LumberJocks

Question using 5th Cut Method

  • Advertise with us

« back to Jigs & Fixtures forum

Forum topic by zipmac22 posted 07-02-2017 05:08 PM 741 views 0 times favorited 3 replies Add to Favorites Watch
View zipmac22's profile

zipmac22

17 posts in 693 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: .5395
Back: .3075
5th 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


3 replies so far

View TheFridge's profile

TheFridge

8336 posts in 1326 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.

View Loren's profile

Loren

9639 posts in 3488 days


#2 posted 07-02-2017 05:15 PM

I haven’t done it in quite some time but
as I recall you cut a wider piece off for
the 5th cut and the amount of taper is
4-times the amount your sled is out of
square. A 1/64” out-of square might be
hard to spot, but x4 it becomes 1/16”.

You came up with something a bit less
than a tenth of an inch so I think you’d
want to move the fence (or try paper
shims to figure out how much) about
a quarter of that or .178/4

Ng’s method is probably more scientific
than mine. Getting any saw to cut
cabinet panels dead-square is something
of a hassle I’ve found. In most work it
doesn’t matter but I’ve fussed with frameless
cabinetry and in that it’s really important.

View Rich's profile

Rich

1987 posts in 429 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.

-- No matter how much you push the envelope, it'll still be stationery.

Have your say...

You must be signed in to reply.

DISCLAIMER: Any posts on LJ are posted by individuals acting in their own right and do not necessarily reflect the views of LJ. LJ will not be held liable for the actions of any user.

Latest Projects | Latest Blog Entries | Latest Forum Topics

HomeRefurbers.com