So now that I eventually got to gluing down those 3/4" 2.5" wide unfinished Brazilian Cherry planks, I'm seeing that a lot of them spring much more than I'd like. Some of them I could straighten with a tool (see below), but some just refuse to straighten no matter what effort I apply to them. Hence, gaps.

How wide the gaps may be allowed to get before they can't be hidden with the finish? (I'm planning to use Waterlox Original Satin)

About the tools - I considered the clamps from http://www.strapclamps.net/, but something in the way they're presented and sold rubs me the wrong way, so I decided to make my own contraption (made a few of them, here's the picture (too big to embed)). They work fine, but still, they'll be a drag to store between jobs (too big) and I wonder if there's anything else that does the same job (holds the rows together), but is not unique and exquisite, but is commonly sold, say, on Amazon?

Or, a simpler alternative - I wonder if a wedge made of a plank offcut, propped against a piece of plywood screwed into the subfloor next to the last row, will do the job?

If you are getting gaps between rows, you will need to snug them up before the last row. If you are close to the wall, make the rip and then use some pry bars or wedges to hold the wood until the glue sets.I would not go more than two or three feet wide before snugging up. You would need to have the glue set up before you loosen the wedges and continue. Strap clamps can tighten the flooring as you go and will hold as the glue starts to set up, so you can add another 2-3 foot wide run before re-clamping as you work across the room.

I use the strap clamps from strapclamps.com all the time, they work great. Just wondering why your not using a nailer.

Couldn't make myself do it.

I've done some things with wood over the years, and rebuilt some others (in particular, this 24x8' second floor loft framing and subfloor I'm working on now) - and grew to hate the nails as a fastening solution. Inevitably, in my mind they're associated with sloppy jobs, based on what I see.

In my woodworking, I'm using only screws, and only Torx screws unless they're not available for the size required.

I know that nails are believed to have some advantages over screws (an indisputable one is shear strength), but so far, I'm yet to have a screw fail.

No screws here (pondered about steampunk ship-like installation with brass screws or plugs for a bit, but then discarded the idea), so glue it is. I've glued some planks down already, happy with the result so far.

Well then....lol But the nailer pulls the wood together and fastens it. What ever turns your crank as my ma used to say.

Looks like my luck is different.

Got an identical looking product from Amazon (looks like a fresh new arrival, wasn't there a few days ago), and it's a dud. Take a look at the first picture below (note the above 90° angle), and you'll see that it just *can't* clamp properly - too bad I didn't see this until *after* it snapped off a plank already glued down and damaged it. Then, of course, I took another look - and turned out that all four I bought are identically inadequate.

I'll see if I can make them work with a little bit of suasion or intimidation but I think I'll send them all back, according to "vote with your dollars" principle.

Wonder if it is the same product strapclamps.com is selling, though - they're identical to smallest details I can see - compare the second picture below with the picture on the site.

Strap clamps model is very similar but the ones ihave got a curl to them so they grab around the tongue really good.