Tablesaw Crosscut sled

[jack dempsey]

Hello,
I am preparing to make a tablesaw crosscut sled. I am not sure what material to use for the runners. I would like advice/opinions on using the steel runners like the ones sold by Incra as opposed to using hardwood for the runners. If you have made these sleds I would like your insight.
Thanks, Jack

[glenn bradley]

I have sleds with Incra aluminum rails, UHMW rails and QSWO wooden rails. All have performed well for years. More important to me as my sleds evolved are adjustable fence,

367580

replaceable fence and base inserts and a good safety area for the blade to stay covered at the rear. Here's an old one (http://www.sawmillcreek.org/showthread.php?50581-Sled-Purpose-Specific-1) but, has most of the features I still use.

[jack dempsey]

Glen,
Thanks for the information. You correctly point out other important features that are just as critical as the runners. Thanks, Jack

[Pat Barry]

Glen,
Thanks for the information. You correctly point out other important features that are just as critical as the runners. Thanks, Jack
Is this going to be a production tool or for hobby use? Assuming the latter I would go with oak and wax the runners. You should go with double runners regardless.

[Doug Garson]

I have used left over engineered hardwood (basically plywood) for runners with good results. I attach them with screws (no glue) so they can be replaced if they wear but after about 5 years of hobby use they are still good.

[Jim Becker]

I prefer wood for this kind of application...you can zero in on the exact width and depth you need based on your saw's specific slots and any variances from "standard". A stable wood should be used, however. QSWO was already mentioned and that's a good choice for this. And, of course, wood is usually less expensive than buying metal components.

[John Gulick]

I have used left over engineered hardwood (basically plywood) for runners with good results. I attach them with screws (no glue) so they can be replaced if they wear but after about 5 years of hobby use they are still good.

+1, we have used a similar sled for years with success

[Mike Cutler]

Hello,
I am preparing to make a tablesaw crosscut sled. I am not sure what material to use for the runners. I would like advice/opinions on using the steel runners like the ones sold by Incra as opposed to using hardwood for the runners. If you have made these sleds I would like your insight.
Thanks, Jack

Jack
I just used some scrap hardwood from the shop. I think it's jatoba. Making runners from steel would be nice, but you would have to drill and tap in place through the face of the sled.

Here is a video that covers making a basic, highly accurate sled. (I think the sled in the video is too big personally, but I have a crosscut slider on my table saw, so I don't need a crosscut sled for panels. It also covers the 5 cut method to set the fence.

https://www.youtube.com/watch?v=UbG-n--LFgQ

[andy bessette]

Steel runners would just screw up your table saw top.

[Peter Christensen]

Steel runners would just screw up your table saw top.

I have to ask how? Most saws come with mitre gauges that have steel bars for the slots. That said I just use hardwood and by the time it is worn enough to affect the cut the sled itself is cut up enough (fence and slot) to warrant making a new sled.

[Matt Day]

Tell us oh great one, how so?

Delta had it wrong for 70 years with steel miter gauges on the Unisaw?

[andy bessette]

Tell us oh great one, how so?

Delta had it wrong for 70 years with steel miter gauges on the Unisaw?

Use your head! A miter gage is easily placed directly in the slot because it is very visible for that operation. A sled's runners are totally hidden from view while the sled is wiggled around to find the slots.

[Peter Christensen]

Never had that problem with either. I've always placed the sled or mitre gauge past the blade and slid sideways until it drops into the slot / slots, then draw it back. I'll admit to a few scratches and dents to the top but they are all over it, after all it is meant to be used, not caressed. ;) Each to their own though. Thanks for explaining your reason.

[jack dempsey]

Thanks for all of the explanation and advice. I think for me the first sled will be wood runners, probably quarter sawn oak. One thing that I have learned will be that there will probably other sleds that follow for particular uses. So thanks again. Jack

[Frederick Skelly]

I generally use UHMW plastic for runners, unless you want to spend the money for the adjustable metal ones. Lee Valley and other companies sell it. Link (http://www.leevalley.com/us/hardware/page.aspx?p=32045&cat=3,43576,32045).

[Matt Day]

If I remember correctly, if you have slop with the UHMW ones you can countersink a small screw and as it tightens the UHMW will expand a bit taking up the slop.

[Frederick Skelly]

If I remember correctly, if you have slop with the UHMW ones you can countersink a small screw and as it tightens the UHMW will expand a bit taking up the slop.

Yes. That's just what I do.

