Building up base, machining/tapping weld metal?

[FlyFishn]

I am looking at making some manifolds and one idea is to use thinner metal then beef up the area around the ports so I can drill and tap with more "meat" than what would be thin without building up.

From what I know trying to cut welds with bimetal reciprocating blades is the base metal is soft and the weld is super hard = dulls blades. That is going to pose a problem for drilling and tapping.

Is there a rod that would be ideal for this? Base metal is A36.

I am contemplating sourcing some 60601 aluminum instead, if I did I would just go thicker and not mess with building up around the port, but I have suitable A36 here already.

[Mac's Crew]

How are you planning to drill and tap... because yes it will cause problems unless you prep for it.

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[MinnesotaDave]

I am looking at making some manifolds and one idea is to use thinner metal then beef up the area around the ports

In my opinion, this is the wrong idea.

Use a nice thick piece and then don't worry about it

[FlyFishn]

How are you planning to drill and tap... because yes it will cause problems unless you prep for it.

Form the manifold with its holes that I can (ports and mounting). Then weld the additional metal and drill/tap the last port.

The holes will be drilled on a drill press and the tapping will be done by hand.

As far as the hole size and tap size - I have a full lettered/numbered bit set. I am not sure what size tap I am going to use - either 1/8" NPT or 1/4" NPT, most likely the 1/4" NPT will be required for the larger set. In any event, I can size up on the drill size if that will help alleviate the tap snagging in the harder material.

Bits are cobalt.

Another important tidbit is the tapped port is very low pressure, like maybe 1/2psi/14in WC.

[FlyFishn]

In my opinion, this is the wrong idea.

Use a nice thick piece and then don't worry about it

The thickness of the manifold means separating parts further. The thinner the manifold the less separation.

[psacustomcreations]

A bit of clarification on type and size of manifold might help.
Intake or exhaust manifold for an engine and if so, what size.
Water distribution manifold and what size and number or type of ports. Plus water preasure.
Air distribution manifold. What pressure, number of ports
Etc
Etc




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[Mac's Crew]

Your welds and the area around it will be hard and brittle. Use a heavy cutting oil and a tap guide like this.

https://www.amazon.com/dp/B07CSRBPXZ...G3TVMAN4WK0V74

This will help stay straight, I would also suggest not going more than 1/4 turn before backing off to allow chips to fall.

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[FlyFishn]

A bit of clarification on type and size of manifold might help.
Intake or exhaust manifold for an engine and if so, what size.
Water distribution manifold and what size and number or type of ports. Plus water preasure.
Air distribution manifold. What pressure, number of ports
Etc
Etc

Intake manifolds for between 3-4hp or so up to 22hp. They will mount under carbs. Gas injection (LP/NG). So a large intake port (throttle body diameter) and a small gas port. When the carb is pushed out so is everything attached to it, or that the carb sits between.

Not sure how that helps answer the question of building up material with weld metal and drilling/tapping.

[albrightree]

Intake manifolds for between 3-4hp or so up to 22hp. They will mount under carbs. Gas injection (LP/NG). So a large intake port (throttle body diameter) and a small gas port. When the carb is pushed out so is everything attached to it, or that the carb sits between.

Not sure how that helps answer the question of building up material with weld metal and drilling/tapping.

I think because many people here may have built something like the device you're making, we're all trying to parse out what seem like a riddle to us, although its clear as day to you. Drawing or picture would certainly help.

Adding to steel items is a method of last resort used mostly on capital investment equipment that has many man hours into it. I have done build up work on plastic injection molds the where worn or damaged the surfaces were polished to a mirror finish , making a new part from scratch would take over 60 man hours to duplicate. Another one was a HUGE Vickers proportional hydraulic control valve for a 200 ton ram on a plastic injection molding machine. Mechanic damaged it when disassembling(remember when taking something apart to check for more bolts if it doesn't come apart easily, then, have someone else look before using crowbar, and BFH) It is often cheaper to use CNC to machine away what you don't need rather than add, especially on steel parts where warpage, and hardening will occur from welding. Its awful spending the extra money on cobalt or carbide tools, only to break them in the part.

