Monday, August 22, 2016

Ikea Allen Key and Wrench Measurements: Trying to estimate?

What size are common Ikea Hex Keys and Wrenches?
Up until yesterday, despite having put together over a dozen pieces of Ikea furniture and having accumulated about a half-dozen keys/wrenches, I did not know -- only a half dozen because I didn't start collecting them until more recently. Why would I want to know anyway, they come "free" with the furniture set every time. And most of them seem to be roughly the same size.

But if I'm putting together so much furniture, why don't I do a bit better and get myself a better tool that doesn't make my fingers ache after assembly? Like a ratchet with changeable sockets? Guess it could also be useful if I threw out all my keys and needed to do some work.
Hex Key and Wrench Collection: Six hex keys, one wrench
Ikea Hex / Allen Key Dimensions: Trying to get an estimate
I've been meaning to do this forever but didn't have a caliper and didn't feel like doing it with a cheap plastic ruler. There was also that thing about having to pay for a ratchet and a collection of heads once I had measurements. So, guess who finally got a caliper and decided to get that ratchet?

Below is a video of measurements being taken of a small collection of hex keys and a wrench that should have come from Ikea. This was my first time using a caliper in years, maybe even a decade, so accuracy is definitely not guaranteed. The last time was in high school or college. Thank goodness for Google. Video and images should be high enough in resolution to be able to read the caliper.

Video

Summary of Estimates: Imperial or Metric?
If my measurements were anywhere near accurate, the collection of six Allen keys -- shown in the photo above -- only turned up three different sizes. Whether they were supposed to be imperial or metric sizes, I do not know. Note that the caliper was plastic and bought for CA$ 5 at a hardware store. It was only ever checked against a $1 plastic ruler. The measurements were also so small that a bit of movement could have resulted in the measurement changing by a fraction of a millimeter -- caliper did not have a lock or fine-adjustment wheel.
Estimate of Wrench Size: ~13 mm (0.51")
The wrench was measured on the flat side because I couldn't figure out how to do it on the round, angled side. I've used both sides of the wrench for the same nut size and they seemed to work -- whether I was supposed to or not was a different question.
Estimate of Big Allen Key Size: ~7.6 mm (0.30")
The biggest hex key probably came with a table. Only one of these was among the six keys. For reference, 5/16 of an inch is 0.3125".
Estimate of Medium Allen Key Size: ~5.7 mm (0.22")
I don't remember what the second biggest hex key came with. Again, there was only one of these in the group of six keys. For reference, 7/32 of an inch is 0.2188".
Estimate of Small Allen Key Size: ~3.6 mm (0.14")
The smallest of the hex keys was interesting in that I had four of them. They were all shaped differently to some degree but measured essentially the same. Only one image is shown here but all four are in the video. And for reference, 9/64 of an inch is 0.1406".

As you can see, only the wrench appeared to land closely to a whole number in metric. The Allen keys seemed to all have decimals. Was that because the CA$ 5 plastic caliper wasn't perfect? I didn't know what I was doing? The keys were manufactured that way? Or were they imperial sizes?

I tried converting the imperial measurements to fractions with denominators of 8, 16, 32, and 64. The converted values landed pretty close to some SAE bit sizes I found for sale online. If only I had another set of calipers to check? Asking Ikea directly would probably be a good idea.

So now then...
I haven't picked up a ratchet yet but will do so over the next while and also pick up a set of hex key bit sockets in metric or SAE. This should give me the opportunity to see how closely the head sizes match.

Update: Measured the keys and wrench again with a new, $20 metal caliper that was manually operated, not digital, but had a fine-adjustment wheel. This caliper was also not calibrated. I did test it against a few old Allen keys I had, not from Ikea, that had labels. The measurements on the caliper matched up pretty well with the labels on those keys. Nonetheless, the readings I got were ~13.0 mm for the wrench, and ~8.0 mm, ~6.0 mm, and ~4.0 mm for the hex keys.


Reminder: Accuracy not guaranteed.

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