Author Topic: Pre welding instructions  (Read 9637 times)

Tom Fisher

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Pre welding instructions
« on: August 14, 2015, 03:54:36 AM »
Here I am again. We are getting ready for a 3 month trip and I am trying to get everything up to snuff. I have an aluminum, approx. 1 inch tube, behind the panel where the exhaust sticks out, that has a broken weld on each end. (Someday I'll tell you how that happened). I know a company that welds aluminum and they will weld it for me. I found (in the manual) a 7 point list of things that need to happen before we weld. 2 of them I can not find ie, 1. Disconnect terminal plugs from the engine Electronic Control Unit located on the passenger side of the engine block. I have no idea) 2. Disconnect all plugs from the Allison Electronic Control Module located in the Electrical Bay at the driver's side front of the vehicle.( I hunted but only see the HWH box). One last question, how do you reach the wiring on the alternator to disconnect? I will keep looking, thanks for any  help.
Tom

Dave Atherton

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Re: Pre welding instructions
« Reply #1 on: August 14, 2015, 04:53:13 AM »
Tom, we have welded on several pieces of equipment and motor home frame. What was a SOP'disconnect batteries and place the ground clamp with 6 inches where you weld. Next thing fire extra prep time and
Fire fighting equipment on the spot. Look very close what will burn ( spray on foam will light and burn like gasoline). Remember it is not the weld that will light the fire but the hot welding spatter that will cause problems. Dave Atherton Retired Cat mechanic

Edward Buker

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Re: Pre welding instructions
« Reply #2 on: August 14, 2015, 07:54:00 AM »
Dave,

I am a little curious if when you disconnected the batteries, was it both the ground and plus leads? Did you then tie the two leads together, ground and + lead?

If you left the ground on the battery but removed the + lead, did you then tie the plus chassis wire to that ground with a jumper cable? To me this seems safer, to tie the +/- leads to the same voltage plane so the ground and + always sees the same voltage while welding.

Later Ed

Tom Fisher

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Re: Pre welding instructions
« Reply #3 on: August 14, 2015, 02:32:12 PM »
Thanks for reply's. I haven't done anything yet, just wanting to protect all the computers on board. I just can't find the items the manual states to unhook prior to welding.

Dave Atherton

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Re: Pre welding instructions
« Reply #4 on: August 14, 2015, 04:04:27 PM »
Tom, we remove both and tape both ends could come in contact with movement. I would like put
out a suggestion. Many times when you have a broken part, the prep before welding and location
to get correct welding angle to weld can a little tricky. Sometimes I have found if room premit to
make part, angle, plate tube etc. and go with a bolt up repair.sometimes welding alum the heat
sometimes will affect weld area ( even with good weld ) will break right next to the weld with little
movement. Dave Atherton Retired Cat Mechanic

Bill Randle

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Re: Pre welding instructions
« Reply #5 on: August 14, 2015, 08:54:08 PM »
Tom, regarding:
Quote
2. Disconnect all plugs from the Allison Electronic Control Module located in the Electrical Bay at the driver's side front of the vehicle.( I hunted but only see the HWH box).
If it's not in the electrical bay (most aren't), then it's under the console on the drivers side where the shift pad, etc., are. Slide the driver's seat back and remove the side panel (several screws) then pull the panel out of the way. The Allison box will be mounted to the outside wall in the upper right. It says Allison on the outside and is black. There's also a silver metal Allison box. That is not the one you want.

Doug Allman

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Re: Pre welding instructions
« Reply #6 on: August 25, 2015, 07:44:48 PM »
Dave Atherton, we have to repair the hitch tube on the coach as it has gone to an oval shape from towing. We want to add a  small plate to each side of the tube that would be predrilled on lathe. Weld plate to tube and then drill out tube to plate hole size.
Are you saying that we can disconnect the battery cables and keep the ground very close to the welded area will be adequate.

Dave Atherton

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Re: Pre welding instructions
« Reply #7 on: August 26, 2015, 06:29:14 AM »
Doug, this is correct keep ground as close to work as possible. I would also suggest to grind the paint
off where ground will be connected, this way ground is not traveling along painted metal seeking a good
Ground. Dave Atherton

Lee Welbanks

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Re: Pre welding instructions
« Reply #8 on: August 26, 2015, 09:34:16 PM »
Tom, we remove both and tape both ends could come in contact with movement. I would like put
out a suggestion. Many times when you have a broken part, the prep before welding and location
to get correct welding angle to weld can a little tricky. Sometimes I have found if room premit to
make part, angle, plate tube etc. and go with a bolt up repair.sometimes welding alum the heat
sometimes will affect weld area ( even with good weld ) will break right next to the weld with little
movement. Dave Atherton Retired Cat Mechanic

Tom,

If at all possible go with a bolt on repair for whatever this aluminum part is that has broken. I have fab'ed and welding on all kinds of aluminum on trailers and trucks during my years and have found that it is almost impossible to get old worn aluminum clean enough to get a good quality weld, and I can almost bet money that the part will break. They will scab a weld on it with a spool gun and it might hold until you get out the driveway. I would if possible figure out a way to make a bolt on repair.

Dave Atherton

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Re: Pre welding instructions
« Reply #9 on: August 27, 2015, 01:06:11 AM »
Lee, thank you for your thoughts on welding, out minds run on same channel. What is going to happen
and reason I suggested fab part, drill and bolt. Sure the weld may or may not seen but it is the thought
taking care of a real nice motorhome and having area of not nice looking repair welding. If that was steel
that was broken not a problem in the world to make look like factory but not with Alum
May I suggest to Tom post some pictures and let us give a better idea to make this repair right.
Dave Atherton retired Cat mechanic

Lee Welbanks

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Re: Pre welding instructions
« Reply #10 on: August 27, 2015, 03:44:23 AM »
Dave,

About the only was I would even attempt a repair like this would be to fish plate at least one side with a double plate across the broken joint and Tig weld if one could get the parts clean enough with a grinder and sanding disc.

Dave Atherton

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Re: Pre welding instructions
« Reply #11 on: August 27, 2015, 05:22:06 AM »
Lee, cannot agree with you more again. the only way that give anykind of good weld is the TIG
Welding with fish plate. forget the spool gun. Tom can get us some pictures of broken area, I
feel we can help tom  Dave Atherton Retired Cat Mechanic