[Ben Rivel]

Yea I personally could never figure out why any one would want to use wood over UHMW for sled runners. I mean the stuff is slick as can be in its natural state, can easily be tweaked for a perfect fit, will last forever and you dont have to worry about it expanding or warping for any reason.

[andy bessette]

Yea I personally could never figure out why any one would want to use wood over UHMW for sled runners...

One often uses what he has on hand. The runners on my sled are oak and have held up fine for decades. Never a problem with wood movement.

[Ben Rivel]

One often uses what he has on hand. The runners on my sled are oak and have held up fine for decades. Never a problem with wood movement.
Okay yes, that is a valid point.

[Ted Reischl]

Pretty obvious someone here is not familiar with the properties of cast iron. One is not going to dent a slot in a cast iron table with a steel runner by "wiggling" it around.

[Dan Cameron]

Is this going to be a production tool or for hobby use? Assuming the latter I would go with oak and wax the runners. You should go with double runners regardless.

Can you explain why to use double runners? A single runner sled has EXACTLY the same number of guiding surfaces as a double runner sled, and is affected less by humidity and temperature.

[Matt Day]

I think the general guideline is if it's a big sled, use two runners, if it's small use one.

I wouldn't use a large sled with one runner. I would think it could introduce too much stress on the runner and its fasteners.

[Keith Outten]

I use Dupont Corian for runners for the same reasons that Jim Becker mentioned plus Corian won't ever swell from moisture. You can sand it as easily as wood and cut it with any shop saw. Apply wax on the runners and they will slide like their on bearings. I have a truck load of scraps so the runners I make are free.

If you need some material to make Corian runners let me know the rough size, you pay the shipping. I have both 1/2" and 1/4" thick Corian.
.

[Dan Cameron]

Jack, lots of good (and some not so good) advice here on sled runners. I would like to make a case for using a single runner. Consider that the center to center spacing of two runners will not be EXACTLY the same as the spacing of the saw slots. The sled spacing will, of course, change with changes in humidity. Say the runner spacing is greater than the miter slot spacing. The sled will be guided by the outside edges of the two runners. The inside edges of the runners never make contact with the slots and thus these two edges have ZERO affect in guiding the motion of the sled. Similarly, if the runner spacing is less than the slot spacing the inside edges of the runners alone guide the sled. I have heard comments that a double runner sled is more accurate because there are twice the number of guiding surfaces. Is NOT true! A single runner also has one left and one right guiding edge as well. As a matter of fact, a single runner sled can be made more accurate for the amount of free play does not have to be large enough to accommodate the changes in the runner spacing with humidity change. An advantage of a single runner is you can use the runner in one slot for zero-clearance applications and that same runner in the other slot for dado and bevel use. And yes, that sled is easier to construct.

[Mike Cutler]

Thanks for all of the explanation and advice. I think for me the first sled will be wood runners, probably quarter sawn oak. One thing that I have learned will be that there will probably other sleds that follow for particular uses. So thanks again. Jack

Jack
Yep, you'll make more than one, that's a guarantee. You'll also find out what features are important to you.
I've made a lot of sleds, for various machines through the years. Some I've kept, some were tossed once that project was done. The nice thing is that they don't have to be expensive.
I just got done making a coping sled, and somehow or the other, it was dead on 90 degrees right off the bat. Not a single tweek required. I couldn't believe it. That'll never happen again.

[Frederick Skelly]

I use Dupont Corian for runners for the same reasons that Jim Becker mentioned plus Corian won't ever swell from moisture. You can sand it as easily as wood and cut it with any shop saw. Apply wax on the runners and they will slide like their on bearings. I have a truck load of scraps so the runners I make are free.

If you need some material to make Corian runners let me know the rough size, you pay the shipping. I have both 1/2" and 1/4" thick Corian.
.

Keith, say I wanted to rip Corian into pieces 3/4" wide by 24" long and use it on a sled -
* What sort of blade do you need to make such cuts? (Surely not my Forrest WW-II?)
* Can a normal contractor saw do that with the right blade or do you need a 3-5 HP saw?
* Does the Corian drill/tap/screw to the sled, or does it have to be glued?

Just curious as I never thought of Corian for this application (or anything else but counters).

Thanks,
Fred

[Matt Day]

I'll do my best to help answer the corian questions.

-regular carbide blade. I use an older one, but wear a mask and get ready for a dust storm!
-No need for a 3-5hp saw, corian cuts easily.
-you can tap corian but it doesn't have much holding strength. I'd drill and countersink the corian and put screws in from the bottom but don't use a drill to put in the screws as corian cracks easily - screwdriver for that.

