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Rotax 912ULS Ignition problem

n518jh

Member
The pain goes on! My 2010 RV12, #120330 has had a continuing ignition problem; and this Forum has been 'sort of' helpful , but the problem persists. This as far as I have got to date. Either the engine starts beautiful, or not at all. When it doesn't start, I take off the top cowling and jiggle wires around the ignition modules. Sometimes it starts beautifully. Sometimes not at all.

So, what wires connect both modules either to ground or to power? That seems to be the best guess at this time. The electrical diagram doesn't work for me so far. Any suggestions? Is there some 'starting' wiring that might affect both modules? This is a two year problem, and the plane has become a hanger queen! Mark
 
I have a RV 12 120989, I had numerous electrical connection problems day one! The Rotax started with the two switches off, I was turning the engine over to check oil . I also had a prob. with ignition not getting power, it was wiring connectors inside the two white connector blocks, the white ones closest to the ignition modules. All the connectors were over crimped, ie wires cut or under crimped. It was very hard to find the badly done connectors in the white connector blocks because when pulled on the wires felt secure but were not connected to the pins!! I was able to correct the problem , all works well now! There was serious quality control problems, I hope Vans has more over sight now, I was never to get an answer, because was it Rotax or Vans? No one will tell me who is responsible for the bad quality control. Hope this Helps Benfra
 
I have a RV 12 120989, I had numerous electrical connection problems day one! The Rotax started with the two switches off, I was turning the engine over to check oil.

I hear what you are saying… but the Rotax 9-series engines will not produce spark when turning propellor slowly by hand even with ignition switches in the “on” position. Rotax uses Capacitive Discharge Ignition that is powered by coil windings on the back of the engine. Ignition is not powered by battery. Engine must be spinning ~ 500 RPM to generate enough voltage to power ignitions, thus making hand-starting the engine very difficult at best.

This is different than a magneto ignition system that often utilizes an impulse coupling to retard spark at slow cranking speed. The impulse coupling momentarily increases magneto rotation speed to generate spark when the spring-loaded coupling releases at the preset ATDC timing. This is what makes aircraft magneto ignition systems so dangerous when turning prop by hand. Magneto, even with no impulse coupling, when removed from engine will still produce spark if turned by hand.
 
When you say it doesn't start, are you saying the engine turns over via the starting motor but doesn't fire and continue to run or are you saying it doesn't turn over via the starter motor?
 
Ignition

Refrence my post , the Rotax was turning over with starter with ignition switches off!! benfra
 
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Either the engine starts beautiful, or not at all. When it doesn't start, I take off the top cowling and jiggle wires around the ignition modules. Sometimes it starts beautifully. Sometimes not at all.

So, what wires connect both modules either to ground or to power?

I'm no expert but don't know of a common power wire that affects both sides. Rotax trouble shooting even included switching the red wire from one connector to the other to see if the problem moves.

Are you 100% positive that when your engine runs it is running on both modules? How do you prove that? If it is only running on one module in the first place, maybe you do not have a common wire problem.

I'm don't know of a common ground, but it might be worthwhile to clean the grounds from the wires that with eyes that are attached to the right intake manifold.

I infer from your comments that you've looked at 74.00.00 especially chapter 3 of the heavy maintenance manual.
 
Refrence my post , the Rotax was turning over with starter with ignition switches off!! benfra

I'm assuming you have two toggle switches for the ignition p-leads and a separate pushbutton or rotary start switch?

The engine should turn over but not start if the ignition toggle switches are off and the starter is engaged.

If the engine starts with the ignition switches off, you have one or two open p-lead circuits.
 
The pain goes on! My 2010 RV12, #120330 has had a continuing ignition problem; and this Forum has been 'sort of' helpful , but the problem persists. This as far as I have got to date. Either the engine starts beautiful, or not at all. When it doesn't start, I take off the top cowling and jiggle wires around the ignition modules. Sometimes it starts beautifully. Sometimes not at all.

So, what wires connect both modules either to ground or to power? That seems to be the best guess at this time. The electrical diagram doesn't work for me so far. Any suggestions? Is there some 'starting' wiring that might affect both modules? This is a two year problem, and the plane has become a hanger queen! Mark

Do your modules have a green or yellow stripe? Earlier ones had a problem if i recall.