Aren't most manifolds aluminum anyway ?

[TJS]

I must be missing something here. Just get threaded NPT bungs and weld them in. Look at McMaster or other supply. Even ebay has threaded NPT bungs and they are super cheap.

[FlyFishn]

I think because many people here may have built something like the device you're making, we're all trying to parse out what seem like a riddle to us, although its clear as day to you.

I must be missing something here. Just get threaded NPT bungs and weld them in.

I am trying to make do with some things I have - material and processes. I don't have the ability to mill the parts, nor do I have a lathe. I have 3/4" A36 bar that I've had around here for years. It was a project I started years ago for a fold over ham radio tower base that never went anywhere. So I cut it apart a couple years ago and started using it for other things. One project of note was I made control cable mounts for an outboard boat motor (25hp Johnson from '93 I think).

In any event, if what I am working through doesn't make sense to you guys because you have better tooling - that's fine. I don't. I asked a question to detail a process that I may want to do because I questioned what I may be doing due to prior experience dulling saw blades in welds. Since drill bits and taps cut metal also - it would make sense that weld metal might be a challenge to machine. So the idea in the thread was to find if there was a type of electrode that will allow metal to be built up that will be "easier" to machine than others.

To the last above point - I would imagine a 60,000psi class rod would be easier to machine than would a 70,000psi class rod. So that would be the 6010, 6011, etc. as opposed to 7014, 7018, etc. However, ductility would be a rather important quality. I could see where a brittle weld (such as produced by a 7014 rod) would be problematic trying to tap - if the weld metal cracks it could easily jam and destroy the tap.

So from those who have built up material and machined it - is there a rod that will be best suited to what I am after? And by "best suited" I am using that term in the perspective of it being the process of choice here, and not your process of choice if given better tooling options that you may have access to which I do not.

[FlyFishn]

Aren't most manifolds aluminum anyway ?

Not sure if "most" are, but it is an option. That is something I am considering - a block of 6061. However, I don't have it so I would have to source it.

[FlyFishn]

Drawing or picture would certainly help.

This is a sample from a commercially made kit. The manifold is for a Honda GX690 engine, same as the large one I have. However, the shape of the manifold doesn't matter. The geometry of the mounting bolt pattern and the intake hole (large hole) are the important factors there.

The red arrow points to a threaded port on the side. That is the fuel inlet.

So to picture the set up - make the manifold block thinner and the built up welded area would be above and below the threaded hole so the part has more meat around the threaded hole.

I do not know how thick that manifold in the picture is. I believe the threaded port is 3/8" NPT, so that may give some size perspective (3/8" NPT is NOT 3/8", like a bolt - the dimension is the ID of the pipe, so threads more like 5/8" OD).

[Welder Dave]

If the small engine(s) need a new manifold, what shape is the rest of the engine(s) in? Seems like it's not a project worth pursuing.

[TJS]

Re-read my post again. I never stated you need any kind of machine tooling or equipment. These are threaded NPT bungs where you just weld them on/in with a fillet weld. You could prob even find a NPT connector at the big box stores, cut it down a little and weld that on/in the hole. Of course you need to make the hole but you knew that. You could have purchased them on McMaster yesterday, had them at your door step today and welded them on by the end of the day. We are all telling you this route because building up a weld and trying to drill and tap it will cause frustration and broken bits and taps, let alone look like monkey turds. We have been there and done this. If you are hell bent on welding up a pile and drilling and tapping so be it. We told you so.

[Kelvin]

I am looking at making some manifolds...

Lookout for Mister ShrinkWarp!

[smithdoor]

The best metal for manifolds is stainless steel. I weld use 304 stainless it will polish too.

I have made from A36 as low cost in my shop and was tractors and no one care if it had rust.

The worst part is jigging up for milling. After first time I bolt flanges in place and welded tubing in place. A ligh sanding on belt sander it was done and no milling and fast.

