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Author Topic: Cutting titanium gear  (Read 1158 times)

Offline Howard Olson

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Cutting titanium gear
« on: August 23, 2021, 04:33:04 PM »
Does anyone know how Glenn Lee cut the material to make .21 proto and F-40 landing gear? It looks sheared, but I work for an airline and no shear we have in our shop will touch the stuff.

Online Dan McEntee

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Re: Cutting titanium gear
« Reply #1 on: August 23, 2021, 07:32:10 PM »
     Hi Howard!!
  Are you talking about sheet stock? In this day and age, I would think water jet if it's a complex outline. I don't know if a laser would do it. If it's just straight cuts on flat sheet, you may be able to do it with a good quality abrasive cut off discs in a 4" or 7" angle grinder to gut it close to a line and finish with a grinder.  I don't know how Glenn would have done it but he was a crafty guy. If I had to make a guess it would be a cut off disc like I described or a carbide tool of some kind.
    Good luck!
    Dan McEntee
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Offline Dave Hull

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Re: Cutting titanium gear
« Reply #2 on: August 23, 2021, 10:02:58 PM »
Howard,

I would talk to Bill Hughes. I suspect he was familiar with the tooling/technique that Glenn used.

I have used a few Lee gear and seem to recall the same edge that is typical of sheared parts: the top edge is rolled and the bottom fractured, just like any die or shear operation.

While there are definitely shops out there that shear Ti, one of our racing guys had some specialty parts cut using water jet. If you have a shop around that will work with you on just a few pieces and already have your parts drawn in CAD, that might be an option.

For one-off stuff, I was surprised to find that an ordinary hacksaw works well as long as you can cut it straight. A new blade that has not been "muscled" to follow the line (and thereby affecting the tooth set on one side) is helpful. Drilling is no problem in a drill press using a fresh drill and plenty of pressure on the quill. Babying things makes working Ti a lot worse, not better. Be sure to clamp the work--do not try to hand-hold it!

You don't want to make sloppy, oversize cuts because the normal stuff in the shop isn't going to clean up the edge easily. A regular grinding wheel is not really up to it. A sanding disk is better, but....

Good luck with your project. If you already knew all this stuff, thanks for your patience.....

Dave

Offline Mike Greb

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Re: Cutting titanium gear
« Reply #3 on: August 24, 2021, 12:03:00 PM »
I cut Titanium on my mill, carbide end mill at a fairly low sfm, 1/4 two flute endmill at about 2000 rpm,  and about .001" per tooth feed, "Fogbuster" for a small amount of coolant. I would have to look on the program for the exact feed and speed numbers.

Offline Howard Olson

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Re: Cutting titanium gear
« Reply #4 on: August 25, 2021, 09:51:53 AM »
Thanks for the suggestions. I didn't think of just trying a hack saw. Cut off wheels work but you don't get much mileage out of them.  Water jet is probably a great option. Have to find a place willing to do small numbers.

Online Dan McEntee

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Re: Cutting titanium gear
« Reply #5 on: August 25, 2021, 12:29:38 PM »
   If it's all straight line cuts on sheet stock, 3/32"  or 1/8", you might just have to find some one with a 1/2" power shear. Shears have a capacity that varies for different materials. Most foot operated, (or stomp) shears will handle 16 ga. steel and aluminum, but only about half of that in stainless steal. I never had the need to cut any titanium, but just making an educated guess, a 1/2" power shear might handle titanium that thin. But finding a shop that you can just walk into and ask that has that capacity may be hard to find. Check into local vocational and trade schools to see if they can help. The Niagara shear we had where I went to welding school was 1/2" capacity so we could shear 3/8" thick practice and test plates. It takes a shear that big so it has clamping power enough to hold the stock from moving during the shear.
   Type at you later,
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Offline Howard Olson

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Re: Cutting titanium gear
« Reply #6 on: August 26, 2021, 08:51:28 AM »
There's a guy in the circle masters club who is a supervisor in an EDM shop. I didn't know that would work. Can probably get it done for the cost of a 6- pack. We cut titanium up to
.030 on a stomp shear in our sheet metal shop but it will barely leave a mark on heavier weight stock.

Online Howard Rush

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Re: Cutting titanium gear
« Reply #7 on: August 26, 2021, 09:31:30 PM »
The stress man made me scrap some titanium pushrod ends because I'd cut them with a Dremel Dangerous Disk.  He said that heat casts a spell on titanium and makes it evil. 
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Offline Howard Olson

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Re: Cutting titanium gear
« Reply #8 on: August 27, 2021, 11:37:47 AM »
I asked a Mitsubishi Aviation structural engineer and he said that's true but for this application if you take it slow it will be ok. He offered to make them for me but I want the option to get more and/ or different types.

