Byrd Shelix head, why must you taunt me?
Thanks for the extra info, Scott.
It's taken me the better part of a week to get the cutterheads swapped out, mostly because the bearings were tricky to deal with.
I purchased a replacement set of bearings from a local industrial supply place - SKF 6202 2RSJEM and SKF 6203 2RSJEM, total of about $24. The original bearings are marked Nachi 6202NSE and 6203NSE. I've seen the 6202 and 6203 numbers in other suggested replacements (e.g., NTN 6203LLBC3/L627 and NTN 6202LLBC3/L627), so I would guess that they're probably a dimensional standard for the industry. The dimensions are 15mm X 35mm and 17mm X 40mm; not sure which of these is a 6202 and which is a 6203.
I originally tried to get the bearings on with a set of custom-drilled 2x4s that the new cutterhead could mount between and 4 pipe clamps that would squeeze the boards together (2 on top and 2 on the bottom). The bearings didn't want to go on, so I tried freezing the cutterhead and trying again the next day. I didn't notice any difference, though, and the freezing created a big mess as water condensed on the head.
After letting the head warm up for a day I tuned up the jig a bit more and was able to get both bearings on to within 1/8" - 1/4" of their final resting places, but they just didn't want to go on any further. I cranked the clamping pressure up and banged on the outside of the jig with another block of wood, but nothing worked. I thought I'd better try to get the bearings off, reclean the mating surfaces, and maybe apply a little bit of teflon dry-lube to help the bearings slide on. But now the problem was how to get the bearings off again...
I ended up with this
puller set from Harbor Freight. It worked fine on the larger bearing, but the smaller bearing on the short end of the cutterhead didn't allow for enough clearance to get the jaws of the puller between the head and the bearing. I spent a couple of hours modifying the puller with a Dremel tool, but it never really worked right and I ended up cutting the bearing off the shaft. Interestingly, the original bearings and bearing supports on the HSS cutterhead came off pretty easily with the puller.
By this time I was despairing of ever getting the bearings right, so I threw myself on the mercy of a local (independent) auto parts store with a machine shop in the back. I was suspicious of the new bearings after all the abuse I had put them through, so I just had them install the original bearings on the new head. They charged $20.
Everything went pretty smoothly after that. With the help of Scott's description, I was able to get the outfeed table moving correctly. It turns out this is actually covered in the manual after all, but it's under "gib adjustment". Both infeed and outfeed tables should be held by a single wing screw on each side. The allen screws with lock nuts are there to adjust the "gibs" which control the mating pressure on the table dovetails. Too tight and the tables won't move when the wing screw is loosened (as in my case). Too loose and the tables have some horizontal play in them. So if there are problems, first adjust the gibs so the table adjustment works correctly, then set the height of the outfeed table and tighten the wing screw only.
Unfortunately, the cutters on the Byrd Shelix head seem to protrude more than the knives on the original head. I was able to raise the outfeed table sufficiently to accomodate them, but the infeed table just doesn't go up high enough to come even with the outfeed table. My minimum depth of cut is currently 0.05", or the better part of 1/16", which seems excessive. I'm going to have to take apart the whole base assembly and see if there's some kind of stop that limits the motion of the infeed table. Hopefully I can adjust that to free up a bit more adjustment room. There's an exploded view in the parts section of the manual that shows the dovetails, but it's not clear from that information alone exactly what the limitation on motion is. And since the infeed table comes mated to the base from the factory, there's no manual section for putting this part of the device together.
My first impressions of the Shelix head in action are that it seems to work OK. I haven't tried any hardwood yet, but I replaned some framing lumber scraps I had done with the HSS head to see if I could see a difference in the finish. It comes out about the same. There's slightly less tearout, but overall the finish is rough/fuzzy and there is some evidence of scalloping. I don't notice a difference in noise level or feed effort. It could be that it wants a shallower cut, but I'll have to get my infeed table in order before I can test that.
Yann, you asked about planer heads. Byrd has started making a head for the DeWalt DW735; they are rumored to be working on a couple of other lunchbox planer heads, but nothing's available yet. I had actually preordered a DW735 head to take advantge of the live.com eBay sale ($411.98 delivered with bearings minus 25%; write to routerbitman on eBay and he'll put one up for you), but now I'm having second thoughts. If the results are similar to the jointer head, it's going to be a step down in finish quality. The Shelix cutters should last a lot longer, which seems to be a huge issue with planers, but it seems to be something of a tradeoff.