Corian also works good for router table tops. I've made a ZCI before but I don't think it's worth it, plywood is a lot cleaner and more forgiving.

[Bruce Page]

There's a lot of different runner material to chose from. I went with UHMW rails and have no regrets. It machines easily, is impervious to humidity, and very stable.

[Clark Harbaugh]

I previously had QS oak runners, but they would give me grief when the humidity would change. I moved to adjustable aluminum ones (can't remember if they're Incra or some other brand I found...) and love them.

[jack dempsey]

Wow, thanks again for everyone taking time to share all of this information. It sure is helpful. As I said I imagine there will be additional sleds in my future after this initial endeavor. I hope to finish one tomorrow. Jack

[Dan Forman]

I just bought a 24 x 24x 3/8" sheet of UHMW for sled runners, figure that will be a lifetime supply. I was quoted $40, but when I went in to pick it up the guy spontaneously dropped the price to $30. FYI - it comes in either black or white, I was told that the white is food safe, not so the black. The white is more expensive, and less durable due to the increased processing, so I got the black. I'll try to refrain from eating any of it. If you live in a larger city, you can probably find it locally through a plastics distributor, there were several who stock it here.

The nice thing about having an Incra fence, I was able to dial in the width of each slot to the nearest thousandth (left is a little wider than the right), and got a perfect fit for each on the first try. I'll be making three sleds, one large and one small crosscut, and two miter sleds, the latter three for box making. I will be following the William NG video for the two standard crosscut and a miter crosscut sled, and another design from Fine Woodworking for the one for vertical miters.

Dan

[Dan Cameron]

I think the general guideline is if it's a big sled, use two runners, if it's small use one.

I wouldn't use a large sled with one runner. I would think it could introduce too much stress on the runner and its fasteners.

Only one runner at a time is in contact with the TS slot, so there is not added strength from a second runner.

[andy bessette]

Only one runner at a time is in contact with the TS slot, so there is not added strength from a second runner.

Not exactly.

For a large sled two runners can distribute loads over twice the runner attachment area (and number of fasteners) of just one runner, as when the outer edges (for example) function as a single wide runner. Additionally dual runners minimize the leverage which could be applied to a singe runner.

[Pat Barry]

I've found that two runners work better than one - that was the reason for my earlier recommendation. I feel that the setup is much more stable with two runners. I can see how there is logic behind the idea that one runner will get the job done, but in my own use, I found my single runner sleds (more than a couple of them) to be a bit on the loose side. Perhaps this was to a deficiency in my manufacturing technique - so be it - the double runner eliminated the issues I had.

One advantage of a single runner sled is that you could actually use both miter slots - dedicate one for normal square cuts, and setup the other for 45 degree cuts (for example). Can't do that with a double runner sled.

[Matt Day]

Only one runner at a time is in contact with the TS slot, so there is not added strength from a second runner.

Do you own stock of one runner sleds Dan? This is the third time in this thread you've been adamant that one runner is the way to go.

[Dan Cameron]

Nah, I'm just trying to help people from falling into the trap "if one runner is good two have got to be better", The first sled I ever built was a two runner. I built it in the hot dry summer. Come winter it wouldn't drop into the TS slots. Literature I have read predict plywood size changes (not thickness) of approximately 0.1 percent for a 40 to 75 percent humidity change. Runner to runner that's .01 inches. My current sled has .004 in free play. Nuff said?

[Matt Day]

. Nuff said? Yes please

[Alan Schaffter]

I don't like the way wood, UMHW or worst of all aluminum slide against cast iron. I have always used 3/4" X 3/8" cold rolled steel for all my sleds and jigs. It always slides smoothly. And I only use one runner. The price, when purchased from a metal supplier is often cheaper than buying UHMW runners from the usual WW suppliers, though you may need to buy it 10' or longer lengths- it will last forever.

Miter gauges, including those with long fence extensions only have and need one runner. Two are not needed and just too much of a pain to get aligned perfectly.

Also, if you are using a runner that is subject to wear, I suggest you cut a shallow dado in the bottom of the sled first. That way when it is time to replace the bar, the new one will align automatically.

[Chris Fournier]

On small infrequently used sleds I used one wooden runner. On my large sleds that saw tonnes of use I used aluminum bar stock and two runners because it was easy to tweak and when it got sloppy I'd use a centre punch to tighten everything up. Set one runner up for the square and then fix the second runner. One runner just as good as two? On a full sized sled? Nope.

[Alan Schaffter]

One runner just as good as two? On a full sized sled? Nope.

What are you trying to cut on you sled? a 10' long 2X12? Something more appropriately cut with a chop/slider saw?

