What is the application?
How were the bearings lubricated originally?
What type of bearings.
Imperial bearings are not interchangeable with metric. If the dimensions are the same someone somewhere has been pulling someone elses leg at some point and either the old imperial bearings aren't imperial or the new metric bearings aren't metric.
I have seen quite a bit of damage caused by the sealed bearing hype. In some places they are adequate. In some places they are better than anything else. In some places they can cause damage that costs thousands of euros to repair in a matter of weeks.
For instance you cannot replace self aligning spherical ball bearings with sealed grooved ball bearings.
For instance there are some uses where open grooved ball bearings will last at least 10 times as long as sealed.
The longer version of this:
I'm cleaning up an old planer (the bigger version of the one I did before). Evrything is imperial. I got the bearing out and thought it was imperial 1"x2"x3/4" probably; I didn't measure, just got the code.
The code took me to this: https://www.qualitybearingsonline.com/l ... 5x52x18mm/
Which confirms "Imperial" but then lists as 25x52x18.
I thought that might be sloppy listing, but no, the "Imperial" bearing is indeed nicely metric.
That opened more options (for deep grrove bearings oif that size), including sealed-for-life.
So then my question became whether it mattered sealed vs unsealed. The current ones are unsealed. They also hold the block and so reeive quite a bit of dust potentially.
I think I read on here someone saying they always use sealed (perhaps on a Union raduate thread). Is there a downside? They seem to be slightly less expensive.
Sorry for the mental spaghetti of the original post!
If the code is the same, so the bearings should be also.
North America, a reasonably large user of bearings, is still imperial for much of its industrial kit (stuff in use presently, rather than brand new, for the latter I don't know), so imperial bearings are available. So find a NA bearing supplier and look up the code on their site, and see if what specs they quote match with the UK/EU supplier you have already found.
It's also worth taking a bit of time to understand the letter suffixes too. For example, there are high-temperature bearings designed for use inside engines, where the bearing only achieves the correct tolerances _after_ it has got pretty hot (otherwise it has excessive play). You probably don't want those in a woodworking machine, unless they are explicitly specified by the manufacturer!
That's a bit annoying, in that classic motorbikes in particular are a market for imperial bearings, but I suspect probably only the high-temp type.
But... at a guess, the bigger the imperial bearing is, the more likely replacements can be had, on the basis that smaller kit is likely to have "gone metric" a long time back. Worst case you might need to source in the USA and take a deep breath before shelling out for the cost - but you should get them.
All my kit is metric presently, but I usually replace the chinesium ones with SKF oil-sealed ones, partly for quality and partly for ease of cleaning - there is negligible risk of forcing sawdust and other stuff into the ball races. Given the size of machine, the bearings on my Kity's planer block are huge, and show no sign of play, although it's probably at least third-hand.
In my very limited and amateur experience with both belts and bearings you need to 'turn detective' before ordering. Hope you find what you need.
I’d use a 6205 2RS which is a bog standard bearing with a 3mm shim washer to make it 18mm rather than 15. The price difference you will see is massive. Shim washers are standard stuff. For a PT I’d just use standard clearance bearings as opposed to C3
The other thing to consider about sealed or not is how the machine was designed to be lubricated. If it is meant to pressure greased/oiled then you don't want seals as this will stop fresh lube entering the bearing and flushing out the old, potentially dust laden lube.
Trouble is few woodworkers in my experience undertake regular lubrication of their machines!