3-D printed sled review

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DuctTapeandRocketFuel

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I am an early adopter when it comes to technology, and when it comes to my model rockets. I like to try out new ideas, and incorporate them into my designs, and test how they can make construction, and logistics easier, and less complex.

With that being said, when I designed my first electronics bay for my first dual deploy rocket, I did a lot of research to see how others had tackled the problem, how they laid out components, etc. I saw that most were home-brew designs, and while that was fine, the end product was bespoke to the rocket in which is was built. This meant that an altimeter, and sled would be needed for every single rocket build that would require electronics. I wanted to streamline this design process, and be able to use the sled containing the altimeter, switch, and battery in multiple rockets, saving lots of time, money, and materials making one-off av bays for every rocket.

I was glad to see when Andrew Diehl (aka Landru) had similar ideas, and was already in the prototype stage of such a device. Once available, I purchased one 54mm and one 76mm sled, and wanted to share my initial thoughts and what my experiences have been so far.

They are orange colored and are available directly from Landru's Etsy site. He claims they are compatible with a variety of different altimeters including Stratologger, HI-ALT 45, and Raven

The appealing aspect to me is that the sled has a built in switch holder for a Schurter turn switch, integral battery compartment for a standard 9VDC battery on the back side, and standard spaced built in holes for all-thread to pass through. Combining all these features into one unit makes this a very compact and versatile system.




I decided to use a Stratologger with a 76mm sled to make a interchangeable sled system for several rockets I have. The first problem I ran into with a 'fits all' sled, is the Stratologger does not fit. (Insert Homer Simpson, “D'oh”). The bosses for the battery compartment interfere with the components on the underside of the altimeter. (Same problem on the 54mm sled).
sledmod1.jpg

This posed several potential hazards, so I needed to raise the altimeter a little higher to get proper clearances. All I had on hand was some 0.25 inch spacers for 4-40 screws. (1/8 inch would have been sufficient.) This lead to a second problem. Since I had to use longer screws, the #2 wood screws provided would not work as intended. I decided to switch to 4-40 hardware for additional strength. This lead to a third problem. I couldn't just drill out the bosses and attach with nuts on the underside because this would interfere with the integral battery compartment on the backside of the sled.

This would mean I would have to drill and tap the bosses for attachment. In order to do this, I needed a 4-40 tap, #43 drill bit, and a drill.
sledmod2.jpg sledmod3.jpg sledmod4.jpg

This lead to a fourth problem, because of the low melting temperature of the material the sled is made from, and because its rather soft, only hand tools should be used. I used a 5/64 inch bit because I didn't have the #43 bit available, and I used a pin vise to hold the bit. I kept a careful watch and a steady hand to prevent the bit going through the material crooked. I had to take some time because the soft material easily clogged the bit. After the holes were enlarged, I switched to the 4-40 tap in the pin vise, and going slow to prevent the tap from going crooked, or stripping out the soft material. I placed on my spacers, and inserted in some nylon machine screws to complete the altimeter install. I trimmed the bottom screws with the inside of the battery compartment. Here is the complete modification. I used nylon to try and not wear out the threads in the plastic.
View attachment 168975 sledmod6.jpg sledmod7.jpg

All wired, and ready for a the next launch.
sledmod8.jpg sledmod9.jpg Battery cover not attached.


Missile Works is also selling sleds in a blue color made by Landru as well. The Missile Works sleds are only compatible with their RRC2+ and RRC3 altimeters. I found no problems mounting the RRC2+ directly to their 38mm, and 54mm sleds. I will review these separately and in more detail at another time.


So to recap here is my final thoughts on these 3-D sleds:

Pros: Sleds engineered and manufactured for a specific platform work great.

Cons: 'One size fits all' will need modifications for proper fit and operation.

Improvements I would like to see in future generations of 3-D sleds: Since the HI-ALT 45 is no longer in production, I would focus on products that are currently available, and adjust the stand-offs to those loggers form factors. It would also be nice to have a 'blank' sled for those who need to customize for a specific application. With the growing popularity of PIC controlled electronics like Arduino and its offshoots, this would be a prefect application for these electronics. I would also like to see sleds for tracking devices from various manufacturers. Being able to move trackers from one rocket to another would be another great time and money saver.

Being an early adopter means that you should not expecting perfection, and I know that there is always a learning curve when it comes to making and perfecting a product. I think these are wonderful products, and future revisions will make them even better and user friendly. I would like to congratulate Andrew on a job well done in making such an ingenious device, and wish him the best on making them in the future.
 
Perfect Flight makes this hardware pack of standoffs
just for their electronics............

I use these on all of my altimeter mounts,,,,,
even other brands of altimeters..............

They work great and are easy to use and install..........

They may have saved you a bit of trouble...........

Teddy
 
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I'm using the blue Missile Works sleds in my first DD (38mm). Everything fits perfectly in my stock Super DX3 avionics bay. I will be flying it for the first time this weekend hopefully.
 
To add my experience so far:

I've just built two AV bays with these sleds, but haven't flown them yet. Both are 54mm; one has a Raven2 in it, and the other an RRC2+. Both went together with no issues - everything fit great with no modifications needed. Mine DID come with stand-offs and the proper length bolts/screws. The Raven one I got direct from Landru and the RRC2 one I got from Missileworks; both were ordered pretty much as soon as they were available.

If I had to quibble, I might say that perhaps the screws that hold the battery cover in are just the slightest bit on the short side. They will likely do their job just fine, but maybe just a millimeter or two more length would feel more secure.

I like these sleds a lot.

s6
 
Thanks for the review!

The sleds should have come with a bag of appropriately sized nylon standoffs and #2 screws, all which perfectly fit the stratologger, raven, and HiAlt 45. Apparently I either forgot to include them in the shuffle, or they are still somewhere in the packing material (it's a tiny clear bag)

The Hi_ALT 45 is only supported because it happens to have exactly the same footprint as the Stratologger. I'm trying to only support the currently manufactured electronics in an effort to prevent the sleds from completely becoming swiss cheese :) Blanks will be available soon as well, so you can mount anything you want.

~Andrew
 
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