[Chips O'Toole]

I'm building an arbor press stand. I got myself a Klutch fixturing table and a couple of Fireball Tool squares, and I've been using them while welding the parts together. The new tools are very helpful for locating things and holding them in place, but it looks like welding things while they're clamped does not prevent warpage. Maybe it reduces warpage, but I find that things still bend. For example, I welded two 31" legs on my stand, and where they join the top, they're 9-5/8" apart. When I was finished welding them to the top, the other ends were 1/4" closer. I had to make a piece of wood 9-5/8" long, drive it between the legs to spread them, and leave it there while I welded other parts to the legs.

The stand I'm working on is sort of a steel box. The top is a piece of plate, there are four legs coming down from it, and there will be a base made from rectangular tubing. I've been clamping one part in place at a time, welding it, and then moving on to the next part.

Would warpage be reduced if, instead of doing one part at a time, I tacked the whole thing together and then finished the welds? I'm thinking that a box which is tacked together so it's square will tend to hold itself square as the tacks are enlarged.

12 01 19 arbor press stand basic box finished small.jpg (228.98 KiB) Viewed 2930 times

[Mike Westbrook]

I think of warp as heating a spot it expands but then is frozen in place controlled warp is what your after lots of tacks in opposing directions then short fast welds and time to cool the less structural ....example plate vs box tube .....the worse because force only has two directions on plate but four on tube etc clamping can actually pre stress some welds for every weld or action there's another reaction it comes with patience and practice a boarder of tacked Angle under the plate would have directed the forces better and added metal to distribute the heat or on the top side would keep things from rolling away look up some flame straightening vids

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[Chips O'Toole]

If you do a lot of short welds and then complete them, how do you avoid ending up with really ugly welds? I don't know about you, but when I tie into a MIG weld, it never looks like a single weld.

[Mike Westbrook]

I'm a tack o holic !! Go in a little hot on the corners then start the completing weld just past the tack go back to the corner this builds some heat to blend then speed over to the start point with practice it makes even nicer welds because ....corners like to blow out if you end there due to heat build up ... so you have already added metal there..... I tacked my 10-k car trailer together before finishing it that allows you to make adjustments and improvements as you go easier than fixing a fully welded joint

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[LtBadd]

Concerning your table, I would tack it first then jump around with the welding, your putting stress into the part so the measures you take help to reduce the pulling. Still when you're done you may need to go back and re-weld, pull, push, clamp, cuss and such things to get it square.

In general as you build you'll learn what you can do to get the metal to behave. If you haven't seen this old video by Lincoln on Prevention and Control of Distortion, it's worth a watch or 2

[Chips O'Toole]

It sounds like the biggest mistake I made was welding one part at a time.

The stand is not bad. I think I can force it straight when I attach the remaining pieces. If not, there is always the grinder.

I would like to have flame-straightening as a serious option. I can use my TIG torch, but it doesn't seem to be the best tool for the job. I have a gas rig, but I still haven't found an acceptable deal on bottles.

[Mike Westbrook]

On most things tacks will hold the entire thing together plenty strong infact alot of things get over welded and don't allow flex in some usees like a trailer or snow plow

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[Chips O'Toole]

I think a lot about the fact that things are overwelded, but it bugs me to leave big gaps that look bad. For example, this stand would look pretty awful if the tubes were not sealed to the plate.

Maybe I should start using Bondo.

[Mike Westbrook]

I think everyone would totally weld that !


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[Chips O'Toole]

I had a very interesting time trying to bend the arbor press stand back into shape.

I found several problems with it. First, the front legs were warped toward each other, and so were the back. Second, the front set of legs was warped toward the rear set. Third, the front and rear sets were not parallel from side to side. They were opening like scissors.

I cut a piece of wood to the appropriate size to force the front set and rear set apart so they didn't point inward. I jammed another piece of wood between the front pair and rear pair. Then I had to clamp a couple of the legs together, because forcing them apart to the right distance at one point made them too far apart at another point.

I tacked the lower crossmember in place, joining it to one set of legs, and then I used a wood clamp to pull the other set of legs up to where it would also be centered on the crossmember. I had to move things about 3/8". Then I tacked it in, took all the clamps off, and finished the joints before the tacks could explode.

The stand appears to be less than an eighth of an inch out of flat now, so I don't think it would have come out much better had I done it CORRECTLY. I'm not positive about everything yet, but it looks good, and surprisingly, the top is flat.

There is a considerable amount of stress welded into the stand. Anyone who tries to cut it apart is going to get a surprise.

The remaining parts that have to be attached shouldn't cause any issues.

Next time I do something like this, I'll try to put as much of it together as possible before tacking it.

12 02 19 arbor press stand with lower crossmember attached small.jpg (257.2 KiB) Viewed 2807 times

[Chips O'Toole]

I ended up cutting the top off this thing, leveling the uprights very precisely, welding some supports under the top, and putting the top back on using SHORT welds. I wrote about it in another thread.

I ran beads across the bottom tubes to pull them straight, and then I ground the beads off. Three of the four tubes are now straight. The fourth one didn't quite straighten, but I can always shoot another bead onto it.

01 16 20 arbor press stand after disassembly and new welding underside small.jpg (207.71 KiB) Viewed 2596 times

[BakHeat101]

Where I retired from we had some tight tolerances (0.30 to 0.60) to hold post welding. Flatness, squareness and frame members being parallel post welding. It was fairly common these weldments wouldn't get machined so to get the weldments back into tolerance we used a torch to straighten. Heat opposite the weld to straighten into tolerance.
Here's a few tricks we used.
You can't get steel straight if you don't start with straight steel.
We'd build frames 0.30 to 0.60 wide to allow for dimensional shrinkage from welding heat.
Everything got clamped down.
Use turnbuckles or bracing to hold square.
When practical, we would back break a weldment to the weld table with clamps to get an arch in it while it was welded and do not release it until it was cool to the touch.
Use thick aluminum plate (1.00 to 2.00'' thick) clamped to the back side of the area being welded to act as a heat shield.
Straightening with a torch takes some practice to get a "feel" for it.