MAG-DRO™ Caliper Bases
A simple idea executed right
Text, photos and video by Tom Hintz
Posted – 11-1-2011
I am sure that people have asked me about fixtures for calipers that would let them use these high-precision measuring tools on their woodworking or metalworking equipment. While I have given the idea some thought I nor anyone else that I am aware of have not come up with ideas like those offered by MAG-DRO™. The MAG-DRO™ tools are not complicated in concept but I expect that the details behind making them so well and so easy to use are where the real brainpower was expended. And the MAG-DRO™ Caliper Bases are Made in America!
The MAG-DRO™ tools are designed to fit most 6” calipers that are so common in many home and pro workshops. These tools are relatively small and simple looking but are capable of making precise measurements.
The bodies of the MAG-DRO™ Tools are made primarily of high-grade plastic that has been cleanly molded to ensure providing a stable platform for your calipers. The plastic itself is tougher than we usually find in small tools but extensive internal reinforcement ribbing was added to the Miter Slot Base to insure rigidity for accurate readings from the calipers.
In a Pinch
Both MAG-DRO™ Bases have a slot for capturing the caliper arm. One side is taller so that the tapered Derlin® washer under the thumbscrew can hold the caliper against that side without slipping out of the slot. The shape of the slots and how the washer locks the arm in place allow full function of the sliding caliper jaw and the flat rod that usually runs along the bottom of the arm. Both of the MAG-DRO™ Bases also have nicely made, threaded brass inserts that accept the thumbscrew. This might seem like a small thing but it represents an additional manufacturing expense that is aimed directly on making these tools more durable for the end user. We just do not see very much of this kind of design concern/expense these days.
Magnetic Caliper Base
The Magnetic Caliper Base has a strong magnet built into the bottom that lets you secure your caliper anywhere on a table saw surface. It also can be used on planers and virtually any other equipment that needs such a measurement and has a magnetic-capable surface. If you need to place the Magnetic Caliper Base on a non-magnetic surface such as when building a jig or fixture in your shop a special metal- plate with countersunk screw holes and screws is included in the package.
The Magnetic Caliper Base is just as comfortable on a vertical surface as it is on a horizontal one. The magnet is more than strong enough to hold the Magnetic Caliper Base and your caliper steady for measurements. That surface versatility makes the Magnetic Caliper Base compatible with lots of not-so-common uses, especially those where you need to “invent” your own wooden base. The possibilities for the Magnetic Caliper Base are pretty much limited only by what you can think up!
Miter Slot Base
While the primary use of the Miter Slot Base is obvious, there are a pair of beveled screw holes cast into the body that can let you dream up other uses that might be unique to your shop or needs. The base is also long enough that it can be clamped to a surface without interfering with the caliper operation.
The Miter Slot Base is also cleanly molded from high strength plastic and designed to fit the very common ¾”-wide by 3/8”-deep miter slots found on most table saws, band saws, router tables and other equipment. The base has a pair of molded in tension arms on one side that maintain a snug fit on the miter slot. This includes the common T-shaped slots with the exception of those with an uncommonly thin upper lip usually in the -.225” or narrower range. That type of T-slot is usually confined to smaller, lower-priced saws and other power tools.
In the Shop
The grooves in the Magnetic Caliper Base accept the calipers easily and the tapered washers beneath the thumbscrews lock it in place securely without applying a bunch of pressure to the caliper arm. Since nothing but plastic contacts your caliper there is no damage done while using the MAG-DRO™ Caliper Bases. Throughout the evaluation I never had a caliper slip or change position in any way unless I wanted it to move. It is important to note that your caliper comes out of the MAG-DRO™ Caliper Bases as easily as it goes in so you are not tying up your caliper.
The Magnetic Caliper Base develops a strong bond so it and your caliper stays where you put it if the surface is in fact magnetic and sort of clean. I tried this Magnetic Caliper Base on several vertical surfaces in my shop – including a few that had not been “dusted” in recent memory - and it stayed put on all of them. The steel plate that comes with the Magnetic Caliper Base makes applying it to shop-made jigs and fixtures simple.
The Miter Slot Base is also very secure in all of my miter slots thanks to very precise molding and the tension fingers. The length of this base along with its snug fit means that you can move it along the miter slots without developing side-to-side movement.
When used with modern digital calipers the MAG-DRO™ Bases are even more versatile. Being able to establish zero anywhere within its range of movement with the push of a button lets you measure tiny adjustments to bits, cutters or fences very easily. Of course larger adjustments are also very easy to quantify.
The MAG-DRO™ Caliper Bases are well made tools that with minor care on your part will last a very long time. I like that the MAG-DRO™ Caliper Bases use a common 6” caliper without tying that tool up when not being used for these purposes. That lets you extend your measuring dollars a bunch while adding accuracy to your shop. That kind of dual purpose is not common in woodworking. I suspect that the versatility of the MAG-DRO™ Caliper Bases will not be fully understood until we have them in our shops for a while and have time to explore ways that we can use them.
The fact that the Magnetic Caliper Bases are very reasonably priced is another attraction. The Magnetic Caliper Base sells for $9.99 and the Miter Slot Base for $7.99. (10-30-2011) That is very short money for the wide-ranging utility these bases have in the average woodworking shop.
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