.....the only major part I can't find is the Riving knife
If you only use it for cross cutting then the riving knife won't be needed (it also says that in the DW manual). TBH you only need the riving knife for rip sawing - sometghing which is downright dangerous to do on a radial arm saw and is best avoided. More important, I'd say, is to ensure that your fence is in the right place (so that the blade is behind it when the head is in the park or home position. Other things to consider is to have some form of side guarding on the blade and/or an adjustable nose (1970s/1980s guarding leaves a LOT to be desired), an automatic return to home position mechanism (a heavy counter weight tied onto a washing line which runs over a pulley wheel and tied to the head will do the do) and that you adequately guard the home position with a home position box
Yes, I know, you're a DIYer - but the laws of physics recognise no such boundaries and knowledge of safe practice is always worth acquiring. Take a look
here and
here for more info
...and the slide bearings are a little lumpy
It might be the bearings (AFAIK a DW special item and only really available from them as they have specially machined "tyres"). Problem is that the bearings run in ways machined on the inside of the arm casting. Under heavy use these machined ways can wear and get damaged. They can also get pitted if the tool is stored in a damp shed, for example (the arm is cast iron). The only cure I know is to replace the arm, which is pretty pricey.
I've spent a bit of time getting it square and level, and it's pretty accurate and makes quite repeatable cuts.
If you do a lot of mitre cuts the saw will tend to go out with a degree of regularity. This is because the frame that the column is bolted onto is rather thin flimsy folded steel. The frame on the bigger industrial models was far thicker and less prone to this happening. On my last one I got so fed up with it that I had a sheet of 1mm steel welded onto the top of the frame and gussets welded into the corners on the underside - that cured it!
If anyone knows these beasts, is there an easy way to determine the difference, and how many of the parts would be interchangeable?
That I don't know. The original was Italian-built RAS was the DW110, followed by the DW111 then the original DW125. I had a DW111 and a DW125 at one time and more recently have owned a DW1501 (basically a longer arm version of the DW1251). A lot of the parts (other than the blade guards and switch gear) are interchangeable. I imagine the DW1251 or DW1253 (3-phase, no less) would be much the same
