Accurate hacksawing

[rdennett]

I was looking at the mechanic's exercises in The Complete Modern Blacksmith and one thing I know I need to learn is how to accurately saw with a hand hacksaw. If I scribe a line on a piece of metal and try to hacksaw it, the cut will invariably be out of plumb. I know that practice makes perfect, but does anyone have any tricks for accurately starting and maintaining a hacksaw cut?

Thanks,
Rob

[Rob Browne]

Rob,

The best thing I ever did was to get a good hacksaw frame that could be really tightened. It has a square frame at the front, not just a bit of bent tubing, and it tightens up on a cam motion in the handle.

With the blade REALLY tight I find I can now cut as straight with a hacksaw as I can with a good tenon saw whereas before it used to curve to the left every time.

Cheers

[Dale Russell]

Slow & easy , Inhale / foward stroke , exhale / backward stroke , slightly lift on the backward stroke .
Take your time , it's " not " a race , when cutting " BIG " stock set yourself a number of strokes , have a rest , then more strokes , ect till it's cut all the way through .

Try not wiggle the blade from side to side , u'll break teeth off .

Use the correct TPI ( teeth per inch ) for the job too .....

Ian Lowe used ta cut as straight as a dog's hind leg when he first lobbed here , now u'd think his hacksaw cut's where done in a chop saw / bandsaw ...


Dale Russell

[HWooldridge]

Sharp blade, very taut, spray some WD40 or light oil on the blade before starting and during the cut, rotate work if possible to start all sides on a scribed line, etc. The other comments listed above are also valid.

[Bob JS]

'let the tool do the work' is what my teacher always used to say.

[Charlotte]

My salvation was the high tensil hack saw frame. It has a lever incorporated into that pulls the blace very tight. Much tighter than I can get it by turning a wing nut.

They are also much quicker to change blades on.

BTW. Buy good blades, the right tooth size, and change frequently. Two things I've learned not to ecomonize on Sand paper/belts, and hacksaw blades.

[Finnr]

Right hand on the handle left on the front of the saw. Then do like Dale says.

Finnr

[Jocko 58]

Also use full strokes don't rush take ur time and don't grip the saw to tight
ONYA MATE:cool:

[keithgartner]

I use wax or crayon as lube on the blade so chips don't stick. And the material must be clamped tight, in a good vice, on a good bench, if the material vibrates the blade bounces, and the teeth wear unevenly, and start scaloping. Also watch the blade not the saw frame.

[Mick]

Shoot Rdennett yoiu must by your blades from the same supplier I do. Every blade he sells has got a bend built into it.

[Ratel10mm]

As well as all the good tips so far, I was taught to try to make my driving arm like a piston, i.e. let the elbow be the hinge and try to keep the forearm going straight forward & back. Place your trigger finger along the handle as well, it helps keep your wrist locked which in turn helps keep the action linear.

[Bill in Oregon]

Sure would like to see a photo of one of these high-strength, high-tension cam-lock hacksaws.

[easilyconfused]

A balanced stance is important too, one foot in front of the other a bit. That way I can use my whole body, not just my arm. Keeps from tiring me out and lets my lock my forearm a bit better to keep things true.

[johnptc]

safety tip

righted handers cut on the right hand side of the vise

that way when the cut is complete you wont smash your hand into the vise

i hate pain :)

[John B]

Use a hacksaw blade with the correct pitch of teeth for the job in hand, fine pitch for hard materials and light wall tube, coarser pitch for softer materials.

Select the correct type of blade for you, All Hard or Bi metal

At least 3 teeth should be in contact with the metal at all times,

Teeth on the cutting stroke for large hacksaws face forward, and can be tensioned by various means, cam locks, wing nuts etc,

On the small frame hacksaws teeth face to the rear, and rely on spring tension of the frame to hold them in position

Correct tension on blade, (secure blade, remove all flex, then apply three full turns on the wingnut)

Secure the workpiece firmly and square to you when sawing, and at a comfortable height

Use the correct stance, feet apart and in line with the sawing line(s), and both hands holding the saw frame in line with the marked line.

