Thanks so much for making your videos, I appreciate the amount of time you take to make them, your videos helped me medal 6th in regionals without any testing, we only build one tower and used that same tower for the competition. However, I was also wondering if you could post a video about the non-bonus tower, just like you I also neglected this part, but Troy somehow made a 4.3 gram tower nonbonus and held the full load and didn’t break, meaning that they could beat your benchmark 5.9 gram tower. So could you make a video on testing some non-bonus towers.
Hi! Thanks for the kind feedback and congrats on your results. The goal of my channel isn't to demonstrate the best possible device, just to get teams started on what would be a very good device. I didn't bother with a non-bonus build for a couple reasons. First, unless someone comes up with a non-symmetric design that works well (which might be possible), the tower would look exactly like this one with just different material choices. You can just scale my jig in the XY only to play around with that if you want. Second, I still think the bonus design has a ton more potential than I've shown with the benchmark build. Remember, my benchmark tower held 18.57 kg for an actual efficiency of 3121. That means the design could be optimized to nearly that efficiency at 15kg, which would be a ~4.8g tower or a 4100+ score. I don't expect that perfectly, but I do expect scores close to 4000 using the bonus design if you are looking for what could potentially be top 5 national scores this year. Good luck!!
Thanks for your reply, and also concerning the cross-bracing density, I can’t find websites that sell cross bracings 1/16 by 1/16 36 inches or less at the density I would prefer. Do you have a site where I can get specific densities. I already tried specialized balsa, but their sticks are way too expensive with 20 bucks on shipping and national balsa but they require 50 dollars order purchase, and I would be getting too many cross bracings I wouldn’t use(136). Do you have another site where I can get specific densities for the crossbracings that charge a bit less (not 2.25 dollars per stick, adds up with the amount of testing I do) and don’t have an order minimum.
Specialized Balsa is the only place I know of where you can specify the density. For me, buying pre-cut sticks is way too expensive. That is why I recommend you buy balsa in 4" sheets and cut your own. It will be much, much cheaper and you'll have even more control over the material. It's more work, but it's worth it. Be sure to watch my Balsa Library video if you want to see how I cut most of my sticks from sheets.
Hi Balsa Engineering, For my last invitational, my tower weighed 6.41 grams and supported 14.1 kg. However, I haven’t been able to achieve a tower score above 3000. My best attempt so far was a tower that weighed 6.98 grams and held 16.8 kg. The tower that held the most weight was 7.17 grams and supported 19.7 kg. I would really appreciate your advice on how to build a tower that can score in the 3000 range. Thank you!
Hi! It sounds like you are well on your way to building a 3000+ tower. It really comes down to careful material optimization and balance. It takes just the right wood to get the perfect build. I would suggest you try and replicate my benchmark tower as close as possible if you want to hit the 3000+ mark, at least as a starting point. First, cut all the material for your next build and weigh every piece and layer like I show in my notes. Compare you material exactly with what I have to see where yours is different. Your 2865 tower is a very good competition result and if your 7.17g build had an actual efficiency of 2748, so if you properly scale that down to 15kg, that would result in a 15000/2748 = 5.46g tower that would score 3663! So you already know how to build the tower you are after, you just need to zero in on the optimal material. Good luck!!
Hello! What would be the effect if I added a horizontal cross member intersecting each x in the middle? This would halve the distance of the leg between each cross bracing, so you can use a lighter leg?
That is certainly something you can play around with, but all those extra cross members will add a lot of weight. You'll have to experiment to see if that added weight is more or less than the amount you can lower the leg mass. Another benefit of cutting everything ahead of time is that you can figure out if you can even build a tower that is overall lighter before you glue anything. I always like to estimate the final mass of the tower before actually starting construction to know if it's worthwhile or not with what I'm trying to achieve.
Hi Balsa engineering, I was wondering what is the best method to store a tower to it doesn’t get heavier overnight, as that has happened to my towers. Maybe it’s from moisture? Thanks!
