Beginner Questionaire for JN1C3 #3: Sizing down Plywood

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Blog entry by Jason™ posted 09-16-2012 09:37 PM 3260 reads 0 times favorited 18 comments Add to Favorites Watch
« Part 2: Beginner Questionaire for JN1C3 #2: Part 3 of Beginner Questionaire for JN1C3 series no next part

Hello again everyone I would like to ask another question on here since all the previous ones I have asked were answered and now I understand what I was doing wrong or what the case was.

I am currently gathering materials needed to build a TableSaw Workstation that can be seen in the Shopnotes issue #89

The question for this series is what are some of your ways of cutting down large sheets of plywood or MDF and getting them squared up?? “Using a Benchtop size Table saw” I DID NOT CUT A FULL SHEET OF PLYWOOD ON MY SMALL TABLE SAW!!
When I built my crosscut sled I now understand what I did wrong with this one, I made it too small!!
It does however do really well at squaring up smaller pieces!

I would like to know what techniques I could consider in gettin my pieces to size without wasting to much materials. You could say that I am copying a design from off of here that a certain lumberjock did in a blog style post on here with complete sketchup pics,designs,cut list,materials list, the whole 9!!!

Can be seen here:

To practice I bought a sheet of OSB “for practice”. Along with 2 sheets of MDF and a sheet of Plywood all 3/4”. The OSB was really cheap and I wanted to work with it first to practice and make sure I could perfom well on this and not just start into a $40 sheet of MDF.

I also don’t currently have a circular saw to cut it to manageable size to work on my saw. I used a jig saw on the sheet of osb to cut into 3 pieces. Then when I tried to start cutting on my table saw I could not find a way to get a straight edge to start with. I did however try using a jointer style fence attachment on my table saw but I really dont think that this worked that well. This was pretty much a piece of MDF as a sacrificial fence attached to rip fence and then adding a 1/4” piece positioned at the rear part of the blade back to the end of the MDF fence. I really think I just need to make a panel sled but I didn’t really wanna use more materials that I don’t have to do this. But this might be the answer I need who knows.

Well I hope you all can understand my gibberish on this problem.
All ideas,comments welcome and also negative ones as well. (Someboby telling me im hopeless and theres nothing I can do might be the answer who know)

Thanks guys for reading and I hope to hear what you have to say!!!

18 comments so far

View taoist's profile


124 posts in 3550 days

#1 posted 09-16-2012 11:20 PM

Cutting down full sheets(4×8) on a table saw is dangerous, a pain, and an inexact science since you have to have a fence that absolutely will not move and you have to push the stock up against the fence and forward at the same time.
Years ago the wife bought me a Ryobi (circular) skill saw for $35.00 on sale at Home Depot. The only thing it really gets used for is cutting down 4×8 sheets of stock. I also bought a 2 piece aluminum extrusion fence that i can clamp to the stock to use as a guide for the skill saw at HD for $30.00. When the 2 pieces are joined together it is 98” long and each piece is like 49”. You could just as well use a small 4” wide strip of plywood for the skill saw fence and have a 50” piece and a 96” piece. You can measure the diagonals for square on a full piece of plywood and cut it to square up if it isn’t. I think you are making it harder than it has to be.

View Woodmaster1's profile


1709 posts in 3646 days

#2 posted 09-16-2012 11:27 PM

Try renting or borrowing a circular saw. If you lived near me I would give you one. A circular saw would be the best way. Did you use a straight edge with the jig saw?

View camps764's profile


867 posts in 3419 days

#3 posted 09-16-2012 11:56 PM

Agree on the circular saw. You don’t need a big expensive saw, just something that you can use occassionally.

Also, Harbor Freight has clamp on straight edge guides, work great for circular saws and breaking down big sheets of plywood. I picked up a 50” guide the other day for $22.

Visit some pawn shops, I guarantee you can get a circular saw for dirt cheap.

-- Steve

View Nicky's profile


711 posts in 5151 days

#4 posted 09-17-2012 12:04 AM

I use a circular saw; an old skill saw. Taoist ’s suggestions for using a nice straight edge makes this process quick and easy. Cutting a 4×8 sheet down on the tablesaw is difficult at best. When I know what I need I’ll have the lumber yard rough cut and do the final on the tablesaw. An alternative is making a strait edge your self, see for an idea.

-- Nicky

View Jason™'s profile


87 posts in 3186 days

#5 posted 09-17-2012 12:13 AM

So everyone is suggesting and applying the same message to me that I need a circular saw and yes I DO!!!
But I cut the sheet down to manage able sizes and began to try and get a few pieces to the actual size needed like 23×23 and 23×30 3/4 but it seemed like I could not get a nice straight even looking panel.

The main question I had was how to take a wavy chopped looking edge of a board that was achieved with a jig saw and get it back to straight on my tablesaw?!?

