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Useful but with compromises

Bosch now allows you to adapt your old hole saw set to their Power Change system.

This mandrel and the addition of a adapter nut kit does exactly what you’d expect: it allows you to change hole saws quickly without having to unchuck the hole saw, fight to remove the mandrel that was jammed to the hole saw by the drills torque and then fit a new hole saw to the mandrel and chuck it. If you have to switch from cutting different sized holes such as holes for faucets and drain pipes or the two holes in a door when installing a lockset you will appreciate using these accessories.

Several items exist in the Power Change product line which can be confusing so take care when adding items to your cart:

Mandrel only:

- PCM12 1/2″ Mandrel
- PCM38 3/8″ Mandrel
- PCMSDSPL Mandrel with SDS-Plus shank

Mandrel kits:

- PCM12AN 1/2″ Mandrel w/ two adapter nuts (small, large w/ locking pins)
- PCM38AN 3/8″ Mandrel w/ two adapter nuts (small, large w/ locking pins)
- HE1 comes with 3/8″ Mandrel with stacked thread adapter nut for enlarging holes

Adapter nut kits:

- CK1 6-pack of adapter nuts: 2 small and 4 large adapter nuts for small to medium hole saws
- CK2 6-pack of adapter nuts: 2 small and 4 large w/ locking pins for small to large hole saws
- AN01 2-pack of small adapter nuts (9/16 - 1 3/16″)
- AN02 2-pack of large w/ locking pins adapter nuts (1 1/4 - 6″)

Confused yet?

The best way to get started is probably to buy the HE1 and CK2 kits. This will give you a 3/8″ mandrel, adapters for your hole saws and the ability to enlarge holes that were cut too small. I’m really not sure what the advantage of the 1/2″ mandrel is other than the fact that most hole saw mandrels are 1/2″ and probably designed to cut 6″ holes. The 3/8″ mandrel seems perfectly capable to me.

Pros:

- affordably priced
- ability to swap holes saws in seconds
- easy to fit adapter nuts

Cons:

- run-out creates wobble were none existed previously
- can no longer store hole saws in your case (depth and stacking problems)
- no ejector spring/mechanism (who does?)

As could be expected from a quick change system, run-out with the hole saws can be an issue. Some adapter nuts are made better than others and you’ll find that you can reduce or eliminate the run-out by rotating the adapter nut to one of the other 5 hex positions possible in the mandrel. Sometimes this works, sometimes not. Either way it partially defeats the purpose of a quick change system wasting your time and is why I gave the product 4 out of 5 stars. Be sure that the top of your hole saws is flat so as not to further compound the run-out (something Bosch has probably taken into consideration with their own hole saws).

Something else I have noticed about the Bosch holes saws with the power change adapter nuts, is that of the three nuts (small, large, large with w/ locking pin), Bosch always uses a nut with no-pins and adds a washer. This is obviously a cost saving measure but I wonder if the addition of the thin washer reduces the chance of run-out.

Something I don’t understand about the CK2 kit is that the washers included for the small adapter nuts are too large to fit properly. The CK1 kit which includes 4 large nuts without the locking pins comes with no washers at all. Someone didn’t think those kits through properly. I would have included small washers with the small nuts and large washers with the large nuts and added more threads to the nuts to compensate for the thickness of the washer.

If you don’t have a set of hole saws with these adapters I’d recommend buying a complete Bosch set that does rather than select a favorite brand of hole saws and try to adapt them to this quick change system.

Update (2/6/2012): This item is currently on sale here for the lowest price I’ve seen.

The featured review for this product, Bosch PCM38 3/8-Inch Bi-Metal Power Change Hole Saw Mandrel Tools & Hardware, was written by Mel D..

The average rating for this item is 4 out of 5 stars, according to 3 reviews.