[Roger Marty]

Hello,
I am preparing to make a tablesaw crosscut sled. I am not sure what material to use for the runners. I would like advice/opinions on using the steel runners like the ones sold by Incra as opposed to using hardwood for the runners. If you have made these sleds I would like your insight.
Thanks, Jack

I need to make a new sled. I've used oak runners and I had problems with them seizing up due to expansion. For my next one I'll try quarter-sawn instead.

I actually HATE making table saw sleds because I really struggle with the process to make it perfectly square. Yes, I've seen the YouTube videos where you rotate a piece of wood 4 times taking a cut to measure the total amount off. But trying to nudge a fence into alignment with that whole screw method is just tortuous for me.

If anyone is reading, any recommend plans for a fence that is adjustable?

[andy bessette]

...any recommend plans for a fence that is adjustable?

You can make final adjustments with a hand plane.

[Chris Fournier]

What are you trying to cut on you sled? a 10' long 2X12? Something more appropriately cut with a chop/slider saw?

Not set up for a chop saw as I see them as site trim tools and break out saws but the stock that I often use is too large as I don\t have a sliding unit. So yes larger pieces of lumber and doors. No one ever told me my tablesaw couldn't do it and as it turns out it always did! Thankfully I now have a larger slider. Crosscut sleds are one of my favourite shop built items!

[andy photenas]

I am not trying to toss a wrench in the gears here but I cant believe how many ppl like the wood runners ! I dont like them and would not suggest anything other then adjustable nylon screw style bar. https://www.amazon.com/Kreg-KMS7303-30-Inch-Jig-Fixture/dp/B0002QZ4SA/ref=sr_1_4?ie=UTF8&qid=1505311820&sr=8-4&keywords=miter+bar+adjustable

For me the $30 bucks was well worth the time saved trying to make a perfect wood runner that does not bind at some point in the slide. I was very surprised at how well the adjustable ones work.
I made 14 through double wedged tenon doors like this at a very hi end quality using this kind of track and those are some very heavy cope cuts that nearly all came out perfect.

[Keith Outten]

I cut Corian with any saw, type of blade or router bit in my shop. My preferred method is to cut it on my band saw with a one inch blade. The last runner I made was for my band saw slider, I machined it on my CNC Router because it wasn't a standard 3/4" by 3/8" slot and I wanted the fit to be very accurate for my one runner slider.

I often drill and tap holes in Corian for joining parts then use epoxy on the threads when I screw them together which makes a very reliable connection.

As mentioned earlier we all have a tendency to use the material we have on hand especially shop scraps when we can. UMHW is probably the best material for runners in my area because of our very high humidity but I have a truckload of scrap Corian so its my second best option. I did recently purchase some UMHW for a job so I will have some for the next set of runners I make. I have used King Color Core material in the past, its a close cousin to UMHW. Its my understanding that there isn't any adhesive that works with UMHW so that is a concern on some projects.

[Phillip Gregory]

I've found that two runners work better than one - that was the reason for my earlier recommendation. I feel that the setup is much more stable with two runners. I can see how there is logic behind the idea that one runner will get the job done, but in my own use, I found my single runner sleds (more than a couple of them) to be a bit on the loose side. Perhaps this was to a deficiency in my manufacturing technique - so be it - the double runner eliminated the issues I had.

One advantage of a single runner sled is that you could actually use both miter slots - dedicate one for normal square cuts, and setup the other for 45 degree cuts (for example). Can't do that with a double runner sled.

Double runners make it much less likely you will be able to slightly twist the sled in relation to the runner, and thus bind up the sled. I have a small table saw miter sled I built using one runner, and it is possible to torque it radially and slightly skew if (not quite bind it) if you are not paying attention to how you are feeding.

Cutting a synthetic polymer material is best done with a TCG blade, and generally one with zero or negative hook. Specify the tooth pitch to the thickness of the material being cut, for cutting runners and such, you will want a pretty high tooth count blade such as an 80T 10" blade as the stock will be at most 3/4" thick. A 100T blade may even be more appropriate for cutting the thin stuff.

One thing nobody has mentioned is that there are other tools out there that are by design better equipped to do precision crosscuts than a tablesaw. A sliding tablesaw, good quality radial arm saw (not some Emerson-made Sears/Ryobi/Ridgid or a <=12" Black and Decker-made unit, but an old cast iron DeWalt or new Original Saw Company unit, or an OMGA saw), or even a decent SCMS would do better than a tablesaw for precision crosscuts. I have Grizzly's 10" 3 hp Unisaw clone, and it is a pretty decent 10" cabinet saw, but it is much easier and more precise to do crosscuts on my 61 year old 900 pound DeWalt GE radial arm saw than to do them on the cabinet saw. The Neanderthals among us would recommend a backsaw and a guide, and that can be very precise in the proper hands.

