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6 Tips to building a better Cross-cut Sled for your Tablesaw

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A cross-cut sled for the table saw is a must have jig for any serious woodworker. More accurate than a miter gauge, it also makes cross-cutting any board easy and safe. However, in order to provide the proper results it must be built with care. I made my first sled last year, following a plan in a popular woodworking magazine. Yet, in a matter of months, the maple runners swelled so much that the sled wouldn't slide in the miter slots. That's when my type "A" personality kicked in and I became determined to learn all I could about the ins and outs of building a cross-cut sled that would last. That research forms the basis for the tips and techniques presented in this instructable. And, while I can't take credit for any of these great ideas, I think you will find the insights of some very talented woodworkers helpful.
 
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Step 1: Tip 1: Milling the Sled Runners

Picture of Tip 1: Milling the Sled Runners
The runners ride in the two miter slots and guide the sled as the workpiece is pushed past the blade. They are most often made from hardwood such as maple or white oak, however, steel, aluminium or plastic runners are also options. Wood runners are more commonly suggested, most likely, because of the moderate cost. The disadvantage of wood runners is that the wood can swell with changes in humidity making smooth travel through the miter slots difficult or impossible.

Tip #1: Since most wood movement is with the grain, mill the sled runners with the grain running vertically as shown in the photo. This will minimize or eliminate side to side expansion of the runner in the miter slot.

Miter slots can vary slightly in size but most are 3/4" wide x 3/8" deep. Most plans call for milling the runners for a snug yet smooth sliding fit with no side to side play (also called slop). However, if the runner width swells too much it can become a problem and, as I mentioned, this is where I ran into trouble with my first sled. The good news: Tip number two allows some wiggle room when milling the runners to width.

Note: The height of the runners should be less than 3/8" so there will be some space under the runner for sawdust debris
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nitsuj10987 months ago

This may not be of much help now, and maybe it won't matter to you. But on most saws, you can adjust the table in relationship to the blade. On most of the ones I've done, it's a simple job requiring you to loosen the table fasteners just a bit, then tap it around until you get a nice true reading with a dial indicator mounted in a miter slot.

Great instructable! Do you have any trouble with the MDF warping or expanding?
KentM (author)  bricabracwizard9 months ago
MDF and Plywood are both very stable materials. For this reason you don't need to worry about warping or expansion when using them on a project.
kbyrne10 months ago
My question is I have a craftsman circular saw mounted under a 3/4 piece of wood. The miter slots are of wood. My sled rides free and clear. I have run out with a brand new blade. A small width piece of wood is real close with a carpenters square but as the width
increases so does accuracy. How do I compensate with run out of circular saw? Any ideas would be helpful. Kevin
sconner111 months ago
My question is: Why not build a whole sled in one piece with the blade all the way down, turn the saw on and slowly raise the blade up and run the sled through to make the perfect slot?
KentM (author)  sconner111 months ago
That's the way it is usually done, which is why this approach intrigued me so much. I liked the fact that it allowed me to mill runners to fit the miter slots with a little play in them. When the halves are pulled together the runners both press on the blade side of the miter slots providing a smooth, accurate slide to the sled. The benefit as I saw it was that now I didn't have to worry about the runners ever binding in the slots, which can happen when you mill them for a snug, sliding fit as recommended in traditional sled designs.
spin49811 months ago
For me, this is the clearest and easist to follow description of how to construct a sled I've seen. Thanks for that.
Juliaschild11 months ago
Good ideas, I would suggest finishing the whole thing before attaching the Masonite, as MDF will accept moisture and swell badly if in a humid situation. Also I slightly bevel the long runner edges facing away from the main board so the unit drops into the slots easier. I usually use 3/8" Teflon sheet for the runners, you can get it from plastic suppliers.
UHMW costs less than Teflon, works great, available from McMaster. It's also good for things like oar lock sockets.
Best thing I've ever used is Phenolic, but its nasty on tools and smells horrible.
I screw the runners on as the Teflon does not glue.
charlessenf-gm11 months ago
Very impressive for only 1000 of the requisite 10000 hours ;) Actually, it is very good looking. One thought from a fellow who has built a couple of these (albeit no where near as pretty) over the years and thought to pass along a thought about the guide rails / runners. The composite 'lumber' sold for decks might prove more stable and slippery and less susceptible to moisture-induce swelling. And, it would only take a free scrap or two from a neighbor's deck project to suffice for a few sleds or similar jigs.

