Ripping Plywood

[Mountie]

Hi to all,

First of all let me apologize if this isn't in the right forum....I have 5 sheets of 4x8 birch plywood that I have to rip into strips 8' x 11 7/8ths" wide. I just bought two Rigid flip-top work stands and have a third roller stand for support..my question is, What's the best way to set up for these cuts? In my past experience in ripping plywood I made all my cuts on the floor of the shop using an eight foot cutting guide that I made...I'm just a little worried in where to set up the roller stand as I have heard that the roller type of stand can "pull" the workpiece away from the blade. I'm using the plywood for some cabinets and at $70.00 a sheet I don't want to screw these cuts up.

Sorry, I know this is a pretty basic question but my TS experience is pretty slim.....

Thanks!

Rob

[Bruce Cohen]

Rob,
If I was you, I'd use a circular saw with a good blade (Freud) and a straight edge to do the job. Either cut on the floor with a sheet of 1" rigid insulation under the ply, or use two saw horses with a 2x4 grid (I'll send you the diagrams for either if you want them as I'll have to draw them up).

For me, this works waaaay better than trying to wrestle the sheet on the table saw and supports. The chance of kick back is overwhelming on the table saw. Along with the possibility (probability) of drift and messing up the cuts.

PM me if you need the diagrams or/and more info.

Bruce

[Mountie]

Hi Bruce,

That was the way that I have ripped full sheets in the past...I was going to do that again, but with needing to rip so many pieces of the same dimension I thought that using the TS would ensure the repeatability of the cut width so that all the pieces were the same....am I wrong in this?

Rob

[radhak]

Rob,
You are right : that's a lot of repetitive cuts that could be managed better on the TS. If you understand the caveats of this (less safe on TS, but not insurmountable), you might want to do some prelim work

a) Instead of using flip-tops, you could build an outfeed table. I took inspiration here, and was done in an hour or so; I used simple legs with the folding leg brackets from Rockler.

b) You will also need in-feed support. I guess you could use your roller stands or flip-tops for this. Make sure they roll easy, but not too fast, and positioned such that you should be able to stand and guide the ply against the fence all along.

c) Use a feather-board fixed at one position to limit the cut to the width you specified while you reposition the fence before each cut. This page http://www.josephfusco.org/Tips/Hand...20Plywood.html has a good approach of making the feather-board rigid with the help of a backer-board.

And yes - the presence of a helper person would be invaluable during this exercise.

HTH.

[Tom Slick]

I often cut the sheet into rough oversize pieces with the circular saw then do a finish cut with the table saw. Not fast but much more manageable.

[TiminIndy]

I often cut the sheet into rough oversize pieces with the circular saw then do a finish cut with the table saw. Not fast but much more manageable.

I think he's trying to get four 8' x 11 7/8ths" out of a 4' x 8' - basically using the entire sheet.

[mpc]

The roller stands can "pull" the workpiece if their axle isn't perfectly perpendicular to the workpiece feed direction. The new style rollers - which are a series of larger balls in holders instead of a single rolling cylinder - don't exhibit this problem because the balls can rotate in any direction instead of being limited by an axle shaft.

Since the desired final pieces are 11 7/8ths, that sounds like you basically need everything you can get out of the raw stock - just giving up the blade kerf. So cutting oversize initially and then doing a final trim pass on the saw isn't an option... unless you buy a lot more raw stock and get 3 instead of 4 final pieces from each raw panel. So... the first things that come to mind are:

1: infeed and outfeed support are going to be critical. I'd use the roller on the infeed side, and the Flip-Top stands on the outfeed side. Position the Flip-Tops on either side of the blade so one catches the workpiece, one catches the leftover raw panel. Position them so they'll catch the centerline of each piece - you don't want any "balance" issue trying to tilt the panels. That also means you'll have to move them after each cut as the leftover piece gets smaller and smaller.

2: Instead of those stands, since you have so many pieces to cut - and the raw stock is expensive - it'd pay to spend a little time and money to make more solid - and larger - supports. A plain old sawhorse that's almost as high as the BT3's tabletop can support the far end of a sheet of cheap plywood or whatever... fasten the near end of the cheapie plywood to the rear rail of the BT3. Other posts on this website show various hardware gizmos that folks have dreamed up to inexpensively attach stuff to the rails. Remember, you don't absolutely have to have a fancy attachment gizmo, nor one that's adjustable for other projects. Do you have the BT3 "accessory kit" that includes dinky router fence pieces? If so, take them apart and use those brackets on the rear BT3 rail instead. Actually, the outfeed doesn't HAVE to be fastened to the BT3's rear rail... attaching it to a second sawhorse so it's just below the BT3 table height and near to the rear of the saw is good enough. Just make sure things are stable - that the friction of the workpieces won't push the saw nor the outfeed stuff around. A "test cut" with the saw OFF and blade lowered completely is a smart idea.

