Help With Punching Holes For Table Base

[01tundra]

I'm in the process of building a table base similar to the one pictured below for our deck.

 

I'm using 2" x 1/4" flat stock (A36) for the table legs.  The main horizontal bar running under the table slab that connects the two table end supports together will be 1-1/2" x 5/8" flat bar (A36).

 

The tie bar (that the 1/4" thick wedges are driven in to) that connects the legs and horizontal support together will be 5/8" x 1/8" flat bar folded with the joint landing in the middle of the hole drifted in the horizontal bar (if that makes any sense).

 

Any ideas on what would be a good way to drift the rectangle hole (5/8" tall x 1/2" wide) for the tie bar to slide through in the legs and horizontal support bar?

 

I was thinking the maybe slitting the bars, then stepping up to a round 1/2" punch, then using a rectangle drift to finish them out, does this sound like a reasonable approach?

 

Thanks.

 

 

[Jim Kehler]

To look like the picture you would need a punch close to the size of the hole. If you use the method you describe you will either have more material around your hole than the pic or a lot more work bringing the piece back to size. Remember this is only one blacksmith's opinion.

[ThomasPowers]

Looks like you need to slit the cross piece and drift them to size and then close them back up, slip it through the other pieces and heat the ends with a torch and re-drift them and put the tusks in and let it cool drawing it tight.

[Mainely,Bob]

In the realm of "form should follow function" this is an impractical joinery technique as by the time you make it work (I`d do it as T Powers suggested) the wedges become redundant and are only a non-functional added design feature as the wedges are not what really holds the joint fast nor are they needed as if you knock them out the table still cannot be disassembled.
If I wanted to highlight that area with a design feature I personally would do something like a larger rivet of a dissimilar metal, such as bronze, and work the oversize heads of the rivets to add a more significant design feature. But that`s just me.

[anvil]

if the definition of function were to incorporate "creating an emotion", then all elements in this joinery are needed, and do it in a bitchin' manner.

i would slit and upset the hole, then drift to final shape.

hope you will post pics.

[01tundra]

if the definition of function were to incorporate "creating an emotion", then all elements in this joinery are needed, and do it in a bitchin' manner.

i would slit and upset the hole, then drift to final shape.

hope you will post pics.

I agree.

 

Would you mind defining "upset the hole" for me so I am clear on what you are suggesting?

 

Thanks.

[JNewman]

I have to agree with Jim here.  I would not slit and drift that hole,  I would punch it close to or even to size.  You are removing more of the metal in the hole that way and you won't have to make as much allowance for the leg growing longer, nor would you have to calculate slitting length and fight to bring the sides back to size. 

 

I think you could punch all 4 holes in the time it would take to slit, drift, upset and then work the sides back in for one hole. 

 

I would also suggest arc(or forge) welding the ends of the 1/8" x 5/8" pieces together.  The weld will be hidden inside the joint.  Otherwise I think your wedges could end up pulling the ends apart.    If you feel the need to forge weld it I would either weld it as a round link then square up your corners or weld a piece in the middle between the 2 sides so you end up with an 8 with an  extended middle section.  But seeing as this is a contemporary feature I would probably just electric weld it as it is buried.  

[01tundra]

I have to agree with Jim here.  I would not slit and drift that hole,  I would punch it close to or even to size.  You are removing more of the metal in the hole that way and you won't have to make as much allowance for the leg growing longer, nor would you have to calculate slitting length and fight to bring the sides back to size. 

 

I think you could punch all 4 holes in the time it would take to slit, drift, upset and then work the sides back in for one hole. 

 

I would also suggest arc(or forge) welding the ends of the 1/8" x 5/8" pieces together.  The weld will be hidden inside the joint.  Otherwise I think your wedges could end up pulling the ends apart.    If you feel the need to forge weld it I would either weld it as a round link then square up your corners or weld a piece in the middle between the 2 sides so you end up with an 8 with an  extended middle section.  But seeing as this is a contemporary feature I would probably just electric weld it as it is buried.

 

I had thought about welding the seams on the links to keep them from pulling apart when the wedges are driven in.

 

I was orginally thinking that the link was a solid piece with a slot punched through it, but it doesn't appear to be that after I studied the picture more.  Maybe it is, not really sure.  I just thought that bending a piece of flat bar made more sense.  

[VaughnT]

For the key piece, I'd use some half-inch square stock and draw out the ears that are going to wrap around the wedges.  The ears are welded back to the center of the cross piece, hidden from view by the forged iron all around them.  This would give you the strength you need in the middle of the joint, but eliminates all the mess of punching and drifting and getting it wrong a dozen times.

[01tundra]

Vaughn - That makes sense to me as well.

 

Since this is going to be a self-taught (with the help of friends on this forum) lesson, I may end up trying both methods.

 

For punching the holes I found a strange looking rectangular punch of sorts in my tool box that is the exact correct width and length, do you guys think this would work for the task at hand?  I'm not worried about the future life of the punch, as long as it will make it through this project I can always rebuild it later.

