why do hacksaws cut on the pull?

I reckon that if the king of hacksawing motorbike engines pushes his blades, that’s probably the best way. Allen Millyard has done some quite extraordinary engine builds in his shed.

Just as an example (about 3 minutes in).

A hacksaw typically supports the blade from both ends. Whether the blade is being pulled from the handle end (a pull cut) or from the other end (a push cut) should make no difference to the blade, only the ease you have in cutting.

Unless of course your hacksaw is really flexible. In that case it may fail to keep the blade in tension on a push cut.

Andy

Hacksaw blades should be mounted in their frames with the teeth facing forwards. They are designed so that the blade will cut on the push – the forward stroke – rather than the pull, or backwards stroke. The correct orientation for mounting will sometimes be indicated by an arrow marked on the blade. "

And that's for a fully supported hacksaw blade. A mini-hacksaw, use your own judgment, after ruining a blade :-)

It's hard to get a picture showing the tooth profile, but the cutting edge is closer to vertical, while the trailing edge has more of a slope. The teeth can also be staggered from side to side.

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Home photography version (arrow towards right is push direction):

The coating on a new blade, can obscure tooth shape.

Paul

No the same way on the push should normally be used. This thread is the first I've heard of cutting on the pull, Odd things you may find work better especially if you cannot get the handle and you hand in, but generally is push like all saws except for electric jig saws some of which have blades made to cut both ways. Brian

The one use of pull with a hacksaw (or any other) blade is with a padsaw. I've a couple of pull saws from Aldidl; the samall one is a pad saw and the big one is vary good for v. narrow cuts. Always takes a while to get used to them - and the teeth are bloody vicious!

So if you have a hacksaw (*) with a push blade, and you've tightened the tensioning mechanism as tight as you can, but the blade still buckles and bends (sometimes irreversibly) immediately on the handle side of the work being cut, what can be done to rectify the problem? I've found that this has happened with most hacksaws that I've used, and I've resorted to reversing the blade so it cuts on the pull stroke which causes the problem to disappear. It's worst when cutting very thin metal sheet which is a similar thickness to the spacing of the teeth, because that often causes the teeth to bind in the metal and the blade buckles before you have had chance to stop pushing it forwards.

(*) Either a junior hacksaw with a fixed frame or a full-size hacksaw with a frame in two halves which can be set to lock at various lengths to accommodate different blades.

My apprentice supervisor told us you must always have 3 teeth in contact with the work. (similar rule for files)

Not a huge choice with Junior hacksaw blades but 12" come in a range of tooth spacing.

Junior hacksaws are flexible

:-) I was given one while on holiday in Felixtowe, around 1951. Spoiled my holiday as I was keen to get home and put it to use!

Mine isnt and works fine with the blade in push mode.

I've never had a 12" blade buckle like that. Bear in mind that if the tension is high enough (higher than the resistance load applied on the forward stroke) then the blade is always pulled. I was taught that the blade should be slackened off after use. This was in the days before the hardened points, when the whole blade was hard. I don't know if it helped at all, but I still do it.

Buy a better hacksaw. Or maybe you are pressing _REALLY_ hard. I've had no problems.

Andy