I'm in the process of installing a thumb and wondering if I weld just the sides or all the way around the cylinder base plate. I've seen it both ways looking on line. Tia
It depends on the shape of the base plate. We used to get them in a diamond shape where we welded all the sides and left about an inch on the ends open. The weld beads would be whale tailed just before the curve on the ends. We also used to see the plates that looked like they had four legs that were parallel to the sides of the stick. Those units got welded on the outside ends and inside ends but the inside curves were left clean. The inside of the legs were whale tailed. If you don't whale tail the weld beads at the ends in my experience they alway crack. Maybe someone here has a different experience?
With the rounded ends, I'd personally weld around them, being careful to stop or start well into the straight section and stagger the start-stop point of your multi passes. A little pre and post heat and peening the bejebus out of it with the needle gun help a lot with stress. This is a all hearsay, and you best bet is to call the manufacturer (or one of the many that sell a similar product), and see what they say.
Its a werk brau thumb if that makes a difference. The instructions on the website only really say not to weld across the stick and not much else.
That's the diamond style. Don't weld around the end. Start your whale tail just before arc at each end. Those plates have generally fallen out of favor in the industry because they tend to make the stick do what was called beer canning in the middle at the ends of the plate. I always check for cracks on the stick at the ends of the plate when ever I see one of those.
Something like this?
Check with the hoe manufacturer's welding recommendations. They should have a recommended electrode, minimum preheat temperature, and possible a maximum interpass temperature. The recommendation not to weld across the stick is always good advice. Never weld crosswise on any beam. And no, I would not weld around the corner. Leave about 2" unwelded at the end. Cat tails on the weld optional, but there are valid opinions that if Cat tails reduce cracking either the weld/weld parameters are wrong or the joint design is poor.
Thanks for the replies, I ended up preheating, staggering my weld placement and cattails. The only recommendation I didn't do was the stick welding, I burned it in with dualshield.
Nice work Hoshaft ! Installed my thumb attachment in the mid 1990's when they were just coming in to style . Went with the oval style base plate against the stick . Built the thumb out of 1" bar stock & stiff arm & boss ends were donated from an old IH TD 20 dozer blade frame . Was all continuous welding with 6011's first pass & 7018's second . No edge was left without a weld bead . Funny part was we were at a job site today & this cat walks up rapping about the cab on the excavator being on the wrong side ..... I'm like *** ! Dude .... We run American made iron
Nice job of welding and all looks good. Dual shield works great and it gets the job done fast. Throw some paint on it before you put it to work.