Repairing Farmall H case - chunk missing

[tech3627]

We are restoring a 1943 Farmall H and have this chunk missing in the case. According to the service manual, this case is "gray-iron casting." Searching online some people braze, some people weld. I have not welded or brazed cast iron before. I have an oxy-acetylene cutting torch, and several welders available including SMAW, GMAW, FCAW, and GTAW. I'm thinking it is best to braze this based on what I have read so far, but would like people's advice. Most people say to preheat, but some say that it is not necessary. The case is completely bare right now but obviously is too big to fit in an oven. There should not be pressure on this part of the case, and it is not structural. The bolt was actually still tight and unthreaded from the hole. I assume water got in the bolt hole and it froze and broke the piece off. I do not have the piece that broke off, the entire area would need to be built back up to get it to look correct. This is a high school restoration project to be used at competitions. It needs to be a good repair. What do you recommend?

 

[Chester5731]

Two part epoxy. Drill and tap.

 

[Janicholson]

Clean the break with a new wire brush (small stainless is best)Grease up a platform bolt and screw it in the hole. clean excess grease off of the bolt, but leave it
coated. Put gorilla tape around the break making a near perfect contour, Use JB weld to fill into the void. use a skewer to work the material into the void. warm the
repair with a heat lamp at 2 ft or co (not hot). after the material has hardened to the point that it is solid, but not completely hard (test the left over material) turn
the bolt out and in 1/2 turn to assure it will come out. when cured plus one day, pull the tape and sand to match the surrounding material. Jim

 

[RusselAZ]

Absolutory. There are some miracle epoxy's available now. Do not put enough heat on that casting to weld it.

 

[Fawteen]

Just to be clear, the reason for NOT welding/brazing the repair is that you can't possibly control the heat on a casting that big (it can be done, but not by Joe Homeowner) and unless it's heated and cooled EVENLY AND SLOWLY, it WILL crack and then you've created more problems than you've solved.

 

[caterpillar guy]

Since it does not hold anything of importance I would do like Jim said with the JB weld or even could try the epoxy on it. IF it has to be welded or brazed then get a good bit of charcoal and set a flame then while it is getting going set the case on the coal this will heat it as the fire comes up to temperature without cracking the case. Set some old sheet steel like roofing around it pretty close to hold the heat in with a piece over the top. Let set for a few hoursa or till case is hot. then either weld or braze up to look like the other side. Once done welding or brazing let fire go out and cover with some kind of an insulation to let cool slowly like over a days time or a bit longer. then it would be fine when cool to hold your hand on. That is how smaller castings are welded or brazed. Some times in cold locations or big castings they use one of those weed burner type torches to help with heating and keeping it warm while welding and during cooling so they don't cool to fast.

 

[redtom]

Just my opinion, but it looks like you
have that rear housing emptied out of
gears, etc. Therefore, I would just get a
different rear housing. It would be right
once and for all. There are a lot of H
carcasses around and Rear ends are usually
the last part sold in a salvage yard and
in my experience usually end up scrapped.
A good search may even yield one donated
to the youths.

 

[EFV]

Redtom has the best answer but you're also teaching machinery
repair to students. Have them research replacing casting and
epoxy fix and see what they choose. Neither answer is wrong,
just different. Going to be lots of choices your students will
make in life like this might as well see how their minds work .

 

[BarnyardEngineering]

What you're going to find in researching "epoxy repair" is a lot of grumpy old pharts crabbing about how it's not a good "proper" repair.

For an epoxy repair you need to get everything clean. I'd thread a bolt into the remains of the hole then slather on the JB Weld. Once the JB weld has had time to cure, the bolt should pop loose of the JB weld. Doesn't say much for the bond to the casting, but it doesn't have to be strong, just pretty, right?

If you're not going to fix it with an epoxy, I would TIG braze it with silicon bronze rod. You have fine heat control and a "cleaning" action with the TIG.

Should you choose the replacement route, I would give a TIG repair a try. It will be a good learning experience for you and your students.

