Needham, Mass. — Arms crossed, TV host Ted Reinstein stands on the set before a wooden workbench and listens closely as the producer tells him how to hold a piece of board.
Then, as the tape rolls, Ted picks it up and asks the camera, ''How do you know how to choose the right kind of wood?''
When he starts to answer his own question - ''The more you know about wood, the happier you'll be. Trust us on this'' - a forklift bearing a giant log barges onto the indoor scene, like a fugitive from a construction project.
''Wait!'' calls an off-camera voice. The scene has to be reshot.
The problem wasn't the forklift's strange intrusion. That was all part of this episode of ''The Popular Mechanics Show,'' a TV version of the 93-year-old - and by now almost legendary - American magazine. Something else had interfered, a minor problem with a camera angle or the placement of props.
Several other aborted attempts are made to shoot the scene, being taped at Channel 5 in Needham, Mass. Each take is cued with a wave of red cloth tied to the end of a pole, and each one is torpedoed by some pesky detail.
The mishaps are examples of the myriad problems that come with a show of this kind. Each program has eight to 10 segments. That's a lot of detail - some 50 separate elements per show. Thousands of details have to be right. After all, this is the TV version of a magazine that over the decades has appealed not only to the layman but to the hardcore Yankee tinkerer and the hands-on householder as well.
The new daily series, premiering Sept. 25 on the Discovery Channel, has a big stake in getting things right: ''The Popular Mechanics Show'' is a demographically venturesome plunge into daytime TV - specifically late afternoon. According to ratings, that's largely female territory. The producers are hoping a show full of gadgets and an exploration of how things work can become ''daytime for men,'' adding a hefty male component to a traditionally female viewership.
''The Discovery Channel has a predominantly male audience in the evening,'' says series producer Andy Schulman. ''Here is a show that can bridge over'' to the daytime. He describes two focus groups they convened to test audience reaction to the TV version of the popular magazine. ''The nonsubscribers liked almost everything,'' he recounts. ''The subscribers liked it, but also wanted more,'' because they knew some of the magazine resources were not being tapped. This told the producers there were two audiences out there, and as a result they cover more items in greater depth than originally planned.
But will it succeed?
Jon Hughes, a professor of English and journalism at the University of Cincinnati, says he often reads the magazine and thinks, ''A lot of what 'Popular Mechanics' does is very visual and could be converted to television quite well.''
If he's right, one of the reasons will be host Reinstein. He must preserve lightness and humor amid the minute-by-minute minutiae, making sure he and the experts don't appear to be taking it all too seriously. And so far he seems to be doing just that.
As the ''intruding'' forklift operator jumped off the vehicle to join Reinstein at the workbench, for instance, Reinstein quipped, ''Got a driver's license for that thing?''
He must also know how to ask obvious questions that represent viewers' ignorance. ''I see my role as Mr. Curious on the show,'' he said after the morning's shoot. ''We have experts who can lay wood floors, make your lawn green, fix a computer. I'm the person who says 'I have the broken computer, I need my disposal fixed.' ''
What's Reinstein's biggest challenge as host? ''It's the breadth,'' he says, ''having to deal with so many different aspects - people, location, production elements.''
This series will offer much more than how-to advice - available elsewhere on TV. It combines science, do-it-yourself, and a nonstop quest into the mystery of everyday objects - the mechanics of a golf swing, how to charter a fishing boat, the science of roller-coaster design. Each show has one major cover story. One recurring segment, ''How It Works,'' explains how everyday things operate, such as a garbage disposal.''
Reflecting this broad reach, the set includes several ''home bases'': a kitchen, a garage shop, a family room with a home entertainment center, and an outdoor deck.
The magazine is a jumping off point for the show's material. ''We use the magazine ... to give us general ideas for subject matter and how to approach them,'' says Bruce Marson, vice president and general manager of Hearst Broadcasting Productions, coproducers of the series with Discovery. ''But we're not going back into old issues and making television segments. All the segments we do will be fresh material.''
But none of it, Mr. Marson says, can replace the magazine. ''Video can catch people's interest,'' he says, ''But it will never replace the printed page for ease of use and convenience and for depth and detail. In the print magazine you can actually see the blueprint and sit and study it. On TV it just goes by. It's two different approaches.''