I used a piece of this stuff to make a threshold a year or so back and found it milled well (ran it through my planner on a sled to create the trapezoid shape needed for the application) and has worn well in the elements ever since.

Again, nice project.
KentM (author)  charlessenf-gm11 months ago
Very creative suggestion. It sure beats spending money on expensive plastic or metal runners.
guitarpicker711 months ago
Interesting project!

A hopefully helpful comment - have you considered using poly plastic runners as guides? I had the same problems with wood runners: shrinking, swelling, splintering, wearing grooves, etc.

I saw a big $$ factory sled with plastic runners- polyethelene. I didn't want to spend good money on plastic- I found that a 1/2" thick poly kitchen cutting board would provide all the plastic strips I needed. This poly plastic material is easy to cut with regular shop tools, including a jointer! My first set of poly runners lasted longer than the sled!

When I visit the thrift stores, I always look over the kitchen wares area and I have collected a good number of poly cutting boards, a few almost a full inch thick! Of course, one could pay full price for some virgin poly, but it's not necessary.

Keep having fun in your shop, but keep it safe!
KentM (author)  guitarpicker711 months ago
Another cool idea! Thanks for your input. Definitely worth trying.
Bill WW12 months ago
Great job as usual, Kent. Appreciate the "tip" approach, each one can be utilized independently. The use of MDF ad hardboard is great; they are flat, smooth, true materials. No need to go to plywood.
Wow, where did you get those great large triangles?.

Thanks much,
Bill

KentM (author)  Bill WW11 months ago
Thanks for the nice comments. It's always a pleasure hearing from you. The drafting triangles belonged to my father who was a professional artist. Inexpensive plastic ones would be just as good and should be readily available at any craft or art supply store.
Bill WW KentM11 months ago
Kent, I have about a dozen triangles, dating back to my first college drafting class in 1963. But the triangles your dad used are unique due to their size. Larger is better!
studleylee11 months ago
Thanks! I learned some things in this and that's always good. I need to make this sled: I've always hesitated on using the table saw w/o one, especially if you work alone. I also need wing supports for a 4x8 sheet work. thanks for this instructable! The 5 cut test was a cool concept. I snagged those swf files for ref :-)
I8mAll11 months ago
Spot on old chap,
it's such an elegant solution. It creates such a "Dho!" moment then "Why aren't they sold like that." Thank you for telling us about it and illustrating the job so well.
JTD
AJMansfield11 months ago
This is something I will probably actually do, unlike most of the instructables I see.
advaldo11 months ago
Very very good, congratulations. Please allow me make a suggestion to complement your project and security.

Sorry I can't insert the image, so I post the link:
http://api.ning.com/files/TmSqT3jmw6UdFXdU5JCXrzIYwKtReo5kdTiSWNw1S-*7D10e*02DpRibUvR7MDL9s-gvBI7bwDcaKNe2jyNAfVmnk*VSIW1xeyWw6tHRpxg_/CCSled.jpg?width=721
grooverjamesr12 months ago
My only major problem I found is cutting the sled in half at stage #2, This will make the board out of square at this stage and every attempt at squaring it later will cause extra work.
The way to accomplish the same goal is to mount the fence to the large piece of MDF as shown later on, mount one side of the fence, true it up with a square, then screw in the other side of the fence.
Using all these framing squares is eliminated and the sled should be at 90 degrees.
KentM (author)  grooverjamesr12 months ago
Building the sled from separate pieces isn't something I came up with. This is the approach taken by a professional woodworker named Alan Turner and the technique can be found at finewoodworking.com. There is certainly nothing wrong with the traditional method you prefer. However, I do disagree that building the sled the way I describe will make the board out of square. Remember, each half has the excess cut off using the runners to create a perfect zero clearance on each side of the blade. Once the halves are clamped together, you still have to square the fence to the sawblade when mounting the rear fence which is the same method you describe. I guess if you were concerned about not being able to rip a squared piece of MDF in two accurately you could cut each piece individually. Then you wouldn't have to cut the sled base in two at all.
All I am saying is by not cutting the board in half there is only one piece, squared already and when the fence is attached it is squared to the sled. Then the initial rip mad in the center of the sled, cutting out all the measuring and aligning done with the triangle squares you show.
Your way is fine, if you want to do it that way as you said my way is fine too. I watch a lot of youtube too and read Wood Magazine and most show it being made as I suggested. The sled made, the right or left side of the sled is attached to the fence and then squared and the sled clamped, then screwed in place when it is squared, then the center line sawn.
baschwar12 months ago
What if your table saw doesn't have miter slots ? I have a ryobi contractor saw on a folding base... thoughts ?
bwschool baschwar11 months ago
they make bolt on slots for that saw and sell on ebay to guide tools
baschwar bwschool11 months ago
It's like this saw but 1-2 generations older: http://www.homedepot.com/p/Ryobi-10-in-Table-Saw-with-Wheeled-Stand-RTS31/202517812#.Uk5ShCgukmI -- the left side of the table slides and has a couple keyhole slots for bolts... I guess you could rig something up that way and have a guide off the right side of the table to keep things square..
Bill WW baschwar12 months ago
No miter slots is new to me also. But maybe you can accomplish the same objective by putting the runners outside the saw table, so they hug the edges.. They would be like outriggers that guide the sled along the outer edges of the table. Same principle, but I do not know your saw. Worth looking into, the sled is a really valuable addition.