Offline Bill Hughes

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Re: Cutting titanium gear
« Reply #9 on: August 27, 2021, 12:39:30 PM »
Glenn lee sheared the Ti for his Landing Gears.
Bill

Offline Howard Olson

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Re: Cutting titanium gear
« Reply #10 on: August 27, 2021, 04:05:52 PM »
Thanks Bill thats what I thought. Must have been a killer shear he was using

Offline Dave Hull

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Re: Cutting titanium gear
« Reply #11 on: August 29, 2021, 06:55:44 PM »
Them dang metallurgists and their 882 alpha-beta transition....

Here's one Ti source that would agree with Howard's source:  "...cutting with regular aluminum oxide cut-off wheels is highly ineffective, as it often leads to heat damage." ---Struers Inc.

However, they go on to say:  "The solution to this problem is to use silicon carbide cut-off wheels, which have been developed specifically for sectioning of titanium."  Note that this article was about preparing inspection samples and sectioning, but our model parts are pretty much in the same size range as their metallurgical samples, and the guidance should apply.

More here:  https://www.struers.com/en/Knowledge/Materials/Titanium#cuttingmounting

The Divot

Offline Paul Smith

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Re: Cutting titanium gear
« Reply #12 on: December 23, 2021, 11:01:41 AM »
The stress man made me scrap some titanium pushrod ends because I'd cut them with a Dremel Dangerous Disk.  He said that heat casts a spell on titanium and makes it evil.

I thought that the primary virtue of titanium was its ability to withstand jet engine heat.
Paul Smith

Online pmackenzie

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Re: Cutting titanium gear
« Reply #13 on: December 23, 2021, 12:32:50 PM »
I thought that the primary virtue of titanium was its ability to withstand jet engine heat.

Better strength to weight than steel or aluminum.
Not sure it is used in the hot section of turbines, there are better materials such as Inconel for that.
Mainly used in the compressor section due to its high strength to weight.
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Offline Robert Whitley

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Re: Cutting titanium gear
« Reply #14 on: December 23, 2021, 10:06:21 PM »
For a local shop that would likely do small quantity water jet cutting try custom motorcycle or hot rod shops.
Many of them now have water jets in house for custom parts fabrication.

Offline Lyle Spiegel

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Re: Cutting titanium gear
« Reply #15 on: January 05, 2022, 03:53:10 PM »
I'm surprised no one has mentioned what specific grade of titanium is being discussed.
The most well known work horse alloy  in aerospace is Ti-6Aluminum- 4 Vanadium, however this grade can be difficult to cut accurately with mechanical tools. Even if you use water jet, laser cutting or wire EDM the ductility needed for cold bending is poor.
Best choice is known as Commercially Pure Titanium,Grade 1 is the softest titanium and has the highest ductility. It has good cold forming. I spent my entire career as metallurgist in aerospace so this is my free advice
Lyle Spiegel AMA 19775

Online pmackenzie

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Re: Cutting titanium gear
« Reply #16 on: January 05, 2022, 04:52:19 PM »
I have made some parts from type 1 Titanium it is very easy to work with.
In my case it was parts for a wave soldering machine, because solder does not stick at all to it.
But not sure it would be a good choice for landing gear, it is pretty soft stuff.

(The solder does not stick to it, but it does sort of "nibble away" at it over time. kind of interesting to see)
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Online Dan McEntee

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Re: Cutting titanium gear
« Reply #17 on: January 05, 2022, 08:44:23 PM »
I'm surprised no one has mentioned what specific grade of titanium is being discussed.
The most well known work horse alloy  in aerospace is Ti-6Aluminum- 4 Vanadium, however this grade can be difficult to cut accurately with mechanical tools. Even if you use water jet, laser cutting or wire EDM the ductility needed for cold bending is poor.
Best choice is known as Commercially Pure Titanium,Grade 1 is the softest titanium and has the highest ductility. It has good cold forming. I spent my entire career as metallurgist in aerospace so this is my free advice

     He is talking about landing gear for speed models, probably a bolt on mono-wheel type, so stiffness is desirable here. depending on how he attaches it, he probably doesn't even need to bend it, but that is just a guess.
   Type at you later,
    Dan McEntee
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Offline Lyle Spiegel

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Re: Cutting titanium gear
« Reply #18 on: January 25, 2022, 08:54:53 PM »
Having spent aa good part of my career as materials engineer for both Pratt & Whitney and GE Aviation, I know of no jet engine where you could find a titanium part past the  compressor . Depending on the pressure ratio the compressor air can be "hot" but not any where  near the temperatures in the "hot section" down stream from the combustor or turbine section. I'm only referring to classic alloy, not specialty materials known as Titanium Aluminide.
Lyle Spiegel AMA 19775


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