# Shrinkage - Need Refresher



## rustydog (Oct 19, 2012)

I want to weld a 1/4 allthread connector to the head of a 3/8 bolt.  Both have been cleaned and chamfered.

I know when I weld I get shrinkage or warpage.   What procedure should I go through to minimize the distortion?    If I stitch should I let each stitch cool b4 the next or continue the process hot.

Any tricks or thoughts will be appreciated THANKS


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## 7HC (Oct 20, 2012)

rustydog said:


> I want to weld a 1/4 allthread connector to the head of a 3/8 bolt.  Both have been cleaned and chamfered.
> 
> I know when I weld I get shrinkage or warpage.   What procedure should I go through to minimize the distortion?    If I stitch should I let each stitch cool b4 the next or continue the process hot.
> 
> Any tricks or thoughts will be appreciated THANKS



So the connector (I'm just trying to picture this) will stand on the bolt head and you'll weld the two together; and I'd guess that the OD of the connector will be pretty much the same size as the bolt head?

Ok, not knowing what welding process you're using I'll go for MIG, but the prodedure will be pretty much the same for gas or TIG.

Assuming the bolt isn't a foot long, put the bolt with the connector on top, horizontally in the bench vise, connector against one jaw and the other end of the bolt against the other jaw.  Tack the face that's on top, then rotate it 180 degrees and tack again, then 90 and tack, then another 90.  You now have the two joined with four tacks.  Place it vertically in the vise and weld the whole joint.  
You can then either grind the weld smooth or turn it in the lathe.

Now, what exactly are you making?  :thinking:


M


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## November X-ray (Oct 20, 2012)

I'm too trying to visualize the set-up, but one thing to try to do to minimize distortion from weld contraction would be to allow enough space to begin with so the contraction will not draw the material unequally. An example would be if you were taking two pieces of flat bar and lay one flat and then stand the other up. If you either lean the upright piece away from the first side to receive a tack or use a tiny wedge (a flat screwdriver works) to gain some small gap space. It may take a practice piece to determine how much the weld will contract, but once you get the hang of it, it becomes really easy!

Now if you are concerned with warping, thats mainly a result of localized heat input (joules) and depending on what material is used, how thick or thin, what process is used and the final finish bead size, there are various techniques one could use to reduce or eliminate the warping.

Good Luck!


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