I’d like to build a cross-cut sled for my table saw and following a bit of research, it seems most authors recommend using baltic birch or similar hard-wood plywood for the base. Is there any reason 3/4 MDF shouldn’t be used?
And second question, where do people get real baltic birch ply?
Thanks
Replies
WoodRiv,
Baltic birch is lighter than MDF and does not have as strong an adversion to contact with water at the edges. MDF is, however, dimensionally stable and much easier to find (and I might add cheaper). Over the years, I have made sleds out of several different materials and have had no problems with MDF (except it's so #### heavy).
The last baltic birch I got from one of the local cabinet makers supply houses.
Best!
-nazard
MDF will work fine. It's not as sturdy as Baltic birch plywood, so it will likely get dinged up around the edges pretty quickly. It's also not quite as dimensionally stable, so a two-runner crosscut sled made during the summer in Idaho may bind a bit during the wetter winter weather.
Vendors that supply kitchen cabinetmakers often stock Baltic birch. A "real" lumberyard can usually order it for you.
For smaller pieces, up to 24" x 30", Rockler and Woodcraft will ship it to you. (Of course, it costs quite a bit more that way.)
-Steve
Baltic Birch is the common name we Knotheads use. Ask your local lumber yard if they have "European "ply or some other high-ply-number product.
Frosty
"I sometimes think we consider the good fortune of the early bird and overlook the bad fortune of the early worm." FDR - 1922
Baltic birch is best purchased from a plywood dealer, not HD. The best material for a sled is 1/4" aluminum plate with steel runners. Thinner is better.
Fair to better woodworker here.... I had a 'shop' made cross cut sled.. It was very beat up over time.. I went for new wood and then I thought of the new? Rockler Sled with a GAUGE for angles.. My old one just had pencil marks.. So far I like it ALOT! I did not get the auxiliary cut off thingi' I made my own!
I think it is OK and not worse than that for the price.. OK, so it is some sort of Plastic covered MDF? I for one use MDF ALOT and never have a problem with it unless I lay a wet 'coffee' cup on it!
Thanks!R. Lonning
By the way.. I have used it more than several times and still like it.. OK, so not my own work but it is NICE! I do not work fer' Rockler!
Edit: By the way, I never found a use for the cut-off when making the first cut for my saw.. I'll keep it for a few years to see if it is useful!
Edited 4/21/2008 11:12 am by WillGeorge
WoodRiv,
Here's a description of how one is made. I found this on Knots several years ago and used it for mine. It goes into great detail, especially with respect to making it square for accuracy.
I don't remember who authored it so if someone knows please chime in. Hope this helps. Also, Highland Woodworking sells a kit for same and has their plans for one:
http://www.highlandwoodworking.com/index.asp?PageAction=Custom&ID=86
Regards,
Bob @ Kidderville Acres
A Woodworkers mind should be the sharpest tool in the shop!
Excellent article. I'd tried UHMW plastic for rails, (they were sold specifically for that purpose) and found the swelling around the screws made them unworkable. Thanks!R. Lonning
Wood,
found the swelling around the screws made them unworkable.
Now that's just not right! :>)
This issue can easily be worked around by predrilling and countersinking the screw holes which you would want anyway. There should be no residual swelling but if there is, simply remove with sandpaper on a block of wood.
Now are ya gonna be saying that you may need to make several test cuts to get the fence spot one are ya? There's all kinds of ways to defur that feline!
Also, the rails don't have to fit the mitre slots perfectly but they do need to be fitted so there's no slop for the whole sled. If they're just a scosh shy the outside or inside of the slots.
Regards,Bob @ Kidderville Acres
A Woodworkers mind should be the sharpest tool in the shop!
"This issue can easily be worked around by predrilling and countersinking the screw holes which you would want anyway."
Even better, counterbore the holes and use pan head rather than flat head screws. That way, the force of the screw head doesn't tend to squish the plastic outwards.
