# Question using 5th Cut Method

 Forum topic by zipmac22 posted 07-02-2017 05:08 PM 946 views 0 times favorited 3 replies
 zipmac2229 posts in 1056 days 07-02-2017 05:08 PM Hey Y’all, I’m making a cross-cut sled for my Bosch 4100 tabe saw. I tried to square up the cross-cut sled, but I’m not sure if I’m figuring the math correct using the 5th cut method. I wonder if anyone could look over my numbers and see if I’m on the right path? Here’s the measurements from my fifth cut. Front: .5395Back: .30755th Cut Length: 9 5/8” or 9.625” Length from pivot point to end of the fence: 29.5” I came up with .17776623 I’m still un sure of what I need to do with the (.17776612) to give me the distance I need to move the fence. Do I use a feeler gage closest to (.17776697)? I do know that I need to move the fence back since it’s a positive number. Thanks for your help! Chris﻿ -- Chris, Central Texas

## 3 replies so far

 TheFridge10744 posts in 1689 days #1 posted 07-02-2017 05:13 PM William Ng explains it and shows how to do it in his video on making sleds https://m.youtube.com/watch?feature=youtu.be&v=UbG-n--LFgQ -- Shooting down the walls of heartache. Bang bang. I am. The warrior. Loren10477 posts in 3850 days #2 posted 07-02-2017 05:15 PM I haven’t done it in quite some time butas I recall you cut a wider piece off forthe 5th cut and the amount of taper is4-times the amount your sled is out ofsquare. A 1/64” out-of square might behard to spot, but x4 it becomes 1/16”. You came up with something a bit lessthan a tenth of an inch so I think you’dwant to move the fence (or try papershims to figure out how much) about a quarter of that or .178/4 Ng’s method is probably more scientificthan mine. Getting any saw to cut cabinet panels dead-square is somethingof a hassle I’ve found. In most work itdoesn’t matter but I’ve fussed with framelesscabinetry and in that it’s really important. Rich3883 posts in 792 days #3 posted 07-02-2017 08:58 PM Distance to move fence = (A – B) / 4 / L X D Where A is front, B is back, L is length of 5th cut and D is distance of pivot. So, your error is 0.006 inches per inch, and you are correct that the fence should move 0.177”. Since the error is positive, the fence should move back, as you said. You can watch the William Ng video mentioned earlier, but basically, you are going to clamp a blocking board touching the fence, pull the fence back and then push it back to the block with a 0.18” feeler gauge in between and secure it there. Edit: Obviously, you’ll have to stack multiples to get that. Mine only goes up to 0.03 for a single gauge. You can also probably stack 0.177 exactly, but it doesn’t really matter much at that point. -- Half of what we read or hear about finishing is right. We just don’t know which half! — Bob Flexner

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