LumberJocks

Narrow stock mitre sled

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Project by LittleBlackDuck posted 07-31-2016 02:23 PM 1246 views 4 times favorited 16 comments Add to Favorites Watch

Boys and Girls,

I’m sure that most of us have been confronted by mitre cuts in long, narrow and thin stock. While most veterans have devised their own methodology and sacrificial fingers, I had to create a new ”skin” for a 22.5° set of cuts so I thought I might as well take some happy snaps and document my mitre sleds for any novices out there that are yet to design their own signature jig.

The reason why I made this jig is because I quickly discovered that I could never get two bevelled edges on opposing edges of narrow stock to finish up the exact size required. I always used to sneak up on the cut as the bevelled edges always seemed to slide under length stops and I continually struggled keeping the piece parallel and once moved you are really starting positioning again. Anyway I had issues with the traditional sleds.

Now what I do is cut the stock to exact size and use this jig to put the bevel onto it. As all it is doing is cutting the corner off the bevel, there is little work being performed and strong clamping pressure is not mandatory and medium pressure is sufficient.

The jig was initially cannibalised from a “traditional” mitre box jig for 45° cuts but got slightly mutilated when I had to make a few different degree cut. It finished up in 2 halves and morphed into a LHS sled. The dimensions are not critical as the width will be mutilated by the saw blade as you run it along the table… just ensure you have an adequate working space to the left of the blade for the workpiece and maybe a clamping system. The length is arbitrary, but as this is meant to be a small part jig, I can see no benefit in making it several meters long, so keep it short enough that you don’t need to revert to bifocals or binoculars to see the far end of it.

The secret to making it versatile is to make ”skins” for the cutting surface(s). I use a mitre track down the length of the base to permit further flexibility. I make up my skins of 3mm and 6mm DMF sheet goods to permit the use of standard 9mm T-tracks.

The base consists of 18mm MDF with a 3mm then a 6mm MDF sheet on top. These are “halved” by the track. One hint I will give now is to carefully measure the cutting side top 6mm MDF piece and place the screw holes so that the piece can be of any orientation and the screw holes will line up (more on this later). Now KEEP this as a template and create new ”skins” using the marked screw holes for subsequent drilling. Ensure the screw holes are placed in such a way that there is sufficient overhang to be able to cut a bevel edge. Note that when you flip the piece to use for another angle there should be a slight gap between the former cut edge and the T-track, but it should not be sufficient to be of concern (otherwise cut a sliver for a packer). This way you can replace the ”skin” as many times as you like without turning the base into a cheese grater with random placed screws.

As with all my projects I start off by designing something/anything in SketchUp and after looking at it for a few hours I decide what I can make out of it.

The screw hole placement on the left (non-cutting ”skin” is not paramount) for the equation. You may have noticed (and if you haven’t go back and have a look) the base has a 45° bevel, this is not really important but it does clear the timber to ensure it can accommodate a max of 45° ”skin” without additional scarring. It is the 6mm MDF top ”skin” that provides the cutting surface and should be more than thick enough for small stock.

To make the ”skin” reusable I highly recommend accurate angle measurement. I use a Wixey angle gauge and I feel that it’s mere .1° accuracy is sufficient not to be detectable by my failing eyes. The accuracy of the angle is required for both the build specifications and retainment of the top cutting sides edge (hey you can cut a new one each time if you want). I also pair up a dedicated skin for the backing board with the base which I use for visual alignment purposes only.

Now for accuracy I have devised this methodology for creating a fitting/alignment jig for the small piece along the cutting edge. The 10° in the diagram was for this specific ”skin”... You can choose your own personal 10° angle.

Take a piece of MDF the same thickness as your top ”skin” and ensure that one end is perfectly straight and preferably square, somewhere between 100-200mm wide. Place the width across your sled and cut a 24-30mm wide piece and put aside (remember it has a 90° edge and let us name this piece Aloysius). Now cut another piece about the same width which should now have two edges the same angle as your sled and call it Hephzibah. Place Aloysius on its end and glue Hephzibah with the long edge width against Aloysius. You should now have a bevelled edge leading into a 90° edge. Mark this edge as the action part. The other edge (should have two adjoining bevelled edges and is infertile).

You will need to make a packer/spacer (let’s call it Aristotle) the thickness of your base and any additional ”skin” if used (do NOT include the thickness of the top skin). In the diagram my spacer was 21.7mm thick (this needs to be as exact as you can make it for accuracy) which was made up of theoretical 19mm and 3mm MDF (should be 22mm but was probably made in China and they cut back on thickness to cut costs… also most likely lost in the katakana translation).

Now to set-up using Aristotle and Aloysiusand Hephzibah.
Place Aristotle next to the jig. Does not have to touch but provide a flat surface for A & H,

Now place Aloysius above Hephzibah on top of Aristotle and push the bevelled part Hephzibah into the cutting bed. The 90° piece Aloysius on top should protrude above the top surface parallel to the cut line.