-Steve
Steve,
Ah yes, a bit more fur off that rascal.
Regards,Bob @ Kidderville Acres
A Woodworkers mind should be the sharpest tool in the shop!
I think Gary Rogowski uses MDF on his sled in FWW. Check the archives if you can. He uses hardwood for the fence and front support and for the runner. Tom
Tom,
Thanks for the tip. I found the article (link below) you referred to and also a short video where Gary is using the sled referred to in the article. Rogowski is one of my favorite contributing editors to FWW. His advice is really down to earth and always useful.http://www.taunton.com/finewoodworking/SkillsAndTechniques/SkillsAndTechniquesPDF.aspx?id=27684http://www.taunton.com/finewoodworking/Workshop/WorkshopArticle.aspx?id=5283
Really like his Stupid Block!
Regards,Bob @ Kidderville Acres
A Woodworkers mind should be the sharpest tool in the shop!
I have built several sleds out of 3/4 MDF and they work great Some were a bit heavy so I built some smaller ones for specific purposes, one for crosscutting upto 13 inch, one for 6 inch and below, 2 for 45 degree, and one small one that i've heard called a shooting board type. I had the same problem with the UHMW strips, I ended up sanding around the screws alot, but now they work fine. I like the maple runners I built the best so far. I've had no problems with wood movement as of yet.
Tony
Thanks again to all for the great suggestions. I'd stuck my UHMW rails back on the shelf after my bad experience, but now I see I can dust 'em off and try again. The article Bob sent also gave an excellent explanation of how to make wood rails. I had purchased the sled kit (phenolic rails and blade guard) from Highland Hdwre so now I've got all kinds of options. I've been looking at MDF for a base because the chunks of plywood in my scrap pile are pretty wavy and don't seem to be good candidates for a sled base. I'll need to check with the cabinet makers in the area and see if they'll sell me any decent plywood.
As Bob indicated, getting the fence accurately aligned with the blade is key. I've read several methods to do this. Any suggestions based on what has worked?
This is another reason that I like counterbored holes and pan head screws, rather than countersunk holes and flat head screws: You have some wiggle room with the precise positioning of the runners.
As for the actual alignment process: Trial and error. Snug up the screws, but don't fully tighten them. Install the sled, do a test cut, measure the angles, take the sled out, tap the runner(s) with a wooden block and a small hammer. Lather, rinse, repeat.
-Steve
I'd rather adjust the fence instead of the runners as that's the business end of the fixture not the runners.
Regards,Bob @ Kidderville Acres
A Woodworkers mind should be the sharpest tool in the shop!
I just nudge the saw a bit to the left.
Steve,
So you find it better to move the rails rather than the fence?
Assuming it's a two-runner sled, you're going to have to do some tweaking of the runners anyway, so you may as well position the fence square to the baseplate, and do all of the alignment via the runners. But after that initial setup (when you're replacing the fence, for example), it clearly makes more sense to leave the runners and baseplate alone and adjust only the fence.
-Steve
Steve,
you're going to have to do some tweaking of the runners anyway
I respectfully disagree with tweaking the runners and the following is just my opinion and everyone has one as the old saying goes!
If the TS is aligned properly, i.e. the mitre slots are parallel to the blade in your basic TS setup then the slots are in alignment as they should be, not just for a crosscut sled but for other reasons as well. This should be done before even considering making a crosscut sled.
That being said there should be no need for fiddling with the runners. Messing with the runners only further complicates the process of setting up an accurate crosscut sled. Again, the fence is the key in my opinion.
To place the fence, I secure one end of the fence and, using a framing square laid against the sawblade, use the other end of the L to establish a starting point for the non fixed end of the fence, bringing the fence snug to the L and securing it with a long finish nail. Then make a test cut and check for square. Adjust the fence if necessary by pulling the finish nail and moving the fence accordingly until the cut is square.
