Grizzly has up graded their 17 and 19" extreme band saws by changing the trunnions to cast iron, and raising the price $200. Are cast iron trunnions really worth $200 (or 25%) more? The old saws actually weight a couple pounds more.
Or course not, but there may have been other improvements, plus the cost of raw material is skyrocketing so it was, perhaps, a good time to give an overall increase.
Depends...
If the previous designs have been found to be too light and flexible, surely.
As Edwin points out, metal costs have increased dramatically over last several years as well as transportation costs (it costs Griz to get stuff here before the transportation to you) and so on.
It is also true there's far more to "value" than simply material costs.
Then there is the consideration that cast iron, as opposed to aluminum, doesn't make a good abrasive like AlOx, preserving the contour and clearance, thereby accuracy, for a longer time. Stamped metal isn't in the same league, of course.
Cast iron is harder. It machines better. It's rich in graphite, which helps moving parts move smoothly instead of sticking and galling.
I recall hearing that another advantage is the extra weight/density of cast iron, which gives the wheels more inertia, like flywheels.
Which dampens vibrations and helps machinery last longer. Not sure why trunnions would need more inertia, though.
Possibly he meant momentum. Extra momentum in a rotating piece of cast iron would minimise 'slowdown' in the blade when entering a workpiece that's higher in moisture or denser or harder (like hitting a knot).
Just a guess. A WAG at that :-).
"Trunnions" don't rotate, however...
"Mass" would be the most likely relevant property related for them as well as simply more strength/rigidity if as previous hypothesized the former tended to be undersized so they flexed under load or warped when locking in place...
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He just confused the trunnion with the wheels. The trunnion is the cradle the table sits on that allows it to be angled. The only significant advantage would be if it keeps the table locked more securely. I dunno what the grizzly's are like, but once I lock the table on my delta if I try to move it the whole saw moves not the table. But that's also true of my little pos ryobi 9" bandsaw and I assure you there is no cast iron to be found anywhere on it.
On my new grizzly 8" disc / 1" belt sander the table and trunnion for the disc table are both cast iron, however they didn't machine the mating surfaces, just rough painted castings that don't particularly fit well together. I mention this not to imply anything about grizzly's band saws, but just that sometimes they like to be able to throw around "cast iron!" this and that to look better on paper without actually being any better. I had to toss the trunnion in the trash and make my own fixed support to make it usable.
-Leuf
That's typical Chaiwanese craftsmanship -- cut back heavily on finishing, finish only where it counts. I see they've lowered their standards. It's time you learned the fine art of scraping cast iron.
He did. Oops.
I really don't mind if they cut back and only do it where it matters, but if they don't do it where it counts either then it's a problem.
I was supposed to be able to lock that table in place with the two TINIEST wing nuts you've ever seen too. The motor pulley keyway wasn't cut all the way through and the face was machined at an angle ( >.05" variation) which made it rather tricky to try to align the pulleys. Grizzly sent me new pulleys, a new table, and even a new sanding disc. The new motor pulley had the identical keyway problem but was at least flat.
At the core of the machine it's a pretty slick design, the belt is able to be setup to do internal sanding, and you can switch between the two pretty easily. It's the only machine I could find that could do internal sanding like that, and I had a specific application for that. It's too bad they put their top priority as cost/ease of manufacture, a distant second functionality, and little thought at all to useablity. I've had to make lots of modifications, and I'm not done yet. The platen is wider than the belt so you can't sand into corners, or only on one side at a time. And it's held in place with hex head bolts. Cuz yeah, I want to keep a 10mm ratchet next to the sander all the time. So I'm going to have to replace those bolts and grind an 1/8" off the platen. I'll probably find something else after that.
-Leuf
LOL. An earlier post in the thread mentioned cast iron wheels and it seems I promptly forgot what we were talking about. First signs of aging I suppose :-)
You're not there yet if you don't recognize that the mind is the SECOND thing to go....
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