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Ultralight Saws
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John Hillyer
(TrNameLucky) - MLife
Punch not drill? on 11/26/2013 20:45:24 MST Print View

It's been a long time since I worked in a shop, but my first instinct would be to use a hydraulic punch. Drilling would be an expensive slow pia operation which would not be commercially viable.

Delmar O'Donnell
(Bolster)

Locale: Between Jacinto & Gorgonio
DD on 11/26/2013 20:57:43 MST Print View

Roger, I know the DD says it's OK for sharpening carbide, but have you tried it? I'm imagining it would take a tremendous toll on the diamond grind wheel in the DD. Carbide is rough stuff! Not as tough as diamonds, but would likely give the binding material a run for its money.

I wouldn't do it just because I don't like purchasing diamond wheels frequently, but I guess it can be done. Your other advice on how to drill is good; I would add that the saw blade must be very firmly clamped. You don't want a bit catching the saw blade on breakthrough and whipping it around like a helicopter blade. I'm sure the OP know this already; just posting it for anyone who is going to try this in the home shop. The drill press is often cited as one of the "most dangerous" tools in the shop for that reason. I probably have more drill press injuries than any other shop injury (besides hammer-on-thumb dysfunction).

Honestly I like the spot-annealing tip the best so far, I'll have to try that sometime with my acetylene torch. Interested to see if I can keep the annealed spot reasonably small.

I wonder if a spot welder could anneal.

Edited by Bolster on 11/26/2013 21:00:48 MST.

David Gardner
(GearMaker) - M

Locale: Northern California
Re: Re: drilling hardened steel on 11/27/2013 00:04:18 MST Print View

"Trying to make the back edge of the blade into a knife is doomed to failure in most cases. Only the teeth are really hardened; the rest of the blade is relatively soft. This is deliberate and good blade design. So any edge you grind will die quickly."

Roger, I already sharpened one, so we'll see I guess. I will say though, the non-teeth portion of the blades is the toughest steel I have ever dealt with and took a long time to sharpen. I once used a single cobalt bit, without resharpening, to drill 200 holes in a pair of disc brakes, which ate a HSS bit in a couple of seconds. I used the same bit on a pruning blade, with oil and pressure, and it only made it through 3 times. If that's not "hard" I can't even imagine how tough the teeth are. At any rate, when camping I usually just carry a small Victorinox and cut nothing tougher than a fish or tent cord.

John, right now I'm in R & D mode, so drilling makes sense because I can do it in my home shop. If I go into production, I will contract with a local machine shop that I have worked with before, and do the cutting by plasma, laser or water jet, depending on what they advise. At that point I probably won't even use round holes for lightening, but rather slots or triangles.

For now, I plan to try a combination of spot annealing (great tip Smoke!) and Roger's suggestion of using a masonry bit. If that doesn't fly, I'll plunk down the $30 for a solid carbide bit. Delmar, I made a small spot welder from a microwave oven transformer and will try that first. I will also try the pencil torch and nail/rod techniques for comparison.

I really appreciate all the responses and information from everyone on this thread.

Edited by GearMaker on 11/27/2013 00:06:27 MST.

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Punch not drill? on 11/27/2013 00:35:56 MST Print View

> my first instinct would be to use a hydraulic punch.
I have this vision of punches shattering...

Cheers

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: DD on 11/27/2013 00:44:58 MST Print View

Hi Delmar

> the DD says it's OK for sharpening carbide, but have you tried it?
Yes, lots.
I made my own 6-axis tool&cutter grinder. For steel (inc HSS) I use a Cubic Boron Nitride (CBN) wheel because steel can be a bit rough on the diamond wheels. Believe it or not, the carbon in the steel reacts with the diamond, eroding the diamond when hot. (I grind as cool as possible anyhow.)

But for carbide I use diamond wheels of various shapes. The resin-bonded ones are not all that expensive these days. I have to make my own tooling for the stove production you see: shaped miniature cutters. So yes, I have done a lot of diamond machining of carbide. It's the only way to go, and the finish is wonderful.

> the saw blade must be very firmly clamped
Oh my god yes! Fingers ...

> Spot annealing with a torch: messy. Not at all enthused. The affected area would be much larger than you think. But with a spot welder - for sure. Been there, done that - in various guises. It's a neat way to do micro-brazing of a joint too.