[Roy Turbett]

I generally use UHMW plastic for runners, unless you want to spend the money for the adjustable metal ones. Lee Valley and other companies sell it. Link (http://www.leevalley.com/us/hardware/page.aspx?p=32045&cat=3,43576,32045).

You can make runners from inexpensive kitchen cutting boards.

[Frederick Skelly]

You can make runners from inexpensive kitchen cutting boards.

Yup. I've done that too.

[Steve Peterson]

You can make runners from inexpensive kitchen cutting boards.

My thoughts exactly. I recall paying under $10 for a large poly cutting board at Walmart. It had a juice groove that I cut away, but it still yielded over a dozen runners.

Steve

[Edwin Santos]

For all the talk about runners, I feel the back fence is a more important subject. It's important to use a stable material.

If wood runners get tight and bind, you can always resolve it with a swipe of a hand plane or a little wax. If the back fence moves, even slightly, it's a bigger problem, and usually why I end up making a new sled. So you could say I've learned the hard way to use laminated baltic birch for the back fence. Any stable material will do.

It's useful to have a one runner sled with a single square fence at the leading edge, for cutting larger panels square. Norm Abrams used to demonstrate one in some of his episodes.

[Chuck Nickerson]

Do you own stock of one runner sleds Dan? This is the third time in this thread you've been adamant that one runner is the way to go.

Dan is an amazing engineer and woodworker with no great need to hear himself talk. For more than a decade he and I belonged to the same WW club.
It took me longer than it should have to learn to pay attention to what he says.

[Johnny Barr]

For those saying 2 runners for large sleds and one for small sleds, have a look at this video.

https://www.youtube.com/watch?v=4p0UTVUXh48

I have a cross cut sled, panel sled, miter sled, bevel sled and even Incras miter express sled (my favourite) all made with one runner using Incras miter sliders.

Also for those worried about fence squareness and not wanting to do the 5 cut method, have a look at this video

https://www.youtube.com/watch?v=AdXTtTnJAvk&t=68s

I have tried both methods of squaring fences and the dial indicator way is just as accurate, quicker and less mess. In fact the only cut is a test cut to see if its square. Dial indicators are not expensive and have other uses.

[Jerry Olexa]

I like hardwood strips and wax them before use...Have had good success with them.

[Jerry Olexa]

I also vote for TWO runners for stability..

[Bert McMahan]

But trying to nudge a fence into alignment with that whole screw method is just tortuous for me.

You don't have to do nudging to get things the right way. I don't know what you mean by screw method (unless you mean just, the screw that holds the fence down to the base).

What I'd recommend is doing the 5-cut method to find your angular error in inches per inch. Measure out as long of a distance from a known pivot point (i.e., one screw) as you can comfortably work with- ideally a couple inches from the opposite edge- and put a mark there. Multiply this distance by your error to get the amount that second point needs to shift. Get a stack of feeler gages that's equal to your error, then put that stack up on the mark you just made. Next, push a piece of scrap up against the feeler gage and clamp it down. Pull out the feeler gages and pivot your fence up to the scrap; you will now have moved it by exactly your error. Clamp the fence down then screw it into place.

You can repeat it a couple of times if you want to get it really dialed in. I haven't done this to a crosscut sled yet but I used this method to square up my cheap Ryobi miter saw; took me around a half hour to do it the first time. I iterated a couple of times to get the error as small as I possibly could, and it's held well. It shouldn't be a pain to do.

I haven't tried the dial indicator method, but as always there are many ways to skin a cat!

[Robert Stanton]

I have experienced too much flex when using only one runner. Even with double stacked baltic birch.

[Dan Forman]

William NG has a great video explaining the five cut method and how to build a cutoff sled. I highly recommend watching this!