@Woodmaster = I think if I used a straight edge on a jig saw it would break the blade!

View jeff_wenz's profile


152 posts in 4609 days

#6 posted 09-17-2012 12:32 AM

I use a circular saw. I have piece of 4×8’ foam insulation (from Lowes) that I lay on my driveway, then lay the plywood on it and cut using a straight edge to guide the saw. I set the blade depth so it it just a little deeper than the plywood thickness. If the cut is going to be a fininshed edge, I use blue painters tape on the plywood cut line to help prevent chipout.

A decent blade for the saw helps prevent chip out, too.

-- Jeff, North Carolina

View Grumpymike's profile


2480 posts in 3374 days

#7 posted 09-17-2012 01:37 AM

Like everyone else here I use a circuler and a streight edge … place your streight edge so that the bottom of the saw rides up against the streight edge and rip out your pieces. with a bit of practice (two cuts maybe) you will be cutting as streight as the tablesaw … no wavy edges.
for the existing wavy edge, use the factory edge against the fence and rip your new line.

-- Grumpy old guy, and lookin' good Doin' it. ... Surprise Az.

View tsangell's profile


216 posts in 3752 days

#8 posted 09-17-2012 01:50 AM

You can also take a board that is straight and screw it along the wavy edge. That will lit you rip the opposite edge straight, for a start. After taking off the screwed on guide, you can then rip the workpiece to width. Use double-sided tape if you don’t want the screw holes.

View taoist's profile


124 posts in 3550 days

#9 posted 09-17-2012 02:27 AM

Have you made sure that your table saw fence is parallel to the blade(usually done with a micrometer or a dial gauge) and that your miter gauge is 90 degrees to the blade ? Those are the first steps to setting up a table saw. If you want square you must do these first.
Woodmaster is suggesting that you use a guide for the jig saw shoe to ride up against and thus keep the cut going straight.

View Jason™'s profile


87 posts in 3186 days

#10 posted 09-17-2012 02:50 AM

Yea I understand what he is saying. I did try that when I had the full sheet laying. A long board up parallel to my line for the side of the jigsaw to ride against to get a straight line and it cause the blade to bend really bad. This didn’t work out for me at all!! Also if I don’t have a factory edge at all? What should I do? Then what do you consider Mike?

View taoist's profile


124 posts in 3550 days

#11 posted 09-17-2012 03:30 AM

Sounds like you are trying to guide the jig saw rather than let the saw run along the guide you have attached to the plywood. Measure the distance from the side of the jig saw blade to the same side of the jig saw shoe and attach a straight board at that distance from where a straight line is needed to cure the curvy line. Then carefully start the jig saw with it pressed against the straight board guide. If you let it run straight, there should be no blade bending. As for a straight factory edge, you need a board that you know is straight and attach it to the wood and then run it through your table saw, if it is already squared up. A speed square isn’t perfect but will get you close when you are squaring up your table saw and a tape measure will help you find a straight board. when you go to the lumber yard you can get 1”x stock that is pretty square and straight if you sight it before you buy. Look down the edges to make sure there are no crowns or dips in the edges.

View americancanuck's profile


474 posts in 3669 days

#12 posted 09-17-2012 09:53 AM

I recently purchased and posted a review of the Kerg rip cut circular saw guide. I have used it extensively and find it incredibable!! I can now cut peices from a full sheet right to size in half the time it would have taken with a straight edge guide. The price is under $35.00 and will work with any circular saw. for about $75.00 you could save much more than that in wasted wood when cuts are not straight or square.

-- Retired and lovin it

View oldretiredjim's profile


206 posts in 3444 days

#13 posted 09-17-2012 04:23 PM

circular saw with 1 1/2” aluminum angle and clamps. I have a 4’ and 8’ piece of angle depending on what I am doing. If you are careful you get pretty straight edges. I can’t imagine doing it any other way.

View Bsmith's profile


330 posts in 3729 days

#14 posted 09-17-2012 06:05 PM

Sounds like you’re not having problems getting it to size, it’s getting it square afterwards. If that is the problem and you’re try to cut 2×2 squares that shouldn’t be a problem with a bench top table saw. First question, what type of fence are you using on your table saw? Start with your smaller piece that has two factor edges and place one factor edge against the fence and make a cut just larger than finished project. Rotate clockwise to the second factor edge and make a cut just slightly larger than needed. Rotate clockwise now to to your first cut edge and cut to demension. Rotate one last time and cut to desired size. Check for square, set back and marvel at your achievments. If this isn’t the problem disregard. Good luck.

-- Bryan

View tsangell's profile


216 posts in 3752 days

#15 posted 09-17-2012 08:33 PM

Something like this, courtesy of Wood:

Reference edge for ripping.

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