27-Nov-2022, 02:07 PM (This post was last modified: 29-Nov-2022, 12:36 AM by iFly4rotors.)
Since there is a lot of information to cover and graphics that I will be working on, this thread is a work in progress. That said, please feel free to comment or offer information. .......................................................................................................................................
Before we begin, let’s take a look at some of the options for building your own frame. First, let us consider using a CAD program to design a frame. There are many options for using and instructional videos for using these programs, however, The.Ronin has produced a very good thread that is specific to frame design:
Once you have the design in a CAD file, what do you do with it. If you have a a CNC milling machine or a 3D printer, then it could be cut or printed by the designer. Or, the file could be sent to a person or company that will cut or print it. Done. On the other hand, let’s consider that the fancy software and tools are either not available or maybe just more complex than one wants to deal with, but we still want to build our own frame; maybe something that is a little less complex and can be built with minimal tools or maybe from a material that is not normally used. You know, something that a Handy Man might build with the tools that might already be available: hand tools, hand held power tools, maybe various cutting devices such as saws and moto-tools, and maybe a bench grinder or maybe just some grinding stones for a drill or moto-tool. Being a Handy Man and an old school DIYer, I have often thought about building some of my own frames; simple and easy to construct; Not because I have to, but because I want to because I think that it would be fun, interesting, and I could get something that I could not buy. Plus, I can use what ever material that I choose. Specifically, I want to build a small format aluminum frame; maybe a 3 inch. A small wooden frame might also be interesting. However, these are certainly not the only materials. Other materials that would work include carbon fiber, fiberglass, plexiglass, Lexan plastic, wood, and perhaps other things. The tools that one has available might influence the choice of material. Having considered many frame types, styles, and construction; I believe that the two easiest frame types for a DIY project to be a simple “H” pattern and a simple “X” pattern, however, there are some hybrids that would be pretty easy to construct as well. Since I want to keep these builds and this thread reasonably simple, I will focus on the "X", the "H", and a hybrid of "H" and "X" patterns.
NOTE: These frames are extremely flexible and can be cut to any size. Also, the construction bolt size and spacing can be any size or dimensions. ALL material, sizing, and spacing is determined by the builder.
27-Nov-2022, 02:09 PM (This post was last modified: 26-Dec-2023, 01:48 PM by iFly4rotors.)
X pattern From what I can tell, the X pattern frame offers some of the best flight characteristics. The energy from the motors seems to move through the arm to the center of the quad. Consequently, I will start with an X pattern DIY frame. Although the X pattern is pretty simple, there are actually many methods for constructing it. Some are more complex than others and some require more fabrication. That said, I want to start with something that is very simple and easy to construct. So, let’s begin. The first design is simple and consists of 2 pieces of material for the arms and an anchor plate. These pieces are connected in the center with a central primary bolt. Each arm set has 2 additional, secondary, bolts that secure the arms to the anchor plate. These 3 pieces of material make up the frame base. Optionally, another rectangle piece that corresponds to the anchor plate could be used for a top deck plate. If a toothpick style is desired, then the anchor plate would be square, a whoop FC board would be used, a whoop canopy installed on top to hold the camera, and the battery attached to the bottom. Another option would be the bus or fuselage style that we see in most freestyle frames. In this case, a rectangle anchor plate would be used with a corresponding rectangular top deck plate and those plates spaced apart with standoff columns. The battery could be mounted on the top deck plate or under the main/bottom frame plate. The materials are 2 arm bars (2 motors per bar) and a square or rectangle anchor plate and optionally a top deck plate. The size depends on what the builder wants. If the FC mounting pattern is a square, then the secondary arm bolts could be spaced the same as the FC or stack to allow mounting directly onto the arm bolts. The construction is pretty simple. The anchor plate is sandwiched between the two arm bars which provide each arm bar with a smooth solid mounting surface without the need for spacers. A central primary bolt holds all 3 pieces of material together while each arm set has 2 additional secondary bolts that secure that bar to the anchor plate. For a rectangle anchor plate we might optionally have a corresponding rectangle top deck plate and standoff columns to hold it.