3: Keeping the workpiece against the fence will be your biggest problem. Attach a longer, and straight, piece of wood to the fence to extend it well forward of the BT3 tabletop - this will help you with the initial lineup. Screw a thin piece of plywood, masonite, whatever to the bottom of this piece so it forms a "shelf" to help hold the workpiece. Something like: _____||
Put a vertical support (to the ground) on the ends of this extension for extra rigidity. That gives you a little more support and it helps keep the workpiece from trying to slip under the stock BT3 fence.

When cutting the large panels with the table saw, if you can beg/borrow a friend or neighbor, that'll really help. Put them to work initially helping lift the workpieces to the infeed table or front edge of the saw. Once the workpiece is against the fence and positioned ahead of the blade, have them turn the saw ON and move to the rear of the saw - without going near the blade or under the workpieces - don't want to risk "bumping" stuff. Have them help catch the outfeed. They should NOT try to "steer" the work against the fence or blade, nor should they help pull/push the work across the saw... just have them gently support the workpieces from below as they exit the saw - so there's less tendency for the pieces to want to tilt up/down - if you don't have much outfeed table area. As the cuts finish, you push the pieces past the saw blade to the rear edge of the saw (ideally onto the outfeed tables) and then the helper keeps the workpieces there while you shut off the saw power. Since the BT3 power switch can be hard to reach when large plywood panels are being cut, a beefy extension cord is an alternate way to KILL power to the saw if the cut goes wrong - something the helper can do. Do NOT use the extension cord to turn the saw ON; instead make sure the saw switch is OFF, plug the cords together, then turn the saw ON with the switch normally.


If the 11 7/8ths dimension isn't absolutely essential - instead getting "all I can get out of the raw stock sheet" is the goal - the "final pass" may be done with a router. Cut the boards on the saw first, trying to get the desired size. Then, when everything is cut, compare the width of your workpieces. Pick the NARROWEST one. If the cut edge isn't perfectly straight, run that piece through the saw with the blade taking half or even a quarter kerf (i.e. not even a blade's thickness worth of wood) to get as straight an edge as possible. Lay this board on the benchtop, or across sawhorses, across 2x4's clamped to your Flip-Tops, etc, so it becomes a reference/pattern piece. Then, using small bits of double-sided tape (e.g. carpet tape) attach one of the other boards to the top of this piece. Let the edges overhang the pattern piece... and trim the workpiece to the pattern using a router with a pattern (bearing guided) flush cutting bit - pick a bit a little longer than the thickness of your workpieces (one workpiece - NOT the thickness of the reference plus a workpiece) and the bit must have the bearing at the end opposite the router. Trace the pattern and you'll get identical dimensions on the other boards. Of course, keep the router FLAT to the workpiece (it'll want to tilt since only half the base rides on the workpiece...) and route in the correct direction (i.e. the router should move AGAINST the rotation direction of the bit where it contacts the workpiece... if the router seems to want to "run" along the work, you're feeding the router the wrong way!). This will trim all of the other boards to match the reference/pattern piece.

mpc

[cabinetman]

a) Instead of using flip-tops, you could build an outfeed table. I took inspiration here, and was done in an hour or so; I used simple legs with the folding leg brackets from Rockler.

b) You will also need in-feed support. I guess you could use your roller stands or flip-tops for this. Make sure they roll easy, but not too fast, and positioned such that you should be able to stand and guide the ply against the fence all along.

HTH.

An outfeed and a right side table makes a table saw much easier to use. Depending on what fence system you have, the right side would be sized for the maximum size your fence allows.

You could make it much easier to size the sheets on the TS, by first splitting the 4x8 in half first (into 2x8's, approximately) with a handheld circular saw. Half sheets are half weight.

.

