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Cutting plywood into 12 inch strips

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Forum topic by Hubert48 posted 01-02-2017 02:52 PM 1335 views 0 times favorited 11 replies Add to Favorites Watch
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Hubert48

2 posts in 349 days


01-02-2017 02:52 PM

Hi all. I am brand new to the woodworking game. I am afraid I may have bitten off more than I can chew white the project I promised my sister I could build for her.

To make her cabinet I need to cut sheets of plywood into 12 inch strips 8 feet long. I have had numerous people tell me not to put full sheets on the table saw, which is fine, because I don’t have one.

I started with a wooden straight edge, but it would flex and my cuts bowed in the middle. I upgraded to an aluminum straight edge which helped, but I am now having trouble getting each cut the exact same width. Please help.


11 replies so far

View gwilki's profile

gwilki

170 posts in 1312 days


#1 posted 01-02-2017 03:12 PM

Hubert: You should not have any problem using a straight edge of any material, so long as it is rigid and well clamped. I’m assuming your are using a circular saw. Is that correct? If you are using a jig saw, you can use the same process, but they are more subject to rough cuts because of blade distortion.

The key is to go slow and pay close attention to making sure that the saw stays against the straight edge. This is especially true with a jig saw. Using the right blade will help a lot, too.

You can buy carriers that attach to your saw and that ride on or over a straight edge. These take all the “work” out of making sure the saw stays right to the straight edge. You can make them, too, but since you say you are very new to this, you may not have the tools you need to make them.

If you provide some more info on the kind of saw you are using, I may be able to help more and I’m sure others here will, too.

-- Grant Wilkinson, Ottawa ON

View knotscott's profile

knotscott

7788 posts in 3214 days


#2 posted 01-02-2017 03:15 PM

Most sheet good suppliers will cut down full sheets to manageable sizes for little to no cost. Accuracy is not their strong suit though…they’re usually within an 1/8” or so.

It is possible to cut full sheets on a full size saw, but it’s easier to have the supplier cut them to smaller sizes first. If you plan to stick with woodworking, I’d consider getting a decent table saw. Then you can still have the sheet good supplier cut full sheets to rough size, then you can cut the pieces precisely on your TS.

-- Happiness is like wetting your pants...everyone can see it, but only you can feel the warmth....

View HorizontalMike's profile

HorizontalMike

7661 posts in 2753 days


#3 posted 01-02-2017 03:16 PM

Another option you may have not thought of is using your Big Box store’s panel saw. I have been know to use HD’s panel saw to cut 4×8’ sheets in half (to make it easier for me to use my own TS. I would imagine that they could do just what you need. They might charge you for the additional cuts, but that would be nominal. Just a suggestion…

-- HorizontalMike -- "Woodpeckers understand..."

View jtp79's profile

jtp79

32 posts in 372 days


#4 posted 01-02-2017 03:20 PM

Kreg makes an attachment called rip cut or something that goes on your skill saw. Works very well up to a certain width. I believe it adjust out to 20 inches or so.

View JBrow's profile

JBrow

1274 posts in 759 days


#5 posted 01-02-2017 06:10 PM

Hubert48,

It sounds as if the plywood is not well supported during the cuts. An option would be to purchase a piece of 4’ x 8’ Styrofoam insulating board at the home center. The foam board can be placed on the floor and the plywood on top of the foam board would be fully supported. The circular saw blade depth set to cut through the plywood would keep the foam board in good shape for quite a few future projects.

A method for ensuring the width of each ripped strip of plywood is identical is to make a pair of gauge blocks. The gauge block would be a piece of scrap wood with a second piece of wood screwed to the first to form a lip (the shape of an L). The L end of the gauge block would lock on the edge of the plywood and the opposite end of the gauge block would contact the edge of the straight edge guide. The length of the long leg of the L of the gauge block would determine the width of the plywood strips. Maybe the sketch can clarify my description…

View tomsteve's profile

tomsteve

667 posts in 1058 days


#6 posted 01-02-2017 06:43 PM

you haven’t bitten off more than you can chew.
ya just picked a project that youre going to learn skills on.

View clin's profile

clin

751 posts in 835 days


#7 posted 01-02-2017 07:22 PM

JBrow nailed it. Many ways to skin this cat, but his would work well for you with minimal additional investment. Homemade gauge blocks are cheap.

I’ve used the foam board on the driveway technique for awhile now. Used to use saw horses. The foam board technique is so much better. As JBrow said, the plywood is fully support. Just cut into the foam a bit. I use a pair of 2’x8’ foam pieces. Two pieces store easier for me. You can make a lot of cuts before the foam needs replacing.

-- Clin

View rwe2156's profile

rwe2156

2716 posts in 1319 days


#8 posted 01-02-2017 08:19 PM

Hubert,

First off, if the plywood is 3/4 is shouldn’t be bowing that much unless you’ve only got support on the ends.

I routinely rip full sheets of ply on the tablesaw with no problems. The reason people do not like to do this is they are either scared or don’t know how to do it properly/safely. There’s definitely a technique to cutting ply on a TS. Basically you always feed with diagonal pressure toward the fence. You stand at the corner of the sheet and feed always watching the fence/ply contact, never the blade. You never cut a board with the narrow edge along the fence, you use a panel cutting sled. You also need an outfeed table.

The simplest way for a novice is to use a circ saw, a good blade and a straight edge. Any of the suggestions e.g. foam sheet, etc will work. Personally, I don’t like crawling around on the ground, so I use sawhorses and support the wood with 2×4’s.

One option is to break the piece in half with the circ saw, then use your TS.

FYI, if you cut a full 12” you will only get 3 pieces from a sheet, so make them something like 11 1/2 to account for blade kerf.

I really like a 40 tooth Diablo blade you will get a nice clean cut.

-- Everything is a prototype thats why its one of a kind!!

View Hubert48's profile

Hubert48

2 posts in 349 days


#9 posted 01-03-2017 03:04 AM

Thanks guys.

I am using a 7.5 in makita cordless circ saw with a 40 tooth diablo blade.

Since my original post I dug out the Kreg “Rip Cut that somebody bought for me a year ago, but I’m still not getting the results I need.

I have been using foam board that I glued to a sheet of OSB on saw horses from the start.

The gauge block idea sound like a real winner. Gonna try that tomorrow. Thanks for the help.

View JoeinGa's profile

JoeinGa

7724 posts in 1846 days


#10 posted 01-03-2017 01:53 PM

For cutting plywood you might consider getting a blade that has more then 40 teeth. You’ll get a cleaner cut with less tearout.

-- Perform A Random Act Of Kindness Today ... Pay It Forward

View lndfilwiz's profile

lndfilwiz

96 posts in 1439 days


#11 posted 01-03-2017 04:01 PM

http://www.factoryauthorizedoutlet.com/kreg/kreg-rip-cut-circular-saw-guide

-- Smile, it makes people wander what you are up to.

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