 

[cwtech]

If you elect to go with an epoxy fix, I suggest drilling small holes or grinding slots into the broken edges of the casting.

These will allow the epoxy to key into the casting and provide resistance for the epoxy to break away from the casting.

I believe a metal-filled epoxy should be used.

 

[Ellis Kinney]

I like the epoxy solutions others have suggested. It is a large hollow casting and putting enough heat in one place to weld it will (maybe) cause it to crack
someplace else. Bates Corp in Indiana will have another casting. Ellis

 

[DoubleO7]

(quoted from post at 11:23:34 11/20/23) If you elect to go with an epoxy fix, I suggest drilling small holes or grinding slots into the broken edges of the casting.

These will allow the epoxy to key into the casting and provide resistance for the epoxy to break away from the casting.

I believe a metal-filled epoxy should be used.

This is a good idea to add to the idea of using JB or similar epoxy.

Might use a section cut out of a gallon milk jug. Then clamp it to casting to get the right shape around the corner.

One wrap of teflon tape on the bolt might also allow threads to form yet not prevent removal of bolt.

 

[stevieb49829]

I agree with the epoxy/JB weld, since the repair is not structural. I didn't see it mentioned in the replies, but I'd use some PVA mold release on the bolt. It's commonly used in fiberglass molding. You won't need much so you might ask around anywhere they are using fiberglass and ''borrow'' some. Use a small artist paint brush and paint several coats on just the bolt, once it's in place. The problem with putting it on the bolt first is that this stuff rapidly turns to a plastic film, and would peal off as you put the bolt in place. If it drips or runs onto the metal, wait a few minutes and peal it off with a tweezers where you don't want it to be.

Another way would be to use a nylon bolt when you do the repair. The 3/8 size is commonly used to hold a toilet to the floor flange. If your bolt is bigger than that, you might be SOL. steve

 

[Tgrasher]

Use the JB Weld in 1/4 inch layers, laying
in pieces of aluminum screen wire small
enough to fit across the area, just like
when doing fiberglass. Use a little fine
sand on last coat to give texture.

 

[Charles in Aus.]

I have one suggestion .
Aside from repairing the broken piece I would be tempted to deepen the existing hole and to use a slightly longer bolt . If there is enough metal below the bottom another quarter inch will go a long way to allowing the bolt to perform its original task and may stop any epoxy repair from being damaged by future mechanical work .

 

[Duner Wi]

I would set a jet heater next to casting for at least an hour and then braze the broken piece back to location.
Slightly more educational even if it does not work for you.

 

[stevieb49829]

Or put a stud in, and epoxy over the whole thing. Pretty easy to screw a nut on the stud and finish it off with a file and a little epoxy on the top to look just like a bolt.

 

[John Garner]

I'll encourage you to take some time to
read through the Technical Support section
of Lock-N-Stitch's website:
www.locknstitch.com

The foremost (in my opinion) industrial
specialists in cast iron repair are Lock-
N-Stitch here in California, and Reynolds-
French in Oklahoma. Both have websites
showing some of the broken castings they
have successfully repaired.

Having said that, I think your job is well
suited to an epixy repair. I've done
similar repairs with Devcon Plastic Steel,
Marine Tex, and PC-7 filled-epoxy putties,
and consider those products to be well
suited to such tasks.

 

[dhermesc]

The broken piece is gone according to the OP. He did say the there is enough of the hole left that the bolt still held.

 

[dhermesc]

Since the remaining threads are enough to give the bolt grip I would go the epoxy route. I would also spend some time looking up the best epoxy to use and not automatically go the JB Weld route. If
they can glue metal to the remaining portion of a bone (crowns in your mouth) I would think there would be some highend epoxy that would fill that corner out nicely and be a permanent repair - especially
if it doesn't have to be a key in holding the bolt in. A small tube for $50 - $90 might seem excessive but it would still be many times cheaper than some of the other routes proposed here.


I would then also make sure the head of the bolt is sealed so you don't get water down that hole again.