barri Posted December 12, 2015 Report Share Posted December 12, 2015 Marc quoted in his video that .005" error over 24" in the real world was good enough. I get .0067 over 24" and the large rectangle left over from the 5 cuts appears to have four 90 degree angles as well as a test cut, checked with a set square. I guess that if my sled can only cut to a bit more than 24" and current cuts of that length appear square then i should stop here and start enjoying my sled but I am curious as to where others have stopped and said that's good enough. By the way, I have almost no places to put more more screws as that was my 4th attempt. Would you stop here or should I try to get under .005" over 24"? What is considered an acceptable figure to aim for? .008"? .004"? Where did other people stop? Quote Link to comment Share on other sites More sharing options...
Popular Post Eric. Posted December 12, 2015 Popular Post Report Share Posted December 12, 2015 Remember that's .0067" divided by five. It's such a microscopic discrepancy that it won't matter in the context of woodworking. You could chase your tail all night with your feeler gauges and only improve enough that you would never know the difference.If you put a square to your cut and it's square...it's square. Go build something. 9 Quote Link to comment Share on other sites More sharing options...
barri Posted December 12, 2015 Author Report Share Posted December 12, 2015 (edited) Actually the error here (.0067") was after dividing by 4. You should be dividing by 4 not 5 as the error is magnified 4 times over the 4 cuts to get back to the start. The 5th cut is for the test piece. Edited December 12, 2015 by barri Add clarity Quote Link to comment Share on other sites More sharing options...
Eric. Posted December 12, 2015 Report Share Posted December 12, 2015 Then get the feeler gauges back out. LOL 1 Quote Link to comment Share on other sites More sharing options...
barri Posted December 12, 2015 Author Report Share Posted December 12, 2015 BTW Marc's error of .005" was after dividing by 4 Quote Link to comment Share on other sites More sharing options...
Chris H Posted December 12, 2015 Report Share Posted December 12, 2015 I am with Eric, you are close enough. You and mother nature are going to make bigger errors throughout the project. If you have a quality square and it can't tell the difference, you are there. I used to spend a lot of time worrying about getting my machines perfect, and found I improved my quality of work a lot more by simply building stuff and learning tricks along the way. The time spent perfecting machines, in my opinion, can be better spent mastering the craft (or building stuff). Get them good, but stop at good. Perfect is an impossible dream! Quote Link to comment Share on other sites More sharing options...
TerryMcK Posted December 12, 2015 Report Share Posted December 12, 2015 Life is too short to worry about 6 thou - you are close enough. Quote Link to comment Share on other sites More sharing options...
Eric. Posted December 12, 2015 Report Share Posted December 12, 2015 BTW Marc's error of .005" was after dividing by 4And you'll notice he went back and dialed it in further. He said "good 'nuff" after the first round of tests that yielded an error of .005"...but I'll assume that meant it's good enough for YOU if you WANT it to be. Frankly I wouldn't settle for 5 thou out over a 24" span. In real world it probably wouldn't be an issue very often, but I could see it causing some frustrations from time to time if you're an anal retentive type like me who would lose sleep over a tiny gap in something.I thought you were saying your .0067 was BEFORE dividing by four, which would have made your actual number closer to barely more than one thou. I'd definitely leave that. But almost 7 thou? I think you can do better. I'd try. Quote Link to comment Share on other sites More sharing options...
Trip Posted December 13, 2015 Report Share Posted December 13, 2015 ==>Frankly I wouldn't settle for 5 thou out over a 24" span.Isn't there a pill for that? 1 Quote Link to comment Share on other sites More sharing options...
Eric. Posted December 13, 2015 Report Share Posted December 13, 2015 There should be.Here's an example why that would bother me. Say you're setting a plywood panel in the back of a cabinet, rabbeted. You'll see that 5 thou gap at two opposing corners.Granted, in this example it's just a back panel so you may not care because you can't see it, but it's not beyond possibility that you'll encounter the same issue on some show area in the future. I couldn't live with knowing the gap is there, even on the back. One thou I could probably handle...five? Probably not. 1 Quote Link to comment Share on other sites More sharing options...
Trip Posted December 13, 2015 Report Share Posted December 13, 2015 Just playing with you -- I wouldn't let 5thou slide either... I've got four or five sleds -- they are all within 2thou... Quote Link to comment Share on other sites More sharing options...
barri Posted December 13, 2015 Author Report Share Posted December 13, 2015 OK I'll have another bash and report back. I hope I can find spots for new screw holes. I will label the screw holes that I have now so that I can return to the current setting, which is pretty good, just in case I make it worse. I'm anal about this too. Eric the .0067 error was AFTER dividing by 4. The above poll is for errors after dividing by 4 as that is the true error over the length of the test piece Quote Link to comment Share on other sites More sharing options...
Trip Posted December 13, 2015 Report Share Posted December 13, 2015 ==>I hope I can find spots for new screw holesEpoxy-fill existing holes and drill new ones once dialed-in. Quote Link to comment Share on other sites More sharing options...
