Which way should the blade face?

[David Powell]

I have just finished bringing a power hacksaw back to life. There is no relieving device for the pressure on the blade, The crankshaft revolves in an anti clockwise direction when I stand facing the crank side of the machine, The blade which was in the machine was arranged to cut on the pull stroke. Is this correct? Regards David Powell.

[JoeLee]

I would say yes. Every one of those type saws I have ever seen cuts on the pull stroke.

JL..............

[projectnut]

You don't mention the brand or model saw. As previously mentioned the vast majority of power hacksaws do cut on the pull or back stroke. Having said that there are a few that cut on the forward or push stroke. Knowing the brand and model would certainly help in this situation.

[Doozer]

You don't mention the brand or model saw. As previously mentioned the vast majority of power hacksaws do cut on the pull or back stroke. Having said that there are a few that cut on the forward or push stroke. Knowing the brand and model would certainly help in this situation.

Fact of physics that it is better to absorb the forces into the fixed and more rigid jaw.
Brand does not matter.

-D

[David Powell]

The machine was made by the Perfect Machine Company, Galt , Ontario, before 1923 when they went broke. The nearest similar, but not identical machine is a Sterling, seen in a Youtube video. Perhaps a case of plagiarism, or licensing. Now.with a few repairs it cuts straight and runs very quietly. Regards David Powell.

[I make chips]

Yup, pull the material into the fixed jaw.

[projectnut]

Fact of physics that it is better to absorb the forces into the fixed and more rigid jaw.
Brand does not matter.

-D

Brand and model could very well matter. Roysterford made several models. Their Excelsior model cut on the push stroke while some other models cut on the pull stroke. Covel also made a model that cut on the push stroke.

[Doozer]

Just because they made it that way
does not make it right. Lots of bad
engineering makes it out into the world.
If I had a "backwards" machine, I would
set it up to run pull stroke. But you can
do what you want.

-D

[old mart]

The only one I remember cut on the pull stroke, I don't know which way round the vise was.

[Toolguy]

Some of them are designed to cut on the push stroke and lift the blade on the pull stroke. You can't always just turn the blade around.

[BCRider]

You sure about the no relief idea? I know that a lot of them don't SOUND like they relieve the pressure. But I do recall the couple I saw in my youth and videos on YT seem to confirm that most, if not all, have something that at least reduces the pressure.

That actually makes sense too. We want to relieve the pressure but we don't want to actually lift the blade and let it crash back down even a short way at the beginning of each stroke. That would tend to snap teeth off in short order.

[larry_g]

If you can; hold onto the end of the guide bar if it has one and run the saw. Can you feel an oscillation in the load your holding signifying a changing force on the blade? My power hack saw cuts on the push stroke and I have the manual that says so.

lg
no neat sig line

[BCRider]

If you can; hold onto the end of the guide bar if it has one and run the saw. Can you feel an oscillation in the load your holding signifying a changing force on the blade? My power hack saw cuts on the push stroke and I have the manual that says so.

lg
no neat sig line

You can see that on some of the YT videos where the person lifts and holds the frame up.

[redlee]

All the ones I had cut on the pull, used a cam to raise on the push.

[Michael Edwards]

Fact of physics that it is better to absorb the forces into the fixed and more rigid jaw.
Brand does not matter.

-D

I have a Kasto PH which is designed to cut on the push stroke, and lifts on the return. In addition, it has a provision to switch from back jaw being fixed and the front movable to the opposite.

Large shapers also commonly cut against the movable jaw and were designed to do so, the brand of which does not matter.