Start the cut by lightly drawing back the saw until at least 5 teeth are cutting, then using the full length of the blade establish a steady rhythm (40 to 80 strokes per minute English or metric, keeping an eye on where the cut is going, this can be controlled by angling the vertical axis of the saw. You can use your thumb adjacent to the marked line to steady the blade until a starting groove is established

Use a relaxed grip on the saw, but enough to keep control of where the blade is going

Steady Pressure is applied on the cutting stroke (forward for the large hacksaws, backwards for the small frame only hacksaws) release the pressure on the return stroke to avoid excessive wear on the blade

In use All hard blades give a better straighter line than bimetal blades which have a tendency to flex and buckle as they loose tension as they get used
NOTE all 'all hard blades' are what they say, and if you are not experienced at sawing you may break them easily

Cheap blades should be avoided if you want decent results and prolonged saw blade life

Don't saw when you are fatigued, take a rest and then resume using the same set up.

NEVER start a new blade in an old saw cut

Ease off the pressure as you reach the end of the cutting to prevent damaging yourself.

It is not advisable to try and saw metal that is black to red hot, or metal that has been quenched after being forged, it will dull the teeth

I think that has covered the basics, and like all hand crafts, you need to practice!

Having said that when you are experienced at it you will need very little effort to clean up or size to fit mating parts, Care with the saw means less filing to lines, but then thats what milling machines were made for.

[rockstar.esq]

As an electrician I've cut miles of pipe, angle iron, and sheet metal. On thinner stock I've found it's easier to approach the cut from one end to the other as opposed to trying to cut the widest part all in one shot. The advantage is that the cut forms a channel to guide the blade once you've got a good start. Another tip is to extend your index finger from the grip. Most high tension hacksaw frames have a guard in front where you can put your finger. I find it harder to over grip the saw handle with my index finger extended. Beyond that, pay attention to which direction you seem to favor. If you're angling to the right, move your whole body right a little and vice versa. Before long you'll have feel for how you have to set up the workpiece relative to your body position. At that point the blade will track nicely without as much effort.

[clang]

Most folks don't move their hand in a straight line as they stroke..also they tend to rotate their wrists. Moving in a straight path helps a whole lot...clangue

[Ten Hammers]

This is my swage stand. Notice the saw hanging on the front. I believe it is a Nicholson. The other pic is just one I swiped off the net. Almost exact same saw but different color and brand. I also have the second saw in a toolbox. These saws have stowage for blades in the top tube. Excellent saws. Many times it is much faster to use the hacksaw and the vise than to go around to the chopsaw. Even if the piece is a bit hot.

[David E.]

All the good advice has already been given, good frame, good blades and remember the teeth always point away from you and you cut on the push stroke not the pull:D take your time, nice and steady does it.

[ThomasPowers]

Let me throw a ringer in: my hacksaw has a 30" blade. It's a piece of metal cutting bandsaw blade mounted in a bowsaw frame. I punch the holes a bit closer together than the wood blade so there's more tension.

Vey handy to have in the truck behind the seat it's amazing how often it's been used to subdivide roadkill steel, get things at the dump/scrap yard, etc.

[kubiack]

The Blacksmith Journal had a few articles on forging a hack saw, issues 73 and 74. The author reported the ability to hold a high blade tension and good accuracy. They look like a viable alternative to a good commercially made unit.

[Ten Hammers]

Junior and others have indeed forged their own hacksaws. Something I intend to do someday. Getting a good start is the key. Will make a difference if you are sawing 1/4 x 1 1/2 bar or angle iron. The vise ( or other holding device ) should be a little below waist level for me. In this location I can use my whole body sometimes ( rocking hips ). If I am building celtic crosses I draw lines to stay on. A good quality 18 tooth blade is about all I use. I also try to use the whole blade ( sometimes banging the inside of the frame on the stock I am sawing). You get close to the end, you better slack off because you may get your knuckles on the vise. Steady even strokes. Running a hacksaw like a power jigsaw speed should be avoided. A piece of 1/2 square should be cut in a few strokes if you have a good blade and good form. If you split an end you are drawing, you can clamp the stock in the vise and back off the end about 1/2" and saw a couple strokes, make a kerf and twist the split end off. You can then re-forge. This doesn't happen much to me but it does happen occasionally.