Okay here is what I feel must be the stupid question of the decade but I am having nothing but problems at the moment.

As the login implies I am a bit crazed at times and this post will no doubt exhibit that.

I am installing a glue down solid hardwood floor. Using Bostik's Best and the other appropriate Bostik products.

I have installed a large section of herringbone through the formal dining and living area.

Trying to go back now and square up the area with a circular saw. Seemes like a good plan then install the border around it and finish off the rest of the room to the walls.

Problem is in cutting a bloody straight line. I have a straight edge that is more than straight enough for the distance. I can secure said straight edge well enough also. Yet every time I make the cut using a circular saw I end up with a wave to the cut. At first I thought it was the straight edge so I went though and double checked all of that I reset it and then made yet another slightly wavy cut.

Then I tried a few other things including a lot of vocabulary not needed here.

Last thing I have done is falling to last resorts I grabbed a blade stiffener from my table saw and said it must be the blade flexing. Well I added a 5 inch stiffener to a 7 1/4 inch circular saw and I still seem to be getting a wave. It is not as bad as it was but it is there.

HELP!!!! What the heck am I doing wrong, or should I just rip everything up and have carpet put down and sell all my tools since I seem to be an idiot with them at the moment.

Thanks for any help

Sounds to me like the herringbone isn't flat. If you run the circular saw across the area and it's "bumpy" from one board to the next, it will throw off the angle of the cut.

That could be the problem. If that's the case the saw would need to run on top of a guide rail like the Festool setup. You are not bumping into overwood that way. They return top dollar on eBay.

Not using a festool but a similar type of guide rail from eurekazone.

And to prevent chip out I have put 1/8 hardboard or masonite depending on what you like to call it on top of the cut.

I was thinking that would help with keeping things pretty well flat and consistant rather than the potential bumps or cathing for whatever reason on the board bevels.

This is the guide rail I am using
http://www.eurekazone.com/products/detail/sgs.html

Maybe it's your saw. Only quality pro models will make good cuts. Also, I know on the east coast, many like those sidewinders but for me, a worm drive is the way to go for power and control. If all else fails, use a GOOD router and a carbide dado/rabbeting bit. The way I do it is to chalk a line where I want to cut. Then measure back for the base offset (2.5" or so usually) and attach a wood straight edge to the floor. Then follow the straight edge with a router. You can only take about 1/4" max per pass. It's slow, messy but it won't chip the surface either. When I must make the very best cut, this is my prefered method.

So I guess I am not sure what level the saw is but it is a Milwaukee Heavy Duty Adjustable Tilt Lock. Which I seem to remember spending a fair amount for it (135+ but it has been 6 years or more so no bets on my memory), not that that indicates quality but it to me at least gets it to a reasonable category. It is not a worm drive and for most of what I do it seemed at the time a worm drive was a bit overkill.

I have also tried the router plan some and was getting chip out. Was using a solid carbide spiral bit, of which as I write this I may be using the upcut bit rather than a down cut bit, and was more concerned on that tool since the guide I have I would be running against and not on top of so the potential lack of flatness on the herringbone may come into play. I guess I could add the hard board on top to flatten things a bit, and maybe help on the tear out.

What are you useing for a strait edge ?

Ealier post has the link to eurekazone.com

The saw guide they have is what I am using.

Roughly 6 inch wide extruded aluminum track with the adapter plate to go on the saw.

OK, here's the deal. That Milwalkee saw should be fine. I suggest it is your "straight edge" gizmo. I'd get rid of that and do this. Sand flat/flush the area you want to saw/trim. Doesn't have to be prefect, you just don't want to try cutting an uneven floor. Now using a chalk line, line out exactly where you want to cut. Then measure back the off set from the blade to the side of you circular saw base. Everyone's different. Just let's say it's 3.5". Then snap an additional line where you are going to attach a wood fence guide. Using 1"x3" pine boards for the fence/straight edge, finish nail them (the fence boards) SECURELY into the floor on the fence chalk line. You don't need lots of nails; you just need to have you fence board straight, free of any movement with a good egde to follow on. Since you're using a sindwinder saw, the motor needs to be on the opposite side of the fence (so you can see what you are doing) and you should be cutting on the outside of the border and the fence sits toward the field. Using a GOOD blade, simply follow the straight edge with your saw. This should be easy. If you are getting wavy cuts, it's because you are not keeping the saw base flush to the straight edge. Also, I suggest not tying to cut all the way through at first. You are over concrete. As the blade hits the concrete, it dulls it rapidly. So, cut about 5/8" through then after all the trimming is done, go back and and finish this cut. By the time you're done, the blade will be toast. This is all I can think of and how I would do it. If the saw didn't work, then try the router. If that's not working, may I suggest hiring someone to do that part because you may not have the skill to make the cut.

Something else I might add. Some of the thin kerf saw blades can deflect a bit when you push them too hard/cut too fast. Get the thickest 40 tooth you can find.

On getting rid of the straight edge that is okay in that I can use it as the "pine board" I guess. The challenge with the rest of the solution is the floor I am installing is prefinished and is a glue down so it is not one I can just go sand flat.

The blade is one I have thought about while travelling for work this week and was thinking that getting a new blade would be of relevance in case I had killed the one on there and also going through making a couple of passes with the saw rather than trying to go through the whole thing at once. The wood is very dense and it may indeed be the thin kerf is having a challenge, but I was hoping that the blade stiffener there would eliminate any flex in the blade.

Other option is just going with the router routine, I have tried with a spiral bit but on the other hand the bit may not be the best of choice and was also an upcut spiral rather than a downcut.

Now I just need to get home and actually try some of this, but that doesnt happen till Saturday.

If you could post some pictures, it would really help us to help you...

Well after a week of travel and the frustration of not being able to try anything, it would seem the answer was pretty simple.

A standard to thick kerf blade using everything else the way it was with saw and straight edge being used as intended, not thrown away, and I have a very straight line.

Replaced the Frued Diablo thin kerf (.043) with a Tenryu 60t plasti cut blade (.058). Not the ideal rake angle and such but still an ATB on the plasti cut and what was available on short notice.

Thank you to everyone that posted comments and suggestions.