Fabrication: Tips and Tricks of the trade

[turbostang]

First things first - ALWAYS wear safety glasses. Even on the most simple of tasks.

It OFTEN is a topic of discussion and one that needs to be stuck, there's a lot to learn and sometimes it's easier to learn from someone who's done it before you -

• "how do you do this?"
• "How do you do that?"
• "What's best here?"
• "Why do XXX like this?"

I'll add to this thread over time, I just don't have specific pictures with me right now.

I'll show, bad welds, good welds, welds that are too cold, and welds that are too hot. Mig Welding, Tig welding, lathe work and milling.

I'll show, HOW you weld a flange to a pipe the RIGHT way, and WHY it's the right way.

I'll show WHY a GOOD fit is important on a butt weld, and what happens when it's not.

Anyone else, post up your ideas, detailed procedures and some sort of explination.

Also, we've ALL done it at one point in time - injured ourselves fabricating something. Post up SAFETY tips for anyone that could do that same thing...

PLEASE feel free to check my math, debunk links etc - but provide facts. Also, add to it, I'll post it in the original thread.

One that comes up a lot, metric conversion from MM to inches or inchess to MM.

.039375
10MM x .039375 is .39375 inches (3/8 is .375 fwiw)
.375" / .039375 = 9.52MM

(the same reason a 10MM wrench loosely slips over a 3/8 bolt, and a 3/8 wrench strips 10MM bolt heads)
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Why do I burn up drill bits so fast, or why is it not cutting right?

(assuming it's sharpened correctly)

There's a reason, a good one. SFPM, surface footage per minute - The distance the tip of the flute travels for a single revolution, calculated over a minute.

Fact: Most hand drills operate in the 0-1200 RPM range

Surface footage = RPM X D (diameter) X Pi / 12

Soft 1018 steel, which is common is best machined around 80-120SFPM.
Using a .375 drill bit: 800 X .375 x 3.1416 /12 = 78.54SFPM.

(this is below recommended 'guidelines', but sometimes is all you can do with a hand drill - There are other factors to consider, such as cooling, chip loading and material hardness. Softer materials such as aluminum will drill much easier. Also, smaller drill bits need a LOT more RPM than a standard drill can produce, so you have to be generous with chip clearing and cutting oil)

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[Darren M]

Looking forward to future posts!

[Blue88Coupe]

Looking forward to future posts!

x2!

[turbostang]

ok, here's the first tip that I have to offer. This is a VERY simple one and is OFTEN overlooked.

We've all been plagued by leaking collector gaskets at one time or other, and it usually stems from overtightening the bolts and warping the flanges...and last but not least, improper initial installation.

First, Notice the tapering of the edges of the flange: There is a punch-in side, which is the top and usually the most distorted of the two sides (caused by the punching/stamping process). The opposite, the OUT side or the side that's usually against the opposite die, is 99% of the time, the flattest and most accurate (can be told by the nice square edges). This is the side you want TOWARDS the gasket.

When welding flanges like collector flanges, header flanges or just about anything of this nature, the flat side, or the punched-out side should be towards the gasket as noted above. Sometimes, if the press is using GOOD dies, the punch in and punch out sides will not be as obvious to the untrained eyes. A quick cleanup on the belt sander, flat file etc.. will show the high and low spots associated with their respective sides. (In this picture - note the shiny ring around the collector, between the nuts - this is a dead indicator of the punch-in side. The oppsite side will be near 100% cleanup)



Next, Note the welding INSIDE the collector ring. This is to prevent warpage in the wrong direction. MAJOR improvement in sealing. Also, note welded nuts - In my application the V8 S10, you have to be a contortionist to be able to get to the nuts on the opposite side, so welding them makes life MUCH easier.



Now, you're on the home stretch - if you welded them properly, the cleanup will be minimal and in some cases not even necessary.

Stay tuned for more!!!

Additional info - Torch, plasma, and laser cut flanges will have the same features, and are equally important to have the cut-in side at the top.

[red90cobra]

tig or mig?

[turbostang]

The ones pictured are MIG welded.

[donnie90stang]

I noticed the hammer marks on the flange so I would add, that if your puttin the flanges on and having trouble... dont beat on it too much with your standard hardened steel hammer. The indentions left from the hammer could also cause sealing problems. If you dont have the proper hammer to prevent this, a block of wood between the piece and the hammer will absorb the impact of the hammer while still being effective.

