Log-dog

J

jake pogg

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Dec 20, 2015
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After a recent brief discussion on the subject in "It followed me home",a friend asked me if i could help one of these follow him home.
Getting back home after many months absence i thought it a great project to warm up the forge.
Here's the result so far.The distance between points is 18",but,there's enough beef in that 3/4" round to stretch it out to as far as 24",or better,it'll be the new owner's decision.
https://imgur.com/a/96m630o

Materials are an old 3/4" dia bridge-timber type bolt(that felt stiffer than structural grade,but maybe it's just a few months away from my anvil),and a section of a similar dia. hex shaft for the pivoting end.
And unless my brain did something dyslexic(i've had no internet in the meantime),it's as per Square_peg's specs,rigid end being in-line,and the pivoting one perpendicular to the dog's axis.
 
Now,i hate to disappoint those that think that a blacksmith is a "strong,silent type"...:)...But its a fact(M.T.Richardson's "The Blacksmith's Journal" is a great proof)that forging is an extremely cerebral trade.Many smiths were literal,and often read and wrote about the ins and outs of their occupation.From 17th c. onward the mechanical forging was advancing very rapidly,and the information Had to be exchanged,for a guy to keep up on all that was being learned.

There's `always a solid reason for why a forging looks the way it does,understanding this "why" is critical for doing the job correctly.
So the following is not just bs for bs's sake,i just want to share the thoughts that caused me to make decisions in the way that i have.

Really,there's just a couple details that make a simple project like this mildly challenging,and both have to do with Upsetting.
Upsetting is one of forging processes where the material is pushed together,back into itself,in order to make a thicker section than the original stock.
One case that necessitates this is a square corner.
A proper square corner cannot be just bent.Bending elongates stock,making a bent corner weaker than surrounding,the parent stock.
In order to avoid it one must accumulate almost 1 1/2 of the original dimention at the corner.
So here's the preliminary bend on that 3/4 round:
https://imgur.com/a/Y9ZH1Xb

And here,after a few heats,is that corner upset into what it must be,it is in essence a 3/4" square,plus some degree of fillet on the inside,to prevent a stress-concentrating point of weakness:
https://imgur.com/a/IXpmyb1
(if you can picture the section of any industrial structural member,angle iron,or an I-beam,it'll have all these features).

Steel transfers energy the same as a wire does electrical current,and it has to do that a certain way.I actually have used lousy,bouncy/bendy log-dogs in log-building,and it was miserable,trust me.
 
jake pogg said:
After a recent brief discussion on the subject in "It followed me home",a friend asked me if i could help one of these follow him home.
Getting back home after many months absence i thought it a great project to warm up the forge.
Here's the result so far.The distance between points is 18",but,there's enough beef in that 3/4" round to stretch it out to as far as 24",or better,it'll be the new owner's decision.
https://imgur.com/a/96m630o

Materials are an old 3/4" dia bridge-timber type bolt(that felt stiffer than structural grade,but maybe it's just a few months away from my anvil),and a section of a similar dia. hex shaft for the pivoting end.
And unless my brain did something dyslexic(i've had no internet in the meantime),it's as per Square_peg's specs,rigid end being in-line,and the pivoting one perpendicular to the dog's axis.
Click to expand...

fJzmZMb.jpg


gSknUJM.jpg


That is terrific Jake! Thank you for sharing your work. It needs a name now?
 
Well done, Jake! It's tough to upset steel like that for a good square corner.

jake pogg said:
And unless my brain did something dyslexic(i've had no internet in the meantime),it's as per Square_peg's specs,rigid end being in-line,and the pivoting one perpendicular to the dog's axis
Click to expand...

I guess it depends on which end you want to set where. The key is that each end is set in line with the grain of the wood. With that dog I would set the short end in the timber first and then pivot the other end down into the support log.

I'm interested to see how you made the connection.
 
Yes, log dogs, form and use, a neglected subject matter. Thanks for bringing it up Jake, it's about time.
I agree with you that under dimensioned log dogs are no pleasure working with. Which is no reference to size, not that I have experience with log puppies but I am skeptical.
I'd say you've got the orientation of the blades reversed though.
 
Darn it,gents,apologies for a confusing topic.i've a Very funky reception here,and lost a big part of the text,and a number of photos.
I'll try to recap this briefly:

...And really the only other salient point were the openings,at the pivoting end.
Forging is capable of magic that machining could never dream of...For example,one could punch a hole in stock of a dia. equal to that of stock itself,or even more.
However,the material surrounding such an orifice may be critically weakened in the process.And the way to prevent it is once again,the upsetting.

This is the 3/4" med.-C hex shaft that was used for pivoting end.
Initial upset of stock:
https://imgur.com/a/SnRkLCp

Upset slitted:
https://imgur.com/a/bhNDbSl

The edges of the slit are upset in the vise to compensate for the upcoming drifting to size:
https://imgur.com/a/bPJeEfS

Drifting to final finished size(1/2"):
https://imgur.com/a/cWNNQZl

The corresponding part of the main shaft is treated the same,upset-slit-upset-drift.
You may notice the similarity with some other tools,like the spikes for log-chains...
(that "tab" on the top was also left for a similar reason,to be struck).

Both parts drifted to 1/2" I.D.,and a length of roundstock of that size is used as rivet.
 
