Cutting plywood sheets with table saw


Niku

Recommended Posts

I recently used a sheet of plywood to build a box. While the box is sturdy enough, it's not something that I'm proud of. There are just too many gaps (1/8"-1/4") at the joints..  These gaps were caused because the plywood pieces used to make the box don't have uniform dimensions. The pieces are not uniform because my table saw wouldn't stay "on track." By this I mean that while using the saw, I kept noticing that the sheet of plywood kept drifting away from the guard/rail on the right side. No matter how hard I pushed the sheet towards the blade, it kept moving away from the line I had intended to be cut. The result was that the lengths of two parallel sides of the same completed panel sometimes varied by as much as 1/4" or more. I hope I've made myself clear, but let's just say that the dimensions of one of the  completed panels are: 28-11/32" & 28-14/32 (7/16)" and 18-8/32 (1/4)"& 18-12/32 (3/8)".

Now that I look at the measurements, the differences seem trivial, and I think that I might be too fussy. However, when I look at the gaps, they don't seem trivial; they seem unacceptable. Anyway, I want to do better in the future. Are there attachments for table saws that keep sheets of plywood from drifting off the chosen path? Some say that you should not try to cut plywood sheets with a table saw. Are they right?

Link to comment
Share on other sites

When dealing with full sheets I try to not to. If I'm ripping the full length,  I'll leave about a blade width on and make another pass on the saw with feather boards to hold it straight and eliminate any burning.  I would love to not have to cut plywood on the table saw but until I get a track saw,  that is the best finishing edge.

As far as devices,  feather boards and board buddies are helpful to keep something against the fence buy you can still make it wonky if you don't push it through straight. 

Link to comment
Share on other sites

C Shaffer,

That's not very helpful. I hope others have different ideas.I might add that when I started looking into this, almost everyone said that you should NOT use a table saw to cut up a 4x8 sheet of plywood. I thought that was the reason for my poor quality box, but then I started seeing some people who said that you shouldn't use a circular saw for this purpose, that the saw of choice was a TABLE SAW. I hope someone here can come up with a logical tie-breaker. [MOST say not to use a table saw]

Brendon_T,

Thanks for the tips. I'm going to check-out what you suggested. I had never heard of buddy boards, but the list of things I've never heard of is a long one.

 

Link to comment
Share on other sites

They're really isn't a most here.  Everyone is set up differently.  If your full size saw is a sort of island with plenty of support front, back and side,  there is no issue I can see.

For those of us who don't have 10' in front and behind the blade,  another option is needed.  Whats best for one isn't best for all.  

Link to comment
Share on other sites

Those differences are far from trivial & you are not being too fussy. you should expect the error to be maybe1/128" or less on a cut. If your table saw is properly dialed with a good fence & good technique, you should be able to cut them dead on. Brendon's tip of cutting oversize & then doing a final trim is a good one, especially if you're dealing with full sheets. 

What kind of saw & fence do you have?

Link to comment
Share on other sites

Shaneymack, 

 

It must have a name. What is it?

drzaius,

I don't know what kind of fence I have, but it came with my Ryobi portable 10" power saw. I'm glad that you used the word, "fence." I can now more adequately explain the problem. I try to keep the wood pressed against the fence (natually), but the piece of wood keeps being pushed  away, and I'm not capable of resisting the force. I don't understand how that force is being generated, but it's there. Finally, the idea of making two cuts instead of one sounds good to me. I had plenty of room to do that, but I just hadn't expected a problem. That will probably solve the problem; in fact, I'm going to build another box tomorrow to see how I do. Thanks.

Link to comment
Share on other sites

Niku, what Shane posted is a track saw.  The fence on the ryobi saw is notorious for not locking down and not staying locked.  Some of your issues may be technique, but really you shouldn't be pushing a full sized sheet through that saw.  Rough cut with a circular saw and homemade guide, then finish with the table saw is best.  

  • Like 2
Link to comment
Share on other sites

Woodenskye,

Thanks. That sounds like good advice to me, even though I don't like circular saws. The truth is, I'm sort of afraid of them. Too much power. Too much noise. One slip and....  However, smaller circular saws might be the answer. I have a battery-operated 6-1/2" circular saw, but it has insufficient power. Maybe a 6'1/2" or smaller with a lithium battery would be the right answer for me. Anyway, thanks again. 

Keggers, 

The only problem with that is that some of the workers at Home Depot (my supplier) have demonstrated their inability with such things. I have to really keep my eye on them to make sure that they don't cut the wood in such a way that there is too much wastage. They always seem to forget the thickness of the blade has to be taken into consideration. . 

 

Link to comment
Share on other sites

Shaneymack, 

 

It must have a name. What is it?

drzaius,

I don't know what kind of fence I have, but it came with my Ryobi portable 10" power saw. I'm glad that you used the word, "fence." I can now more adequately explain the problem. I try to keep the wood pressed against the fence (natually), but the piece of wood keeps being pushed  away, and I'm not capable of resisting the force. I don't understand how that force is being generated, but it's there. Finally, the idea of making two cuts instead of one sounds good to me. I had plenty of room to do that, but I just hadn't expected a problem. That will probably solve the problem; in fact, I'm going to build another box tomorrow to see how I do. Thanks.