[turbostang]

This one was too good to not post in this thread, I'll have one soon. (the "slidehammer" tool)




Oh, and I'll be getting one of those tables too!!

[Darren M]

That's cool. Thanks for posting this. I have a question. How did he build the "post" with out welding it to the parent metal? I'm assuming they were grossly different metals? (Only watched it once.)

[turbostang]

Darren - the post is actually built up welding rod, there's nothing actually welded to the broken pin; that's why he explains that welding on DC current doesn't melt the aluminum, it's not near as "hot" as the AC current.

[Darren M]

I figured he just built it up, like the intake you did. However I figure the aluminium would heat up and melt/weld before the hardened steel that was stuck in the hole to bgin with. I have sooooo much to learn......

[turbostang]

The trick lies in the ac/dc current...

[Acrotom]

This is a neat thread - some good ideas here.

I have a tubing notcher that uses hole saws to cut "fishmouths" in tubing so the tubes will fit correctly for welded joints. Some of these tools need to be modified so the hole saw will align with the center of the tube that is being cut.

The information below shows one way to modify these tubing notchers to improve the hole saw/tube alignment. There is also another tip to make the tool more versatile. You may have already seen this information on another thread, but it is re-posted here.

The fix for the alignment problem is to install a 1/16" thick steel plate between the tubing clamp and the tool frame to space the tubing out so it lines up with the hole saw arbor.


The tool looks like this:



The shim looks like this:



and the shim is installed here:



The 1/16" shim is placed between the clamp assembly and the frame. The clamp assembly is then installed over the top of the shim like this - (the shim is the thin white line under the clamp):



The better quality tubing notcher is the "'Ol Joint Jigger", and they cost more, but it's a better unit (picture below). It has three bolts that secure the clamp assembly to the frame, so it is more solid. It's also made of better steel.



Another tip: If you need to cut notches at an angle that is steeper than the tool allows - None of my tubing notchers would work at some more extreme angles - You can make another clamp assembly that re-positions the tube at a steeper angle. I made one, and the modified clamp is pictured next to the original clamp below.



The clamp fixture was rolled back (see arrow in photo) to allow the tube to be notched at a steeper angle than the original tool would accomodate.

The notcher works OK with the shim in place, it's fairly accurate. Your notcher may need a shim of different thickness, depending on how much it is misaligned, and how picky you are about the accuracy. Hope this helps.

Tom

[turbostang]

Excellent post Tom! I completely missed the part about the steep angles in the other thread - that's thinking outside the box!

I'll also add - Anyone who's used one of these knows exactly what Tom's talking about, but it gets a little more complicated than just modifying the angle of the clamp mechanism. The store bought hole saws are a bit to shallow to cut these steep angles - they have to be modified as well. I haven't done it yet, but when I do, I'll post pictures. Long story short, you have to take a hole saw, cut the top off of it and weld an appropriate sized piece of tubing inbetween the two pieces to give it more depth ability. Pretty simple, just needs to be fairly accurate in alignment.

[Acrotom]

Excellent post Tom! I completely missed the part about the steep angles in the other thread - that's thinking outside the box!

I'll also add - Anyone who's used one of these knows exactly what Tom's talking about, but it gets a little more complicated than just modifying the angle of the clamp mechanism. The store bought hole saws are a bit to shallow to cut these steep angles - they have to be modified as well. I haven't done it yet, but when I do, I'll post pictures. Long story short, you have to take a hole saw, cut the top off of it and weld an appropriate sized piece of tubing inbetween the two pieces to give it more depth ability. Pretty simple, just needs to be fairly accurate in alignment.

Just a thought, but if you are going to the trouble of modifying the store bought hole saw, it may be worth while to make your own hole saws with a higher tooth count?

Some tubing is pretty thin, and the hole saws have large gaps between the teeth. The cutting action chatters pretty bad - particularly when the hole saw is passing through the middle of the tube - because the tubing falls between the teeth on the hole saw. (although this is probably less of a problem with race car fabrication where tubing is typically 0.065" or thicker)

I have looked for hole saws that have teeth similar to a hack saw blade, but have not found anything.

Perhaps some enterprising (machinist type) feller could wrap a piece of tubing with a band saw blade (with about 24-32 teeth/inch), and braze it all together to make a fine tooth hole saw.

I'm too lazy for that, so I just use store bought hole saws and cut very slowly.

Tom