I see you are up in Sun City. I don't have my plans or plane handy as I keep them up north but i might be able to swing by and help you out. Also there is a mechanic for SLSA RV-12s over at Glendale who might be able to advise as well.

As I recall the white connectors to the Ignition came pre-done I assume by Rotax as Van's wouldn't have anything to do with that part of things. We had to scalp one white wire and run it through the steel connector holding the ignitions on the the mount, and many of us added an extra ground wire on the left side of the engine to the attachment point of the original VR. Proper grounding was a continually discussion on here in the "old" days as I recall.

If you have the plans for the engine mounting/wiring section (40 something), you might want go thru those step by step on the wiring.

PM me if you would like to talk further.
 
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From your previous posts you indicate you have the older “Teal Label” non soft start ignition modules. As others have advised, these have a history of failing in a way similar to what you are experiencing. Heating or cooling them may bring them back to life, (this is a diagnostic test, not a repair procedure.) Unfortunately with this failure mode there is no other simple way to definitively test them, other than swapping with known good modules.

Yeah Lockwood might be able to do something for him. Worth a call for sure. They might be able to get Rotax to cover some of it. They have had some success for me with 3 sets of carb floats.

Lockwood also did my 5 year carb rebuild last year - record turn around time and engine ran like new. Best part was I threw my old spark plugs in and they called me to discuss and ask if wanted the old plugs back...lol.

Nope just felt it was running a little lean and wanted to confirm it!
 
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Lockwood, CPS, or LEAF may be able to furnish a "used" CDI for testing. A couple of years ago LEAF sent me a used CDI. Turned out problem was carbs so I returned CDI to LEAF. I don't know if generosity is still available.

For what its worth - I'm still running original green label CDI's with non-soft-start now @ TT=633
 
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Advanced Start Module (ASM) Ignition. The “advance” in performance comes from retarding the spark to After Top Dead Center (ATDC) during start-up, and then reverting to the normal Before Top Dead Center (BTDC) settings after the engine is running. The result, of course, is easier starting. Standard on 912 series engines delivered beginning in January, 2010, this modification can easily be made to earlier 912s by replacing the two CDI black boxes with ones marked as part number 966-727, and replacing the flywheel hub. The newer engines with the improvements installed at the factory have a yellow stripe on the CDI boxes. Check to see if you already have this improvement on your 912 by checking the CDI boxes for the new part number. Further information is detailed in Rotax Service Information SI-912-020.

https://www.rotax-owner.com/pdf/SI-912-020-R4.pdf

(scroll down a bunch of pages)
 
My old 2009 Aerotrek had both modules fail in this way. The diagnostic trick from Lockwood is this: if it won't start don't touch a thing except to put an ice pack on the top module for a few minutes. In my case it immediately started. Once started it will continue to start and run all day, but likely need ice again the next day. Someone in Europe repairs them, but quickest fix is a new module or two. My understanding at the time was they don't tend to fail entirely, meaning once they start will continue to run. If you always start on both modules you could have one in this failure mode for years and never know it, as long as one of them is good for the start.
 
My old 2009 Aerotrek had both modules fail in this way. The diagnostic trick from Lockwood is this: if it won't start don't touch a thing except to put an ice pack on the top module for a few minutes. In my case it immediately started. Once started it will continue to start and run all day, but likely need ice again the next day. Someone in Europe repairs them, but quickest fix is a new module or two. My understanding at the time was they don't tend to fail entirely, meaning once they start will continue to run. If you always start on both modules you could have one in this failure mode for years and never know it, as long as one of them is good for the start.

Apply heat or cold - sounds like my Doctor.
 
CactusMan

My plane is hangered at Glendale airport. #5 middle blue hangers. 480-249-6543
To answer the questions and suggestions from the group; thank you for the comments. Clarifying; The battery is fully charged, the engine when starting spins like a top, and either fires on both modules or not at all. And the start/ no start can be within 15 minutes of working around the engines that's what so damm frustrating, and it can be either way first start, then not, no start, monkey with wires and it starts, then put the cowling on and no start.

