Brian Grella's (Garage Woodworks) horizontal mortiser
Brian has written extensively about this mortiser, you can read his article here
With Brian's permission, I have included a few pictures of his machine here, because I want to comment on how he approached the challenge of controlling the horizontal and vertical motion differently.
Originally, Brian experimented with using some ball bearings running against wooden rails to control the parallel motion. He solicited my opinion in an email:
"I am in the process of building my own horizontal mortiser. I want to build it from supplies that I have lying around. I don't have any drawer guides so I am toying with the idea of using roller skate bearings for the guides. If they don't perform, it should be an easy swap to drawer guides (I hope)."
I was intrigued, but unsure that this would provide enough stability, especially vertically.
I think the slop (play) in the drawer slides is by design. It's there to take up any inaccuracy and wood movement in the cabinet. Otherwise, the cabinets using those slides would have to be incredibly precise.
Brian then switched to using shafts with bronze sleeves for the horizontal slider mechanism. He used two parallel sets of shafts. This makes getting the alignment just right crucial. I asked him how he did it. His answer:
"Good question. I secured one end of the shafts in holes. Then with the bushings in their blocks, I slid them onto the shafts. I then screwed two of the blocks to the table (one per shaft) and slid the table down to the other end. This gave me the right alignment to secure the opposite side of the shafts. After that I had to attach the other two blocks (held the bushings). It slides great. I had a little problem with the sintered bushings (pre-oil filled) having their oil wicked out by the mounting blocks. If I were to do this again I would seal the hole with poly first. It was easier than you might think. I thought if I didn't get the shafts exactly parallel that it would jam. It wasn't a problem.
More reader projects, including several more slot mortisers.