Difference between SFIC A2, A3, A4

[sssman]

What is the difference between A2, A3, & A4 interchangeable core systems? Is there a way to tell which system is used with just a key?

[WOT]

What is the difference between A2, A3, & A4 interchangeable core systems? Is there a way to tell which system is used with just a key?

They both have the same highest depth, then the increment in the depth vary depending on the system.

Here's a root depth chart from Best Access Systems.

You should be able to tell the system from one or two keys and a caliper accurate to thousandth of an inch.

[sssman]

Is any one system more common than the others? Why would you want to use a system with fewer possible combinations? Also, could you recommend a good caliper & a vendor? Thank you.

[2octops]

A2 is the most common.

If you want a good caliper get a Starrett. You can get a clone for about 1/20 the price of a Starrett and they will work just fine for most things unless you are doing machine work.

[2octops]

A2 is the most common.

If you want a good caliper get a Starrett. You can get a clone for about 1/20 the price of a Starrett and they will work just fine for most things unless you are doing machine work.

[WOT]

Is any one system more common than the others? Why would you want to use a system with fewer possible combinations? Also, could you recommend a good caliper & a vendor? Thank you.

A2 is the most common.

Get the 6" $16 digital caliper (a metal one, don't get a plastic one) with 1/2000" resolution and 1/1000" accuracy from Harbor Freight. I think this is as accurate as you can get with a caliper. It should hold up ok for a while as long as you don't drop it or get it wet.
Something like this:
http://www.mini-lathe.com/Mini_lathe/Re ... aliper.htm

What sets apart a higher end, expensive calipers is they're available in cutting fluid resistant model for using it in a metal shop.

If you want to go for accuracy beyond that, you need to get a micrometer.

[sssman]

How about this one: http://www.lockpicks.com/index.asp?PageAction=VIEWPROD&ProdID=471

Does it matter that the depths on the Best root depth chart go to the ten-thousandths, while the caliper only measures to the thousandth? Will a few ten-thousandths of an inch make a difference when cutting a key?

[WOT]

How about this one: http://www.lockpicks.com/index.asp?PageAction=VIEWPROD&ProdID=471

Does it matter that the depths on the Best root depth chart go to the ten-thousandths, while the caliper only measures to the thousandth? Will a few ten-thousandths of an inch make a difference when cutting a key?

That's exactly the same caliper, but in a smaller size. I use the 6" and it's just fine. Harborfreight has the 4" and 6" for $16. If you print out their webpage, they'll match the price in store.

ICORE keys are very hard to work with. For one, the tolerance is very close and the keyway shape is such that it's hard to grip straight in the key machine. Unless you have a BEST key vise grips, you could find yourself being forced to cut the key slightly too high, then hand fit with a file, checking with caliper.

[sssman]

So according to the depth chart posted, a 0 cut should be 0.3187". However, I took a micrometer (HPC key micrometer) reading of a key, and the 0 cut reads 0.321". This key works in the lock. The micrometer is calibrated correctly. Am I measuring incorrectly or is that chart wrong?

[WOT]

So according to the depth chart posted, a 0 cut should be 0.3187". However, I took a micrometer (HPC key micrometer) reading of a key, and the 0 cut reads 0.321". This key works in the lock. The micrometer is calibrated correctly. Am I measuring incorrectly or is that chart wrong?

Your reading is too high by 2.1 mils but this is within functioning tolerance. What are you using to cut the key?

[sssman]

I am using the A1 Pak-a-Punch. But because it is a 0 cut, isn't that irrelevant? I was under the impression that a 0 cut was no cut, just the depth of the key blank itself.

[zeke79]

Some cases a 0 or even a 1 cut in automotive is blank height but in most cases a 0 cut will still take material from the blank. This simply allows the blank manufacturers to have looser tolerances on the blanks since the first cut is still removing material. If no material were removed from the blank for a 0 cut then quality control would have to be much higher and therefore blanks would cost much more.

[WOT]

I am using the A1 Pak-a-Punch. But because it is a 0 cut, isn't that irrelevant? I was under the impression that a 0 cut was no cut, just the depth of the key blank itself.

Then 2.3 mils is about the best you'll do. #0 is a valid cut depth. Blanks are most likely sized a hair above #0 cut, so that the punch will take off a little bit and be exactly at 0. If it was slightly too low, it would make the blanks useless.

If you're cutting from depth keys and the blanks are close enough to 0, sometimes you can get away with skipping them.