At this point I clamp the fence so it won't move and flip the sled over and secure with a screw. I then make another test cut to make sure everything is still aligned and if so, add additional screws to lock it in place.
If ya want a micro-adjust fence that's another smoke to burn.
Regards,
Bob @ Kidderville Acres
A Woodworkers mind should be the sharpest tool in the shop!
Edited 4/22/2008 11:34 am ET by KiddervilleAcres
If your sled has two runners, how do you ensure that they are (a)spaced the right distance apart, and (b) sufficiently parallel, without some tweaking?
-Steve
Steve,
Not to be contrite but please see the rtf document, which goes into it in great detail. If you have a another way please post so I can add it to the document for others to see.
Regards,
Bob @ Kidderville Acres
A Woodworkers mind should be the sharpest tool in the shop!
Edited 4/22/2008 11:46 am ET by KiddervilleAcres
Edited 4/22/2008 11:46 am ET by KiddervilleAcres
OK, I am lost how do you do a two runner sled? What holds the thing together or am I missing something here?
Doug
Doug,
Both the front and back of the sled are held together with a portion of fence that is higher than the blade so it doesn't cut completely through the fences thus holding each side of the table intact.
Foe example: http://www.highlandwoodworking.com/index.asp?PageAction=Custom&ID=86
Regards,Bob @ Kidderville Acres
A Woodworkers mind should be the sharpest tool in the shop!
Perhaps I am too much of a perfectionist (or have spent too much time in machine shops), but I have yet to find sled runners that are so straight and parallel that they can't benefit from some post-assembly tweaking.
-Steve
Steve,
I agree with you, to some degree, but the whole idea is to minimize the need for tweaking if not eliminate it entirely. Of course the sleds longevity/accuracy depends on the materials you choose for the components as you know.
Also, a lot of folks seem to think that once a piece is cut on the crosscut sled it's ready for final assembly. Fact is, at least for me anyway, there still may be some tweaking of the pieces left to do.
Combining a crosscut sled and perhaps a mitre fixture that can be attached, along with a well set up shooting board and all told it's a tough combination to beat for me anyway.
Now, have ya got any of that lubricous wood hanging about that ya don't need?
Regards,Bob @ Kidderville Acres
A Woodworkers mind should be the sharpest tool in the shop!
Oh, I have some lubricous wood all right, but, you see, I need every single piece.
It's kind of pathetic, actually. I have little bits of cocobolo that are 1/4" square and 1/2" long that I can't bear to throw away.
-Steve
Edited 4/22/2008 1:46 pm ET by saschafer
Sounds like candidates for some really nice contrasting plug material!?
Regards,Bob @ Kidderville Acres
A Woodworkers mind should be the sharpest tool in the shop!
Possibly, but cocobolo also has a reputation for being nearly unglueable, as a result of its natural resins. So I'm kind of afraid to use it in a way where glue is the only thing holding it in place.
-Steve
I would place the runners into the slots, then place the sled atop them and attach them. That's the way I would do it.
Now, let's talk about shellac.
Edited 4/22/2008 2:43 pm ET by blewcrowe
There was quite a good method for doing this in AW #128. The fence is adjusted after the rails are set. Because the slots are at right angles to the blade you can begin with roughly the correct fence position using a square. The fence is backed up by a brace block at each end. Screw the left hand block permanently in place, and drive one screw through the base of the sled into the fence at the left end so that it can pivot. Place a temporary brace block at the right side, a little shy of the correct position. Take some test cuts on the saw using shims between the fence and the temporary brace until the fence is quite accurate. Install a permanent right brace, and remove the temporary one.
Jim
Hi Jim,
Ive seen this method used several times also. Drilling a hole through one of the blocks and installing a tee knut affords a micro-adjust facility too and makes it a bit less tedious getting the fence square to the blade.
Just my 2¢,Bob @ Kidderville Acres
A Woodworkers mind should be the sharpest tool in the shop!
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