Dave

I am looking at making some manifolds and one idea is to use thinner metal then beef up the area around the ports so I can drill and tap with more "meat" than what would be thin without building up.

From what I know trying to cut welds with bimetal reciprocating blades is the base metal is soft and the weld is super hard = dulls blades. That is going to pose a problem for drilling and tapping.

Is there a rod that would be ideal for this? Base metal is A36.

I am contemplating sourcing some 60601 aluminum instead, if I did I would just go thicker and not mess with building up around the port, but I have suitable A36 here already.

[MinnesotaDave]

Lookout for Mister ShrinkWarp!

I didn't know Mr. Shrink's last name was shortened

Still one of the best videos out there on the subject.

[SweetMK]

In all seriousness,,
pass on making the part out of metal, use some other material that you can work using woodworking tools.
All of the guys that run tractor-pulling tractors make such manifold extensions,,
They specifically do not want metal, so as to not conduct heat.

Maybe carbon-fiber, Kevlar, some other composite?

Is heat conduction a concern to you like the tractor guys??

[FlyFishn]

Got some parts in. It looks like 1/4" NPT will still have sufficient bite in to the manifolds without the build-up. Again, the port is for real low pressure so the threads aren't holding back much force at all. The threads probably will have more force on them from the hose hanging there vibrating than what goes through it. I haven't finished shaping the manifolds yet, just the blanks.

[danielplace]

Guess you said your good now but in the future I would rethink ever planning on adding weld so it will be thicker to drill and tap as that not something that should be part of any original plan that much is for certain.

Lookout for Mister ShrinkWarp!

Make some for everyone. That one was VERY vague.

[danielplace]

Just put a 3/8 pipe to 1/8" pipe adapter just before you go in the manifold plate. Quite certain it would flow enough fuel through that short of a restriction to feed a pretty good size industrial gas engine.

The 1/8" pipe thread should go in 1/2" thick edge just barely.

Never seen fuel inlet ported through the manifold. That is kinda odd setup. How does it get to the fuel bowl from there. Takes a 90° turn and comes out face of the plate and into the carb.

[Welder Dave]

Center punching the cut line on a very crude outline? Slightly warm the piece (get the moisture out) before you use soapstone and it will stay on better. I usually run the torch over the cut line before cutting to also help the soapstone line remain. (it also makes sure you can move the torch freely for the cut) It helps in my experience. When cutting you almost never cut in the middle of the line. You cut on one side of it so the piece is the right size and not too small or too large. Have seen lots of newbies want to cut a flat bar into equal length pieces only to end up with all of them too short. You have to allow for the width of the kerf (cut width). Usually about 1/16" but depends on steel thickness. Torch cutting 101 for today.

[FlyFishn]

Thanks for the insight Dave.

I used pencil to stencil the intake dimensions/shapes. So I simply transferred the outline from the stencil outline by nicking the plate with a punch. It works fine for what I am after.

The only dimensions that are important are the mounting holes, port for the fuel inlet, and the intake hole. In that order of importance. I drilled the intake hole on this one with a 3/4" bit. That is a tad under-size for the dimensions of the original intake, but the throttle adjusts for the run speed anyway so I am confident I still have enough volume of air to get through there. Actually, the slight restriction will assist in drawing fuel from the port as that works on vacuum - the more the engine is producing power, the more draw through the intake, the more vacuum, and the more fuel is dispensed from the regulator up stream. There is a flow control valve down stream of the regulator that adjusts the fuel/air ratio also - it isn't simply the one regulator alone. The mix has to be tuned - and that mix changes with the fuel (NG vs LP).

[FlyFishn]

Never seen fuel inlet ported through the manifold. That is kinda odd setup. How does it get to the fuel bowl from there. Takes a 90° turn and comes out face of the plate and into the carb.

The fuel that the side port is for is propane or natural gas, not liquid gasoline or diesel. I am not modifying the carbs/bowls/jets at all so gasoline is sill an option. That will give me 3 fuel types I can run on.