In it he shows how to do the calculations necessary to determine exactly how far to move the sled's fence, in which direction, and from which point, and how to go about this with enough precision to get accuracy within .001" over the equivalent of a 96" cut. He does this in one try! The video is well worth watching, lots of great tips, what to watch out for, way too much information to relate here. I used it to set up the the fence on my Jessem sliding table, which is actually much more difficult to do than a sled, just because of the way it's constructed. My fifth cut was off by .001 over about 80" ( 22 x 18" rectangle). I think I can live with that :)

5 Cuts To A “Perfect” Cross-Cut Sled – William Ng School Of Fine Woodworking (https://wnwoodworkingschool.com/5-cuts-to-a-perfect-cross-cut-sled/)

First do a five cut, starting with a rectangle whose long dimension is at least 24", and whose width is great enough to be very stable resting against the sled fence. Measure the width of the fifth cut piece to the nearest thousandth of an inch, both top (A) and bottom (B), and the length of the cut (C) and record. Measure the distance from the pivot point of the fence to the opposite end where the adjustment will be made, and record that (D).

Now here is the formula, spelled out because I don't have a "divided by" symbol on my keyboard : A minus B; divided by 4; divided by C; times D.

Subtract the bottom measurement from the top, divide by 4 (number of cuts, which multiplies the error on the fifth piece), divide that result by the length of the last cut, multiply that by the distance from the pivot point of the fence to the point of adjustment. This tells you exactly how far to move the fence at the point of adjustment. With the pivot point on the right side of the fence, and adjusting on the left, if the result of the above calculation is a positive number, the fence needs to move down, away from the blade. If a negative number, then it needs to move up, toward the blade. In the video, he explains why each of these factors in the formula are important to the final result, and shows how to reliably move the fence by using a stop block and feeler gauges. It sounds complicated, but in reality it's very simple to do. A calculator is your friend. I was surprised to see that he had the same calculator that I bought over thirty years ago.

Dan



(https://wnwoodworkingschool.com/5-cuts-to-a-perfect-cross-cut-sled/)

[andy bessette]

DF--I enjoyed watching that video. Thanks.

[Johnny Barr]

If you want a simpler, quicker and just as accurate method as the 5 cut method read post #10 above. If your bade has flex or its not parallel to the slots etc then the 5 cut method won't be as accurate. When adjusting fences on sleds and gauges its important to reference off the slots not the blade because those fences are moving via the slots. The dial indicator method is referencing off the slots. This video explains why you should do that ... https://www.youtube.com/watch?v=NrTeFQ0iQ5k

[Alan Schaffter]

If you want a simpler, quicker and just as accurate method as the 5 cut method read post #10 above. If your bade has flex or its not parallel to the slots etc then the 5 cut method won't be as accurate. When adjusting fences on sleds and gauges its important to reference off the slots not the blade because those fences are moving via the slots. The dial indicator method is referencing off the slots. This video explains why you should do that ... https://www.youtube.com/watch?v=NrTeFQ0iQ5k

Yup, even if the blade is not square to the slots you will still get a square cut. People always ask what happens if the blade is not square? Well you get a wider kerf, that's all. Not exactly the same but sorta similar to making coves on a tablesaw - the greater the angle from the blade, the wider the cove.

[Dan Forman]

Hmm, having the blade parallel to the slot is the most important adjustment to make, as all other adjustments are made with the assumption that table and blade are indeed parallel. That is the foundation upon which everything else depends, so it seems it would be important to make sure that that relationship is dead on.

If the blade is out of alignment to the table such that the rear is canted to the right, a crosscut will indeed be be square, (cove analogy works here), although the offcut won't be square. But if canted to the left, unless the work piece is pushed all the way past the back of the blade, which few of us actually do with crosscuts, the result will be out of square if the work piece is wider than the blade, as the back of the board will have been cut by both front and back of blade, whereas the front will have only been cut once.

The beauty of the 5 cut method is that it measures the actual cut, which is always more accurate than measuring the mechanical bits of the saw. That's why you can't just lay down a square to the blade and set the fence with that. Any misalignment, blade flexing, runout and such is already factored in when you measure how the saw actually cuts rather than how it should cut.

The GargaeWorks guy in the video linked to in post #53 did get a good setup, but we never saw how it actually cut, so we can't be sure of how it actually works out. We also didn't see how long he had to fiddle with the fence to get that final result, he edited that part out. Even if it does cut as true as the setup, technically William Ng's result is ten times as accurate (.001 over 8" vs .001 over 80" respectively). Though most of us would be satisfied with the former, if you can easily get the latter, why not go for it? The other thing is, I would have to order that square and wait for it to arrive, whereas with the five cut, all I need to do is find a scrap of mdf or plywood, no waiting. That said, if I already had a square like that, the scientist in me would want to give that method a try.

GarageWoks guy did have a great idea for the wood adjustable runner though!

Dan

[Doug Garson]

Actually you don't need a special square to use the Garage Workshop's method, all you need is a piece of plywood or MDF with one square corner and one straight edge. If you have a quality miter gage you can easily cut a piece that is just that. Or you can make a square like Marius Hornberger, can't seem to link his video but I'm sure you can find it on Youtube.