Hi! I like to use a dry-box to keep all my devices in a controlled environment. I made a video awhile ago showing this process in a lot of detail and the benefits that you might want to check out. I'm showing bridges in the video, but it applies to everything: ruclips.net/video/6zOvHMZLaNE/видео.html
Hi! You can see those dimensions in this video when I show my notebook page, for example at 6:53 Check out the blue numbers on the right side of the page. The bottom layer is 25.5cm (6 pieces), the next layer is 23.2cm, all to way to the top layer which is 7.4cm. Hope that helps!
You can see that in this video when I show my notebook pages. For example, at 6:58 The bottom horizontal layer is at 0.5cm and each layer after that the spacing is 5.1cm.
Hello Balsa Engineering. Thank you for these amazing videos. We wouldn't know where to start with the triangular legs without these great tips. Can you kindly let us know the density of the balsa wood you used in the benchmark build? What is the density of the legs (3/16 x 3/16) balsa sticks and what is the density for the cross members (1/16 x 1/16)? We read through all your responses to the comments and figured the density for the legs should be medium and for cross members it should be light. Is my understanding right? Appreciate your response.
Thanks! Yes, if I recall, the source legs were in the "medium" density range at around 11 lbs/ft^3. I don't have the value for the cross members off hand, but you should be able to compute it exactly from the masses I've shown in my notebook page. They are definitely in the "light" range.
That sounds about right. Probably closer to 3.5g, although I didn’t keep track of that. I did record all the 52.5cm source legs though and they ranged from about 1.9 to 2.2. Only the final sanded weight matters though, so that is the library of material you want to build up to choose from
@@balsaengineering6686 Thank you. I've been at it for the past hour, trying to find the right weight wood. Been getting wood too light, but never too dense, but just finally struck a 3.3. Hopefully I can get more!
hi balsa engineering - for the bottom part of your tower, for your triangular legs, how do you ensure that the tower is standing straight on 3 flat surfaces? Do you sand the bottom of the triangular legs until they are flat and level? thank you!
Hi! I've found in my recent years of building a lot of towers, that it isn't necessary to have the bottom of the legs sanded flat. I always just leave them at an angle and it works fine. That being said, you need to be pretty deliberate to get the legs perfectly aligned from the start. If you check out my assembly video at around the one minute mark, I show how I tape the legs in place on the jig while using a very flat build surface. This works well to make everything nearly perfect: ruclips.net/video/TkUS4W4bOZM/видео.htmlsi=w-yEqXui0G-rYRWH&t=70
Hey balsa engineering, i tried to 3D print the STL jigs that were in the description, but all the actual tower pieces contact the base of my 3D printing machine at only one point, making the print fall over. Are the files supposed to be like this? What should I do to fix the positioning of the prints?
Hi! You may need to rotate the STL files before printing. Your slicer program should be able to do that easily. Just select the object and rotate it, probably just 90 degrees in one direction so it is flat on the printing surface. Good luck!
Hey balsa engineering! I was wondering what kind of glue you use for your legs to minimize weight and whether you have a strategy for adding minimal amounts of glue?
Hi! The short answer is I like to use 50 cps CA glue. The long answer, including techniques, is the dedicated video I made on that topic: ruclips.net/video/55lb2KzSiwg/видео.html
The short answer is 50cps CA glue. The long answer is to watch my 25 minute video I made on this exact topic: ruclips.net/video/55lb2KzSiwg/видео.html Good luck!!
Hello balsa engineering, I noticed that this year you didn’t list the densities for the wood to the left of the tower. You did last year,is there any way you can provide me with those numbers?
@@demonplayz857 I have the mass listed for the entire layer of cross members, so some simple math will get you source stick mass. For example (6) @ 25.5cm at 0.491g is 153cm or 60.236 in. For a 36" stick, that is just 36/60.236 or 0.598*0.491g, so 0.294g for a 36" for that layer. You can then compute the actual density if you want by knowing the volume, just make sure you get your units correct.
