why do hacksaws cut on the pull?

No, hacksaws are designed to cut on the pull.

Well, I've tried the blade both ways, and prefer it to cut on the push myself. the pull then cleans out the debris.

I usually break the blade if I set it to cut on the pull, since the rigid handle, I assume is not so forgiving as the other end and twang, it breaks. Maybe I'm just an awkward sod. Brian

Well some of the more flimsy junior hacksaws can work better if you fit the blade so they cut on the pull, as the springyness of the other side can mean that if it snags, the blade breaks or falls out. Often, also it much depends on what you are cutting and access, but the fact still remains that cutting on the down stroke gives more force to the cut to keep it in the slot. Brian

Don't see the OP so replied here.

Pushing a blade puts it in compression & it may buckle. Pulling a blade puts it under tension - easier on the muscles.

That surprises me. I can see there might be occasions when you'd want to cut on the pull, but I was taught that the teeth should point forwards, and Googling "What is the correct direction for a hacksaw blade?" supports this view.

Not the ones I have. They are generally designed with the blade oriented to cut on the push. The idea is that there is an additional downwards force on the blade from the angle of the 'push'. It is common to start a cut by 'pulling' for a few cuts to make a slot to minimise wander on forward cuts.

The only articles I have seen where cutting on the pull is done is for soft materials.

Perhaps you just cut soft materials like an art student?

While that is correct, hacksaws are meant to cut on the push (where the push helps keep it down and cutting), with the blade pre-tensioned to prevent it buckling.

That is down to the rigidity and quality of the saw frame.

Interesting, I find the opposite, though I might have more control over a pull.

Well I must have fitted them the wrong way round for the 45 years I used them

I have been using them with the leading blade edge forward for 65 years, since my apprenticeship.

BULLSHIT

Brian Gaff snipped-for-privacy@gmail.com wrote

I havent bothered.

Me too, essentially because you can apply more force in the push mode.

The obvious exception is with a power hacksaw on a hand held drill etc but you dont have any choice on which way the blade goes in that case.

Brian Gaff snipped-for-privacy@gmail.com wrote

Never bother with flimsy ones myself.

Yep

Yep, the turnip doesnt have a clue.

When I were a prentice learning how to work metal, that is what we were taught. \Google gets an opinion, not fact

Nope. steel rod mainly

When I bought them, the blade was always fitted to cut on the pull

Push cut was also what I was taught in the '80s.

I have found that if I fit a hacksaw blade so it cuts on the push, the blade tends to bow between the handle and the work that you are cutting, whereas if you fit it to cut on the pull, it remains rigid. I presume this is because the frame is a bit flexible so if you cut on the push, the handle end of the frame distorts towards the tension end and the blade is no longer in tension.

A short hacksaw, with a frame which is thick (and therefore stiff) relative to the distance between the handle and tension ends, has less of a problem than a much longer hacksaw.

If you are cutting wood or fairly thick metal, the teeth are less likely to bind. If you are cutting thin metal sheet which is of a similar thickness to the pitch of the teeth, the teeth are more likely to bind and cause a cut-on-the-push blade to buckle because of insufficient tension.