Slot Mortiser Choices

      Ideas on commercially available slot mortising equipment, and an example of a custom-built rig. January 29, 2009

I periodically get jobs that require slot mortising. For this purpose, I currently use a Woodtek router jig with an XY table and a Z axis on the router (like a JDS Multi Router).

I am considering a dedicated slot mortiser and have done a little research. I ran across a post on another website that suggested saving money on a Griggio or Casadei by purchasing a metal working mill. Has anyone had any experience with this? The mills I've seen go up to about 2500 rpm, which is a little slow, but are much heavier than any wood working mortiser in the $500-750 price range.

Forum Responses
(Furniture Making Forum)
From contributor R:
2,500 rpm is fine. Most mills are three phase so if you go the inverter route you can up the rpm to 5,000. Mills that take collets are harder to find. 2 flute HSS endmills are your best bet for tooling.

You definitely want something horizontal or you will be severely limited in use. I've done several mill slot mortisers with friends. I'd recommend the Laguna. I've been using slot mortisers for over 25 years and am always looking at what's out there. I’ve only seen six used slot mortisers in 25 years so that says a lot.

From contributor P:
What about an overarm router?

From the original questioner:
The overarm router would be good for the stile, but the slot in the rail would be a trick.

From contributor M:
I had the same situation last year. My solution was to build a machine from available parts. I purchased an XYZ mortising table from MiniMax USA in Texas, a nice table that will attach to anything flat and vertical. Then I had a machine shop fabricate a table, milled flat and square, to attach the XYZ table to, as well as a salvaged 3300 rpm motor.

With a direct drive chuck, and a heavy pillow block, all adjustable, I have a nice slot mortiser that is easy to set up, and makes lots of jobs easier. I investigated used metal mills, but their adjustments were really slow, and seemed to be overkill, plus I didn't want to mess with 3ph power inverters.



From contributor E:
To contributor M: what would you think about mounting a router horizontally, with some sort of Z axis crank, then build the XY table with Thompson linear bearings and shafts.

From contributor M:
The table is an accessory for one of their combo machines. I researched using Thompson linear bearings, but I quickly realized that without a full machine shop and foundry at my disposal, I could never build a XYZ table for the price of a factory produced one, at least not a precision one. Also, if the birdmouth cutters are used, they only require 3000-4000 rpm, so the speed of a router is unnecessary. By the way, I'm not trying to push MiniMax, I'm sure the same attachments are available from other places too.

From contributor D:
I agree with a horizontal mortiser. I use an Invicta with two-flute endmills. It is heavy, powerful and quiet (compared to a router). Some of the best money I have spent.

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