MadCow DX3 Massive...Headache

DRAGON64

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My daughter has a t-shirt that reads: "Procrastinators Are The Leaders of Tomorrow!"

So I have owned the DX3 Massive, here-by to be referred to as DX3-M, for about 3-years now, and I work on it a little bit at a time and as such make very little progress... You see, my rocket enthusiasim went from 9 to 11-months all rocketry and 1 to 3-months focused elsewhere, to the polar opposite of 1 to 3-months all rocketry, and 9 to 11-months focused elsewhere. So when my focus is on rocketry, I try to get as much work done on the DX3-M as possible.

The DX3-M was to be my one and done. No more rockets of every color, size and or type, but a simple HUGE 3FNC rocket to focus on. To that goal, the motor of choice was also a one-n-done, and that is the Contrail 98mm motor system.

The problem (?) Well, the couplers... they just do not fit!! And that is my Massive headache. I have sanded all three couplers, and managed to finally get two to fit, but the e-bay coupler (w/ switch band) is a no go in any of the tubes. I have used the heck out of my 1/3 sheet sander (120-grit) and my dependable Mouse sander (80-grit) and its as if the airframes or the coupler are out of round!!! I would take a Sharpie marker and write the letter "C" all over the coupler, let it sink in and dry, then sand until the letters were gone... test fit and repeat.

I am writing this mainly to vent my frustrations, as there are no options for an easy resolution to this problem... sanding on the coupler for and hour and a half straight, apparently just is not long enough... but sanding ultimately is my only course of action... Had I not procratinated for so long, I might have asked MadCow for replacement couplers.

That is all, now back outside to load new sheets on my sanders and remark the coupler with the letter "C"

Why the letter "C" you ask? Well, should I lose my rocketry focus again, then the letter "C" would remind me that this was a coupler tube, and I need to get back to sanding. Fear not, I aim to get this coupler sanded to fit today!!!
 
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I bought my Apogee Level-2 rocket in 2012, it was built by Madcow for Apogee. I lose my health so 9 years go by. I started to put it together and found that the fin slots were not cut 90 degrees, and 1 of the 4 fins was 1/4" shorter than the others. I contacted Apogee who contacted Madcow and they sent me a new airframe and 4 fins. I'd contact them first.
 

Banzai88

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MadCow has changed fiberglass suppliers to Wildman from he-who-has-no-name.

If you're gonna do anything having to do with MadCow and a warranty claim on fiberglass, and it's a legacy kit, do it NOW.

MadCow has very little stock left of it's non-Wildman fiberglass, and the specs of the various pieces are different.
 

AlexBruccoleri

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My daughter has a t-shirt that reads: "Procrastinators Are The Leaders of Tomorrow!"

So I have owned the DX3 Massive, here-by to be referred to as DX3-M, for about 3-years now, and I work on it a little bit at a time and as such make very little progress... You see, my rocket enthusiasim went from 9 to 11-months all rocketry and 1 to 3-months focused elsewhere, to the polar opposite of 1 to 3-months all rocketry, and 9 to 11-months focused elsewhere. So when my focus is on rocketry, I try to get as much work done on the DX3-M as possible.

The DX3-M was to be my one and done. No more rockets of every color, size and or type, but a simple HUGE 3FNC rocket to focus on. To that goal, the motor of choice was also a one-n-done, and that is the Contrail 98mm motor system.

The problem (?) Well, the couplers... they just do not fit!! And that is my Massive headache. I have sanded all three couplers, and managed to finally get two to fit, but the e-bay coupler (w/ switch band) is a no go in any of the tubes. I have used the heck out of my 1/3 sheet sander (120-grit) and my dependable Mouse sander (80-grit) and its as if the airframes or the coupler are out of round!!! I would take a Sharpie marker and write the letter "C" all over the coupler, let it sink in and dry, then sand until the letters were gone... test fit and repeat.

I am writing this mainly to vent my frustrations, as there are no options for an easy resolution to this problem... sanding on the coupler for and hour and a half straight, apparently just is not long enough... but sanding ultimately is my only course of action... Had I not procratinated for so long, I might have asked MadCow for replacement couplers.

That is all, now back outside to load new sheets on my sanders and remark the coupler with the letter "C"

Why the letter "C" you ask? Well, should I lose my rocketry focus again, then the letter "C" would remind me that this was a coupler tube, and I need to get back to sanding. Fear not, I aim to get this coupler sanded to fit today!!!
Is this the 5.5 or 8 inch version?
 

David Schwantz

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To the OP, I am guessing you are correct in that they are no longer round. If you have a lathe, make 2 perfect CRs and install them into couplers and sand them on the lathe.
 

crossfire

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MadCow has changed fiberglass suppliers to Wildman from he-who-has-no-name.

If you're gonna do anything having to do with MadCow and a warranty claim on fiberglass, and it's a legacy kit, do it NOW.

