Cuttting holes with hacksaw

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Finn Hammer
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Cuttting holes with hacksaw

Post by Finn Hammer »

Note: To view images right click on banner R.H. 2021

It may not be common knowledge, that you can cut 2-3mm thick stainless steel spheres with a hacksaw, but it is, have a look.
You need to drill a hole that is big enough to accept the saw blade, and form a tangent to the circle you want to cut. It may take a couple of try's to get that right.
I trace the outline of the tube to be fitted with a speed marker, then scribe around the perimeter.
I trace the outline of the tube to be fitted with a speed marker, then scribe around the perimeter.
It is important to have a stable fixture of the sphere, here is how I clamp it against a 2x4 which is clamped to the workbench.
Half sphere clamped rigidly to workbench by proxy of 2x4
Half sphere clamped rigidly to workbench by proxy of 2x4
The blade is designed to cut metal, and I grind a relief chamfer on the outside trailing edge, to facilitate the cutting of a circle.
Notice the challow chamfer ground into the trailing edge of the saw. this helps the blade adapt to the circle cut.
Notice the challow chamfer ground into the trailing edge of the saw. this helps the blade adapt to the circle cut.
Here we go! Just grab the saw firmly, and don't let it take control.
Cutting with the hacksaw
Cutting with the hacksaw
It only took 15 minutes to complete this 75mm diametre hole.
Finished hole, needs touch up with file.
Finished hole, needs touch up with file.
And here it is ready to weld the viewport into place.
Viewport ready for welding.
Viewport ready for welding.
This is how I make my chamber, the saw must run at a low speed, I use the speed setting #2 on this DeWalt saw, but this will differ between brands. Galling is bound to occour, so when the blade starts to jam, and jerk the saw all over the place, just sprinkle a bit of WD40 on it, only enough to wet the blade, and proceed!

Cheers, Finn Hammer
Rex Allers
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Re: Cuttting holes with hacksaw

Post by Rex Allers »

Finn,

Looks like a decent method. Thanks for sharing the details.

I would quibble with one detail, though. I would call the electric tool that you used a jig saw. I'd say a hacksaw is usually a hand saw for making straight cuts, mostly in metal, though I use them to cut plastic and other materials too.

Here's a picture of what I think is usually called a hacksaw.
Attachments
Hacksaw.jpg
Rex Allers
ian_krase
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Re: Cuttting holes with hacksaw

Post by ian_krase »

You could probably use this technique with one of those "mini hacksaws" that hold the blade at the end and the middle, or one of those Lenox jab saws that takes sawzall blades. Be a huge pain, though.

(I use one of the latter for all my sawing needs. You can put a diamond saw blade in it, which is great for scoring glass and alumina tubing to snap.)
Jerry Biehler
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Re: Cuttting holes with hacksaw

Post by Jerry Biehler »

Yeah, thats a jig-saw, not a hack saw.

Also WD-40 is OK for aluminum but crap for everything else. Use a good cutting fluid and your blade will last a lot longer.
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Finn Hammer
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Re: Cuttting holes with hacksaw

Post by Finn Hammer »

Jerry, Rex.

My bad with regard to the name of the tool. Being a Dane as I am, and English being my second language, I just didn't think of checking, but you are right of course. I would edit the top post if it was possible, but I don't see any button to enter into edit mode.

Cheers, Finn Hammer
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Richard Hull
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Re: Cuttting holes with hacksaw

Post by Richard Hull »

What an up hill battle! It goes to show that where there is a will there is a way. What distinguishes Humans from other creatures is that they are tool makers. For fusion folks, it appears they are tool users. They use tools not specifically designed to do the work on occasion and win in an effort to get the job done at low cost, regardless of the hassle or difficulty in pushing the least expensive tool to do the job.

Nice! I like it.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
Tom McCarthy
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Re: Cuttting holes with hacksaw

Post by Tom McCarthy »

Finn, what did you use to grind the initial chamfer for starting with the jigsaw? Was it just a shallow circle you ground along the outline? Did the jigsaw have a hard time getting into the surface at the start?

I've always started from an outside edge with the jigsaw, never tried biting straight down into a surface.

Cool work.