It's hard to imagine that both modules are independently having the same problem, unless there is a common point. Any other thoughts? Mark
 
My plane is hangered at Glendale airport. #5 middle blue hangers. 480-249-6543
To answer the questions and suggestions from the group; thank you for the comments. Clarifying; The battery is fully charged, the engine when starting spins like a top, and either fires on both modules or not at all. And the start/ no start can be within 15 minutes of working around the engines that's what so damm frustrating, and it can be either way first start, then not, no start, monkey with wires and it starts, then put the cowling on and no start.

It's hard to imagine that both modules are independently having the same problem, unless there is a common point. Any other thoughts? Mark

yeah Rich is out there too i think. Hold old is the battery? I had a battery showing fully charged that was causing problems. Changed it out (actually a batteries plus chain store had one) and that solved all my problems at the time.

I would change out the battery if its original or more than 4-5 years old. Start there. Then call Lockwood and ask for advice - my guess is it is those teal/green modules that are bad.
 
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If the battery cranks the engine fast enough to start then the battery is OK. The ignition modules do not get electrical power from the battery, so that can be taken out of the equation. See post #3 above.
 
Mark,
How are you sure that the engine is firing on both modules? And do you have a conventional rotary switch with spring loaded start position or are you running toggle switches for each module p-lead?
I can't think of anything that would cause the engine to run on both modules or not at all in the manner you're describing. I'm assuming your wiring is conventional.
I've just been through my Rotax ignition system thoroughly (not on RV) and the symptoms you're describing are puzzling, as you say.
 
Mark,
How are you sure that the engine is firing on both modules? And do you have a conventional rotary switch with spring loaded start position or are you running toggle switches for each module p-lead?
I can't think of anything that would cause the engine to run on both modules or not at all in the manner you're describing. I'm assuming your wiring is conventional.
I've just been through my Rotax ignition system thoroughly (not on RV) and the symptoms you're describing are puzzling, as you say.

He's talking about an RV-12 with a Rotax 912 ULS engine. There are switches for the A and B ignition modules, and a spring loaded momentary start key switch. I've had a similar situation in mine. It's an older (2010) installation with two non soft start ignition modules installed, and an add-on soft start module on the A side. We normally start on A, then switch on B as soon as the engine is running. This reduces the possibility of a kickback during starting, which can damage the sprag clutch.

A few times we've seen where it won't start on the A side (newer battery, strong cranking, good power), but would start with both ignitions turned on. I've tried bypassing the aftermarket module; it doesn't make any difference. I'd love to replace both ignition modules with the newer version, but those modules are just a bit pricey.
 
Green Stripe Modules - -

Over the last several years I have stated this a few times, but I had both Green Stripe modules fail between 400 - 500 hours. In about 2012, Rotax had a program where they would sell you two new YELLOW Stripe ones for less than the regular price of one. I'm sure that program did not last long. The YELLOW ones have been very good. Due to Covid, have not flown much in last year. I think I have about 1,450 hours on my plane now. I also added the latest flywheel which really softens the starting process.
 
Ah, so it is possible that when he says the engine starts he is only talking about on one CDI (EIM), not both initially.
My FD had old modules until recently. He could try starting it on the B module. If it works consistently, that simplifies trouble shooting. Or he could start on both and do a mag check to see which module is working.
The intermittent part is always a challenge.
The ice trick might work since the A module is on top (if they're stacked as on my two Rotax 912ULS).
When I had my ignition problem, I got help from Brett Lawton at Leading Edge Air Foils. He has a very systematic trouble shooting approach and is quite patient. Call Leading Edge and then dial extension 154.
 
[QUOTE
It's hard to imagine that both modules are independently having the same problem, unless there is a common point. Any other thoughts? Mark[/QUOTE]

If these are the old-style green-band modules, it's not uncommon that they would both have the same problem. It's a known weakness in the modules called a "cut-in" failure. They are supposed to cut-in at about 1,000 RPM, but instead they cut-in at about 2,000 RPM. So they run just fine if you can get the engine to start. The local (Northern California) Rotax guru says the capacitors get weak over time. The ice test will tell if this is an issue or not. Reviewing my notes from Rotax school, Lockwood says ice it for 20 minutes. In my case that worked every time, and the fix was a new module. Anyone interested in module repairs search the Rotax forum for the guy in Europe. Way cheaper, but not for me. I wanted new when it comes to ignition.
 