MadCow has very little stock left of it's non-Wildman fiberglass, and the specs of the various pieces are different.
His name is Tim from WM
 

DRAGON64

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Is this the 5.5 or 8 inch version?

5.5" airframe

To the OP, I am guessing you are correct in that they are no longer round. If you have a lathe, make 2 perfect CRs and install them into couplers and sand them on the lathe.

One end is out of round, buy just 2 or 3 thousandths, which is enough. Had a rain delay yeterday, so waiting for the outdoors to dry a little so I can get the affected end sanded down, and blended in.
 

AlexBruccoleri

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5.5" airframe



One end is out of round, buy just 2 or 3 thousandths, which is enough. Had a rain delay yeterday, so waiting for the outdoors to dry a little so I can get the affected end sanded down, and blended in.
I have the 5.5" too and it is a great rocket. I did have to sand a lot to get all the parts to fit though. Odd the coupler does not fit. Madcow may have spare couplers. If they do not, check with Composite Warehouse.
 

DRAGON64

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Fin slots... don't get me started on how off the slots are. I worked on the slots with a rat-tail file and got a basic fit, but they do need a little more work. But yes, compared to "glassing" kraft tubing, this kit will geive excellent finished results and will be awesome. I never thught I would get away without sanding a bit.
 

Kallahan11

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My eBay coupler was a real tight fit on my 5.5in DX3 as well, I was at a launch showing the L3CC progress and had the coupler in the airframe but it was so tight I could not get it out. S I thought long and hard about what to do and eventually came up with a genius engineering solution. I pulled harder. It came unstuck and I whipped it directly into my face cutting my self right above the eye requiring stitches. That was April 1st 2016.
 

DRAGON64

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I nearly did that as well. After much sanding this AM, the coupler spins freely in all airframes, and if I let it go, drops stright through... but the slightest little cock-eye, and BAM! She is locked up, and it is a wrestling match to get it out... not sure if my hobby needs require that much tolerance.
 

Kallahan11

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That was only the start to a bad week, apparently at the launch I picked up a skin infection on my leg that landed me in the hospital for four days on IV antibiotics + another half a week of at home recovery. Fun times.
 

Donnager

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There is a very fine line between "Too-tight" and "fits". Unfortunately, there is a similar line between "fits" and "loose enough to jam" if you get carried away sanding, or if you sand it out of round.

Burnishing the bay and the rocket with graphite helped me a great deal on an 8" Prometheus. Also, when you sand down the coupler, the sanding scratches can hurt the fit, so I've had to use finer paper as I get close to be sure the roughness isn't an issue.
 

WILDMANRS

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My daughter has a t-shirt that reads: "Procrastinators Are The Leaders of Tomorrow!"

So I have owned the DX3 Massive, here-by to be referred to as DX3-M, for about 3-years now, and I work on it a little bit at a time and as such make very little progress... You see, my rocket enthusiasim went from 9 to 11-months all rocketry and 1 to 3-months focused elsewhere, to the polar opposite of 1 to 3-months all rocketry, and 9 to 11-months focused elsewhere. So when my focus is on rocketry, I try to get as much work done on the DX3-M as possible.

The DX3-M was to be my one and done. No more rockets of every color, size and or type, but a simple HUGE 3FNC rocket to focus on. To that goal, the motor of choice was also a one-n-done, and that is the Contrail 98mm motor system.

The problem (?) Well, the couplers... they just do not fit!! And that is my Massive headache. I have sanded all three couplers, and managed to finally get two to fit, but the e-bay coupler (w/ switch band) is a no go in any of the tubes. I have used the heck out of my 1/3 sheet sander (120-grit) and my dependable Mouse sander (80-grit) and its as if the airframes or the coupler are out of round!!! I would take a Sharpie marker and write the letter "C" all over the coupler, let it sink in and dry, then sand until the letters were gone... test fit and repeat.

I am writing this mainly to vent my frustrations, as there are no options for an easy resolution to this problem... sanding on the coupler for and hour and a half straight, apparently just is not long enough... but sanding ultimately is my only course of action... Had I not procratinated for so long, I might have asked MadCow for replacement couplers.

That is all, now back outside to load new sheets on my sanders and remark the coupler with the letter "C"

Why the letter "C" you ask? Well, should I lose my rocketry focus again, then the letter "C" would remind me that this was a coupler tube, and I need to get back to sanding. Fear not, I aim to get thiswet coupler sanded to fit today!!!
That is not our product .
how ever it depends how far off it is always wetsand fiberglass, other wise it is just scratching it .
You can also give Madcow a call or e-mail I'm sure they will do there best to help .
I think our tubing is the same
 

cls

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That was only the start to a bad week, apparently at the launch I picked up a skin infection on my leg that landed me in the hospital for four days on IV antibiotics + another half a week of at home recovery. Fun times.

