Miter Jack

[Jim Matthews]

Finally, I can use the one I've been afraid to ruin.

As with so many of your posts, it's only obvious in hindsight.
I've got some thin plastic sheets (LV sharpening kit leftovers)
that should do the trick nicely.

Thanks again.

[Brian Holcombe]

Well played sir.

[Darrell LaRue]

I find it strange that everyone assumes that a mitre jack is used with a plane. Even when they all understand why it isn't a good idea, due to the damage you will inflict on the precisely made faces of the jack.

Clamp up the stock in the mitre jack, then grab a big, long, wide paring chisel and lay it on the face of the jack. Slide it across and pare off the offending bits. The chisel won't dig in, the cut will be precise, and the work will be done perfectly. I suppose you could also use a flush-cutting plane like the one LV sells, but you already have the big-*ssed paring chisel, right?

Darrell

[Kees Heiden]

Maybe because everyone tells us so? Even Ulmia in their advertisements.



They even had a special plane for use on the mitre jack, the Vergatt hobel.

But the paring chisel is a good idea of coarse. You can also use a flush cutting saw, like the french veneer saws.


New-traditional-french-veneer-saw-woodworking-tool-photo.jpg

[george wilson]

They have used them with planes in the Anthony Hay Cabinet Shop in Williamsburg for years Paper glued on with hide glue gives a safety layer,and can easily be gotten off and renewed.

A tip: dampen the paper before you glue it down or it will wrinkle when the glue dries and pulls it together.

[Steve Voigt]

I find it strange that everyone assumes that a mitre jack is used with a plane. Even when they all understand why it isn't a good idea, due to the damage you will inflict on the precisely made faces of the jack.

Clamp up the stock in the mitre jack, then grab a big, long, wide paring chisel and lay it on the face of the jack. Slide it across and pare off the offending bits. The chisel won't dig in, the cut will be precise, and the work will be done perfectly. I suppose you could also use a flush-cutting plane like the one LV sells, but you already have the big-*ssed paring chisel, right?

Darrell

I'm with Darrell. I don't have a miter jack, but I have some homemade jigs, which I use for repetitive operations, that operate on the same principle. I use a chisel and the reference surfaces have remained pristine after hundreds of cuts. I think most of the time, the chisel would be faster. For a really large surface though, the plane would be a nice option.

[Simon MacGowen]

A tip: dampen the paper before you glue it down or it will wrinkle when the glue dries and pulls it together.

Good tip!
Simon

[Hilton Ralphs]

Fine Woodworking had a great article about this jig in issue #190

fw_miter.jpg

fw_190.jpg

You can get the screw press from Lee Valley or Peachtree.

The latter is a Shop Fox version and the quality isn't the best so I may try the Lee Valley version.

[ian maybury]

That's a nice tool/jig - i'm a big fan of anything (much like honing guides ) that takes the variability out of processes. So often the magic is in going for the right set up. There's other variations on the theme about too: http://www.wkfinetools.com/tMaking/m...iterJack-1.asp (pardon if it's old hat to some)

One question. Depending on the details of the alignment there could be some tendency for the moving clamping block attached to the screw to ride upwards from the sloped face as it comes up tight - to cause come misalignment. There's slots in some of the pics about, but seemingly not dovetails as such. Is this a real issue/if so how is it dealt with?

[Andrae Covington]

I'd never thought of using a chisel with a miter jack as well as a plane. Seems obvious now that I've seen it, but that's pretty cool.

[george wilson]

You need to keep the underside of the track of the moving jaw snugged up to keep the moving jaw from rising. Also,I would not over tighten the moving jaw as the whole mechanism is made of wood,and the jaw can fairly easily be made to lift up some.

Personally,I don't have a lot of use for miter jacks. I'm mostly an instrument maker anyway. But,if I wanted one,I'd make the track parts out of metal,and just have the jaws made of wood. It would be possible to do this even if you don't have a milling machine or a lathe. A drill press would do. Just go to the scrapyard,or buy some rectangular bars of aluminum(at least). I'd use steel myself,but i have the means to saw it,etc..

I'd face the lower face of the sliding jaw with 1/8" thick steel,either precision ground,or heavy sheet. Aluminum would be a second choice,but keep it lubricated with paraffin to avoid galling. Screw the sheet to the underside of the sliding jaw.

I think a shooting board would be more reliable. But,you can't do things with a shooting board that you can with a miter jack,such as paring around tenons.

[ian maybury]

Ta George. I hadn't seen one before, and would need to think through possible uses. My instincts regarding the tracks would tend along the lines you describe too.

Hi strength heat treated aluminium (make sure its an anodising grade) is good stuff, something like a 6061T6 - significantly stronger than mild steel - although not quite as stiff. The big advantage (as you know) is that you can cut it very nicely on a table saw - even if the flakes get a bit messy. I've been making an accessory rip fence for my saw this week for example from aluminium angle - no problem at all using a non ferrous metal blade.

Anodising is relatively widely available and not too expensive - it's a decent way of putting a reasonably wear resistant and slippery surface on the stuff...

[Brian Holcombe]

I think a lot of the features of this can be accomplished with both an accurately made tail vise and a paring block or set of paring blocks.

[george wilson]

Of course,the great work of the past was made with all wood miter vises(if any was used on a given piece,that is). So,with care,they do work. Being a toolmaker,I can carry things into the metal realm.

[ian maybury]

For sure there's multiple routes to the same or similar end Brian. I'm guessing that the mitre vise/mitre jack is the sort of thing that would have been used in a fairly specialised/semi production type environment back when hand tools were used for that sort of work...