The arbor is the shaft on your machine. The bore is the hole through the wheel, blade or disc. The bore has to match the shaft, either directly or with a bushing that reduces the bore to the shaft size. Our SuperNova soft diamond wheels have a 1" bore and ship with bushings for 3/4", 5/8" and 1/2" shafts, so one wheel fits all four common sizes. Saw blades and lapping discs work differently: you order the hole size that matches your saw or lap.
Measure your shaft before you order. The last section shows how.
Two words that get mixed up
Arbor is the shaft coming off the machine, the part the wheel slides onto and the nut tightens against. On most cabbing machines one shaft, or an adaptor on each end of the motor shaft, carries a stack of wheels with spacers between them.
Bore is the diameter of the hole through the wheel. You will also see it called the hole size or the arbor hole. It belongs to the wheel, not the machine.
"Arbor size" gets used for both. When someone asks what arbor size you need, they mean your shaft. When a product listing says arbor size, it usually means the bore of the item for sale. Our product pages list it as Hole Size on saw blades and lapping discs.
Bushings: why one wheel fits four shafts
A bushing is a sleeve that sits in the bore and reduces it. A 1" bore wheel with a 3/4" bushing fitted mounts like a 3/4" bore wheel.
That is why our soft wheels are made at 1". With the three bushings that ship in the box, the same wheel mounts on a 1", 3/4", 5/8" or 1/2" shaft. Spare bushings are sold separately if you lose one.
Telescopic bushings, 1" to 1/2", sold as spares.
Two rules follow:
Bushings only go down. A bushing reduces a bore. Nothing enlarges one. A 3/4" bore will not go on a 1" shaft, and no accessory changes that.
Do not drill out a bore. Enlarging the hole by hand almost never leaves it concentric with the diamond surface. An off-center bore causes every problem below.
Sending a wheel in for resurfacing: leave the bushings out. Ship the wheel only, and keep your bushings on the bench.
Our diamond wheels
| Wheel | Sizes | Bore | Bushings included |
|---|---|---|---|
| SuperNova soft wheels (made in our Orange, CA warehouse) | 4" x 1 1/4", 6" x 1 1/2", 8" x 2" | 1" | 3/4", 5/8", 1/2" |
| Nickel bond hard wheels | 4", 6", 8" | 1" | Bushings available for every machine on this page |
| Sintered diamond wheels | 6" and 8" x 1 1/2" | 1" | Bushings available for every machine on this page |
For Diamond Pacific Nova wheels, which we also sell, check the bore and bushing details on the product page.
Saw blades and lapping discs
Saw blades and lapping discs are made in specific hole sizes. You pick the one that matches your machine.
Saw blades. Hole sizes available across our diamond blades (notched rim, 301 compatible sintered, 303 compatible, Pro-Slicer and the CBN meteorite blade):
| Blade diameter | Hole sizes available |
|---|---|
| 4", 5", 7", 9" | 1/2", 5/8" |
| 6" | 1/2", 5/8", and 1" in one 303 compatible kerf |
| 8" | 1/2", 5/8", 3/4", 1" |
| 10" to 24" | 5/8", 3/4", 1" |
| 30", 36" | 1" |
Not every hole size is made in every kerf. The product page shows exactly which combinations exist.
303 compatible diamond blade. Hole size is chosen with the blade.
Lapping discs.
| Disc | Hole options |
|---|---|
| Resin bond and nickel bond, 6" and 8" | 1/2" or no hole |
| Mylar, sintered and acrylic master laps, 6" and 8" | 1/2" |
| Resin bond and nickel bond, 10" to 24" | No hole, 1/4" (Ameritool), 5/8", 1" |
Magnetic and PSA (adhesive-backed) discs mount to a platen rather than directly on the shaft. The hole on those discs is for centering, not for carrying the disc.
What goes wrong with the wrong bore
The problem is rarely that the wheel will not go on. Usually it does go on, and that is the problem.
An oversized bore leaves the wheel sitting off-center on the shaft. Once it spins up, that offset becomes a wobble, and three things follow.