Tom
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Finn Hammer
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Re: Cuttting holes with hacksaw

Post by Finn Hammer »

Tom,

In the first picture, you will see a couple of holes, and it is from inside the biggest of them that I started the cutting. The hole must be big enough to insert the saw blade in it, and preferably also be tangent to the circle of the cut to be made. I first cut clockwise, but found it better for my motoric system to cut counterclockwise.
Starting in a hole is necessary, and it also means that the starting conditions are similar to starting at the edge of a sheet of metal.
Going slow is mandatory, and you find out the good way, the hard way, by blunting a blade by going too fast. That's the way to learn.
Working a jigsaw in wood, it is possible to just dive in, but you can not do that in metals, I think.

Cheers, Finn Hammer
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Rich Feldman
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Re: Cuttting holes with hacksaw

Post by Rich Feldman »

Thanks for sharing, Finn.

Tom's question, and the answer (drill hole in which to start the saw), reminded me of bandsaws. I've worked in a couple of shops where at least one bandsaw had a blade welder attachment.
weld.jpg
Specialized resistance welder for making butt splices, finished by annealing and grinding the bead. Of course if you go through lots of blades, you can save money by making them from continuous blade stock that comes on a large reel. Like with chainsaw blades. Bandsaw blade splices can also be made by TIG or by brazing, according to the Internet.

Perhaps not so obvious is the application for which I was taught how to weld bandsaw blades.
Suppose you need to make a 20 inch round hole in a 24 inch square of inch-thick aluminum. The inside of the circle is scrap, and the outside is the part you keep, as in Finn's pictures.
No problem. Drill a starter hole tangent to the inside of large hole. Cut a sharp bandsaw blade, run one end through the hole, weld blade back into a loop, put it back on the bandsaw wheels & start sawing. When sawing is complete, the blade remains linked with the workpiece. The next steps should be obvious.

Re. the naming of tools, I always thought the one in your pictures was called a saber saw. The name jigsaw brought to mind a reciprocating bench-top tool that holds a narrow blade by both ends, like a manual coping saw, and which I would usually call a scroll saw.
scroll.PNG
scroll.PNG (128.79 KiB) Viewed 8436 times
Today's Internet set me straight. One writer gives some history, then concludes: Today, however, the same type of handheld saws with a short reciprocating blade attached on one side only can be called either a sabre saw or jigsaw, with the choice of names really up to the manufacturer. Either name may or may not include the rotating handle on top of the tool used to make fine turns with the blade. https://www.thespruce.com/jigsaws-and-s ... ce-3536880
I wonder how many installers of wooden trim, such as baseboards, are taught how to properly cope an inside corner joint. Instead of cutting a plain dumb 45° miter on both pieces.
All models are wrong; some models are useful. -- George Box
jamespeterson
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Re: Cuttting holes with hacksaw

Post by jamespeterson »

This is a method that should be followed. I have completed the whole process following this method and it took only a little more than an hour.

I am not satisfied with WD-40 though. Can anyone please let me know a better alternative?
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Finn Hammer
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Re: Cuttting holes with hacksaw

Post by Finn Hammer »

The right thing to do is to use an oil that will emulsify with water, so that it cools and lubricates simultaneously. This solution gets the viscosity of water, and therefore does not adhere to the surface of the part to be machined, therefore it will take 2 persons, one to apply the liquid, another to operate the hacksaw.. And still you will get a mess of liquid splashed all over the place.
But you can use it without the water.
Trade names are region specific, so ask in your local tool delivery store.
Hope this helps.

Cheers, Finn Hammer
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Richard Hull
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Re: Cuttting holes with hacksaw

Post by Richard Hull »

Cutting oils are a study in the technology of machining metallurgy that is a study unto itself. Serious folks with questions in this area will go immediately to self-directed learning.
Oils also relate to cutting methods (how are you cutting) and speeds in addition to materials.

Sadly, all of Finn's early posted images were lost during the great transfer disaster of a year or two ago. When these old posts are revisited and bob to the surface and top of current posts in any forum, we wince at that which was lost. I do have a limited ability when such posts are mine and can edit the images back in, provided I have the images in one of my five old computers still in regular use. Such an effort took me two full months in the FAQs trying to reload images when the disaster struck.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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Finn Hammer
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Re: Cuttting holes with hacksaw

Post by Finn Hammer »

Richard,
When I left click on the links, the pictures emerge, so they are there, somewhere, although not properly embedded in the present source text.
But I do not have editing rights to those old posts.
Cheers, Finn Hammer
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Richard Hull
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Re: Cuttting holes with hacksaw

Post by Richard Hull »

Thanks! I forgot that left clicking on the banner sometimes works, but not always. In this case it did. I edited a single line about this "left click" into the top of your original posting.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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