Good luck.
KentM (author)  baschwar12 months ago
No miter slots? That's a new one on me. I don't have any suggestions, sorry.
earltroske12 months ago
Personally, I thought your instructions were brilliant and clear. I have a really inexpensive table saw and I know that a really good sled will improve my cuts. I've thought about it for a long time. I'm satisfied after reading and seeing what you've done that I was thinking correctly and now I feel confident that I can do this, too. Really appreciated the tips, especially the hardboard. Best tip of them all. Thanks.
Austringer12 months ago
I'm definitely with Joelav about putting a blade guard on the back. I also like put a red line on all my jigs indicating any place where the blade might be. If your thumb is on the red line, maybe you should move it.
Nice sled BTW.
stevel22712 months ago
Enjoyed your instructable. I particularly like that you use a pop-up contractors saw ... it is identical to mine. I don't often see jigs/fixture/tips that work for the smaller saws like ours.
joelav12 months ago
That's a nice, simple sled. Great tip on using the quartersawn faces for runners. I haven't had any trouble with my runners when using the quartersawn faces. There are a few things I feel it is important to mention.

1 - I like to have a blade guard on the back. It ruins the aesthetics of the sled, but is important. When cutting thick pieces, the blade can exit through the back of the fence posing a safety hazard - especially when you aren't expecting it to be there.

2 - I would advise against using automotive polishes on woodworking jigs or equipment. They have a high silicone content which can react negatively with stains and finishes; and are very difficult to remove from wood once contact is made. Instead, try using Johnson's paste wax.

To get the utmost precision form the sled, I use the "5 cut method" to square the fence. It takes a bit of tinkering, but getting accuracy of .001" over 12" is not too difficult. This is the best description of the process I have come across: http://www.thewoodshop.20m.com/five_cut_method_swf.htm
KentM (author)  joelav12 months ago
Thanks for your comments. I saw your cross-cut sled shortly after posting mine and it is definitely state of the art. There are so many great ideas floating around the internet that it pays to do some research and figure out what best suits a persons individual needs. I try to write my instructables to show woodworkers relying on basic power tools and jigs that we aren't limited in creating complex, high quality projects.
FYI, you are absolutely correct in your comments. Johnson's paste wax is explicitly recommended for waxing saw tops and sleds. I should have been more specific and I have updated my instructable thanks to your comment. Oddly, I've never had a problem applying a finish to any of my products and I've used Turtle Wax (not sure of the chemical composition) on my saw in the past. I wonder if the fact that I'm very thorough when sanding my projects has any bearing on this?
joelav KentM12 months ago
Thorough sanding definitely helps, but sometimes that is not possible with thinly veneered plywood. I really like the stacked MDF fence design on this sled. I think I will try that on my next one

Terrific job on this and really good write up
longwinters12 months ago
Have you checked the squareness of the blade to the table? 4" stabilizer discs help with blade wobble that can manifest as inaccuracy
KentM (author)  longwinters12 months ago
I haven't and will look into that. Thanks for the suggestions!
CementTruck12 months ago
That's just wierd! I just watched William Ng's crosscut sled videos last weekend and was planning to build one this week. Today I see your 'ible, and it mentions Ng. I feel like Truman on the Truman Show. *cue strange theremin music.

Good Instructable. I want to build a box jig sled for finger joints as well.
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