Cliff Posted October 19, 2015 Report Share Posted October 19, 2015 Lets take a piece of plywood. We'll say 2' x 4' and set up the dado blade to make a cut length-wise. Fence is parallel to the blade, if properly set up. We make the dado about 1/4" deep, 1.5 inches wide. Wide enough to slip the fence made from two piece of plywood glued together in.Is it now square? Or is fence parallel to blade margin of error more than what is generally acceptable for the margin of error on a sled? Quote Link to comment Share on other sites More sharing options...
Tom Cancelleri Posted October 19, 2015 Report Share Posted October 19, 2015 Cliff, when you install the runners they need to be perpendicular to the fence. What you want to do is install the runners, install the front support fence, and then make a cut about 2/3rds through the board. Once you've done that you wanna install 1 screw into the bottom of the main fence, using a square you want it to be 90 degrees from the kerf of the cut you made and put in a screw at the other end of the fence. Then do the 5 cut test to find out how much you're off. Adjust as necessary. William Ng has a great video on this. 1 Quote Link to comment Share on other sites More sharing options...
Cliff Posted October 19, 2015 Author Report Share Posted October 19, 2015 I know all that, I've built 3 sleds, each better than the last. But I'm looking at different methods.If my fence is parallel to both the slots and the blade. Shouldn't I be able to use it as a reference for both the placement of the runners on the sled base and the fence of the jig itself?For instance:-put glue on runners, put base on so that it is flush with the fence. (I used this method on the last one to position the runners.-now, flip the base over and perpendicular. Run it across dado to make a trench for your fence to sit in. If the fence is parallel to the blade then that trench you just cut will be perfectly perpendicular to the blade now. Just insert your fence and screw it down.In other words, I think you can build a sled pretty well without feeler gauges and such. I'd still use the five cut method to test it's squareness though. But if you machine is set correct - shouldn't it be nothing more than validation? Quote Link to comment Share on other sites More sharing options...
Eric. Posted October 19, 2015 Report Share Posted October 19, 2015 Too much built-in error in that method. It feels like it should work in theory but in real life it never will. Try it.And then when you test it and find that it's not perfectly square, there's no way to adjust it. William's way seems complicated and fiddly...but it's the best way. Quote Link to comment Share on other sites More sharing options...
Cliff Posted October 19, 2015 Author Report Share Posted October 19, 2015 Williams way is what caused me to think on easier ways to do it. It always looks super easy when he does it or Marc does it but I have never found that I can get it reasonably square within 2 tests. So ultimately I end up drilling 300 holes trying to get my fence square. I hate that.I think I will try a test and report back. I gotta think the variables would be controllable. Otherwise - we'd never use a rip fence because it wouldn't provide a square cut.I should have tested this before making the post. That way if it turns out I'm an idiot nobody would know. Quote Link to comment Share on other sites More sharing options...
Eric. Posted October 19, 2015 Report Share Posted October 19, 2015 Williams way is what caused me to think on easier ways to do it. It always looks super easy when he does it or Marc does it but I have never found that I can get it reasonably square within 2 tests. So ultimately I end up drilling 300 holes trying to get my fence square. I hate that.Are you sure there isn't a little slop in your runners? If there's any slop at all you'll never get consistent results from the 5-cut twice in a row...nor will you get consistent square cuts in regular use. I had to replace runners fairly recently...two years of swelling and shrinking finally introduced a bit of slop and I wasn't getting consistent cuts. It's critical that the runners be absolutely perfect. Quote Link to comment Share on other sites More sharing options...