Notice how Aloysius is against the cut line. Also note that the backing ”skin” kerf line is an handy and ideal alignment mark for this angled cut, that I find totally useless and have never used it.

Now push your piece to be cut (let’s call it Costlitimba) against Aloysius ensuring it does not move. Pieces should be small enough that no pressure need be applied to ensure snug fit without disorientation.

Clamp and cut, again ensuring the A & H is not pushed away by clamping pressure. I found that initially the way I set up my clamp it pushed the Costlitimba stunt double about 1mm sideways… I readjusted the clamp cut another victim and voilla…

This picture illustrates the “paired” end piece with it’s mating base ”skin” (both marked with the 22.5°).

If you position your screw holes properly, you can flip the ”skin” and use the other long end as a new cutting edge. This way you can use each ”skin” for 2 different angle configurations. You may notice the slight gap between the track and the flipped side (with the 6° cutting edge) small enough for even an elephant tom straddle.

-- There's two ways to do things... My way or the right way.. LBD





16 comments so far

View bruce317's profile

bruce317

208 posts in 286 days


#1 posted 07-31-2016 02:58 PM

Ducky,
Nicely built and useful sled.

-- Bruce - Indiana

View Dutchy's profile

Dutchy

2015 posts in 1631 days


#2 posted 07-31-2016 03:34 PM

I don’t know what to say, simply because we (at least almost all)use not sled on our table saw in europe and there is often no groove in the saw table either. But I hope this sled will work for you Ducky.

-- My englisch is bad but how is your dutch?

View htl's profile

htl

2194 posts in 622 days


#3 posted 07-31-2016 05:34 PM

I really like your Narrow stock mitre sled and will be making one.
I was just thinking I would be using it with really narrow parts so would be using a stop block clamped to the fence to keep things aligned.
You could then flip the part to do the other side if needed.
Not a very good drawing but you get the idea.

-- There's a hundred ways to do anything, alot depends on the tools at hand.

View kiefer's profile

kiefer

4881 posts in 2130 days


#4 posted 08-01-2016 01:22 AM

Some good ideas here and it got me thinking how I can use some on my sled since it already has a sliding bottom and it would save me from building another sled .
http://lumberjocks.com/projects/165970

Klaus

-- Kiefer https://www.youtube.com/user/woodkiefer1/videos

View LittleBlackDuck's profile

LittleBlackDuck

599 posts in 283 days


#5 posted 08-01-2016 02:22 AM


... using a stop block clamped to the fence to keep things aligned.
You could then flip the part to do the other side if needed.

- htl


Unfortunately that was my issue to start with. To make a mitre cut after the opposite edge has already been doctored, when the bevelled edge is on the base board, there is a tendency for the edge to slightly slip under the stop block. That is why I used to flip the work piece so the bevelled edge is at the top thereby the contact with the fence is somewhat above the base thus clearing any potential stop block/base gap. However, I found this impractical as with my saw I had to then work from the RHS. With low angled cuts the potential to slide under the stop block minimises but then exacerbates as the angle increases. I found that any stop block should have a crip 90° edge clamped to the base to but against the workpied to avoid the “bevel creep”, however, I never fully trusted this practice. That is why I started using this setup metchodology (with A, A & H) prior to using a stop block and eventually just clamped the stock and not used a stop-block.

This is a blowup of the text in above picture and I was too lazy to retype,

You always come up with good ideas so I’d be interested in your take on this if/when you make something for this purpose.

PS. This post is more to detail the method I use to setup a piece (already square cut to size) and the use of “skin”s for different angles tehreby preserve the jig’s base, rather than the physical jig itself.

-- There's two ways to do things... My way or the right way.. LBD

View htl's profile

htl

2194 posts in 622 days


#6 posted 08-01-2016 02:41 AM

Use the stop block to line it up , you’ll still need to clamp the part down to stop the creeping I would think.
My saw tilts to the left and I’m more used to working on the right side of the blade but that’s just me.
Doing it this way the long edge is to the top on most cuts.

-- There's a hundred ways to do anything, alot depends on the tools at hand.

View LittleBlackDuck's profile

LittleBlackDuck

599 posts in 283 days


#7 posted 08-01-2016 02:43 AM



Some good ideas here and it got me thinking how I can use some on my sled since it already has a sliding bottom and it would save me from building another sled .
http://lumberjocks.com/projects/165970

Klaus

- kiefer


Hi Klaus, That is exactly the type of sled I started out with. As I needed to cut various angles between 90° and 45°, I found I was destroving the middle of my base with the different angled kerfs. I then found that using a 6mm sub-base (I call ”skin”) was sufficient to give a solid base for the stock. Unfortunately with little foresight I screwed it to the base in no scientific manner and after a while I hit a predrilled hole and sent the screw on a skewed angle which brought cuss words to my lips.
I then found that I had issues lining up the stock where it was to be cut with the kerf line. People with good eyesight may not have issues but for me it was a chore. Usually your cut mark is on the opposite side of the workpiece to the kerf line (hidden on the bottom if you cut the right end of the piece or above the kerf line if you cut on the left end of the piece using a left tilting saw). I found my option was to transpose the cut line to the side of the work piece which brought in other potential marking errors. I’m sure there are many ingenious ways to compensate for this parallax error, however, I haven’t found an easy one.