The Fabrication Process:
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The following outlines one way to cut and drill the arms and plates which results in arms that have equal spacing without a lot of measuring. Once the first motor mount holes are drilled, this is used as a pattern for the others. This is just one method.
1) Cut the arms to length. 2) Drill motor mount holes in the arms. {maybe clamp an old arm to use as a template} 3) Drill only the center anchor bolt hole in each arm {do not drill the other 2 holes yet} 4) Cut the square or rectangle anchor plate. 5) Drill the center anchor bolt hole 6) If using a 25.5 x 25.5 whoop AIO, then drill the 4 diagonal FC mount holes. 7) Put the bottom arm on the anchor bolt. 8) Put the anchor plate on the anchor bolt and on top of the bottom arm. 9) Put the top arm on the anchor bolt and on top of the anchor plate. 10) Install the nut on the anchor bolt, align the arms, and tighten the 3 pieces together 11) If necessary, use a clamp help hold the pieces in alignment. 12) Drill the holes in the arms and through the plate for the remaining secondary bolts. 13) Insert secondary bolts, add the nuts, and tighten. 14) Done.
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Another option is to measure and drill the motor mount holes for each one separately. This takes more measuring, but can certainly be done.
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The Assembly Process:
Start with the central bolt. If the bolt is down, then start with the top arm. If the bolt is up, then start with the bottom arm. The bolt goes through one arm, then the anchor plate (bottom plate), and then through the other arm. Secure with a nut. I would likely use a Nyloc nut since it will not come lose. Once this is assembled, put in the secondary bolts to secure the arms with the plate. If you have not yet drilled the secondary holes, how is the time to drill them. Arrange the arms, check the motor to motor spacing, use a "square" if you have one, tighten the center bolt very tight, then drill the holes and install the bolts.
Note that it doesn't matter which arm is on top or on bottom.
27-Nov-2022, 02:11 PM (This post was last modified: 26-Dec-2023, 01:46 PM by iFly4rotors.)
Hpattern
The H pattern is another very simple, easy to construct design and has, or at least could have, plenty of space available for the electronics. Some of the DJI quads essentially are built using the H pattern. Even though the arms may not be perfectly perpendicular to the body, it is still basically an H pattern. So, the H pattern is a viable design.
The design is simple and consists of 3 pieces for the main bottom plate (2 arm bars and a central "plate") and an optional top deck plate. For purposes of illustration, I have shown 3 connection bolts for each arm bar which I believe is reasonable; more or less to individual preference. The top deck plate is optional. If used, it should correspond to the main bottom plate standoff column pattern. Maybe only 2 columns on each end instead of the 3 holes that are shown on the top deck plate.
Construction is very simple.
1) Cut the arms to length. 2) Drill motor mount holes in the arms. {maybe clamp on an old arm to use as a template} 3) Drill only the center anchor bolt hole in each arm {do not drill the other 2 holes yet} 4) Cut the rectangle anchor plate. 5) Drill the 2 center anchor bolt holes, one at each end of the plate. 6) Drill the 4 FC mount holes in the anchor plate. 7) On each end, put an anchor bolt through the arm and anchor plate. 8) Install the nuts and tighten. 9) If necessary, use a clamp help hold the pieces in alignment. 10) Drill the holes in the arms and through the plate for the remaining secondary bolts. 11) Insert secondary bolts, add the nuts, and tighten. 12) Done.
... Attachments ........................................................................................................... 1) DIY Classic H frame assembly diagram.
27-Nov-2022, 07:08 PM (This post was last modified: 29-Nov-2022, 01:45 AM by iFly4rotors.)
Hybrid Although there are many frame patterns that could be considered as Hybrid, for the purposes of this endeavor I will consider a Hybrid to be a combination of the X and H patterns which will include the dead cat design.