@@balsaengineering6686for the legs are they actually 52.5 cm long or will it be 51.5cm long? I know you say the little space between the first layer and the ground is around 0.5 m, and from there each section is 5.1 cm long, doing the math it would be 51.5 cm? But on the 5th design you said it was 52.5 cm long?
Hi Balsa Engineering, first off I wanted to thank you for making these videos! I found them really helpful last season and I was able to get second place at states thanks to you! For this seasons build I was wondering which type of balsa sheets (dimension's and density) you used for you benckmark build. Thanks!
Thanks for the kind feedback and congratulations on your success last season! If you check out 7:45 of this video, you can see my notebook page for the benchmark build. There I show the sizes and masses of everything I used from which you can calculate the density. To save some time, I believe the source legs (3/16 square) were about 11 lbs/ft^3 which is in the "medium" range. The cross members were all 1/16 square. I didn't calculate the density, but I'm sure they were in the "light" density range. You can see the mass of the entire layer on the far right side of my notebook page in red. For example, the bottom layer had (6) pieces that were 25.5cm each and the total mass was 0.488g. Good luck this season!
@@balsaengineering6686 how were you able to sand the legs down into the triangular shape you needed? should i just wing it from a corner until it hits the proper length of the tower jig's side?
@@ame9792 You are in luck!! I made an entire video on how I created the legs! Check this one out when you get a chance: ruclips.net/video/MTHygxUS3YU/видео.html
Hi Balsa Engineering! My 3D printer has a base of 220 mm, and it is not big enough to print the bottom layer of the Div C bonus jig (260 mm across). How much impact on the construction of the tower would it be to split the bottom trapezoid and print the two halves separately? (cutting through the middle of the triangle parallel to one of the sides)
Thanks! My overall approach video shows all the details of the jig design and dimensions. Let me know if you still have questions after watching this: ruclips.net/video/_QTOCIHE_1w/видео.html
@@balsaengineering6686 Thank you so much for the help much appreciated. I think I just missed this video when watching this series thank you so much for highly informative videos every year for such build events.
Hi Balsa Engineering! How are you doing? Thank you so much for making these videos and sharing your resources, I really appreciate it! I wanted to ask you what software / app you use to slice the jig? I am asking this because the Tower Bottom STL file is too big for my 3D printer to print so we are trying to split the bottom and print the two halves separately except we don't know how to do that or if we even have access to free resources to do so. Any suggestions? Do you think you could help? Thanks for your time.
Hi! Thanks for the kind feedback! I used a free Microsoft tool called 3D Builder to cut the STL into pieces which worked really well: apps.microsoft.com/detail/9wzdncrfj3t6?hl=en-us&gl=US Some people have said it's not available anymore, so maybe it's a Windows 10 only tool, I'm not sure. I have also read that Meshmixer can do that task as well, but haven't used it for that myself: meshmixer.en.softonic.com/ If neither of those work for you, just google "split stl file" and there are plenty of things to try. Good luck!!
Hi, I am trying to use the link that you inserted in the caption to get info on the jig, however when i click on the link and try to download the files its saying no file to preview and i am unable to get anything off that link. Do you have any idea why this is happening or how i could get the date of the link?
I just tried it and it's still working. It should auto-download a zip file which contains all the stl files. Once you click on it, go to your downloads directory and see if you have it
Hi, balsa engineering! Thank you for the video. Can I just order triangular leg, not sanding the square leg? Because it can make some errors or mistakes.
@@completeandabsolutenerd It's not too hard to make them. I found it was about 2-5 min per leg depending on your technique. It will definitely be much cheaper to make them yourself as well
I like to buy my balsa sheets from Specialized Balsa: specializedbalsa.com/products/balsa_sheets.php To learn how to cut them, please watch this video: ruclips.net/video/bLsTOpmozGI/видео.html Good luck this season!
not 100% sure on the reason for the bottom but the bracing on the top helps with dispercing the weight since the it gives more surface area for the loading block to lay on.