 

 

 

 

[anvil]

I look at this as done with traditional techniques, not with power tools. just my personal choice.

so if you slit and drift you will lose material on the sides of the slit. it will stretch out to make the hole (draw out). path of least resistance etc.

if you slit then upset you keep that material where you want it. this means slit it, take a good local heat around the slit. then hit on the end of the bar to open the slit. the sides of the slit maintain their original cross section, as in the pic and are slightly upset.

then put your tapered rectangular drift in the hole and forge to the rectangle you need.

off the top of my head I would make the slit a little longer than the final length. (final length + 2[width].

a single test piece for the whole detail should let you know what length changes will happen to the parent stock.

for the locking parts. if you are going to bend the flat stock instead of slitting, I would forgeweld the ends and make the rectangle.

on the wedges, you could make some rags (burs) at the part that is hidden in the collar. then heat up the slots w/ torch on both ends and set the wedges. when they cool it will shrink and the rags will bite into the hot iron.

they won't go anywhere. no need to arc weld.

just my two cents.

By the way, just a rectangular punch is as good a way. I would add a detail and have a rectangular frogs eye on the verticals. Just my take, and the slit/upset/drift allows this. Also adds a little more strength to the joint.

[01tundra]

Thanks for all the detail anvil, I really appreciate it.

 

Do you think that slitting a piece of solid rectangular stock would be a better approach than using a piece of flat stock folded over?  I originally thought that slitting such a small piece with the length of slit required would be a pain and it would also be hard to maintain the outside dimensions of the little tie bar (keeping it from bulging).

 

 

[Jim Coke]

Greetings 01,

 

I know it sounds too simple BUTTT .. I will add my 2c worth..  I have had success punching large square holes like yours with a slightly undersize punch.. What I did was to punch 3 smaller holes first which lessen the amount of material to be punched with the larger rectangle punch.. A small but effective cheat would be drill them with a hand post drill of course.  LOL  After complete file to fit...  I hope this helps..

 

Forge on and make beautiful things

Jim
 

[JNewman]

If I were going to forge weld it here are the two ways I would consider welding it .  After welding it the round way you could flatten it to the rectangle.  I never mentioned arc welding in the wedges just doing this weld as an arc weld.  The scarfs should ideally have an upset to avoid thinning during welding although I would probably skip it if I were welding it as a rectangle as the piece in the middle could be sized to compensate. 

[01tundra]

I really appreciate the input JNewman, the pictures help alot.  I had not even thought about welding it as a circle and then flattening it out, but that would be much easier than how I had it shown.

[ThomasPowers]

How about taking a small slice of steel pipe and flattening that?  As it is used with 2 wedges you have a bit of latitude in the needed size and so may be able to find a piece of pipe that would work.

[01tundra]

How about taking a small slice of steel pipe and flattening that?  As it is used with 2 wedges you have a bit of latitude in the needed size and so may be able to find a piece of pipe that would work.

 

Brilliant!  I have some 2", 3" & 4" Sch. 40 black steel pipe in my scrap pile.  I'm going to try that tonight.

 

Thanks.

[anvil]

Do you think that slitting a piece of solid
rectangular stock would be a better approach than
using a piece of flat stock folded over? I originally
thought that slitting such a small piece with the
length of slit required would be a pain and it would
also be hard to maintain the outside dimensions of
the little tie bar (keeping it from bulging).

there is no better or worse. different techniques allow different details.

for example, a piece of pipe or a f_w/arc welded piece of flat stock would have less mass and more rounded corners naturally where a sq bar slit and drifted would give you more mass and sharper rt angle corners. Consider tubing-16 ga,flat stock-1/4 or less all around,1/2 sq ( or even 5/16,5/8) sides 1/4+ but the end could be larger and mushroomed a bit like the other piece.

[anvil]

Notice the details in your pic. The crossbar has an upset head as do both the wedges.

Notice the lock link, the left side appears upset and there is no gap between wedge and link. Not so the rt side. With either type of cross link you could hammer back the link to be snug against the wedge (and secure it from coming loose) and have mushroomed ends like the other pieces. The strap is what? 1/8" or less? this gives a lighter, but nice change in material. A half sq would create a more bold, heavier look. A nice choice of detail, for about the same time spent.

Also if you used solid stock, you could cut the ends on a diagonal so when forged back on the wedge, the edge would be plumb and the upsets equal top and bottom.

Lol, on and on. Lovin the brainstorming.

[01tundra]

Hmmm.......I think I may have found the perfect victim for my little experiment.

 

 

[ThomasPowers]

since they also make couplers that copper pipe slides into there is a large number of sizes available in fairly fine gradations---we used to use them for habaki

[01tundra]

Ended up slitting the 1-1/4" x 5/8" bar with a hot cut chisel (through the 5/8" dimension) and then drifting the hole with my rectangular punch.  I did upset the slit area slightly prior to drifting.  It worked great and was way easier than I had imagined.  Also punched and drifted the matching holes in the four legs.

 

I cut 5/8" wide sections from a copper fitting to make the tie strap.