Ok so IT'S FINISHED and IT WORKS! YIPPEE!!!
Here's the overall finished unit:
The water lines go to a submersible pump in the OSH bucket (the pump that came with the cabking). I've added some inline valves to the various lines. And the pans drain to the bucket on the floor via 3/8" line.
Blade size: My machine was set up with 8x3 expando wheels when I got it, so I figured 7" would be a good size blade to use. Smaller blades would work just fine too I think, and save some money, but on mine a 4" blade would have disappeared under those funny deep hoods it has. As
bitterbrook says, make sure you can see your cutting edge!
Rim Type. The next choice is "continuous rim" versus "segmented rim" versus "turbo" blades. Different people on here have supergrinders with Turbo or Continuous Rim. Nobody has posted about having one with segmented blades. I guess segmented blades might cause chipping, as per
johnjsgems . The consensus seemed to be that continuous rim would be good for cab preforming and rough dome shaping, and turbo, which is much more aggressive, would be good for shaping tumbing rough or sphere preforms, or generally fast material removal. I decided to go for continuous rim, since I'm using it to take down material for cabs, and maybe some rough doming of the super hard ones.
Spacers: Apparently you can use spacers between the blades (CDs or whatever you have on hand), or not. Spacers supposedly reduce the strain on the blades from being squished together and clamped in place, since their rims are fatter than their middles due to the diamond coating. I skipped the spacers since CDs don't have 7/8" holes. Maybe my blades will crack or something . . . if so, I'll update the thread. ;-) But I doubt it. The jam nut is only finger tight. It's not very much strain on the blades. Compared to the strain and flexing the blades on my trim saws put up with, this is a cake walk.
Selecting and finding blades: My machine has a 3/4" shaft, and tile saw blades generally have a 5/8" arbor with a "knock out" that lets you convert to 7/8". (I learned that this is a ring of metal that you can tap/push out of blade, so that the resulting larger hole fits a larger shaft. You can usually see it in the ebay pictures, but you have to email the seller and ask because a lot of them have the wrong picture posted it turns out.) I searched all over the dang place (including some places helpfully proposed by people on here) and ended up buying my blades from Advanta Tools on ebay. Ended up a pack of 10 for $91. A little more than I wanted to spend but whatever.
Comment: I needed blades with the knockout, so that limited my options a lot. If you're building the whole machine and you get to choose what shaft diameter to use, pick a 5/8" shaft. There are way more cheap tile saw blades available for a 5/8" shaft. I saw some with a 5/8" arbor for $6 each on ebay. Next choice is 7/8". Last choice would be 1". (Only the HF blades seem to fit a 1" shaft, and they're currently $17.99 each. Ouch.)
The ones I got:
Blades I boughtAdvanta's ebay shop in case the above link dies:
Advanta Tools Ebay ShopThey also have a website, but it doesn't list the majority of their products. I would advise just calling them up and ordering over the phone. As Scott
NRG shared, it's a family business and their customer service is very good.
Bushing. Next I needed a bushing to convert my 3/4" shaft to a 7/8" shaft.
Amazon has bushings for sorta cheap-ish - $14 for a pack of three. Bronze. They come in different lengths. I got these: (3/4" x 7/8" x 1 3/4" long)
www.amazon.com/gp/product/B01G8X8284/ref=oh_aui_detailpage_o04_s00?ie=UTF8&psc=1.
Plastic would have worked fine and been cheaper but I couldn't find any.
The problem is that when the bushings came, they were .003" too fat. And the hole in my blades was not exactly 7/8", it was like .001" too small. So they didn't fit. Arghghghghghgh!!!!! I put in a cancellation order with Amazon and they said I didn't need to return the bushings. So I decided to see if I could take the diameter of the bushing down a bit with a sanding drum on my dremel. I used the coarse sanding drum, and it worked fine. Took about 10 minutes. Don't hesitate to go for it. Bench grinder would have worked too but more potential for the piece to grab,fly across the room and break your favorite slab.
After getting the diameter sorted, I measured and cut the bushing to length with a jeweler's saw. (Even though I ordered 10 blades, I was carrying one around the house and somehow it got left out when I was measuring the bushing. oops. Oh well, 9 is fine.) 9 blades was about an inch wide overall. Which is plenty. I think a half inch would work fine too, for what I'm doing. I didn't even need to cut it particularly straight since the jam nut helpfully has a nice hollow in the center.
Mounted and tested - works great!
However, I did notice that the edges of the blades didn't line up exactly - some blades were slightly "longer" (larger overall diameter) than the others, and that was annoying when grinding.
Ended up just taking them off and putting them in a different order so it was more of a continuous row. Much better.
As far as actual use: I'd say that if I had my choice, I'd like to also have a grinder with the turbo blades. I tried these out on some extremely hard Swazi agate. A couple of preforms that were too thick or of uneven thickness, so I needed to hog off a lot of material. The verdict is that the continuous rim blades work fine, and definitely work faster than the coarse Cabking wheel (60? 80?), and without the feeling that I'm bleeding money by using up the diamonds. I'd say it's one "step" faster. It's not ridiculously blazingly fast, however. It's just fast-er. Ideally I would have a unit like Scott's (search "Supergrinder Chino Style") that has Turbo blades on one side and continuous rim on the other.
Here's a picture of the scratches left on the rock:
The one thing it's not really good for is grinding the edges of the preforms to shape them. Too many chips on those edges. I can only grind to about 1/8" of my line, then I have to switch to the coarse cabking wheel. Which is fine I guess - it still saves time and diamonds.
Mess: I was worried there would be rock chips and water flying everwhere. In fact, none. No messier than any other wheel. Perhaps because of the cavernous hoods on my unit, not sure. Anyway, no mess, and not really very noisy. Not anywhere near as noisy when using a tile saw, probably becuase my motor is only . . . what did I say in the first post? 1425rpm? something like that. A tile saw is like 2800 rpm.
Balance/Vibrations: Those 9 blades are HEAVY. Heavier than the expando wheel on the other side. However, there are zero vibrations/precessing/whatever. Maybe my bearings are just vintage solid or maybe balance isn't really a problem on lapidary units. Not my area of expertise. Anyway, as you guys said, don't worry about that.
Hope that's helpful to somebody!