight line rather than a contour.

Sherwood

89turbocabmike · 10-03-2005, 04:18 PM

Andy, Aviation snips are less than $20 and handy to have around the garage. Pull off the wheel, lay on your back in the appropriate direction for the snips you buy and just try cutting off an 1/8" to experiment. Both a cutting wheel and air saw do take some experience and care as they are moving fast. One small slip and your bumming. I would agree with Bill that a body air saw with fine blade would do a great job, I have one of those too, but with my turbo flares there is less clearance for the moving blade if you want to cut the edge square. The key is small cuts to prevent ripples due to the radius of the opening.

Any of these methods will work fine when approached with care

Except the saw-zall!

KobaltBlau · 10-03-2005, 04:35 PM

Good idea mike, I'm off to get some offset snips (have the regular kind, but I don't think they would work as well), and I'll try them on a little spot.