Yowch!!! That's terrible. Stay on top of it, please. It can run away in a few hours and go systemic, septic, you can die. I had such an episode 5 years ago, barely survived.
 

Igotnothing

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My eBay coupler was a real tight fit on my 5.5in DX3 as well, I was at a launch showing the L3CC progress and had the coupler in the airframe but it was so tight I could not get it out. S I thought long and hard about what to do and eventually came up with a genius engineering solution. I pulled harder. It came unstuck and I whipped it directly into my face cutting my self right above the eye requiring stitches. That was April 1st 2016.
Have matching scar. EX motor tube, though. Same result. Forehead got in the way.
 

KenECoyote

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My eBay coupler was a real tight fit on my 5.5in DX3 as well, I was at a launch showing the L3CC progress and had the coupler in the airframe but it was so tight I could not get it out. S I thought long and hard about what to do and eventually came up with a genius engineering solution. I pulled harder. It came unstuck and I whipped it directly into my face cutting my self right above the eye requiring stitches. That was April 1st 2016.

I nearly did that as well. After much sanding this AM, the coupler spins freely in all airframes, and if I let it go, drops stright through... but the slightest little cock-eye, and BAM! She is locked up, and it is a wrestling match to get it out... not sure if my hobby needs require that much tolerance.

Have matching scar. EX motor tube, though. Same result. Forehead got in the way.
I had a fg coupler stuck years back and it was stuck GOOD. I was almost going to get a replacement, but instead I tried super gluing two pieces of wood to the opposing inside edges of one end and it was then a cinch to remove it. All it took was that little bit of extra grip and leverage...almost like handling a pickle jar top!
 

Igotnothing

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I had a fg coupler stuck years back and it was stuck GOOD. I was almost going to get a replacement, but instead I tried super gluing two pieces of wood to the opposing inside edges of one end and it was then a cinch to remove it. All it took was that little bit of extra grip and leverage...almost like handling a pickle jar top!
Show off!
 

DRAGON64

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I did manage to sand enough hours away from a day to get the couplers to fit... I may sand away some more to get a little more tolerance stack... not sure if I have enough patience to sand enough shear pin use to keep components together.

Today I am building the motor mount, so I can see how much I need to sand to get the fin slots to better fit.
 
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h6tEoLw.gif
 

DRAGON64

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Changing gears, and shifting to more of a build thread.

My starting point was building the aft centering ring assembly. I ordered (2) wood 1/4" thick centering rings and mated them to the supplied G10 ring using JB Weld.

349183-86796bacad969a71efe3da6320758a35.jpg

The assembly was then mount onto the end of the 98mm motor mount. The motor case of the Contrail hybrid was also installed in to the motor tube, to help center the Aeropac retained to the centering ring assembly. This was done to get holes marked for drilling into the ring assembly.

349332-5cbba1a8e65f345300d6ba3a2bcad015.jpg

This was not quite reliable enough for peace of mind ensuring the holes were aligned, so I designed a hole template and 3D printed it to use as a guide.

349333-b44e17420c4cb2059d077216542ab40d.jpg

The guide was lightly tacked into place with Aqua Net hair spray. I contemplated drilling the G10 ring to fit the #8 hardware, and turn the assembly over to drill through the wood only to mount the insert. My thought process is, since I chose to mount the inserts into wood (with CA thread re-enforcement), should the inserts fail, they will not pull through the G10 ring with the smaller #8 screw hole...

349334-03e4473b27d07eed3dbab07ec310c953.jpg

Dealing with the reatiner and ring assembly turned out well, but took a little time. I built the assembly as I had planned to do, except that I did not CA re-enforce the threads in the wood centering rings.

349466-71171d64deca8c9dabbeb95d340f4b39.jpg

349469-14e5bc075c3fcef6223c7b7613f546c5.jpg

The reasoning behind not using the CA, was that most of the threaded inserts split while being inserted, and became permanent feature of the assembly. All though not as planned, the end result was the same:

349470-0d21488fe6088c5e9db4f9c6ca290a5b.jpg

Note, for all 3D printed articles, I am using PetG materials @ 100% fill.
 
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DRAGON64

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Before the original topic of this thread, I did a fair amount of 3D printing for the DX3-M. One of the items was filling the huge void inside of the 14"L X 5.5"Dia AV bay that this kit has. I printed a very basic sled, that will hold 2 altimeters, two 9V batteries, with slots for using wire ties to securly mount wiring. The sled also needed to be strong:

350666-86242d1cde30206add129a785d044dd2.jpg

The altimeters slight off from one another on opposing sides. Note also, small screw hatches were also printed to secure the 9V batteries, one on each side.

350668-7ef903c5cdb4920eec8a247e03a3c7db.jpg

This is more sled than what is needed, but basic strength and integirty is what I was going for...oh, and functional.

350667-86c493ae1062517c2ac6e64bcff9ba95.jpg

Note, for all 3D printed articles, I am using PetG materials @ 100% fill.
 
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