Cliff Posted October 19, 2015 Author Report Share Posted October 19, 2015 (edited) I have 3 different types of runners, UHMW plastic runners, the Incra steel ones and cedar ones that I made once I got my hands on the Gripper. To the best of my knowledge, the UHMW and incra's should be good to go. In fact I don't recall any slop. I don't think my wooden ones have any yet. The sled is only 2 months old and I cut them a bit big then hand planed them until they just ran smoothly.I think for my test sled with this new method I will try incra to remove the runner variable. Even though I thoroughly hate attaching those things. I like the idea of wooden ones that I can just use glue to get them situated.FYI - Not saying your opinion of my idea is wrong. But it makes sense to me. The one variable I can think of is that my table saw was not set up with a dial guage, just a square. So if the blade is 2 thou off from the slot, and the fence is 2 thou off from the slot - that introduces a possible variance that might make this method completely jacked. Edited October 19, 2015 by Cliff Quote Link to comment Share on other sites More sharing options...
bgreenb Posted October 19, 2015 Report Share Posted October 19, 2015 Too much built-in error in that method. It feels like it should work in theory but in real life it never will. Try it.And then when you test it and find that it's not perfectly square, there's no way to adjust it. William's way seems complicated and fiddly...but it's the best way.That's the key, IMO. Especially given that you didn't set up your fence with a dial indicator, the odds of completely nailing this on the first shot are nil, and at that point you have no way to fix it. Quote Link to comment Share on other sites More sharing options...
Cliff Posted October 19, 2015 Author Report Share Posted October 19, 2015 That's the key, IMO. Especially given that you didn't set up your fence with a dial indicator, the odds of completely nailing this on the first shot are nil, and at that point you have no way to fix it. Yup. I agree. I think before I try this I will pick up that dial indicator. I mean, at most I'll be out $20 plywood to try this. So if it fails I'm not going to cry. Quote Link to comment Share on other sites More sharing options...
bgreenb Posted October 19, 2015 Report Share Posted October 19, 2015 Yup. I agree. I think before I try this I will pick up that dial indicator. I mean, at most I'll be out $20 plywood to try this. So if it fails I'm not going to cry.Nice. Let us know how it turns out. Quote Link to comment Share on other sites More sharing options...
wtnhighlander Posted October 20, 2015 Report Share Posted October 20, 2015 I like your thinking, Cliff. Simplified logic is usually the best, assuming you know all the variables. Please do share your results, as I am just about due to replace my sled! Quote Link to comment Share on other sites More sharing options...
Cliff Posted October 20, 2015 Author Report Share Posted October 20, 2015 It might take me a while. I know I need to make this investment in a decent dial indicator for the table saw - but I also need to get one for the jointer, along with a straight edge. So money just be flying out of my account on set up tools. Quote Link to comment Share on other sites More sharing options...
BobInAustin Posted October 20, 2015 Report Share Posted October 20, 2015 So you would slip the fence in the dado. That fence would then be parallel to the edge of the plywood that was against the tablesaw's fence. But your runners would then need to be perpendicular to that, right? Isn't there still the issue of making two things (dados in this case?) perpendicular to each other? Quote Link to comment Share on other sites More sharing options...
Cliff Posted October 20, 2015 Author Report Share Posted October 20, 2015 Sure, but if your saw is tuned right, it should do these things for you. I'd be using the fence to reference both. Quote Link to comment Share on other sites More sharing options...
BobInAustin Posted October 20, 2015 Report Share Posted October 20, 2015 Sure, but if your saw is tuned right, it should do these things for you. I'd be using the fence to reference both.I guess I am not seeing how you could make the dados for the runners and make them 90 degrees to the previously dado'ed slots for the sled's fence. Quote Link to comment Share on other sites More sharing options...
Cliff Posted October 20, 2015 Author Report Share Posted October 20, 2015 I guess I am not seeing how you could make the dados for the runners and make them 90 degrees to the previously dado'ed slots for the sled's fence.This is an example write-up of how I did my last runner positioning (not my writeup, just one I found):Set the runners in the table saw slots, and place the base on top. Lock the table saw fence against the right side of the base to keep it from moving; it will also serve as an aid in squaring the base to the front edge of the table saw. Glue the base onto the runners. So, If your fence is perfectly parallel to the runner slot and you have a straight base, the straight edge flush to the fence when you drop it on top of the runners means that your runners are now parallel to the fence. Now it can be flipped over and make the dado cut.I mean - like I said, this is my theory. I did drop my base on top of the runners in this way last time, and it worked great, but I never actually needed that to be set up that way because I squared the fence completely differently. Quote Link to comment Share on other sites More sharing options...
