On 4/29/2020 12:22 PM, Clare Snyder wrote:
On Wed, 29 Apr 2020 08:14:13 -0700, Bob La Londe
wrote:

On 4/29/2020 6:54 AM, Terry Coombs wrote:
Â* I'm repairing an aluminum part of a tiller for a neighbor , and
boy-o-boy is that a mess . This part is the main casting that carries
the tines and worm gear , and it's lots of fun to weld . I've been
welding a little then grinding all the crud out of the weld then welding
again . Takes about 2 grindings and the 3rd time I weld it I finally get
a fairly clean weld puddle . The biggest problem I'm having is keeping
the carbide burr(s) I'm using from loading up with soft fresh weld
material . I don't want to use any kind of lube on it to avoid causing
even more problems with contamination so it makes for slow work grinding
out the nasties . This project is not a cash job , he's going to do some
backhoe work for me in exchange . Good thing he doesn't need it right
now because it's slow going . Mostly because I'm getting interrupted by
the bees - they keep swarming and I'm barely keeping up with getting
equipment built to house the new colonies . Things are really poppin'
down here in The Holler !


How about a coated burr? Maybe ZrN or diamond. Do they even make
coated burrs?

Maybe add an air blast to keep chips out of the cut area. It helps with
machine cutting. Why not with manual cutting.



The real problem with things like gearcases is they are virtually
saturated with oil. Surface degreasing helps - I know guys who have an
old dishwasher dedicated to cleaning parts before welding - and
"cooking" helps too. AKA Thermal Degreasing.Boil it in a vat of water
with automatic dishwasher detergent (or even Dawn). Baking a part at
300F for a couple hours is pretty effective at driving out the oily
remnants of contaminants. (an old oven for shop use is pretty handy
too - works for tempering steel too)

The disadvantage is you need to totally dissassemble whatever it is
you are repairing - but to do it "right" that should be standard
procedure anyway - - -

The casting halves are bolted together for alignmentÂ* . The guts are on
my bench . I don't think this is a case of oil contamination as much as
just a lot of dirt ground into the metal . I've been using a 3/32"
lanthanated and a #8 gas lens cup , I'm going to try a 1/8" thoriated
with a #6 cup when I get back on it . I'm getting too much spread on the
arc , running at 120Hz with 35% cleaning . The area where this broke is
heavily webbed and all little tight spaces to weld in . And I ain't the
greatest TIG weldor in the world .

--
Snag
Yes , I'm old
and crochety - and armed .
Get outta my woods !