I’m concerned with the number of people recommending a chainsaw, circular saw or chop saw. Basically all these tools are extremely dangerous if you have little to no experience of them. I did a 2 day course in chainsaws and wouldnt recommend one.
Chainsaw. Plus proper chainsaw trousers(or chaps), boots, gloves ear defenders.
I would say 90% of those presenting in hospital with life threatening to life changing injuries from a chainsaw, though it a great idea to buy a cheap one from b&q or lidl for just such a job.
Circular saws.
Danger of kick back, which is greater as only very large bladed circular saws can cut that deep to do it in a single pass, the majority its 2(55-67mm), one side then the other. Chances are they wont line up and you’ll have a rubbish looking end, but the big danger is you are cutting with the entire blade buried in the timber then that gives the greatest risk of kickback, which even if you are expecting one, can rip the damn thing out your hands and next stop is your legs. the nature of a blade thats spinning upwards means that when a kickback occurs, the saw is going to come back towards you and turn so the blade is facing you(legs,arm,stomach)
Cross cut miter saw. This is the actual proper tool for the job, but most even the larger 10″ blade will only cut to a depth of about 75-80mm.
But there are dangers to be aware of. Namely you dont copy joiners and pull the saw forward over the top and try to do a reverse cut on it. Yes thats a way of doing it, but oak is a hard timber, and the saw blade, especially at full depth will have difficulty. It is far safer to pull the saw into the cut than push back on it. The cut MUST be made slowly, its not a hot knife through butter. Believe it or nay, but too quick can have horrific consequences on what happens to the blade and the arm it travels on, it can bend,twist or buckle and the blade likewise, and that all happens in the blink of an eye. Theres a horrible pic of a big industrial radial arm saw where this has happened, on a 400mm blade and the super strong arm has actually bent to the side.
If molegrips chooses this option, or anyone else. You MUST clamp the timber down, make the cut, allow the saw to return and the guard to close, the blade to stop running, then you remove the clamps, turn it over, reclamp and make the 2nd cut – keeping in mind that one side of the beam is unsupported and may drop or move. You dont rush using this type of tool. Ever ever ever.
Personally I’d opt for a handsaw. A brand new super sharp out of screwfix for 7 or 8 quid, and a candle for waxing the blade as a waxed blade will make it glide through, even if the timber is dry or green(wet) For 30 cuts I’d probably buy 2 saws. According to my big book, oak,especially the denser, and a sleeper will have been selected to be denser “has a moderate to heavy blunting effect, especially in denser timbers”.