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Jigs etc. #1: Mitre Jigs

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Blog entry by BritBoxmaker posted 1566 days ago 2918 reads 12 times favorited 7 comments Add to Favorites Watch
no previous part Part 1 of Jigs etc. series Part 2: The old 60° »

Here are the mitre jigs (sleds) that I use for my box sides. The first is a typical 45 degree job with a square blade guard, there is a stop block underneath (not shown).

There are two additional features however. The first are the two clear perspex stops, for repeatability of cut length, nothing unusual there.

The second is something I’ve started to use to prevent tear out of the end grain on the mitred end. These are adjustable sacrificial jaws attached to the outsides ouf the mitre arms. These are Iroko but any scrap timber, or MDF, will do.

I find that however well adjusted the blade is, for squareness, over a period of time the tips of the mitre arms (where the blade passes through) will wear and the gap become wider. This leads to tear-out of the end grain on the inside of the mitre on the box side being cut. Even with an 80 tooth blade. At the beginning of doing a batch of sides I bring both jaws into the centre of the saw cut region (loosen cross-head screws, move jaws in, tighten cross-heads). Having squared up the blade beforehand I do a pass with no timber on the jig to open up the jaws again. Each time this is done the jaws are good for cutting about a dozen boxes worth of sides, with no tearout.

The second jig is the 60/30 degree one I used for the Vanishing Point box. It has a stop block underneath (not shown).

As its a fresh jig there are no sacrificial jaws fitted yet. However I’ve used the rear section for a dust extraction port this time.

I’ve also used the fact that there is active dust extraction (and therefore partial vacuum) to provide a degree of holding for the box side being cut.

The three holes (3mm diametre) are bored through the whole depth of the mitre arm and allow the ‘borrowing’ of some of the vacuum of the dust extractor to hold the piece being cut onto the mitre arm.
My next project is to adapt the first jig for dust extraction/vacuum holding. After that possibly an adjustable angle jig.

-- Martyn -- Boxologist, Pattern Juggler and Candyman of the visually challenging. http://www.theartofboxes.com



7 comments so far

View patron's profile (online now)

patron

12955 posts in 1939 days


#1 posted 1566 days ago

looks pretty atomic !

great jigs ,
and the under stop idea is great ,
for those absentminded cuts .

thanks for sharing !

-- david - only thru kindness can this world be whole . If we don't succeed we run the risk of failure. Dan Quayle

View BritBoxmaker's profile

BritBoxmaker

4337 posts in 1634 days


#2 posted 1566 days ago

Well spotted David!

-- Martyn -- Boxologist, Pattern Juggler and Candyman of the visually challenging. http://www.theartofboxes.com

View Ger21's profile

Ger21

615 posts in 1729 days


#3 posted 1566 days ago

The sacrificial faces are an outstanding idea. Some day, when I make a sled, I’ll be sure to incorporate them. If I remember. :-)

Well Done.

-- Gerry, http://home.comcast.net/~cncwoodworker/CNC_Woodworker.html

View SPalm's profile

SPalm

4751 posts in 2479 days


#4 posted 1566 days ago

Sweet. I also have a 45 miter sled and find it very useful. I like the replaceable faces and under sled stop block too. Good thinking.

I never thought to apply it to a 60/30 sled. Again, you are a clever guy. Any hints on how to get it set to 30/60? I guess if you have one set, the other follows, but how to get the first set? Trial and error certainly works.

Steve

-- -- I'm no rocket surgeon

View BritBoxmaker's profile

BritBoxmaker

4337 posts in 1634 days


#5 posted 1566 days ago

Steve. Assuming you already have a base attached to its runners first make sure the blade is set parallel to your mitre guage runners (slots). Cut a full slot into the base using the saw’s blade. I set the 60 degree side up first. Having already cut the end of the mitre arm to 60 degrees using my saw’s mitre guage i put a strip of double sided tape along it’s bottom face. With the sled pushed fully forward set the tip of the 60 degree side to the position where the blade is at max. height. Using a protractor or a similarly cut sheet of scrap set the mitre arm at 120 degrees to the blade. Stick the arm down. Drill and screw the arm to the sled from the underside. Cut the 30 degree arm to 30 degrees at its end and tape up the underside. Using your best wooodworkers square to set it 90 degrees from the 60 degree side. Stick down and screw home as before.

Martyn

-- Martyn -- Boxologist, Pattern Juggler and Candyman of the visually challenging. http://www.theartofboxes.com

View bigike's profile

bigike

4031 posts in 1886 days


#6 posted 1566 days ago

great ideas, i like the one with the dust extaction.

-- Ike, Big Daddies Woodshop, http://www.icombadaniels@yahoo.com

View Cozmo35's profile

Cozmo35

2198 posts in 1633 days


#7 posted 1564 days ago

It looks like you put a lot of thought into the design of these jigs! I am sure it will carry through to your boxes.

-- If you don't work, you don't eat!.....Garland, TX

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