Need a tool, Make a tool

My first real machining project. My aircraft mechanic is chomping at the bit now that he knows I've been setting up a beginner machine shop. Suddenly, the sky is the limit and now it's time for me to pay him back. In his defense, I do owe this guy big time. So anything I can do to help out or make his life a little easier, I'm game!

He needs a simple tool that reaches inside a particular jet engine to remove and install the fuel nozzles. Well, wouldn't you know this stupid tool costs $1100. Welcome to the airplane world.

So I find a chunk of steel for free. I hack off about 8" because I'm guaranteed to dork this up.




I need to bore this completely out between .718 and .722. I decided to drill it about half it's length and just work the end for now. His drawing was on a cocktail napkin and lacked details I need.

Outside not too critical he says, so I just give it a bit of a clean.

Drop it in the positioner and drive a cutter by each side without moving it. Having a 3 jaw on the table makes jobs like this a breeze for someone like me. You can see in this photo, I have lots of boring still to do.


.200 Close enough for my eyes. I think this gets milled smaller, but waiting on the boss.


These are wall thickness.


Nothing cosmic so far right? So why the expense? Only thing I can figure is it gets a 3/8" socket drive sunk in the other end. I have the solution for that bs. It's called a cheap socket welded on the end.

If this works for us, I have to do the sister for this tool..... Another no brainer, but slotted. This stupid tool is $1700! I swear these assholes must just throw a dart at a board with dollar figures on it. I will say Rolls Royce will be lucky if I don't crank out a shit ton of these and dump them on ILS or ebay for peanuts!

 

Nice little project. I learn every time I do a job like that and it's nice to be able to do for others. When I make a part from scratch it's one thing, but when someone gives me a part to modify my blood runs a little cold. I've muffed it up before.

Pete

 

Are you going to heat treat them? Fuel nozzle fastener threads are often seized or galled. The time at temp of the super alloys often leads to sufficient corrosion to make removal a pig. Earier use of sillver based anti seize compounds lead to different corrosion issues. It would suck to have the ear shear off an unapproved, unhardened tool, the ear fall into the engine and cause a very expensive shop visit. I certainly would want some legal distance between myself and selling such tools on ebay.

Back when I managed GE90's for an airline, we had to do a set of fuel nozzle replacements at an Asian heavy maintenance MRO. They started snapping off the mount bolts. Rather than stop and try penertrating oil, of 30 nozzles x 4 bolts, I think they snapped off something like 30 bolts. To drill out the broken off bolt shanks, GE provided a drawing for the tooling to align the drill. It was just 1" thick steel plate with 4 reasonably accurate holes. A simple dr. Bolt using available threads, and drill as required. I could make that tool in my basement. The MRO was too useless to make it, or organise it, so as the days to release to service clicked down, we ended up having to pay GE on-wing support to fly out from Heathrow, business class. The guys worked 36 hours straight, and the plane went out on time.

 

I agree with David, and at least radius the bottom corner of those tabs if the design allows, major stress point.

 

Valid points. We have an airplane coming in july for this job so I've got a little time. We still have a set of nozzles that need to get sent back so this one can be used to see if it will even work.
What kind of steel would be better? Just talked to my guy and got some new measurements. Turns out the teeth slots are .25 x .25 so I'll need to start with a thicker piece of metal anyways.
We've tried every antisneeze under the sun and found milk of magnesia works the best. Yes, the stuff you get at the grocery store. Learned that one in the HairForce. I'd rather avoid heat treating and just start with a better quality steel that's still something I can machine.

 

Gotcha. Thanks Dave

 

FWIW, a good friend of mine was an aircraft mechanic, he also had a similar aversion the insane prices for the so called "proper" specialty tool, his collection of self-made tools was pretty impressive. Unfortunately, he's no longer with us otherwise, I'm sure he'd be quite happy to add his voice to this discussion.

 

I would probably use annealed 4140, then heat treated t0 48–52 Rc.

 

There's a man after my own heart. It is ludicrous!!!

 

Fit like a glove! Now to get some proper steel and remake it. Turns out, I can go a little bigger on the id and bigger on the OD. This will allow me to make the teeth wider and should make them stronger.

 

Now to pick the metal and sort out this hardness thing. I don't see this thing wearing out anytime soon, I just cant have these teeth breaking off inside an engine case. So I guess, hard but not too hard? I'm scared to think what kind of hell I'm going to deal with drilling and boring this thing out. We don't give two shits about surface finish so is it a good idea to start with off the shelf 4130/4130, do the machining, leave it a little slack, cook it in the oven and dunk it in the oil? then normalize?

Is half hard kinda like a semi?

 

4130/4140 they are almost the same. You will want to get the metal in annealed state either way. You could just heat treat locally with a blowtorch the spanner tips about 3/4 inch up the tube (flame hardening) . Bring it to a dull red, Then dunk it in oil in a figure 8 swirls. This will give it about 20% more toughness and wear resistance, but less impact resistance.

 

Is this stuff hard as a mother? Or is it's buttery smooth? I do know my old HSS milling cutters bitched and moaned on that mystery stuff. In the lathe, the carbide tipped chinese stuff I have went through it beautifully! I first pussy footed around with it, but once I manned up and hit 1200rpm, it was a sweet ride. The chips were crazy hot however, but tool pressure seemed low to me.

 

Anyone got a suggestion for a parting tool? I've only got a HSS knife thing in a tool holder. Parting that piece I just did was not a fun experience I wish to do again. I want something carbide with replaceable tips. Trouble is, what I find is for b tool holders and not my little axa's....