[Johnny Barr]

The GargaeWorks guy in the video linked to in post #53 did get a good setup, but we never saw how it actually cut, so we can't be sure of how it actually works out. We also didn't see how long he had to fiddle with the fence to get that final result, he edited that part out.


Dan, I didn't want to make this a "my way is better than your way" discussion but that fiddling takes 5 minutes. His other videos show the fiddling. ( https://www.youtube.com/watch?v=UC_iF5pZxmI&t=5s ) and this one ( https://www.youtube.com/watch?v=tZM1OBcC6ok ) As in the 5 cut method you use one screw to use as a pivot and then adjust the fence with light taps until the dial indicator hardly moves (roughly under .002") across the length of the square. Then lock it and make a test cut. I actually did an experiment. Using the dial indicator method I ended up with .002" error over 10" on my engineers square. Then I did the 5 cut method and ended up with the same error over a 10" cut. A test cut checked with that square and a digital protractor showed a perfect 90. I have used the 5 cut method for many years but I'm convinced this alternative is just as good. Actually William Ng's isn't 10 times more accurate. The actual error or accuracy in the 5 cut method is taken after the 5th cut eg .003" over 8". That error is then transferred to the length of the fence. After adjustment and doing the 5 cut method again you won't get .0003" over 8". Using a large framing square with the dial indicator method with an edge closer in length to a cross cut sled fence will achieve the same accuracy as the 5 cut method. I've never seen an 80" crosscut sled fence

In the real world and at the end of the day both methods will give perfect 90 degree cuts. I'd like people to try it. They then can decide which way is easier.

[Alan Schaffter]

Hmm, having the blade parallel to the slot is the most important adjustment to make, as all other adjustments are made with the assumption that table and blade are indeed parallel. That is the foundation upon which everything else depends, so it seems it would be important to make sure that that relationship is dead on.

If the blade is out of alignment to the table such that the rear is canted to the right, a crosscut will indeed be be square, (cove analogy works here), although the offcut won't be square. But if canted to the left, unless the work piece is pushed all the way past the back of the blade, which few of us actually do with crosscuts, the result will be out of square if the work piece is wider than the blade, as the back of the board will have been cut by both front and back of blade, whereas the front will have only been cut once.

Dan

In no way was I endorsing accepting a blade that is not parallel to the miter slot. Skew can result in binding, burning, kick-back, sideways force on the stock, etc. And depending on the direction of skew, the kerf may cut off the line or result in a short board (board stretcher needed :eek: ), and as pointed out, the cut-off may not be square if that is the piece you need (which piece is square depends on the width of the board, height of the blade, whether a full pass is made, and of course, the direction tilt of the blade. Hopefully, any skew is minimal because for some, depending on the saw, adjusting the blade parallel can be a major undertaking.

Of course, there are so many factors that can affect the squareness of the cut- both machine and man caused. There was an earlier discussion about miter slot slop and man-caused fence skew (or flex). The first one can be fixed, but the second is only rectified by skill and attention- even pressure across the back of the fence, not just at the miter bar. In addition to checking the obvious- that the blade is parallel and the miter gauge/sled fence is square, and there is no slop in the miter bar on a regular basis, the blade should be sharp and the miter slot/bar, table top, and fence should be lubricated. How many of us have neglected those last items until it becomes too obvious. How many of us have struggled to feed stock into a tablesaw, planer or jointer, then are amazed how much easier it is after the surfaces are lubricated.

[Dan Forman]

First let me say that I'm sorry if my tone has become argumentative, I'm really just trying to sort things out and thinking out loud here. I don't wish to alienate anyone. I am in the process of building a sled, and want it to be a accurate as possible, so this topic is important to me at the moment. I've been away from woodworking for a while, and have been on a mission to get all of my machines dialed in "dead nuts", at least as far as humanly possible. I want to focus on boxes, and as Doug Stowe points out in one of his books, boxes will be scrutinized a lot more closely than many other woodworking projects, and any errors in squareness on end cuts have a way of affecting the outcome of the joinery of the box sides.

Doug - I found that video on making squares, thanks for mentioning it. In all of the plywood and MDF that I have, the factory edges are rough enough to make the dial indicator dance, but I did manage to get my miter gauge tuned well enough to not show any light against my reference combo square, so I'll give that a try.

