Chain Mortiser Versus Hollow Chisel

Woodworkers discuss the evolution of power mortising machinery: chain mortisers, slot mortisers, and oscillating chisel mortisers. September 17, 2014

Question (WOODWEB Member) :
I am looking to add mortising capability to my shop, for the occasional reproduction window sash. I have the opportunity to buy an old Powermatic chain mortiser at a good price. I'm wondering why these are not made anymore. Is the hollow chisel mortiser a superior technology, or is it just that the chain mortisers were too expensive to make?

Forum Responses
(Architectural Woodworking Forum)
From contributor F:
I don't see either really being made all that much anymore. There are a handful of companies making smaller ones, and maybe a couple making bigger ones like the Powermatic. None of the heavy duty ones are still being manufactured to my knowledge? I think that slot mortisers and CNC machines have pretty much replaced them. I do know from past browsing that finding chains can be one of the issues you may run into with that chain mortiser.

From Contributor O:
I have a Makita chain mortiser that is made for the timber framers. There are others, but are not imported to the US since there is no market for them. I bought it for some huge cedar gates and it worked great - cut that cedar like butter. However, I rarely use it since I have both an oscillating chisel and a hollow chisel mortisers set up, ready to go. I think the advantage for the hollow chisel is that it is easier to change the thickness of the mortise - chisel and bit vs. chain and bar. Also, the hollow chisel is probably safer - at least there are no multiple jagged teeth threatening to grab you.

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From contributor G:
I have owned large chain mortisers and found them to be messy since the chain needs to be lubricated during use. The mortise cheeks also end up being quite rough as well. A square chisel type can be quite slow for production work. I have a slot mortiser now and am very satisfied with the accuracy and ease of use. Changing the bits quickly and easily is great for furniture and mortise locks, etc.

From contributor A:
The chain mortisers were replaced by slot mortisers and more recently oscillating chisel mortisers. The chains are fast and rough. Not a furniture machine.

From contributor R:
For traditional sash you will want a hollow chisel mortiser. Chain mortisers are good for production doors where it makes quick work of a long mortise. The hollow chisel will give you the versatility you will need for sash.

From Contributor H:
I've always thought chain mortisers were neat tools. If I had the opportunity to pick one up at a very reasonable price I'd be hard pressed to pass it up. I think sooner or later it would be just the thing for a project.

From contributor K:
I have a Powermatic chain mortiser, and don't have any issues with the tolerances. I just make the tenon fit whichever chain size I use. However, when plunging it in, the edge where the chain is on its way up will chip out, unless I chop a chisel in ahead of time.