The wheel wears unevenly. The high side contacts the stone more than the low side, so the diamond wears in a band instead of across the face. You lose wheel life you paid for.
The cabs come out worse. A wheel that is not running true does not present a consistent surface. You end up chasing flats that were not there when you started.
The bearings take the load. Vibration that starts at the wheel ends up in the arbor bearings. That becomes a machine repair, not a wheel replacement.
None of this shows up at once. A slightly loose wheel runs, keeps running, and the damage shows up as a wheel that wore out faster than the last one did.
Machines and their shafts
Sourced from manufacturer manuals and catalogs, and from retailer listings where the manufacturer does not state it. If your machine is not listed, measure it or call us at 714-771-7007. For wheel-by-wheel detail on the Diamond Pacific machines, see Wheels for the Genie and Titan.
| Machine | Wheel bore it takes | How wheels mount | Our soft wheel fits with |
|---|---|---|---|
| Diamond Pacific Genie | 1" | Adaptor shaft on each side, one right-hand thread and one left-hand | No bushing |
| Diamond Pacific Titan | 1" | Adaptor shaft | No bushing |
| CabKing 6" and 8" | 1" only | On the motor shafts, after unscrewing the end pieces | No bushing |
| Lortone cabbing machines (Classic, SS, NS8) | 3/4" | Directly on the shaft, with flanges | 3/4" bushing, included |
| Barranca GP-6 | 5/8" | Directly on the motor shaft | 5/8" bushing, included |
| Covington 592VSP | 1" shaft | Directly on the shaft | No bushing |
CabKing takes 1" bore wheels only. Both current CabKing manuals say so. The end pieces on each shaft unscrew so the wheels and spacers can slide on. See Wheels for CabKing 6" and 8".
How to measure what you have
Measure the shaft, not the old wheel. The old wheel may have been the wrong size all along.
Take the wheels off and measure the diameter of the bare shaft, or the adaptor if your machine uses them. Calipers are best. A machinist's rule across the shaft is close enough, because 1/2", 5/8", 3/4" and 1" are far enough apart to tell against a rule.
Check two more things while the wheels are off:
Usable shaft length, from the shoulder to the end of the thread. That sets how many wheels and spacers the shaft will carry.
Thread direction. Some machines use a left-hand thread on one side so the nut tightens with rotation instead of loosening. The Diamond Pacific Genie is one. It does not change which wheel you buy, but note which side is which before you put the stack back on.
Spacers and wheel width
The bore gets the wheel onto the shaft. Width decides whether the stack tightens.
Wheel widths vary. Our soft wheels run 1 1/4" at 4", 1 1/2" at 6" and 2" at 8". Carving wheels are much narrower: Diamond Pacific's 6" Nova carving wheel is listed at 1/4" wide. Swapping a wide wheel for a narrow one leaves a gap that has to be taken up with spacers.
If the nut bottoms out on the thread before the stack is tight, you need more spacer, not more torque.
Questions we get
My wheel came with bushings I do not need. Should I keep them?
Yes. If you change machines or sell the wheel, they go with it. They are also what lets a 1" wheel move between a Genie and a Lortone.
Can I run a slightly loose wheel if I tighten the nut hard?
No. Clamping force holds the stack together along the shaft. It does not center a wheel that is not centered.
Will a 6" wheel fit where an 8" was?
On bore, often yes. On the CabKing and the Diamond Pacific machines both sizes take a 1" bore. Check the guard clearance and the water feed. A smaller wheel sits further from a fixed drip, so the water may need adjusting.
Do I send bushings with a wheel for resurfacing?
No. Send the wheel only.
The bore on my old wheel has worn oval. Is it finished?
No. An oval bore usually means the wheel ran with a loose fit for a while, and as it is, it will not center on any shaft. When we resurface a soft wheel with an ovalled bore, we can fit a new bushing so it runs true again.
What bore do your saw blades come in?
It depends on the diameter. See the saw-blade table above, and the product page for the exact combinations.
Related: Wheels for the Genie and Titan, Wheels for CabKing, Wheels for Lortone arbors, Wheels for the Barranca GP-6, When a soft wheel can be resurfaced.