Johnny - Thanks for posting the Garage Works video. I have been looking at some of his other stuff, and he has some really interesting things on there. As I said before, my "inner scientist" does want to try anything at least once. He actually made a video comparing the five cut method the the square + dial indicator method, timing both operations, and the latter was the fastest. My frustration with him is that in all three videos he made, he never did a fair test of the accuracy of the result. If it was my video, I would have demonstrated the result by doing a five cut on each of the fence settings so we could compare the real world accuracy. Then we would have a real basis for deciding whether the extra time is worth putting in to chase the best result, whatever that might be.

One thing I admire about both Ng and Brian (GarageWorks) is their grasp of math and ability to to put it to use in creative ways to solve woodworking problems. I apparently didn't get the math gene, so I struggle with these things. I went back and reviewed the five cut video, and saw that I did indeed misinterpret it, I had thought that the difference between top and bottom represented the error relative to all four cuts combined, hence the 80" (my test piece ended up about 20" on the longest side), but now I see that it applies to only the length of the fifth cut. Thanks for setting me straight on that!

Alan - You have hit on a key frustration for me at the moment. I'm trying to sort out what may be operator error, and what might be due to the machinery. My Jessem sliding table has been particularly hard to get consistent results with. Last week I thought I finally had it dead on with the five cut method (a 22" square of 1/4" MDF) , but a couple of days later cut a smaller piece of 3/4" ply and it was significantly off. All of this talk about miter slots being parallel to the blade got me wondering if the slider was out of line with the blade, and it turned out to be the case. Given the design of the slider, it's really hard to get dead on, but I did get it better, and the cuts have improved in consistency, at least for now. I also waxed the saw table to cut down on any resistance there.

Dan

[Johnny Barr]

My frustration with him is that in all three videos he made, he never did a fair test of the accuracy of the result.


Dan, perhaps I was getting a little defensive myself but anyway I do agree, he should have shown a test cut with some way of showing the accuracy, for example, make a cut then flip one piece, rejoin the pieces and see if there any gaps. I discovered this method after searching for a way to accurately adjust my Incra miter gauge which I knew wasn't cutting square. The 5 cut method and feeler gauge usage isn't appropriate for a miter gauge and more suited to a crosscut sled. Anyway I tried this method after many years of doing the 5 cut method and loved it. I had it squared in literally minutes. I didn't believe it was square until I checked it with the 5 cut method and it was spot on. Did some test cuts over various lengths and they were all bang on 90. I was still sceptical until I checked my crosscut sled, using the new method, which was squared using the 5 cut method. it had the same error which was virtually zero. I was then absolutely convinced that this was a great alternative. I no longer use the 5 cut method despite it being considered as the definitive way of squaring a fence. While MrGarageWorks should have shown the accuracy I can vouch for it.

Also now that you have explained it, if you get .003" over a 20" length error after all the cuts then you are right the error is .003 over 80". I thought you were talking about the fence. If I got .003" over 80" then I would be ecstatic. That's an error of .0000375 per inch. Outstanding result but I would expect that error after the adjustment using a feeler gauge, not before. The new method can also get within 0.001 or better over 12". I've done that and its not difficult. That's an error in the tenths of thousandths as well. Once again an outstanding result, way beyond what's needed for "normal" woodworking, after all we are not doing precise engineering here. One final comment about the 5 cut method and then I'll shut up about this, the feeler gauge is the least accurate part. You're meant to be able to move it snugly (scientific woodwork term:)) between the fence and reference piece but what does snug really mean. Two different people could differ by thousandths of an inch using the same feeler gauge. One has a tight fit and one has a loose fit.

If anyone owns a dial indicator and a magnetic base then give it a go. You'll be surprised!

[Curt Harms]

I need to make a new sled. I've used oak runners and I had problems with them seizing up due to expansion. For my next one I'll try quarter-sawn instead.

I actually HATE making table saw sleds because I really struggle with the process to make it perfectly square. Yes, I've seen the YouTube videos where you rotate a piece of wood 4 times taking a cut to measure the total amount off. But trying to nudge a fence into alignment with that whole screw method is just tortuous for me.

If anyone is reading, any recommend plans for a fence that is adjustable?

No plans but I made a 'Norm style panel cutter' but made the blade to stationary fence a half smidge over 90*. I then made a second fence that would move a few degrees. Horizontal T nut in the fixed fence furthest from the blade. I put a screw and locking nut thru the T nut so it pressed on the movable fence. This provides a fine adjustment mechanism and helps to keep the adjustable fence from moving. The movable fence is held in place with two screws into T nuts. I made the outside hole in the movable fence a little oversized so there is some adjustment. Tighten everything down then check for square using the "5 cut" method.