BobInAustin Posted October 20, 2015 Report Share Posted October 20, 2015 Maybe you can post pics? I get how the runners would be parallel to the saw's fence. I'm still missing how you get the sled's fence perpendicular to that. Quote Link to comment Share on other sites More sharing options...
Cliff Posted October 20, 2015 Author Report Share Posted October 20, 2015 It will take me a while, I'll post pics and analysis when I run this test Quote Link to comment Share on other sites More sharing options...
bgrella Posted October 20, 2015 Report Share Posted October 20, 2015 Every time I've tried the 5-cut method the bottom of my sled, near the fence, ended up looking like cottage cheese. In my opinion, with regard to accuracy and time involved, you can't beat a dial indicator and a square to set up a sled fence. I've demonstrated the process on video in the past. Not sure if links are allowed here. Contact me if you can't find it. 1 Quote Link to comment Share on other sites More sharing options...
Cliff Posted October 20, 2015 Author Report Share Posted October 20, 2015 Every time I've tried the 5-cut method the bottom of my sled, near the fence, ended up looking like cottage cheese. In my opinion, with regard to accuracy and time involved, you can't beat a dial indicator and a square to set up a sled fence. I've demonstrated the process on video in the past. Not sure if links are allowed here. Contact me if you can't find it.Sure. Toss me a link in PM. I'm right there with ya on the cottage cheese. Quote Link to comment Share on other sites More sharing options...
BobInAustin Posted October 21, 2015 Report Share Posted October 21, 2015 Every time I've tried the 5-cut method the bottom of my sled, near the fence, ended up looking like cottage cheese. In my opinion, with regard to accuracy and time involved, you can't beat a dial indicator and a square to set up a sled fence. I've demonstrated the process on video in the past. Not sure if links are allowed here. Contact me if you can't find it.Llooks good, Brian. I will give this a go on my next sled. https://www.youtube.com/watch?v=tZM1OBcC6ok Quote Link to comment Share on other sites More sharing options...
bgrella Posted October 21, 2015 Report Share Posted October 21, 2015 Llooks good, Brian. I will give this a go on my next sled. https://www.youtube.com/watch?v=tZM1OBcC6okThanks Bob. Here is a more recent demo. The alignment starts around 5:00 : https://www.youtube.com/watch?v=YTlpY_chcio#t=309 Quote Link to comment Share on other sites More sharing options...
sheperd80 Posted November 12, 2015 Report Share Posted November 12, 2015 The whole purpose of the 5 cut method is to eliminate any and all tool error, and to measure error over a much greater distance than the actual sled. If your saw and fence are absolutely perfect then sure, in theory this dado method will give u a perfect fence. But i have my doubts that any saw or fence are that precise. This is the same problem with the dial indicator method above. Sure it will make u a very nice sled, more accurate than ill probably ever need. But the 5 cut method is for those who want that next level of accuracy. By eliminating indicators, fences or squares youre limited only by your patience, the straightness of your fence material, and of course blade runout. Sent from my SAMSUNG-SGH-I747 using Tapatalk Quote Link to comment Share on other sites More sharing options...
Cygnus A Posted November 24, 2015 Report Share Posted November 24, 2015 Did you ever get around to trying this? Quote Link to comment Share on other sites More sharing options...
Cliff Posted November 24, 2015 Author Report Share Posted November 24, 2015 Not yet. I got the table saw fence aligned with a woodpecker saw gauge. But woodworking anything tends to take me about 300x longer than anyone else. Just due to the natural events of life and such Quote Link to comment Share on other sites More sharing options...
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