My shop has two new additions, a hitachi chain mortiser and hollow chisel beam mortiser. These tools are for cutting timber framing mortises in beam sections typical of Japanese wooden architecture. When I first got hard into carpentry they seemed like rare unicorns, not available in the American market. Last time I looked, there’s sellers on ebay offering every major brand now, Hitachi, Makita, Ryobi. And these tools are even more common on Yahoo Japan auctions, just with better prices and more selection. I had intended to only get the hollow chisel mortiser, but at only 6,000 yen the chain mortiser was too good a deal to pass up on, plus I like the color, haha. Take two zeros off to get the rough yen to dollar conversion.
The only shipping option other than Sea Mail was EMS, both of which I assume use USPS to get the box to your door, so this was a major test of shipping and handling reliability. I paid extra for protective packaging, which apparently meant entombing the parcels in heavy bubble wrap. I would have appreciated double boxing at a minimum short of crating, but through some miracle they arrived nearly undamaged, mainly due to the robust quality of the castings and parts on these machines.
Hitachi’s CB21 chain mortiser, as it arrived. It’s used, so of course a bit of rust and a broken plastic adjustment knob from shipping damage. The chain mortisers seem to sell for quite a bit less than the hollow chisel mortisers in general. I could be wrong about this, but it looked like this model is out of production, and I couldn’t find replacement chains from any Japanese merchants which could be part of the low price I paid. I’m holding out hope though that I can find a chain from a different manufacturer that will fit.
I got her all cleaned up and lubricated, ready to test. The chain was still nice and sharp. Both of these machines are meant to run at 100v, and I read through lots and lots of debate about whether or not its advisable to run them at 120 volts without a voltage converter. In general it doesn’t seem to be a problem, but maybe will shorten the motor life a bit. One of the major limitations of this machine is the maximum width of beam it can ride. At full open between the clamps you get about 7.5″, rather inconvenient if you think you’re going to be mortising a bunch of 8×8’s. The chain is 18mm wide, so can cut your typical 30mm wide mortise with a single throw of the axis control. I love though how robust the guide rods and casting are on this thing compared to the Makita 7104. Once I got it cleaned up and lubed its really smooth and rigid.
This is a shot of the lever arm that controls side to side movement of the chain. It has presets for different widths of mortises.
Here’s the other side of that control lever. For some reason as the numbers here get bigger the mortises get narrower, so it has me a bit puzzled. Where I have it set now it will cut a 28mm wide mortise, just wide enough to leave 1mm of wood to clean off the side walls. In total, it may not be a new Mafell, but I really can’t complain seeing as both of these machines plus shipping was 1/3 the cost.
The hollow chisel mortiser arrived this morning, and had me really worried to judge by the look of the packaging. Despite the mangled look of this the bubble wrap underneath did its job except for a bent guide rod on one of the clamping fixtures.
This is Hitachi’s 30mm BS30SA. The ‘SA’ part of the model number means it can handle a 155mm long chisel. The BS30’s are more common and less spendy. I’ve had the good fortune to try this model before, which is why I looked for it specifically, Makita seems to make good hollow chisel mortisers too, and they go for a bit less at auction.
I pulled this machine apart a bit to clean the old gummed up grease from the ways and guide rods and re-lubricate.
Now, 30mm is a big chisel to push through most any wood, so I tested on some red cedar after sharpening the chisel and auger. Western red cedar is cruel to less than a finely honed edge and it crushed on the end grain, anybody know a source for conical diamond hones big enough for a 30mm chisel? I bought this machine with square pegging in mind so next thing I need to find is some smaller chisels, but at least they can be found for sale without trouble. One thing I did try that worked quite nicely was using the chain mortiser to rough a mortise and then paring the side walls with the hollow chisel mortiser with the auger removed, keeping things really dimensionally tight and consistent.
These are the first power mortisers in my shop, I still prefer to make smaller mortises by hand and frankly I’ve put in the time to get good at it, so tradition holds some sway with me. Up to now I’ve drilled larger mortises and then chiseled, which is by no means slow (ok, I’m still slow), but it helps to have the extra efficiencies when working by yourself trying to get your timber cut and assembled before too much dimensional change from seasoning.
What do you think, are these things worth it? I have a couple projects in mind and a good sawmill down the road that cuts local timber, a match made in heaven.