Cheers

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Re: Re: drilling hardened steel on 11/27/2013 00:49:43 MST Print View

For what it is worth, I used a sharpened carbide masonary drill to drill through molded glass. Very slow revs, gentle pressure, a pool of cold water around the tip (plasticene is your friend), and a firm backing. Made two neat holes for my neighbour in a glass thing he wanted to hang up.

Cheers

D S
(smoke) - F
Be Careful!!!!!! on 11/27/2013 07:15:16 MST Print View

>For now, I plan to try a combination of spot annealing (great tip Smoke!) and Roger's suggestion of using a masonry bit. If that doesn't fly, I'll plunk down the $30 for a solid carbide bit. Delmar, I made a small spot welder from a microwave oven transformer and will try that first. I will also try the pencil torch and nail/rod techniques for comparison.<

I would not use a solid carbide bit in a drill press, unless it was a mill/drill. They are meant to be used in milling machines. They cannot stand the chatter generated by most drill presses and will shatter. Flying chunks of sharp heavy carbide is not something to play with.

James Marco
(jamesdmarco) - MLife

Locale: Finger Lakes
Re: DD on 11/27/2013 07:41:45 MST Print View

Delmar,
A lot of what happens with the diamond grinding wheels is they just wear finer. Think of a new extra-fine diamond stone used for honing a chisel. At first it has a few scratches in it where the higher/larger diamonds are. After a few uses, the stone will actually loose these letting you put a smoother finish on the edge. I prefer my older stones to brand new ones for this very reason. They also cut slower.

My DD has done several hundred drill bits, including carbide. I have never even considered changing the wheel because it gives a smoother/sharper edge, used as it is. The jig is a pain in the back side, though. Light pressure, multiple rotations...

A small troth, cut into the carbide before sharpening with a diamond stone/Dremmel tool, can help a LOT trying to drill alloyed steel. This will supply a cut angle of about 5-10 degrees. Some, with high quantities of chromium (some stainless,) can get quite sticky and build up on a 0 degree cutter. This helps clear the edge, though you loose in longevity.

Delmar O'Donnell
(Bolster)

Locale: Between Jacinto & Gorgonio
Carbide on 11/27/2013 07:47:24 MST Print View

Well I'll be darned, Roger. You taught me something new about carbide & carbide tipped bits. Very interesting. I'll try it!

James, thanks for the DD tips.

One additional note on the difficulty of drilling: the two holy grails of a good steel are hardness, and toughness. They stand somewhat in opposition, more of one usually means less of the other, but you can get a steel that's high in both, as you'd find on a survival knife or, probably, a saw blade. A tough steel can be just as difficult to drill as a hard one. So even if you're drilling saw backs that aren't hardened, they're still probably punishingly tough.

Edited by Bolster on 11/27/2013 07:56:51 MST.

peter vacco
(fluff@inreach.com) - M

Locale: no. california
Re: Re: Punch not drill? on 11/27/2013 09:07:44 MST Print View

will a small punch shatter ?

ohh ya ! like gangbusters.n if you stop a moment and ponder how a punch works (is like a shear, but round), you will see that as a punch gets smaller, there is ever less and less of it to deal with the substantial forces involved. all the while, the smaller piunch is not getting a ot shorter, so it's rather sticking up there looking weak and wobbly. it helps if smaller piunches are shorter of course, but there is often a limit to that trick.
bottom line, is that punching does not scale down as nicely as we hope it would.
keep in mind that punching is indeed shearing, and consider how well your material is going to cut with a set of shears.
sometimes a small punch will fail , and just wad up when it hits the plate. pieces of it fly out with vigor.

carbide drill bits.
carbide is not magic. it must be held (and the work) extremely rigidly. no wobbles. no hand held drilling. not anything of that sort.
drill press at least, preferably a vert mill. clamp as well as possible.

that spot annealing trick was still the best tip.

more : the drill doctor. peter not a big fan of that pos. good for sharpening screwdrivers .. you betcha. a crude joke of a tool for real drill work though. worth having one for sure. just not be expecting much in the way of great drill bits out of it.

cheers,
v.

Ed Biermann
(longstride) - F
Re: Ultralight Saws on 11/27/2013 09:15:03 MST Print View

Just throwing this out there.

Plasma cutter?

No experience with one.

I use a Bahco. Cheap on Amazon and replacement blades are available and inexpensive as well. Light enough for me.

This thread has been insightful.