Thanks for the various pieces of advice. BUT!!!
I installed a new ignition module from Leading Edge Air Foils. no joy!
That brings me to almost $2,000 out of pocket to find and fix my starting problem.
What I need is someone with diagnostic tools that can trace the 'juice' from the flywheel on through all the wires to the Spark Plugs. Does anyone know of such a person/tool set??? Does anyone want to buy a great RV12 with just a tiny problem??
 
Have you checked with Roger Lee in Tucson? He is a very experienced Rotax service person and frequent contributor to Rotax Owners website.

Jim Butcher
 
Roger Lee has done some Rotax work for me, but when I called on this, he suggested he wasn't expert on the ignition circuits. I've taken the class he offers, about 2 years ago, but we didn't get into the details of how to trace for a bad circuit connection. Thanks for the suggestion. Mark
 
One new ignition module or two?
Does it continue to sometime start- and when it does it works properly on both sets of plugs - and sometimes not start, as before?

What Brett had me do initially was to take an old set of spark plugs and safety wire them to ground and plug the leads into them. Of course the engine can not start. Turn the starter over and verify there is spark on all plugs. Helps to have a dark hangar. I'm assuming if your problem is the same as the OP, either they will all fire or none will fire. But if only half fire, you can isolate it to one of the two ignition systems.

Make sure all the connectors are completely connected. The molex connectors should produce an audible click when seated.
 
Have you ever tried an O-scope to look at the trigger coil pulses? Long shot, but it would be interesting to compare A and B trigger coil output.
 
Had a similar problem with the engine not starting and not producing the spark at all on either of two ignition systems.

It turned out the the ignition unit grounding ring connector that is attached to the right intake manifold has become heavily oxidised.

Cleaning the ring connector and the place where it contacts the manifold fixed the problem nicely

See the image attached
Rotax_912_Ignition_problem.jpg


.... or the link to the image http://www.rv12.com.au/wp-content/uploads/2021/04/Rotax_912_Ignition_problem.jpg
 
Though I know close to zero about the 100 hp Rotax engine, did learn a little about it when I very nearly purchased a very nice Europa mono wheel with the Rotax up front. The deal breaker for me was when the engine initially wouldn't start, then when it eventually did start, ran very rough.
Upon removing the cowl noted the owner had tie wraps securing the automotive type spark plug leads to the lower spark plugs.
It turned out that the spark plug leads require a 'pull test' of some sort and could be a potential source of ignition problems on this engine, in part because it is a push on connection, rather than the old fashioned bolted up tight connection of the old fashioned airplane engines.
If I was dealing with ignition problems with this engine, would start with plugs (check resistance and condition) then check or replace spark plug leads, check coils and finally work your way back to the very expensive ignition modules.
If the ignition modules have failed, there is a supplier of overhauled modules in Sweden that sells for considerably less than buying from a Rotax dealer.
I fly behind an old fashioned Lycoming and must say I do like the old fashioned spark plug lead connections much better than those on the Rotax. Cheers
 
More suggestions - -

The flywheel 'trigger' leads that come to the bottom of the ign modules are basically the same ( connectors ). The ign boxes are the same. If you carefully mark which is which to start with, you can disconnect, and switch to other component connectors to find out which circuit is the problem. Example - switch A circuit trigger feed to B ign box. Try to start on that system. If no ign, then switch to opposite ign box, and test again. Not giving total details, but you should get the idea. The connectors are the same. You can switch the components around to determine which item is the problem. Mark down what you did if this is confusing to you. Mark A and B circuits to start with so you can go back to original setup when you are done testing. Not sure I saw if you had green or yellow stripe ign boxes to start with ? ? ? ?
 
