Bush Hog repair

[Terry Coombs]

One of the locals brought me a part from his brush hog , it's the
pivot yoke that carries the rear wheels (I think) . The sleeve that fits
it to the pivot pin on the body of the machine is worn , and had broken
the weld on one side , sleeve was split most of the way up .

I'm machining him a sleeve from some 4140-type (acts/welds/spark
tests/hardens just like 4140 but ...) and I will be welding it to the
angle iron frame of the yoke . I can either arc weld it with 7018 or
6013 or I can TIG weld it with ER70S2 (or 308 or 309 SS) - my baby MIG
ain't got the ass for something this heavy . I know they TIG 4130/4140
tube for chassis's , but that's a lot thinner cross section . This part
will be ~1.250" ID x 4.5" long with about a .625 wall thickness , the
original had a 3/16" wall . I don't want to have this thing fail because
of a HAZ failure ... I'm thinking I might need to preheat (after tacking
in place) then control cooling to avoid localized hardening . Thoughts ,
opinions (about the job!) your experiences in the same/similar situation
welcomed . If you think I'm an idiot for taking this on , keep it to
yourself ...

--

Snag

[Jim Wilkins]

"Terry Coombs" <snag...@msn.com> wrote in message
news:oihbhq$6ik$1...@dont-email.me...

Could you weld on a larger tube of more forgiving mild steel and then
press in the 4140?

I'd pick a tube ID within the range of one of my adjustable reamers,
and turn the sleeve OD last to fit.

-jsw

[Terry Coombs]

I'm trying to use what I have on hand ...

--

Snag

[cl...@snyder.on.ca]

On Thu, 22 Jun 2017 16:11:48 -0500, Terry Coombs <snag...@msn.com>
wrote:

Stick weld it with your DC welder tack in place with a single weld,
then preheat. "Stitch" it in place, keep it hot, then finish the weld.
Back off the post-heat and let the weld normalize. Should be better
than factory, where it was likely glued together with a MIG.

[dca...@krl.org]

On Thursday, June 22, 2017 at 5:10:51 PM UTC-4, Terry Coombs wrote:
>
> This part
> will be ~1.250" ID x 4.5" long with about a .625 wall thickness , the
> original had a 3/16" wall .

> If you think I'm an idiot for taking this on , keep it to
> yourself ...
>
> --
>
> Snag

I don't thnk it will matter how you weld it. .625 is 10/16 so over three times the thickness of the original. What you might do is put in a zerk fitting to grease it.

Dan

[Terry Coombs]

The original had a zerk , the new one will too . My main concern is
that the mass of the sleeve will act as a chill . I lit up on a corner
of a big piece with the TIG torch , got hard - real hard . The origin of
this stock is from shipping bracketry for a CNC router setup (5 x 10
table , big!) that a shop I worked at got . I got all the brackets and
bar stock , bar stock was all around 2.5" diameter and 6-8 feet long . I
know the rounds are weldable because they had lugs and stop collars
welded on . I don't recall any particular difficulty cutting the stuff
off ... but I don't want to risk localized hardening and embrittlement .
It may be fine to just weld it up and walk away , but I don't *know*
that it will work OK . Maybe I need to run a bead on a slice of similar
thickness and see what it does . Now why didn't I think of that already !

--

Snag

[Leon Fisk]

On Thu, 22 Jun 2017 16:11:48 -0500

Terry Coombs <snag...@msn.com> wrote:

<snip>
>I can either arc weld it with 7018 or 6013...

6013 is an oinky rod to run. Very prone to worm holes, hard to see what
your doing with it. From what I've picked up on even the Pros aren't
fond of it...

If you can run 7018 well I would go with that. Maybe multiple passes as
needed to match weld depth with thickness of the thinnest part.

If you make tacks here & there you will be preheating the part,
provided the final welds are done soon afterwards.

--
Leon Fisk
Grand Rapids MI/Zone 5b
Remove no.spam for email

[Tom Gardner]

I might be tempted to braze it.