Not a fan of the DD either. Experience with that, yes. But not so positive. Home garage toy. Could by a lifetime supply amount of replacement blades instead. But I am getting long in the tooth.

I like puns.

David Gardner
(GearMaker) - M

Locale: Northern California
Re: Re: Ultralight Saws on 11/27/2013 13:25:52 MST Print View

Ed, do you know how much the Bahco weighs, and its blade length?

Ed Biermann
(longstride) - F
Re: Ultralight Saws on 11/27/2013 15:07:47 MST Print View

6.6oz, 7.25" of usable blade length.

David Gardner
(GearMaker) - M

Locale: Northern California
Pruning Saw Progress on 11/27/2013 17:18:47 MST Print View

Progress report on ultralight pruning saws.

Took a suggestion from my Dad and ground down the back of the blade to lighten it. Carved off 1.7 ounces. Then tried drilling again.

Spot annealing is a beautiful thing. It was like drilling normal steel.

Tried the nail/rod approach first. Very slow, but seemed to work. On the next few holes I tried the spot welder annealing, and it worked well until my spot welder got too hot. So I tried the pencil torch technique, with most of the blade submerged in water, including all of the teeth, and frequent quenching of the entire blade. Drilling through the blade seemed about the same for all of the annealed spots.

Got the 12" blade down to 4.1 oz.

Now, back to the bow saw. The 24" blades arrived today...uncutStock Fiskars blade.

cutBack of blade ground down.

Before and AfterBefore and After

finalThe final product with drilled holes

Derrick White
(miku) - MLife

Locale: Newfoundland & Labrador, Canada
Thanks on 11/27/2013 18:03:03 MST Print View

Your efforts are inspiring David and taking the time to share them them is appreciated.

This site is as much about cutting edge (no pun intended) industrial arts as it is light weight backpacking.

I love it!

Derrick

Delmar O'Donnell
(Bolster)

Locale: Between Jacinto & Gorgonio
Re: Pruning Saw Progress on 11/30/2013 09:58:05 MST Print View

>pencil torch technique, with most of the blade submerged in water, including all of the teeth, and frequent quenching of the entire blade. Drilling through the blade seemed about the same for all of the annealed spots. Got the 12" blade down to 4.1 oz.

Excellent reporting! Thanks much for posting your progress. Very interesting thread. Love the threads on "how to."

just Justin Whitson
(ArcturusBear)
Re: Re: Pruning Saw Progress on 11/30/2013 10:06:13 MST Print View

Nice slim down job David.

David Gardner
(GearMaker) - M

Locale: Northern California
Fun With Slots on 11/30/2013 12:48:34 MST Print View

Thanks for the props guys. Glad you're enjoying this thread. I'm having a blast.

So I took the Dremel to the saws and connected the holes to make slots. Major weight reductions. Got the Fiskar down from 5.9 to 3.0 oz, and the Corona down from 4.2 to 2.5 oz. The cut-down Corona blade sawed through my 4x4 in 24 seconds! Don't really see why the weight reduction would be a factor, except maybe the slots reduce side friction in the kerf.

The weight of the 10.5" Corona is now .6 oz less than my 5.5" folding Gerber (pictured near the beginning of this thread). With the teeth protector and sheath for the Corona they weigh the same.

The slots look really cool, but I think just making the blade slimmer would reduce the weight even more, and would certainly be a lot easier to just grind down than all the drilling, chopping and filing to make the slots. Of course if I go into production the water jet will let me cut all kinds of interesting designs for the same basic cost.

Have added the modified pruning blade saws to my web site. $35, if anyone is interested. www.GOLDGear.co

slots

Slotted blades

corona

Corona slotted and handle drilled

rubber

Corona with Plasti-Dip handle

handles

Fiskar slotted with handle cut out

Expect to finish the bow saw heel/butt/tensioner this week and will report when done.

Edited by GearMaker on 11/30/2013 12:50:40 MST.

Tad Englund
(bestbuilder) - F - MLife

Locale: Pacific Northwest
Re: Pruning Saw Progress on 11/30/2013 17:18:06 MST Print View

David, what did you use for the handle grip (black stuff)? Sorry in advanced if you listed this earlier in the thread (I just read your last post).

David Gardner
(GearMaker) - M

Locale: Northern California
Re: Re: Pruning Saw Progress on 11/30/2013 17:49:08 MST Print View

It's called Plasti-Dip. Obtained from my local hardware store. Comes in multiple colors.

http://www.plastidip.com/