Woodsmith Mortising Machine - any improvements on design?

[John Myers]

I'm planning on building the Woodsmith Mortising Machine, as described in the #217 issue. My initial use for it will be making small mortises for some box designs.
The design uses two sets of drawer slides - one pair of 10" slides for the vertical motion, and a pair of 18" drawer slides for the horizontal motion of the table. I'm wondering if there is a better alternative to using drawer slides? Would using miter track and something like Microjig Zeroplay miter bars work better? I'm just thinkiing that drawer slides might not hold up over time, and may introduce some slop.
John

[John TenEyck]

At the risk of further wrath by some members, I'll try to tread carefully here. Drawer slides always look like such an obviously good solution for moving the mortising tables but every one I've seen has too much slop for accurate work. I can't remember if the Woodsmith design talked about it and squeezed the slides to reduce the amount of play in them, or if I saw that somewhere else, but I think the amount of slop is just reduced, not eliminated. Another problem with drawer slides is they can get loaded up with sawdust.

When you think about how a horizontal mortiser works it becomes clear that a little slop in the X and Y planes is unimportant but any slop in the Z (vertical) direction when cutting the mortise (or tenon) is a real issue. Cutting to the chase here, I think you'll find solid runners to offer everything you want in a runner with no compromises. Simple, rugged, no play in the Z-direction. Hard maple works really well, though there are other choices.

John

[glenn bradley]

What John said . . .

[Jim Dwight]

The Woodsmith horizontal router table has a mortising attachment that works with miter guage slots and metal bars. I haven't made it but it seems like it could work. I wouldn't use drawer slides either.

[Jim Andrew]

The new Grizzly catalog has a Horizontal Slot Mortiser on page 145. Looks interesting. I already have the Go540 or I would be looking at ordering it.

[John Myers]

Thanks for the advice. I think I'll try using miter slots with solid runners (something like the Microjig zeroplay bars). That said, I'll want to reduce friction between the moving planes. Any material suggestions for this? A laminate surface, perhaps?

[Jim Dwight]

laminate or melamine particle board. Sink cutouts can be a cheap source of high density particle board covered with laminate if you can find a source. Waxing the surface helps too.

[John TenEyck]

There is very little friction between a well fitted and waxed hard maple runner and a well fitted dado in Baltic birch or even MDF. If the RH in your shop moves around a lot then you would be better off using UHMW plastic or anodized aluminum or steel miter bars. Friction won't be a problem with any of them if you cut the dados to fit the bars. I've been using an X-Y mortiser for about 10 years now and you actually don't want zero friction. This is another poor attribute of drawer slides in my opinion. They don't have enough friction. The ideal motion is one that moves easily and smoothly, but requires some conscious input by the operator.

John

[Andrew Joiner]

The new Grizzly catalog has a Horizontal Slot Mortiser on page 145. Looks interesting. I already have the Go540 or I would be looking at ordering it.

Wow! Shiraz must have changed his mind. http://www.sawmillcreek.org/showthre...-slot-mortiser

[Geoff Crimmins]

The new Grizzly catalog has a Horizontal Slot Mortiser on page 145. Looks interesting. I already have the Go540 or I would be looking at ordering it.

And it's less expensive than a Domino.

[Jacob Mac]

The new Grizzly catalog has a Horizontal Slot Mortiser on page 145. Looks interesting. I already have the Go540 or I would be looking at ordering it.

I will have to drive down to Springfield in May to check it out

[Alan Schwabacher]

If you look at the freely downloadable plan for the combination router table at woodsmithshop dot com, it has a component that is a slot mortiser. In contrast to the other Woodsmith plan, this one uses solid runners. It is a lot like the one you can get free from John TenEyck's website.