Won’t start

Not Starting started about a month ago. After some consults I replaced my 9 year old Odessey battery with a new one. Still turned over great but no start.
Using information in this post I pulled all the top plugs, safety wired them to the cylinder, and checked for spark. IGN. A good spark on cylinders 1&2. Now ign. B only NO spark. Okay, both ignitions on and same, yes A and No B, cylinders 3 & 4.
Switched A & B leads and now Both A & B we’re sparking, Ugh.
Switched back to proper configuration and Both A & B were sparking. Reinstall spark plugs and the engine started immediately. Recowled and now 5 days later planned a start up and flight, but again same story, turned over great but NO fire up.
So ignitions are removed and I’m checking with Lockwood as I understand they are the only service center who has test equipment for these ignitions.
I’ve seen information about other sources for ignitions on a prior post here, on Rotax Owner, and a Kitfox friend said he read about another source on their forum. My ignitions are Yellow strip, 10.2471, which I was told translates to built in 2010, and was number 2471 off the line, but there is another 10.xxxx number on the side with the part number. P/N 966727 on both.
Any suggestions for further testing or information about ignition availability from other parts providers would be appreciated. Have a safe 4th of July!
 
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Call LEAF. They may be willing to send you a used CDI for trial, perhaps on condition that if you find yours is bad, you will buy new unit from them. Don't know if they do this anymore, but worth trying...
 
I received an email from Sport Flight who offers 2 CDI boxes for $490+$15 shipping for their system. They suggest moving the boxes off the top of the engine because of the usual enemy of heat and vibration. Their boxes come with a 36inch lead to accommodate the remote mounting and a couple of other features like a separate start feature and a PC hookup to fine tune the box.

Has anyone tried these CDI boxes?
 
ROTAX CDI BOXES 4 AND 6 PIN • $245 • NOW AVAILABLE • New aftermarket CDI Boxes for Rotax 912 and 912 S engines with inbuilt soft start. $245 plus S&H. • Contact Allistair Wilson - SPORTFLIGHT INTERNATIONAL LLC , Owner - located Bloomfield, IN United States • Telephone: 812 384 4760
https://barnstormers.com/classified-1604831-Rotax-CDI-Boxes-4-and-6-pin.html

This is the link set to me out of Barnstormers. I haven’t tried a call yet but in the follow up email Allistair Wilson provided the above number and an additional cell 765-602-0136. Allistar claims high popularity with these CDI boxes in Europe, and picture he set me looks very different than what in on my Rotax now. I’m not that interested in lots of changes or modifications.
 
My guess would be that he’s selling these:

https://www.ignitech.cz/en/vyrobky/bikes/rotax/rotax 912 and 914/rotax 912 and 914.htm

On the one hand, I don’t think there is anything all that complex about the Rotax CDI box, and coming up with an equivalent or better design wouldn’t be all that difficult for someone who is, as they say, “skilled in the art”. And there are some PCB manufacturers and assemblers in that part of the world who really do excellent work.

Then there are also incompetent twits producing unreliable junk. In between you have really nice stuff with firmware written by people who really don’t know what they’re doing.

If it were a jet ski or a motorcycle or something, I’d certainly be inclined to try it out. I’m not quite as certain I want to do reliability testing in the air, though. I’m all about the E in E-LSA or E-AB, but there is a point when things get just a little too “experimental “ for me. That’s just my own take on it, worth every penny you paid for it.
 
I had to replace the B module (lower one) due to intermittant ops, it would fault 3 out of 10 times. I would notice no drop at 4000 rpm or when shutting down turning off A would kill the engine...swapped leads and problem followed B so I replaced module through Lockwood. I didn't like the cost but its cheap when you consider the alternatives...
 
Both my modules are on their way to Lockwood for the $50 testing, you get $25 credit if you buy a new module.

I’ll see how they fair under the testing cycles.
 
Any resolution for anyone on this issue?

Looks like we are having the same gremlins now.......
 
Any resolution for anyone on this issue?

Looks like we are having the same gremlins now.......
Many times what seems like an ignition problem is really a carburetor problem. Even after watching the Lockwood troubleshooting video I was absolutely convinced I had an ignition problem. Nope. Carb idle circuits were setup too rich.

However, having said that, go take a look at the ignition wire chaffing issue I had with my 912 ULS in this post. It is an area under the coils that is hard to inspect and I have since talked to more than one person who had wire chaffing in the same area. Although this didn't end up being my problem, I am surprised that it wasn't.
 
