Dumb Question? Rip vs Crosscut - Safety

[dkerfoot]

I needed to trim less than an inch off a couple boards that were roughly 2'x2'.

They each needed a smidge taken off of two ends - one with the grain and one against.

In that situation, is it dangerous to just use the sliding table or rip fence both ways (one or the other for both cuts).

I am using the Craftsman 21829 (Red BT3100 on wheels).

I understand why you wouldn't want to use the rip fence for crosscutting short, wide pieces. Does the kick-back concern apply for larger boards as well? Is the concern just a matter of the size of the cut-off, or does the grain direction somehow add to the danger? If so, how?

Thanks!

[mschrank]

First...there are no dumb questions here.

Second...in this case you are fine to use the rip fence for both cuts. Although named "rip" fence, it applies more the to size/shape of the stock rather than the grain direction.

[LCHIEN]

First...there are no dumb questions here.

Second...in this case you are fine to use the rip fence for both cuts. Although named "rip" fence, it applies more the to size/shape of the stock rather than the grain direction.

there are no dumb questions esp. when it comes to safety.

2' is going to be too much width to crosscut anyway.
As long as you have enough length along the rip fence to control the board without its wanting to yaw because of its width, you can safely rip it. I would certainly rip off one or two inches if I had a 2'x2' board to do.

Probably plywood, few real boards are 2' wide... the terms rip and crosscut don't have much to do with the grain when plywood or MDF is involved. since the former alternates grains by layer and the latter has no grain.

[dkerfoot]

Probably plywood, few real boards are 2' wide... the terms rip and crosscut don't have much to do with the grain when plywood or MDF is involved. since the former alternates grains by layer and the latter has no grain.

Doh! Of course...

It was plywood and as obvious as the answer is (now), you just brought perfect clarity to a foggy area...

I appreciate the answers. I was pretty sure I was fine either way, but sometimes it is good to double check to see what I don't know I don't know. Ya know?

Thanks!

[drumpriest]

Not to really disagree with Loring about the rip vs cross cut on plywood, but I will note here that you should look at ply's top veneer as a grain orientation. The reason is to select a good blade to make your cut. You can cut either direction nicely with an ATB high tooth count blade, but if you cross cut ply with a 24T rip blade, you'll get a lot of tear out.

You can rip ply with a rip blade and the tear out won't be too bad.

Other than that, I completely agree with these guys. Use the fence that makes you the most comfortable when making the cut. DON'T use BOTH fences at the same time.

[LCHIEN]

Not to really disagree with Loring about the rip vs cross cut on plywood, but I will note here that you should look at ply's top veneer as a grain orientation. The reason is to select a good blade to make your cut. You can cut either direction nicely with an ATB high tooth count blade, but if you cross cut ply with a 24T rip blade, you'll get a lot of tear out.

You can rip ply with a rip blade and the tear out won't be too bad.

Other than that, I completely agree with these guys. Use the fence that makes you the most comfortable when making the cut. DON'T use BOTH fences at the same time.

this is really detailed here, but yes, a plywood or lmainate blade with ATB (Alternate top bevel) teeth and lots of them will cut plywood best.

Yes, a ripping blade (like a 24-tooth) will cut WITH the top grain OK but I would only use it if you had it on the saw and IF you did not want to change it for one cut... that kind of blade is for cutting long fibers with the grain and in this case will not splinter veneer (cutting with the grain).
The overall preferred blade would be the high tooth count (60-80) ATB. THis will cut the veneer with minimal chipping in the cross grain cuts AND do the with grain cuts well, too.

[Jnam]

Just as a question but would a jonter work in this case, perhaps set to say 1/16" with each pass?

[LCHIEN]

Just as a question but would a jonter work in this case, perhaps set to say 1/16" with each pass?

well that would peel off 1/16th on each pass, he said he wanted to take off a couple of inches so that's a lot of passes. The final resolution would only be to the nearest 1/16th inch but you could make an adjustment for the last cut less than 1/16th. I think the real problem is that you may if you bear down at one end more than the other may uniformly take off more at one end than the other while still being straight... with 16 or more passes this may be quite noticable. The ripping method I would think it the fastest and the most likely to get guaranteed parallel sides!

[Russianwolf]

I have a slightly different take on crosscutting/ripping.

Ignore the grain direction. The long side of the board needs to be against a fence. Period. This gives you as much control as possible.

In your case, it doesn't matter since your piece is square, except as noted the SMT isn't designed for this size material.

[drumpriest]

Mike, that's actually exactly what we've been saying. The rest of the discussion has been about which blades to use when cutting ply. And Loring, more info is USUALLY better than less. ;-)

[JimD]

I do these sort of cuts using the rip fence even if it isn't the long side against the rip fence if the difference is not too great. My limit is intuitive rather than calculated but probably around 2 to 1. In other words, I might trim a bit off a piece two feet long and 1 foot wide by putting the 1 foot side against the rip fence. I would probably not do this with a piece 3 feet wide by 1 foot. You have to have enough of the board against the rip fence to prevent it from going into the blade at an angle or changing angle as the cut is made. The greater the ratio between the sides, the more risk you are taking of kickback.

Please do not try 2 to 1 if it makes you uncomfortable just because I said I do it. 1 to 1 is certainly safer. .7 to 1 would be even safer. I think 3 or 4 to one is clearly too much length for the length on the rip fence.

Jim