Fabrication 101

[sailah]

Originally Posted by xcflyn

About that hat you owe me Just kidding, looks great!!

Maybe time to nOOb up this thread with some Sailah machining. This should be in Fabrication 001 Copied this from my build thread

Got my stuff back from the waterjet guy.

First the Dong is Done

Fits well, I knew I'd have to grind it where the welds from the tab attach to the frame. No biggie, and the bolts line up great. I'm going to punch some holes in it and hopefully find a good peg position when the new IMS pro pegs arrive. My waterjet guy looks at me when I walked in and said "WTF is that??"






He also made a plate that the fuel pump will bolt to. I had to open up the hole slightly to about 60 mm. I don't use my 4 jaw chuck often but tonight was one of those nights





Here it is bolted to the plate





And the 4" square tubing I'm basing the surge tank from



I need to find a sealant for the threads as they will be exposed to gas, didn't really think that through. Any suggestions? I bought some Loctite No 567 sealant as it was recommended for gasoline.

[xcflyn]

Originally Posted by sailah

About that hat you owe me Just kidding, looks great!!


Got my stuff back from the waterjet guy.


I need to find a sealant for the threads as they will be exposed to gas, didn't really think that through. Any suggestions? I bought some Loctite No 567 sealant as it was recommended for gasoline.

Wait a minute- skip the hat- how about you have me do little water cutting for you on the discount plan ? I still gotta make good with you some how !
couldnt that piece have blind tapped holes so you dont have to use sealer ? I just hate to count on sealer, you know how it is, less chances you give it to leak- the less chance it leaks.

[xcflyn]

Originally Posted by Laconic

A hand brake lever for something quick?

Close- jacks, snowmobile jacks (powder jack). They are actually 100% made in the USA- 90% right here in Colorado - in my shop . The company owners used to farm some of the work out but I managed to get most of it into my hands. For a few months out of the year it is pretty good work, no home run job, but it makes some money and they really do have a great product.

Here's a new one - not a vent cover either -

[boardrider247]

Originally Posted by sailah

Any suggestions? I bought some Loctite No 567 sealant as it was recommended for gasoline.

567 is my favorite thread sealant for everything (I have used almost every kind out there). If it's recommended for gas I would go with it.

[troidus]

Originally Posted by sailah

Here it is bolted to the plate



And the 4" square tubing I'm basing the surge tank from



I need to find a sealant for the threads as they will be exposed to gas, didn't really think that through. Any suggestions? I bought some Loctite No 567 sealant as it was recommended for gasoline.

Originally Posted by xcflyn

couldnt that piece have blind tapped holes so you dont have to use sealer ? I just hate to count on sealer, you know how it is, less chances you give it to leak- the less chance it leaks.

He'd need about twice the thickness. I'm thinking that you start with twice the thickness, but mill out everything on the back side except for the screw bosses, leaving raised cylinders 2.5x the screw diameter to accept the threaded holes. That way the plate doesn't protrude from the end of the tank any more than it does now, but allows for blind holes. I'd leave a smooth radius around the bosses to reduce the chance of cracking. Just don't drill and tap too deeply into the bosses to keep the ends from fracturing, and mind how much threadlocker is put in there.

[xcflyn]

Originally Posted by troidus

He'd need about twice the thickness. I'm thinking that you start with twice the thickness, but mill out everything on the back side except for the screw bosses, leaving raised cylinders 2.5x the screw diameter to accept the threaded holes. That way the plate doesn't protrude from the end of the tank any more than it does now, but allows for blind holes. I'd leave a smooth radius around the bosses to reduce the chance of cracking. Just don't drill and tap too deeply into the bosses to keep the ends from fracturing, and mind how much threadlocker is put in there.

Good idea. It almost looks like he could just go about 1/8" thicker in material. Those bolts are not sticking out the bottom by a thread even. Maybe mill the dia of the hole and use a good bottom tap? May save the machining of the inside if he can just be a little thicker in material ? Guessing the material is already .250+"

[troidus]

Originally Posted by xcflyn

Good idea. It almost looks like he could just go about 1/8" thicker in material. Those bolts are not sticking out the bottom by a thread even. Maybe mill the dia of the hole and use a good bottom tap? May save the machining of the inside if he can just be a little thicker in material ? Guessing the material is already .250+"

I don't know what the specs are for threaded fasteners in plate aluminum, but for rivets in sheet aluminum, Boeing specifies that edge margin is 2.5x the fastener diameter. That's why I picked that number. I would guess that he needs at least the diameter of the fastener of undisturbed metal between the bottom of the hole and the bottom of the screw boss.

[sailah]

Remade the part using 3/8" plate. Bored the center hole on the lathe. transfer punched the holes, drilled 5mm holes close to the bottom using drill stop on the press. Tapped using a M6 but I need a bottoming tap to get all the way down. Have one on order.

The one I made came out nicer than the waterjet part. I spent hours laying those out in CAD, took 30 seconds with a transfer punch and the holes are more accurate.

You can see the stock donut gasket so I used some longer button head M6 bolts I had. I also clocked the fuel pump so that it will fit in the corner of the square tubing.

[troidus]

Would there be any benefit in radiusing the pump bore so the donut sits down lower and has a larger contact area and you can use shorter screws? Might reduce squeezeout.

[sailah]

probably but I was trying to get the part made. I thought about grinding a radius on a turning tool then got lazy

[Laconic]

Originally Posted by sailah

probably but I was trying to get the part made. I thought about grinding a radius on a turning tool then got lazy

You shouldn't need to do a radius, just a groove for the o-ring to sit in. Pretty sure the o-ring needs "containment" to work properly.

Or does it compress into a groove in the pump? I can't see it too well.

[sailah]

Originally Posted by Laconic

You shouldn't need to do a radius, just a groove for the o-ring to sit in. Pretty sure the o-ring needs "containment" to work properly.

Or does it compress into a groove in the pump? I can't see it too well.

I believe you are correct the groove is in the fuel pump flange on the tank. I'll chuck it up and redo it.

[Laconic]

Originally Posted by sailah

I believe you are correct the groove is in the fuel pump flange on the tank. I'll chuck it up and redo it.

If you have a Machinery's Handbook, there's a good discussion of how o-rings are supposed to work.

Gland/groove depth should be 80% of o-ring cross section and 50% wider. You probably knew that, but I like reading the handbook.

[xcflyn]

Originally Posted by Laconic

If you have a Machinery's Handbook, there's a good discussion of how o-rings are supposed to work.

Gland/groove depth should be 80% of o-ring cross section and 50% wider. You probably knew that, but I like reading the handbook.

That is correct, I always thought that seemed way big until I understood that with a o-ring seal the mating parts still "mate" and the O-ring is just compressing into the groove. I know on break down repairs there were times that we would use a 60/40 rule - as long as it was 60 -40 it would work "good enough" in low pressure situations to get the machine running. In those situations we would also short cut and use the tool on the shelf that was close. We seemed to get lucky 99% of the time, but we also were in the process of making a correct part while the quick fix was being used.
BTW- next to thumbing through the McMaster Carr catalog, I too like to read the machinery's handbook. Guess some people are weird that way

[Laconic]

Originally Posted by xcflyn

BTW- next to thumbing through the McMaster Carr catalog, I too like to read the machinery's handbook. Guess some people are weird that way

+1, but it can get costly. We buy tons of stuff from them here at work.