Me not being so keen on the concept suggesting, as it does in my mind anyway, the log dogs remain fixed and flipping the work piece so you are always sure to be chopping opposite them. It is almost a sacred tenant to me that the position of the work piece remains undisturbed from the time the dimension of the beam is laid out on the end-grain until the first two parallel sides are finished, the set-up as a whole, that the trestles are parallel somewhat critical . In this regard I also prefer short log dogs, no more than 20 cm in length maximal.
 
All really well done, Jake! I asked about the connection because it looked so professional.

jake pogg said:
The edges of the slit are upset in the vise to compensate for the upcoming drifting to size:
https://imgur.com/a/bPJeEfS
Click to expand...

Really cool! I wondered how you had achieved that. I figured there had to have been some upsetting (which is always much harder than it looks).

jake pogg said:
Both parts drifted to 1/2" I.D.,and a length of roundstock of that size is used as rivet.
Click to expand...

That's a good beefy rivet. And if it ever comes loose a few hammer blows will make it tight again.
 
Up-setting the corner is a great feature not only providing for an improved surface for pounding in, (and out because the better way of releasing is not hammering up in between the blades but hammering down on the front of the corner), but I have noticed such corners being much less prone to deformation, (mushrooming), over time, nothing less than logical since up-setting is necessarily concentrating more mass at that place. The cheap-skate alternative route is pinching both sides at the outside of the bend to bring out a sharp corner. It will clearly not stand up to too much hammering this way.
 
Many thanks all you guys for such constructive,informative advice.
(i've not the bandwidth to watch Bob Ross,alas;i do admire the man totally,his forging competence is mindblowing...).

Square_peg said:
Really cool! I wondered how you had achieved that. I figured there had to have been some upsetting (which is always much harder than it looks).
Click to expand...

Thanks,Square_peg,and yes,i always found the upsetting the most challenging...it just somehow never got easier for me...:(...
It's often easier to make a weld,sounds ridiculous but somehow it's how it is...

However,of many upsetting operations the sides of a slit are the easier one.It's challenging to maintain the vise-jaw pressure(depends on vise condition),and frequently requires tightening the screw with one hand in the process,as the forging is cooling.

From early on people designed and built machinery to accomplish upsetting.Tire-shrinking machine was a handy shop-tool in the past.
Today much of it is done mechanically,and you see them fat-looking upsets even on cheaper tools that i know at a glance would be a b... to do by hand.

p.s.,another view of hinge area https://imgur.com/a/93TaNMf
 
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Old Axeman,thanks.So,in a solid configuration,what were the relative scantlings of a decent dog?(approx.,of course...like 3/4" dia by a couple feet long or about?)
Frankly,i never could be comfortable with any of those...
I'm not a hewer of logs,but in log construction ended up working entirely with the bottom,the "caltrop"-type dogs....
 
jake pogg said:
However,of many upsetting operations the sides of a slit are the easier one.It's challenging to maintain the vise-jaw pressure(depends on vise condition),and frequently requires tightening the screw with one hand in the process,as the forging is cooling.
Click to expand...

I'm fortunate to have a good screw and box in my vise. And at the advice of an experienced mentor I installed a throw out bearing in place of the throat washer. This allows me to reef it down really tight without having it lock up. I just took the screw down to NAPA and let them match up the size.

I bet you don't have a NAPA within 500 miles.
 
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Jake, three sizes were all I ever needed--3/4" dia. x 12"L, 20"L, or 28"L. The legs are best at 4"-5". All also work best with the edges 90 degrees to each other, as discussed, so they can always be driven in with the grain. 75% of all my broad axe hewing work was done with the 20" long dogs.
 
Old Axeman,Thank you Very much,Sir.

I've probably a set to make,and having checked my stores am a bit puzzled.For decent bar stock i only have 5/8" sq.A bit heavy...
I do have access to a bunch of 1/2" plate,and have a strong desire to translate the ratio into that...IF successful,it'd be an elegant solution...(1"-1 1/4" tall?).
However,it'd be a bear to cut off these longish pieces...But we shall see.

Square_peg,what a sweet idea...No,nearest NAPA is 271 miles by air,but i'll see what a few dozen wrecked vehicles will provide...

I did contrive to watch that Ross/Underhill video..(thanks again,Bob!).Ross makes it look easy,his trademark:)...(if anyone has a chance Ross's video on forging a 1" holdfast is fantastic;it's a great illustration of using welding instead of upsetting)...Among other assorted envious thoughts there's one that in spite of all my dedication and commitment to wood charcoal how wonderful it'd be to have a sack or two of good clean coking bituminous...SO much hotter...
 
5/8 to 3/4 (I switch over to your measures) is an ideal range of cross section, or so I'd claim. Jake you mention this caltrop version and it's the same thing I called log puppy - similar in principle at any rate - a contrivance aimed at stabilizing the under-side of the work piece. It's a natural thing considering the forces involved but only becomes necessary because of this tendency of pinching the log way to far above its center of gravity. It's another way of pointing out the consequence of using overly long log dogs. I'd be interested in knowing where this tendency originates and what the rational underlying it could be. For instance, what prompts you to determine the length you choose?
 
jake pogg said:
(if anyone has a chance Ross's video on forging a 1" holdfast is fantastic;it's a great illustration of using welding instead of upsetting)
Click to expand...
I've looked for that but no cigar.:( Do you have a link?

Meanwhile, I found this:

The Woodwright's Shop

Forging the Hold Fast
Season 37 Episode 10 | 26m 46s

Haul out the anvil and forge this essential bench tool! Blacksmith Peter Ross shows how to forge historical versions of this powerful gripper.
https://www.pbs.org/video/forging-the-hold-fast-ut7ymw/


Bob
 
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