28-Nov-2022, 02:19 PM (This post was last modified: 14-Jan-2023, 05:06 PM by iFly4rotors.)
Other DIY frame concepts
Now let's consider other DIY concepts such as using commercially produced replacement CF arms and a set of custom fabricated plates. This is an interesting concept since we don't have to drill the motor mount holes. Also, the arms can be spaced as needed to accommodate almost any reasonable sized props. Plus, there are no issues with the FC mounting pattern since we will be drilling all of the holes anyway.
23-Dec-2023, 09:56 PM (This post was last modified: 23-Dec-2023, 10:00 PM by iFly4rotors.)
Material Options & Considerations Before we look at the materials, let's consider the type of craft to be built. An endurance craft built for easy cruising and NO stunts can get by with a frame with marginal durability and likely less stiff. After all, this craft will be flown easy with easy take offs and landings. On the other hand, a hard core ACRO craft will need a more durable frame to withstand the many crashes (sometime into hard objects) that are likely to happen and a stiffer frame for hard maneuvering.
There are actually several options when considering materials that could be used to construct a DIY quadcopter frame. For the purposes of this thread, let us only consider options that might be both available and workable and put aside materials such as steel and even carbon fiber which is best used with a CNC milling machine. Keep in mind that the assumption is that the fabricator does NOT have a CNC milling machine and does NOT have a 3D-Printer. On the other hand, let's assume that the tools available consist of basic tools such as a hand drill, some type of saw, Dremel tool, files, knives, and maybe snips and an assortment of other miscellaneous hand tools.
From my perspective, some of the materials that would be considered include Aluminum, Lexan Plastic, Fiberglass, Wood, and some types of foam. These materials are available either at a local store or from an internet vendor. Now, let's take a look at these materials from the least likely to the most likely.
FOAM:
Most types of foam would likely not make a good frame, however, there are certain types of foam board (used in construction) that are pretty dense and might be viable for a smaller craft. On the down side, most foams will not survive crashes so it would only be a consideration for a quad designed for easy flights with soft landings. Yes, Foam tends to be fragile, but very light.
WOOD:
Wood tends to have more rigidity than foam, however, the thinner woods would tend to break in any hard crash. Interestingly, some of the early quads were actually built with wood. Hmm. Ok, it would be possible and a contender. Wood comes in a variety of types, thicknesses, and density so there are actually many options. It is also quite workable with the right tools. On the down side, it might be either light and not durable or heavy and durable. Hmm. Yet again, options. While a viable contender, it might not be as good as some other materials.
FIBERGLASS (sheets):
Fiberglass is actually workable and decently strong. I have actually cut arms from fiberglass. On the downside, there are glass "fibers" to contend with and the material is less workable than one would think. Yet, it is possible. Fiberglass has some rigidity, however, it can still bend or break. It may or may not survive crashes. Again, this may depend on the thickness. Still, it is likely a viable option.
LEXAN PLASTIC:
Lexan Plastic is available in sheets of different thicknesses so that the frame can be as thick or think as the fabricator desires. Obviously, thicker is more rigid, but a bit tougher to cut. The thinner sheets have more flex, but are easier to cut and work with. From working with different thicknesses, the thicker material could make decent arms and even plates. The thinner material would only be viable for smaller arms, small frames, and plates. Interestingly, Lexan is crystal clear. Overall, Lexan appears to be viable for a quad frame especially if one incorporates various sizes for different parts; maybe thicker for arms and thinner for plates and such.
There may also be other types of plastic that would work. Also, keep in mind that DJI and other commercial drones are made with plastic. Oh yeah, tiny whoops are also mostly plastic. So, there may be other "plastic" options.