Many times what seems like an ignition problem is really a carburetor problem. Even after watching the Lockwood troubleshooting video I was absolutely convinced I had an ignition problem. Nope. Carb idle circuits were setup too rich.

However, having said that, go take a look at the ignition wire chaffing issue I had with my 912 ULS in this post. It is an area under the coils that is hard to inspect and I have since talked to more than one person who had wire chaffing in the same area. Although this didn't end up being my problem, I am surprised that it wasn't.

It's not the carbs....

I found similar chaffing to wires above the coils, and fixed. However, may need to dig a bit deeper and look under those coils as that could be where the problem is.
 
It's not the carbs....

I found similar chaffing to wires above the coils, and fixed. However, may need to dig a bit deeper and look under those coils as that could be where the problem is.
We had miss-firing on one RV12 that I helped with and after going thru all of the diagnostic checks we found one coil was not firing plugs top 1 and top 2. We had chaffing visible but needed to take out the coil pack to fix the problem. Removing the coils can be problematic. There is very little room to work and you need to be imaginative with your tools. Two gotcha's we found: Those rubber buffers that suspend the coil pack have a heavy washer molded at each end. You have to hold the washer with vice-grips in order to loosen the mount screw or if you torque the screw you will break the rubber. Those buffers are $90 each, as we found out. The buffer that attaches to the right intake manifold can be detached by removing the right carb and tray and the intake manifold. You can then unscrew the buffer by rotating the intake manifold. Plug the intake ports so nothing is dropped into them. The heavy maintenance manual has a somewhat different method that has you remove both intake manifolds, but we did it this way. You will become familiar with Section 74 in the MMH. We had phone help from the Lockwood guru and a very experienced Rotax mechanic. Once we got the coils on the bench we found serious chaffing on 6 of the eight coil wires and the power wire coil Top-1,2 was separated. Before reinstalling the coils we depinned each wire and slipped on shrink wrap and the white chaffing guard you see here.
 

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I received an email from Sport Flight who offers 2 CDI boxes for $490+$15 shipping for their system. They suggest moving the boxes off the top of the engine because of the usual enemy of heat and vibration. Their boxes come with a 36inch lead to accommodate the remote mounting and a couple of other features like a separate start feature and a PC hookup to fine tune the box.

Has anyone tried these CDI boxes?
I have these on my -12 and I'm really happy with them. Alistair is great to deal with and even sent me a photo of an installation he had in process on a -12 (around June of last year). I replaced my OEM modules when I found the wire bundle to the pin connector had numerous areas of jacketing that were bare and arcing. Further investigation also found the lead wires on the both ignition coils were starting to wear through as well. I'd inspect the harness and ignition coil wiring very carefully to rule out any issues. I'm not the first to have this issue. Mine are mounted on the firewall on either side of the brake fluid reservoir.

The quality of the harnessing and jacketing is excellent.

 
I have these on my -12 and I'm really happy with them. Alistair is great to deal with and even sent me a photo of an installation he had in process on a -12 (around June of last year). I replaced my OEM modules when I found the wire bundle to the pin connector had numerous areas of jacketing that were bare and arcing. Further investigation also found the lead wires on the both ignition coils were starting to wear through as well. I'd inspect the harness and ignition coil wiring very carefully to rule out any issues. I'm not the first to have this issue. Mine are mounted on the firewall on either side of the brake fluid reservoir.

The quality of the harnessing and jacketing is excellent.

In just receive my ignitech modules and will be installing them in the next few day. Did you choose to hook up the 2nd source for 12 volt source?
 
In just receive my ignitech modules and will be installing them in the next few day. Did you choose to hook up the 2nd source for 12 volt source?
I know I am interested in how this goes. Remotely mounted modules, away from the heat and congestion on top of the engine seems very logical. Especially if one of those thousand dollar modules fails. Keep us posted.
 
In just receive my ignitech modules and will be installing them in the next few day. Did you choose to hook up the 2nd source for 12 volt source?
I chose not to. The engine starts so rapidly I didn't feel there was a lot to be gained for the bit of additional work. [edit] You will want/need to make a bridge bar that goes across the coils as the previous modules provided this function. I just used a piece of 1/2" x 1/8" 6061 bar stock I had around.
 
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