Popular Post Trip Posted December 13, 2015 Popular Post Report Share Posted December 13, 2015 (edited) I'll give you my method to get you there in one-shot... Been using this workflow for several years and has never failed... Get all my TS sleds, jigs, etc without a single adjustment... No screwing around, no re-drilling, etc...However, my method requires access to a precision square... Since many WTO members have the Woodpecker Framing square, Engineer's square, Starrett Combo square, etc -- the method should be accessible for most. Note: the large Woodpecker square is ideal...The 5-cut method only confirms the setup...Assuming you start with the Ng sled assembly workflow:Make the cut through the rear fence and half way through the sled...Insert a precision-ground bar in the kerf at/in the rear fence : http://www.mcmaster.com/#8954k146/=107ynwiUse a large precision square (Engineering square, Woodpecker's framing square, etc) to register off the bar and front fence.You now have 90d within the precision of the square. In may cases that's within 2-3thou.Tighten front fence...Done.Confirm within 2thou using 5-cut method. I also use the bar to set stops, etc -- lot's of places where precision is required... It's the perfect way to reference the kerf -- as long as you always use 1/8" kerf blades...BTW, use this method to confirm my SCMS setup and just about anywhere else a kerf is your reference... Edited December 13, 2015 by hhh 4 Quote Link to comment Share on other sites More sharing options...
Firehawk Posted December 13, 2015 Report Share Posted December 13, 2015 Sounds like a good method. Some pictures or a video would greatly help a lot of us! Quote Link to comment Share on other sites More sharing options...
Trip Posted December 13, 2015 Report Share Posted December 13, 2015 No problem, next time I replace a sled.... sometime in 2017... Honestly, if you watch the Ng video and just augment the last few steps, you're there... Quote Link to comment Share on other sites More sharing options...
Al Capwn Posted December 13, 2015 Report Share Posted December 13, 2015 No problem, next time I replace a sled.... sometime in 2017... Honestly, if you watch the Ng video and just augment the last few steps, you're there... I am presuming that talking about inserting a brass piece inside the kerf cut and then using your square to reference against that. Something like a brass setup gauge bar? Quote Link to comment Share on other sites More sharing options...
Immortan D Posted December 13, 2015 Report Share Posted December 13, 2015 There's a link to the required 1/8" bar in hhh's post. I guess a 1' bar is enough for this application. Quote Link to comment Share on other sites More sharing options...
Trip Posted December 13, 2015 Report Share Posted December 13, 2015 (edited) I've got 4", 6" and 12". Honestly, I use them all the time at the sled... The ability to get precise registration from the kerf is quite valuable and indispensable for TS-based joinery... I use the 4" when it's a small jig and 12" for sleds... Same goes for Engineer's squares -- from 2" to 18" -- small jigs to large sleds...I also have some 1/4"t x 1/2"w x 2"l for the drawer bottom groove when transferring tails to pins on the Moxon (I built the BC-Moxon w/ tailboard shelf)... Registers the boards at the groove... And since the groove is 3/8" from the bottom.... That plus the 140 trick and you've got the pin boards nailed...2c Edited December 13, 2015 by hhh Quote Link to comment Share on other sites More sharing options...
barri Posted December 13, 2015 Author Report Share Posted December 13, 2015 hhh, a good post. I actually use a thin kerf blade (about 3/32") but I did use a framing square first and placed a metal ruler in the kerf ensuring it was jammed in straight using small wedges. That gave me a good start but maybe my square was out or my ruler wasn't straight in the kerf or I had too many drinks the night before. Quote Link to comment Share on other sites More sharing options...
Trip Posted December 13, 2015 Report Share Posted December 13, 2015 Sounds like you have the procedure down, but need to up the volume on your tooling -- or maybe a little less booze... Whichever works... If you use thin kerf blades, McMaster-Carr sells 3/32" brass bars... Quote Link to comment Share on other sites More sharing options...
Chris H Posted December 14, 2015 Report Share Posted December 14, 2015 Another pretty simple way to get it dead on the first time, is to run the blade through the rear fence and right up to where the front fence would starts. Place your square against the blade itself. Square the fence visually, shoot some screws from the top to hold it in place, but back it up enough to shoot from the bottom and drill/tighten down. It requires a good machinist or precision square. Just be sure you either have a long enough square that you touch both ends of the saw blade on the tooth or get one small enough to fit between the teeth. (Error larger if possible, much easier, and more accurate) I've never had to reset a fence using this method. It's simplicity is why I keep using it. Quote Link to comment Share on other sites More sharing options...
Trip Posted December 14, 2015 Report Share Posted December 14, 2015 Similar to my process, but I use a milled bar registering from the kerf instead of registering off the blade... I find it just easier... And something about rubbing steel against carbide... Quote Link to comment Share on other sites More sharing options...
barri Posted December 14, 2015 Author Report Share Posted December 14, 2015 Got to .0021" over 20". I'm happy with that but in real terms it made no difference. Before when it was over .006" I did a long test cut and it measured exactly 90 deg using a digital protractor. Did the same and it was still 90 deg. So for practical reasons a few thou makes little difference. For what I do this setting is fine. I am not doing precise engineering metal work. I now understand Marc's comment about "in the real world .005" is good enough". 1 Quote Link to comment Share on other sites More sharing options...
barri Posted December 14, 2015 Author Report Share Posted December 14, 2015 Place your square against the blade itself. This method only works if your blade is dead parallel to the miter slots. I prefer to have my square against a straight edge placed inside the kerf as mentioned above. This video clearly shows why. Quote Link to comment Share on other sites More sharing options...
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