ALUMINUM:
Now, let's consider Aluminum which is strong for it's weight and is available in assorted sizes and from various vendors. For example, many hardware stores carry aluminum bar stock in several sizes which can be used for the arms with minimal work and can be cut with a variety of tools such as power saws, manual hack saws, Dremel type tools, and the thinner sheets can also be cut with snips. For the most part, Aluminum can be fashioned with standard hand tools. Yes, Aluminum is a bit more demanding than plastic, however, it is quite a bit stronger.
NOTE: A standard blade can be used in a power miter saw. The trick is to go S L O W and allow the blade to cool a bit between cuts. Don't do too much at one time and don't go too fast.
Some may say that Aluminum bends. Yes, it does, but so does every other metal including steel. The question should not be "does it bend", but rather, how much force does it take to bend the particular aluminum in the particular application. For example, a piece of 1/16" x 1/2" bar stock that is 2 or 3 feet long will easily bend in the middle if one pulls on both ends. On the other hand, a 3-inch length of the same bar stock is almost impossible to bend without tools. Aluminum is actually a very viable material for a quadcopter frame.
All things considered, I am believe Aluminum to be a viable material for a quadcopter frame. In fact, I think that it might be one of the best alternative materials especially for a DIY frame using standard Handyman tools.
23-Dec-2023, 09:59 PM (This post was last modified: 29-Dec-2023, 02:28 PM by iFly4rotors.)
X Pattern - Aluminum For this first batch of cuts, I had purchased several pieces of aluminum bar stock in two sizes from a local hardware store. This stock was cut into 6 inch pieces with a DeWalt compound miter saw and I ended up with a bunch of them. In some respects, this is sort of an experimental run to see how it goes.
The 6-inch length of the arms allows for 2.5" props with a freestyle fuselage AKA "Bus" design or 3" props in a Toothpick style build. The plan is to fabricate the arms and plates for one of each type of quad. This will be Prototype # 1 and # 2 and shipped to LemonyLeprosy as he flies more aggressively than I do. He will also likely get the builds completed before I get back to building.
The Freestyle frame came in at 33.3 grams. Although this is a bit heavy for a 2.5" quad, it is on par with some of the "cine" frames. Also the skeletonization has been kept to a minimum for this first prototype since I don't know how strong or weak the frame is. Some weight can be reduced by drilling more holes to remove material. Notice that the rear has holes for either a single standoff column or two standoff columns (well 3 if you really want them).
Commercial frame Weight comparisons:
GEPRC Phantom 2.5" = 13.7 g HyperLite ToothFairy 2.5" = 25 g GEPRC LineLog20 2" = 53.4 g Darwin CineApe25 2.5" = 66.7 g Foxeer Foxwhoop 2.5" = 54 g
This frame is not a precision work and is a bit rough in spots due to the tools that I was working with. Yet, it should get the job done and will be a good first test.
Armattan cam braces, M2 x 5mm brass M/F extensions, and both M2 x 20mm and M2 x 25mm gold aluminum standoff columns complete the parts needed to assemble the frame. I have included the 25mm option since Lemony needs 15mm clearance and the frame bolts needs about 5mm so add 5mm buffer and you have 25mm. The picture below is assembled with the 20mm high Armattan cam braces at the front and a single 20mm stand off column at the rear.
Also notice that the assembly for both frame styles is precisely that shown in Post #2.
The Toothpick frame came in at 24.1 grams with minimal skeletonization. Instead of the standard 4-hole motor mount pattern, the arms were drilled for the 3-hole pattern of the EMAX Tinyhawk 1103 motors as requested. Lemony has many of these motors and no frames in which to use them. Until Now.
Since this build will use an underslung battery, I have provided a Lexan plate for that purpose. The picture in the attachments is more for illustrative purposes as he will likely use different bolts to close the gap. With this type of product, one has options as to how to put it together. He might not even need the plate. Hmm. Anyway it has been provided.
For the next one like this, I think that I will cut the plate differently which may eliminate the need for any additional plates.
Consider that a DIY frame can have any features that one would want. There is plenty of room for expression in options and variations.
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