[LCHIEN]

If I were doing one or two rips I might do it with a fixed sheet and a circ saw but a lot of rips (15 for 5 sheets) esp. if you want then consistent do iton a table saw. It requires some prep work - an outfeed table and infeed table and the rest oof te stuff that was recommended by other posters.

The question of needing to have exactly 11-7/8th or are you just trying to maximize the width and get four pieces per sheet? A careful rip of half makes 5 rips of full sheets, then you can deal with much easier to handle 2x8 sheets. If uniformity is needed over exactly 11-7/8 then rip in half (yes, CMAN, I agree this could be done with a circular saw and guide - easier to manage the 4'x'8' sheet and get to smaller pieces first), then rip off 11-3/4 off each ~2'x8' with the table saw and then rip a tiny sliver off the leftover piece with the same settings...

[cabinetman]

A careful rip of half makes 5 rips of full sheets, then you can deal with much easier to handle 2x8 sheets.

I would still recommend doing the rips to get the 2x8's with a handheld circular saw. For the inexperienced user, even with the table surrounds in place ripping a full sheet in half can be cumbersome.

.

[Mountie]

Thanks for all the advice ....its greatly appreciated!

As I'm quickly learning, it appears that its going to require a combination of techniques to accomplish this.

First of all, I'm a "one man" project guy and live out of town so the "call a friend" option is out. That being said, you're right, the full size sheets are too much to handle alone with my current set up (BT3100 with the original fence and no side table or out -feed support). I'm going to modify the project size and reduce the length of the rip from eight feet to six feet. I should be o.k. with this and loosing the two feet from the end should make the sheets much easier to handle. I think that I'll also go with the suggestion to rip the sheet in half with the circular saw....I know I can make five precise cuts to halve the sheets and then rip them 11 7/8ths on the BT3100 to get my repeatable cuts.

mpc: I've used the trim router technique in the past to make precise replica's...In the past though, I was only dealing with one or two sheets, not having to replicate many pieces all at once like this. Thanks for the post though, it confirmed some of the ideas I had to make these cuts and confirmed something else for me....I HAVE to build a dedicated out-feed support of some kind. I didn't want to use the saw horses that I currently have as I have mainly used them for rough construction jobs and have no confidence in the work "sliding" along the tops without binding.

Thanks once again to all for the advice....its a great forum here and having people take the time to reply (and in such detail!) really is appreciated.

Best regards to all,

Rob

[TiminIndy]

I don't know if it is sacrilegious to mention this on a table saw forum, but you could get the sheets ripped where you buy the wood (or at least in half). I have had Lowe's rip plywood sheets for me a number of times on their big vertical rip saw (for free). Almost every time, they were very accurate, which obviously depends on the skill of the saw operator. They do it before you pay for the wood, so I guess if they jacked it up you don't have to buy it. I would go in the mid-morning when their A team is more likely to be working and awake. I believe Home Depot has the same service, or if you are going for a better wood selection at a real lumber yard, some will do this for a fee. An added benefit would be it is easier to transport home. You could fine tune with a TS or router at home to make them all consistent.

[Mountie]

You're right, my HD here offers the same service....unfortunately I've had a few issues with cuts in the past and its really dependent on which guy is working at the time. One guy there does a great job and he's made some excellent cuts for me in MDF.

I bought this wood at a smaller yard...it was very busy there that day and I was impatient...not sure how I would have made out with the cuts...it was the first time going to that yard.

All this talk of cutting plywood is a little useless at this point anyhow....it hasn't stopped snowing here for the past two days and I'm spending far more time with my snow blower and a hundred yard driveway than I am in my shop!

Rob

[pelligrini]

Outfeed tables are pretty easy to make. I did a knockdown one for my 21829 out of a hollowcore door. http://www.bt3central.com/showthread.php?t=41179

If you go with the 6' length, and rip the sheets in half with your guide you shouldn't have a problem doing the rest of the cuts on a BT. Be sure to wax your top and tables for easier movement. I also like using the long rip fence when doing long cuts. Featherboards will help by letting you concentrate on just moving the stock and not having to make sure it's against the fence.

Give consideration to the placement of your infeed support. I made a wide infeed table once, but it turned out to be a poor idea. Besides blocking easy access to my switch, it kept me too far from the blade.

[LCHIEN]

great idea on having the lumber shop or retail store do the 1st long rip... Usually its first cut for free, I think they can rip the long way to make your 2'x8' pieces. I guarantee it's much easier to handle 2x8 than 4x8 sheets.