---
This email has been checked for viruses by AVG.
http://www.avg.com

[Ed Huntress]

On Fri, 23 Jun 2017 10:49:28 -0400, Tom Gardner <ma...@tacks.com>
wrote:

Brazing would work. Welding any 4130/40 that thick is going to need
pre-heat and, probably, post-heat.

Here's an article on welding 4130 that we published last year. It took
me a year to squeeze this article out of the experts. I was frustrated
for years by the vast amount of bull that's been published about
welding 4130, and I finally got to the right guy at Hobart:

http://magazine.fsmdirect.com/2016/sept/d/#page7

--
Ed Huntress

[Ed Huntress]

BTW, on page 10, in the black-box sidebar, where it says 0.65 in.,
read 0.065 in.

I wrote that but it was final-edited just after I retired, so I never
had a chance to catch that one.

--
Ed Huntress

[Jim Wilkins]

"Ed Huntress" <hunt...@optonline.net> wrote in message
news:rvaqkchhkvst5lssa...@4ax.com...

Thanks. That's similar to advice Finch gave in Performance Welding.

[Ed Huntress]

Yeah, but it was Finch that gave me heartburn in one regard. IIRC,
he's one of the guys who said you shouldn't braze 4130 because it
"opens up the grain." This apparently is not true. I have checked this
with numerous experts, including the author of _The Brazing Book_.

There was another point that turns up in my "Debunking chrome-moly
myths" sidebar, but I can't recall if it came from Finch. I haven't
read Finch's book for years, so it may have been someone else.

BTW, that butt-welded joint in 4130 tube that I beat the crap out of
with a hammer was one of my welding instructor's qualification pieces
for his Air Force airframe certification. It's TIG welded with 4130
filler, which is a worst-case scenario for the welder. They require it
because the Air Force used to heat-treat their complete airframes,
after welding, back when it was used in a lot of military aircraft.

--
Ed Huntress

[cl...@snyder.on.ca]

Not the only mistake Finch made.

[Terry Coombs]

Excellent ! Tells me what I needed to know to make this a lasting
repair . Preheat to ~450-500° , weld with 7018 , and slow cooling looks
like the best way to get a solid weld with small chance of stress
cracking . BTW , at some point someone corrected that .65/.065 mistake .

Thanks !

--

Snag

[Ed Huntress]

On Fri, 23 Jun 2017 16:49:40 -0500, Terry Coombs <snag...@msn.com>
wrote:

Great, Terry. Let us know how it works out.

--
Ed Huntress

[dca...@krl.org]

On Friday, June 23, 2017 at 5:46:58 PM UTC-4, Terry Coombs wrote:
> On 6/23/2017 10:18 AM, Ed Huntress wrote:
> > On Fri, 23 Jun 2017 10:59:32 -0400, Ed Huntress

If you think I'm an idiot for taking this on , keep it to
> >>>> yourself ...
> >>>>
> >>>> --
> >>>>
> >>>> Snag
> >>>

> Excellent ! Tells me what I needed to know to make this a lasting
> repair . Preheat to ~450-500° , weld with 7018 , and slow cooling looks
> like the best way to get a solid weld with small chance of stress
> cracking . BTW , at some point someone corrected that .65/.065 mistake .
>
> Thanks !
>
> --
>
> Snag

Sorry, but I just can't keep it to myself. How old is the Bush Hog? How much more do you think it will survive? What was the original material?

As I see it you are replacing the original material with one that is about twice as strong. And you are making the part three times as thick.

So my guess is that your repair will last about 6 times as long as the original part. So say the Bush Hog is 7 years old, then your repair will probably last for 42 years or until about 2059.

One Horse Shay.

http://holyjoe.org/poetry/holmes1.htm

But maybe worth doing it right so you know how to do it.

Dan

[Terry Coombs]

I don't know how old it is Dan , but the original material was a mild
steel . I do know that Mike is the go-to guy at the water department
that services us and has always been helpful when I needed help . It's
another learning experience for me ... no such thing IMO as too much
knowledge . One thing I have learned , most people/businesses will do a
repair that is "just enough to get by" , and I don't want that
reputation . Do it right or don't do it at all .