-- There's two ways to do things... My way or the right way.. LBD

View LittleBlackDuck's profile

LittleBlackDuck

599 posts in 283 days


#8 posted 08-01-2016 04:57 AM



... I m more used to working on the right side of the blade but that s just me.
Doing it this way the long edge is to the top on most cuts.

- htl

#4, If I read this correct your setup would be as follows. I’ve market what I consider as the critical point.

If you mark the top edge (or even cut the stock to size to perform a bevel shave), you could use the kerf cut on the backing board as a reference line (will need to swap out for different angles), however for long thin pieces (and more so if its a compound – not 90°) it would be hard to keep it parallel to the cut line. I could probably be missing something simple here (the old adage of forest and trees...) but this has always caused me grief.

Just thought, though I’ve never needed it, my setup process (nothing to do with jig or stop blocks) would be a good solution to non parallel sided or odd shaped work pieces (other than the proposed cut edge).

All this thinking makes my head hurt….

-- There's two ways to do things... My way or the right way.. LBD

View htl's profile

htl

2194 posts in 622 days


#9 posted 08-01-2016 02:01 PM

One other thing to keep in mind the blade is coming down on the wood in the last picture so you will get a much cleaner edge.
Plus it is very easy to make small cuts up to the distance needed.
Like you I’m getting no got to the point where not only can’t see the mark but having trouble bending over to look so making a cut check it for fit then move the fence over just a tad gets er done for me.

One other thing I should add, I don’t use many angle cuts if I can get away with it.
I guess that’s one reason I like the train builds it’s all butt joints, just cut it big and sand till flush.

The way I do things gets it done fast but not as accurate if I cut something small many times I just sand the model and my model may end up smaller because of it.

Attention to details is not my strong point.
It’s like those kerfs on the train engine it looks complicated but it’s just something quick that fills up space.

There no wrong way to do this stuff just what works for you.
I have seen from your jigs that you have set up things to get it just right and it is perfect, I wish I could work like that but just don’t have the patience for it.

I love seeing your jigs and have gotten many a great idea from them.
Some time the jigs are more fun building than the model.
I would guess that’s why I like making the wheels so much,it’s the jig making that’s so much fun.

-- There's a hundred ways to do anything, alot depends on the tools at hand.

View LittleBlackDuck's profile

LittleBlackDuck

599 posts in 283 days


#10 posted 08-01-2016 02:28 PM

My problem is that I’m not as inventive as you guys… If the plan calls for a 37.637° angle I make a 37.637° angle. Not through any accuracy discipline but due to my inability to improvise and I have become a creature of habit that gets easily dictated to.

I used to part my hair on the left until my missus told me it would be easier to part on the right. Fortunately I’ve been able to adapt while I still have some hair left (correction, now right) and after buying a right handed comb I’ve never looked back.

-- There's two ways to do things... My way or the right way.. LBD

View helluvawreck's profile

helluvawreck

23157 posts in 2329 days


#11 posted 08-01-2016 02:47 PM

Nice jig. Congratulations

helluvawreck aka Charles
http://woodworkingexpo.wordpress.com

-- If a man does not keep pace with his companions, perhaps it is because he hears a different drummer. Let him step to the music which he hears, however measured or far away. Henry David Thoreau

View htl's profile

htl

2194 posts in 622 days


#12 posted 08-01-2016 09:24 PM

I wonder if you moved up here would you need to switch back to the left side?
Discerning minds need to know these things.

-- There's a hundred ways to do anything, alot depends on the tools at hand.

View LittleBlackDuck's profile

LittleBlackDuck

599 posts in 283 days


#13 posted 08-01-2016 10:20 PM


I wonder if you moved up here would you need to switch back to the left side?
Discerning minds need to know these things.

- htl


Nothing against Americans, however, I could never move there , because,
- The thought of counting in imperial and 12 cents in a dime totally freaks me out.
- I’ve already trimmed all my finger and toe nails to be able to count in Australian decimals.
- My calculator throws a wobbly when I attempt to enter fractions.
- The missus would be unbearable when you consider the conversion from Kg to Lb is 1 for 2.

As for combing to the left, aren’t your mirrors up north backwards… that should compensate..

-- There's two ways to do things... My way or the right way.. LBD

View htl's profile

htl

2194 posts in 622 days


#14 posted 08-02-2016 12:31 AM

Yep!!! the mirrors are backwards and the toilet water turns in the other direction so you would have to be careful when you flush them.
Did I really type that, well to late now.

-- There's a hundred ways to do anything, alot depends on the tools at hand.

View Dutchy's profile

Dutchy

2015 posts in 1631 days


#15 posted 08-02-2016 07:24 AM



............. and the toilet water turns in the other direction

- htl

That’s a bidet Bruce.

-- My englisch is bad but how is your dutch?

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