roof trusses....I just would like to know.....

[clogs]

I bought a few of those spikey nail plates used in the manuf of roof trusses.....
never manage to get them to sink in the wood and look nice.....I was using a heavy steel plate 20kg and a lump hammer.....
what do the factories use.....? some kind of hydraulic movable press...but sound like a nightmare to use and cant be right.....

I have some smaller trusses to make for a job at home and as before I will use triang or shapes plates made from qual 1/2" ply ..
with screws and resin glue...they have never failed before.....

looked occ on You Tube but with no real succ.....
I would just like to know....

 

[AJB Temple]

Fink trusses (awful things IMO) are frequently made with toothed plates, and they are pressed simultaneously from both sides with a hydraulic press tool. I have seen them being made. I imagine there are versions that can be fitted using a hammer. I think the hydraulic ones push the teeth out through the gaps at the same time. Think garlic press. However, I wasn't really paying close attention.

PS: Other truss designs are available. I just saw Fink being made.

 

[Jelly]

I was using a heavy steel plate 20kg and a lump hammer.....

I have, somewhere a gigantic wooden mallet intended for setting them in place manually, face is bigger than the nail plate, handle about 3ft long, must weigh a good 5-6kg (10-12lb)

That's just to firmly seat them on the truss mind, and would not normally be used to fully drive them (which would require quite a few blows) in a production environment.

what do the factories use.....? some kind of hydraulic movable press...but sound like a nightmare to use and cant be right.....

Almost.

The presses are movable, but only as an integral part of a large jigs which are permanently mounted in the factory, and allow the presses to be slid in and out to accommodate different sizes of truss.

The workflow is almost offensively efficient, and goes something like:

• Set the jig,
• Put the bottom nail plates in,
• Load the pre-cut timbers on top,
• Put the top nail plates on,
• Seat plates with the huge mallet,
• Pull the platens of the hydraulic presses over the plates,
• Lock in place,
• Everyone step away,
• Push the button and wait few seconds,
• Ta Da! All nail plates driven in a predictable and repeatable way,
• Lift truss out with overhead crane and move to storage.

Which is very convenient in mass production, but wildly impractical for any other setting.



I would suspect that to drive the plates effectively by hand, your lump hammer is not nearly generating enough force, and possibly doesn't distribute the force widely enough to drive the plate evenly.

Standing the bottom nail plate on your steel plate, then putting a log with a good flat surface on the top nail plate and hitting it with a full swing from a heavy (say 10kg) sledgehammer might do the trick.

Alternatively, a big dead-blow sledge might do the trick, something like this behemoth from Bahco.

 

[owen]

They always amaze me with how strong they are especially because the spikes are so short. Another alternative is to use nail plates with loads of twist nails.

 

[RichardG]

As a one off I have managed to put a pair in using a G cramp, you have to work your way over the plate gradually squeezing them in. Fine for a one off repair but hopeless for anything else.

 

[clogs]

thanks for the imput.....

 

[Jelly]

As a one off I have managed to put a pair in using a G cramp, you have to work your way over the plate gradually squeezing them in. Fine for a one off repair but hopeless for anything else.

Hadn't thought of that, but it's a cracking idea.

Given Frank has at least one big steel plate already, if he has a second one, then using 3 or 4 G-cramps (or 1 really large g-cramp which is well centered) compressing two steel plates together would probably work and take less time & effort.