Top Chopping Question

[Chevy II]

I am attempting my first time at chopping a top. I have seen a lot of examples where they cut the A pillar horizontal like the tape in my picture. Has anyone ever cut the A pillar perpendicular to the pillar as shown in the black mark? Seems to me this would give you an easier joint to fix that going across it horizontally. And no, the tape is only placed there for show right now.

Also, do you use the tape as a guide for the blade or just use it to mark the cut line?

Thanks for any input.

[Mark]

I cut the A pillar perpendicular, not at an angle.  The tape can be used as a guide.  If you do that, you might go with two pieces of tape, on the outside of the cut line.  That way, if you slip, you only damage material that you are removing anyway.

[Mark]

Too, whenever possible, I try to put a jog or zig-zag in the cut.  The pieces then self-align, and there is more surface area to join as opposed to just a small joint between two pieces butted together.

[Plowboy]

I always cut perpendicular to the pillar. Especially on the A pillar. But, each model is different. There's no one way fits all method. I've actually chopped a '37 Ford pickup. But, it's been a while. You'll either have to lengthen the roof or slant the A pillars. I normally choose to lengthen the roof. Usually, how ever much you chop it, that's how much it will need to be lengthened.

I use the tape to mark the lines. Then saw inside them. But, you can use the tape as a guide also. Depends on what works best for you.

Where you have your tape is exactly where it needs to be cut.

 

Edited November 16, 2022 by Plowboy

[Calb56]

ea0863 posted this image from Hot Rod Magazine in this thread 

[ea0863]

2 hours ago, Plowboy said:

I always cut perpendicular to the pillar. Especially on the A pillar. But, each model is different. There's no one way fits all method. I've actually chopped a '37 Ford pickup. But, it's been a while. You'll either have to lengthen the roof or slant the A pillars. I normally choose to lengthen the roof. Usually, how ever much you chop it, that's how much it will need to be lengthened.

I use the tape to mark the lines. Then saw inside them. But, you can use the tape as a guide also. Depends on what works best for you.

Where you have your tape is exactly where it needs to be cut.

 

Man, that is a good looking truck!

[Chevy II]

Thanks for the replies. I have already removed section of the rear window so I can chop it less than what the windshield and door glass will be. I am planning to extend the roof and not slant the A pillar. Anyway that's the plan. We'll see how it turns out, might end up being a roadster pickup.......

[Chevy II]

Mark, are you saying to put a zig-zag in the A pillar, B pillar or both?

Roger, your build was the one that got me thinking about this build. Mine will be in primer, have the bed shortened, and a 6" scale chop.

[Mark]

Both, when possible, provided you are stretching the roof.  And, try to make the cuts in the "straightest" area; that is, where the least amount of "slant" or "transition" is.  Depending on the shape of the roof being chopped, there are times where that really isn't going to change too much.

If you are chopping a race car body, try to get as much information as possible about class rules.  NHRA Gas class rules allowed for chopped tops, but you weren't allowed to alter the slant of the windshield or rear window.  You had to stretch the roof to keep those angles the same as stock.  Bonneville classes seem to have allowed changing the slant, as well as changing the shape of the windshield opening.

With something like a '49 Mercury, there are articles out there on how to chop that particular car.  The successful Merc chops keep the stock windshield "slant", shift most of the roof forward just a bit, and lean the area around the rear window forward to close much of the resulting gap.  The rear window opening itself is left stock, as the tempered glass cannot be cut.  Other cars with curved rear glass got Plexiglas rear windows in cases where the shape of the window had to be changed.  The earlier stuff with flat glass all around makes for a good starter project, just figure out what you want the end result to look like and start cutting...

[Plowboy]

I've never done a staggered or z cut on a chop. I can see the benefit of it. But, I can also see where it could cause issues for someone doing their first top chop. The '37 Ford's pillars provide plenty of area to glue back together well. Just make sure to use a good liquid cement like Tamiya Extra Thin or Tenax7. 

One tip when it comes time to cut the roof in half: cut from underneath (door frame to headliner) after you cut your top loose. That way, you'll get a perfectly straight cut.

[NOBLNG]

You can also drill and pin the A pillar to strengthen the joint.