How can I access my external firewire drive?

You cannot go from Firewire to USB. Its simply not a connection that can be physically made.

You can however use one of the Thunderbolt ports your Mac has with an adapter for FireWire. Apple offers this one: Apple Thunderbolt to FireWire Adapter - Apple

Some of those old LaCie external drives had optional USB ports and a USB cord that you could use as well.

If that LaCie external drive does not have optional USB, then you will need three adapters to connect it to the current Mac’s.

1. An Apple USB-C to Thunderbolt adapter.
2. An Apple Thunderbolt to FireWire 800 adapter.
3. A FireWire 800 to FireWire 400 adapter.

Those are FireWire 400 ports. I don't think a Thunderbolt to FireWire 400 adapter exists. You need an FW 400 to 800 adapter. I have several, both a short plug & a 6" cable. You could try Amazon on Other World Computing.

It won't connect to the drive. Your drive is using a Firewire 400 port. You will need an extra adapter between the Adapter linked to above and the drive.

Apple does not sell that however. But there are some available on Amazon: IEEE Firewire 400 to 800 adapter - Amazon.com

Drive->Firewire Cable->FireWire 400 to 800 adapter linked to above this line ->Firewire 800 to Thunderbolt adapter linked to in previous post->Mac.

Is this for purposes of nostalgia, or for data that only available on that hard disk? Because for most other uses, a FireWire 400 era hard disk is well along in its useful lifetime, will never be fast, and is likely to be much lower capacity than what is currently available. And you may well spend a fair percentage of a new and more capacious hard disk drive on dongles here, just to connect to this hard disk.

Ah' thanks you are correct, When the OP said current iMac, I missed the iMac 27" late 2015 part.

In that case, then they only need 2 and 3.

An Apple Thunderbolt to FireWire adapter and A FireWire 800 to FireWire 400 adapter.

I would if the data was important use some other computer with a firewire port to get the data off the hd

and get a new external hd which would be maybe cheaper than adaptors and much faster than the around 40MB/sec firewire 400 can provide a sustainable transfer speed at.

FH678 wrote:

This is all old archived files that I was hoping to put on another drive I have. I wasn't planning to continue using the FW drive. There are files that I sometimes wish I could access for current work, so just wanted to be able to get to them when the need arises.

In that case, the adaptors mentioned should work fine. The Firewire 400 to 800 adapter is $7.00 bucks on Amazon.

The more expensive one will be the FireWire 800 to Thunderbolt adapter however at $30 from Apple, though you may be able to find cheaper alternatives.

For a one off, the setup should work fine.

Open Disk Utility, and see if it's there. It may need to be repaired using First Aid from there.

Otherwise, the other option would be to extract it from the Firewire case if at all possible and use another case for it

Another option - which I had to do because the FW port was dead - is to open it up and get a USB to hard disk adapter like these:

Use a Thunderbolt adapter.

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A 2015 iMac doesn't have USB-C ports; the first adapter isn't useful for pre-2017 ones.

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