Brass setup bars are incredibly useful for all kinds of tool setup and measurement tasks in the shop. These Mag Shims, from Fastcap, are quite different, but look to be almost as versatile. Mag Shims are larger than typical brass setup bars, and they come in only two easily identifiable thicknesses: the thicker red shim and the thinner steel spacer.
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The biggest thing that sets these highly visible red plastic shims apart from brass setup bars is the embedded magnets. The shims can stack and stick to each other, or to the steel spacers, or to any ferrous surface.
Since they are made out of plastic, FastCap Mag Shims shouldn’t damage or dull your cutting edges, as long as you keep the steel spacer in the center of the shims and the magnets away from the cutting edge.
Besides being able to stack to create any thickness from 1/8″ to 1-1/8″, FastCap Mag Shims also have rounded corners that can be used as templates for 1/8″, 1/4″, 1/2″, and 3/4″ radiuses, and even the inner notch can be used as a 1/4″ inside radius reference.
Mag Shims come in two different sets: imperial and metric. The imperial set comes with (8) 1/8″ red plastic shims and (2) 1/16″ steel spacers, and the metric set comes with (6) 2 mm red plastic shims and (2) 1 mm steel spacers. Unfortunately, imperial and metric sets are not color coded. If you buy both sets, try not to mix them up.
The imperial version of the Mag Shims are on sales right now at Rockler for $20, thru February 27th, 2015. They are normally priced at $25 at Rockler, Woodcraft, and other FastCap distributors.
Buy Now (Imperial Mag Shims via Rockler)
Buy Now (Imperial Mag Shims via WoodCraft)
You can find the Metric set of Mag Shims over at Tool Nut, where they are regularly priced at $20.
Buy Now (Metric Mag Shims via Tool Nut)
More Info (Mag Shims page at FastCap)
First Thoughts
I use brass setup bars all the time in my shop, but I think these Mag Shims could have a place too. The fact that the shims stay together means they’re going to be better at certain tasks.
Say I want to set the bit on my router table to 3/4″ high. I would need to stack a 1/4″ bar on top of a 1/2″ bar and then use another bar to bridge across the top of the bit and the stack to check that the bit is exactly 3/4″ high.
With the Mag Shims I would stack 7 of the 1/8″ thick red shims next to the bit and then slide the 7th shim over the bit to see if it’s the correct height.
Mag Shims may be easier to use in certain situations, but because they are plastic I wonder how accurate they are. A related question is how close in thickness are the shims to each other? If you take one stack of four, how close in measurement is the other stack of four?
Lastly, are measuring tools made of plastic going to hold up in the shop? One could argue in some ways they might be better than brass. I’ve dropped one of my brass setup bars on the cement floor of my shop and dinged the edge making it less useful. I don’t think the Mag Shims would have the same problem.
What do you think? If you regularly use brass setup bars, or other brands’ tooling setup shims, is this something you would use also or instead?
Here’s an in-depth overview promo video that shows the many ways how the Mag Shims are intended to be used:
fred says
“The imperial version of the Mag Shims are on sales right now at Rockler for $25, thru February 27th, 2015”
I think this should read:
“The imperial version of the Mag Shims are on sale right now at Rockler for $19.99, thru February 27th, 2015”
Stuart says
Thanks for the correction! Ben had it right, and I somehow managed to flip-flop the prices when editing and scheduling the post.
Nathan says
note the metal bits in the plastic – I bet that’s how the maintain the measurement accuracy. I think for woodworking they will be sufficient. I’d still want some brass bars to use with.
Price is about right. would like to see a 1/32’s shim too but that’s probably too tight for most.
porphyre says
I think the innovation here is the radiused edges. Personally, I prefer a “no-stack” solution like Kreg’s bars. You could get sawdust or whatever between these plates. Depending on the strength of the magnets, I worry about them sticking to something I don’t want them to and throwing the measurement off.
Garrick says
A little concerned about the accuracy. Good quality measuring tools will tell us the accuracy, or maximum deviation. Of course nothing is perfect, but knowing how close to perfect a calibrating tool is, is important.
Benjamen says
I agree this worries me a bit also, I wish FastCap would post the accuracy. A measurement isn’t really a measurement without it’s error bars.
I would use these primarily for woodworking, which usually requires less precision than metalworking. Still there are times a 1/32″ mean a tight fit and a sloppy fit.
Jon says
It’s a shame I made my table saw fence (Biesemeyer-style on a 1960s Craftsman) out of 80-20 aluminum extrusion. I suppose I could embed some T-nuts with set screws in the fence so that I could use these shims, but then those are in the way when I need to use the T-tracks for other things, like featherboards. Same problem for those with phenolic, HDPE, MDF, or any other sacrificial fence setup.
Stuart says
I thought the same, but the embedded promo video shows a lot of ways it can be used without a steel fence or tool table surface.
Jimmie says
Likewise, my fence is aluminum extrusion so the magnets aren’t very useful but otherwise a set of stacking shims might be worth keeping near the workbench.
To be honest, I don’t use brass bars for setting blade and bit heights. Instead, I just use drill bits and a small machinist’s square if necessary.