--

Sang

[dca...@krl.org]

On Friday, June 23, 2017 at 8:01:56 PM UTC-4, Terry Coombs wrote:
>
> I don't know how old it is Dan , but the original material was a mild
> steel . I do know that Mike is the go-to guy at the water department
> that services us and has always been helpful when I needed help . It's
> another learning experience for me ... no such thing IMO as too much
> knowledge . One thing I have learned , most people/businesses will do a
> repair that is "just enough to get by" , and I don't want that
> reputation . Do it right or don't do it at all .
>
> --
>

> Snag

I am sure you realised that I was just giving you a bad time. But as long as you are making things better than new, what does the pin that goes thru this look like? I would think the pin would be in bad shape. How hard would it be to build it up with bronze and turn it smooth? I do have some good sized brass bushings, but I imagine the owner would like it done quickly.

Dan

[Terry Coombs]

I planned to call him and ask about the pin , as you say it's
probably worn too . Probably try get him to bring the unit over here so
I can build it back up . If he can't , I can take the baby MIG over and
build it up , but it'll need some preheat . Got a roll of flux core just
for "field ops" .

--

Snag

[Tom Gardner]

On 6/23/2017 10:59 AM, Ed Huntress wrote:
>> I might be tempted to braze it.
>>
> Brazing would work. Welding any 4130/40 that thick is going to need
> pre-heat and, probably, post-heat.
>
> Here's an article on welding 4130 that we published last year. It took
> me a year to squeeze this article out of the experts. I was frustrated
> for years by the vast amount of bull that's been published about
> welding 4130, and I finally got to the right guy at Hobart:
>
> http://magazine.fsmdirect.com/2016/sept/d/#page7
>

I've always been a fan of brazing, probably because an old-timer taught
me and it's a go-to for me.

[Larry Jaques]

On Sat, 24 Jun 2017 09:16:36 -0400, Tom Gardner <ma...@tacks.com>
wrote:

>On 6/23/2017 10:59 AM, Ed Huntress wrote:
>>> I might be tempted to braze it.
>>>
>> Brazing would work. Welding any 4130/40 that thick is going to need
>> pre-heat and, probably, post-heat.
>>
>> Here's an article on welding 4130 that we published last year. It took
>> me a year to squeeze this article out of the experts. I was frustrated
>> for years by the vast amount of bull that's been published about
>> welding 4130, and I finally got to the right guy at Hobart:
>>
>> http://magazine.fsmdirect.com/2016/sept/d/#page7
>>
>
>I've always been a fan of brazing, probably because an old-timer taught
>me and it's a go-to for me.

You must have a lot of gas.

--
The Federal budget is a complex document. However, working
for a President committed to keeping his promises means my
job is as simple as translating his words into numbers.
Mick Mulvaney, Director OMB on Trump

[Gunner Asch]

On Thu, 22 Jun 2017 16:11:48 -0500, Terry Coombs <snag...@msn.com>
wrote:

>

Stick weld it with 6011 with 6013 as a distant second choice.

You can TIG it..but you will need about 225 amps to do it properly
with TIG

Preheat to about 500F...if you feel the need.

Does it make any difference how hard this gets when its cool? This is
not a part that is going to see a lot of sudden flexing....


---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

[Gunner Asch]

Well said! Zerk!

[Terry Coombs]

Only as relates to shock loads and it's likely to see a lot of that .
If it's brittle it's more likely to fail ... moot point because I welded
it yesterday with around 500-600° preheat , welded with 7018 then held
at the same temps for about 30 minutes after welding and cooled it
slowly . When it cooled I checked and it can be cut with a file - sleeve
and weld both . Just what I wanted .
--
Snag

[Larry Jaques]

On Sun, 25 Jun 2017 07:11:11 -0500, Terry Coombs <snag...@msn.com>

Excellent job, Terry.