Yeah, like Bryan mentioned, it's a track saw. Get one and come back here and thank me. Your life will be instantly better. You will be smiling like a goofy teenager his first time with a girl. Its that good. Forget the tablesaw for breaking down sheet goods.

Sent from my SM-N910W8 using Tapatalk

Link to comment
Share on other sites

drzaius,

Why is it necessary to make a guide? Can't you just clamp any piece of straight material to the plywood sheet as a guide? You could call this "making a guide," but I don't think that's what you had in mind.

Shaneymack,

Well, there is the matter of cost to consider, but I'll check on track saws. Incidentally, now that I know what a feather board is I don't see how it would helping in breaking down a 4x8 panel. It would be useful with smaller pieces but not for the whole panel. 

I might be wrong. Correct me if I am. It's just that I don't think you can use a featherboard if the sheet of plywood is larger than the table saw surface/top. Those names don't sound quite right, but I think you understand what I'm referring to.

Link to comment
Share on other sites

12 minutes ago, Niku said:

drzaius,

Why is it necessary to make a guide? Can't you just clamp any piece of straight material to the plywood sheet as a guide? You could call this "making a guide," but I don't think that's what you had in mind.

You can do that, but if you make a guide to fit your saw, then you don't have to calculate the difference between the blade & edge of the plate. Just makes it much easier & you'll find it very handy to have.

Link to comment
Share on other sites

Woodenskye,

even though I don't like circular saws. The truth is, I'm sort of afraid of them. Too much power. Too much noise. One slip and....  

 

Another good reason to get a track saw. The blade is not exposed. It is a plunge saw. Super safe. Mark the lines on your board, sit the track on the lines, push the trigger, push the blade down into the work and slide it slowly along the track. Some models (festool) even have a riving knife to prevent the blade front pinching and causing a kickback. If you can afford it, go this route. Some people claim being able to get rid of their tablesaws once they bought a track saw. Myself, never in a million years but the tracksaw is an awesome compliment.

Sent from my SM-N910W8 using Tapatalk

  • Like 1
Link to comment
Share on other sites

2 hours ago, Niku said:

C Shaffer,

That's not very helpful. I hope others have different ideas.I might add that when I started looking into this, almost everyone said that you should NOT use a table saw to cut up a 4x8 sheet of plywood. I thought that was the reason for my poor quality box, but then I started seeing some people who said that you shouldn't use a circular saw for this purpose, that the saw of choice was a TABLE SAW. I hope someone here can come jump with a logical tie-breaker. [MOST say not to use a table saw]

I gave you three things to check. Not sure how that is unhelpful. If your saw is not heavy enough, you will struggle. If you do not have enough of the sheet supported, you will struggle. Glue is hard on blades and dull blades often deflect. Work can "pull away" from the fence if the fence is or can be pushed out of square. 

  • Like 1
Link to comment
Share on other sites

drzaius,

I think you're talking about something I had thought about doing but gave up because of lack of enough skill to to it: attaching something  to the saw that would enable me to position the blade where I want it to be. It seems as if you could just line up the blade by eye with the cut you want to make, but I haven't found that to be as easy as it sounds. There is, of course, a guide already attached to the saw, but I haven't found  it to be as useful as it should be. All that is needed is a better built-in guide. The ones that come with the saws are mysteriously crude and unsatisfactory. I could build a better one if I had the metalworking skills.

Link to comment
Share on other sites

The tablesaw, especially a portable Ryobi, is much more dangerous than a standard circular saw.  That is amplified when you try to force wood through, and is amplified more when that wood is a full sheet that is hard to control.

Grizzly has a cheap track saw package that is fairly well reviewed.  I think it even has a riving knife.  

After reading your last post, I think you need to go to YouTube and find some tablesaw safety and familiarization videos.

Link to comment
Share on other sites

2 hours ago, Niku said:

drzaius,

I think you're talking about something I had thought about doing but gave up because of lack of enough skill to to it: attaching something  to the saw that would enable me to position the blade where I want it to be. It seems as if you could just line up the blade by eye with the cut you want to make, but I haven't found that to be as easy as it sounds. There is, of course, a guide already attached to the saw, but I haven't found  it to be as useful as it should be. All that is needed is a better built-in guide. The ones that come with the saws are mysteriously crude and unsatisfactory. I could build a better one if I had the metalworking skills.

search youtube for circular saw guide & there will be many examples of various guides you can make. The kind I'm talking about is a crosscut or rip guide. Easy to make.

  • Like 1
Link to comment
Share on other sites

I'm personally not super keen on the home made track for a circular saw.I have two different saws, and  I have two guides and even using the blade to cut it to zero clearance,  the cut quality is still garbage you have to constantly maintain downward and sideways pressure across or along a 48" or 100" cut.. maybe it's my lack of dexterity but I don't think it's anywhere near as good as what you try to mimic. 

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.