School me on taping body lines for blocking

[7E-Bodies]

OK guys, I've been holding off on asking this stupid question but it just doesn't sink in. I've seen it on Graveyard Carz, I've seen it in some of the posts here that you should run a line of masking tape down all of your body lines when you're blocking the primer as well as when you are cutting and buffing. The cutting and buffing I would assume is to let you know to stay off that edge with the buffer wheel but my main question during my paint prep here is what exactly am I doing with this masking tape and why doesn't the tape just get rolled up under the sanding block? I already get it that this technique is to aid in getting laser sharp lines but I just can't see how sanding around that tape is doable. Challenger body lines are what I'm dealing with. It may also help to know that the body side moldings are going back on the car. 

[torredcuda]

Using tape to get straight body lines when blocking primer does work. Yes, the tape breaks down and loses it`s edge after a while even if you are carefull to try and not run over it too much with your sanding block - just pull it off and re-tape. Tape just below the line and sand the top area and vice versa. Taping edges when cutting and buffing it just to keep from burning thru them.

[Rich G.]

Your not sanding the tape. Your basically using the tape as a guide and sanding up to it.

[RUNCHARGER]

You do this on the body line that runs along the center of a Cuda, a good idea for the lower line on a Challenger as well. It helps for you to "see" where the line is with alll the sanding dust. Probably not necessary on the S curve of a Challenger as the angle isn't as subtle where it rolls over. I like to lay tape on when welding 1/4's on as well as sometimes it is hard to see exactly where the lines are. Here I was using the tape to help me line up the doors to the original quarters before I cut them off. That way I knew where to place the new quarters in reference to the properly aligned doors.
As above, you're not sanding the tape, the tape let's you know where the body line is so you don't  "roll over" the body line. I just sand towards the tape, not away from the tape. The body line will sharpen up and you're aiming to have a fairly sharp line that is lazor straight in line from the front of the car to the back.

[7E-Bodies]

@RUNCHARGER thanks, Sheldon! Excellent explanation. Is there any way you could weigh in on another paint prep thread I started several days ago?
https://forum.e-bodies.org/body-shop/5/dp-epoxy-over-lead-joints-ok/27796/

[RUNCHARGER]

I can't weigh in on that one. It sounds like you have it figured out though and Jimmynick's experience seems to agree.

[MoparLeo]

Just make sure that the door hinges fit tight before you set the door gaps. You don't want to find out after you paint.
Member discounts. Over 1,000 satisfied Mopar customers over the last 25 years.

[7E-Bodies]

@MoparLeo correct. All body panels were aligned with weighted doors and new hinges. Gaps were set and tweaked to perfection. Good call though.

[Rdchallenger]

You're using the tape as a guide and it makes the lines sharper so as not to lose them when using high build primer.

[Rdchallenger]

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