Actually, the block doesn't sit on the horizontal pieces at the top, so that's not the reason. Because the base is much wider with this bonus design, the bottom is pretty much in pure tension, for which a horizontal piece can help a lot. The top piece, I just decided to go a little conservative to make sure the legs didn't fold in on themselves. I would recommend you experiment with removing both for your builds and see how it goes! They may or may not be necessary depending on your cross bracing! Good luck this season!
How long did your 3d printing take. My printer is small and had to slice everything for the tower in half and building the jig by pieces. Thank you for all you do for these kids. Very methodical process you have that these kids need to learn it.
Hey Balsa Engineering, I am competing in tower for the first time and would like to play with this design. Where can we find the lengths for tower 5 as this was the most optimized one. The lengths of the cross structures and the legs would be helpful. I was also wondering where you got the specific balsa wood sticks. I would like to get the same ones so that I can minimize any flaws.
Hi! You can find the detailed information on each of these tower builds right in this video. For #5, check out my notebook page at the 7:44 mark. Everything in blue on the right shows the lengths of the pieces in cm. The red is is total mass for each grouping. You can compute the exact density by know the size which is also shown (1/16 square for the cross members). I like to buy all my balsa in sheets from a place called Specialized Balsa. It's not that the wood is better, but it's the only place I know of where you can specify the density range when ordering. I would highly recommend you check out some of my general videos to learn more about getting great material to use. Here is one to get started: ruclips.net/video/bLsTOpmozGI/видео.html
@@balsaengineering6686 Thanks, I'll take that into account. Our club itself has some Balsa wood sticks, I'll see if it matches the density of it. If not I may need to order myself from Specialized Balsa, do you know the rough estimate of delivery time?
I also just want to make sure, the height of each leg is 52.5 cm, the increment for where each cross member needs to go is 4.6 cm. And the length of the cross members itself starts from 25.5 cm and goes till 7.4 cm., dimensions of each balsa stcik is 1/16 x 1/16 inch. the top has 3 (4.5 cm ) sticks.
@@niranjankothandaraman They are a small family-run business, so their delivery speed changes a lot depending on how busy they get. My experience has typically been about 1-2 weeks or so.
@@niranjankothandaraman That is mostly correct. The cross-member layer spacing is 5.1cm (the first one starts at 0.5cm from the bottom). Also, don't forget about the bottom 3 horizontal pieces that are 26.0cm each.
Hi! I think if you do the math to calculate the density of the source sticks I used for the legs, they are around 11 lbs/ft^3 which put it more in the "medium" density range
@@balsaengineering6686 Hey balsa engineering this might be a weird question but im trying to build 5 towers, and im buying balsa sticks that are 36 inches long, how many sticks would I need to make 5 towers (for cross members only). Im thinking of buying 50 sticks but i dont know if thats enough or too much :(
@@steamedfrog8386 Math is your friend :) If you check out at the 9:06 point in this video and see my notes, I show the lengths of all the cross members and horiz members. It adds up to 1055.1 cm which is 415.4 in which if you had perfect utilization would be 11.54 sticks at 36" each. That is not possible though, so add a couple sticks extra for each build. 13-15 for each tower is probably a good estimate. BTW, I recommend buying sheets of balsa and cutting your own sticks, it's much cheaper that way. Good luck!!
@@sillyegbert-mn2zd From the notes in my video, we know the source sticks were 3/16" x 3/16" x 52.5cm. First we can calculate the volume of that in cubic feet. Converting to inches, it's 0.1875 x 0.1875 x 20.669" = 0.7267 cu in. Divide by (12*12*12) to get to 0.000421 cubic ft. Next we know the source stick mass is roughly 2.1g from the video notes. Convert that to lbs and you get 0.00463 lbs. Our final answer is then just 0.0046297/0.00042052 = 11.01 lbs/ft^3. Hope that helps!!
hey balsa engineering, should I order 1/16 * 1/16 inch and 3/16 * 3/16 inch cross members and legs?, also could you tell me what the numbers at the right of your notebook drafts mean?
@@nooby8828 No, the cross members are normal square pieces. The blue numbers are the cross members lengths and the (6) means 6 pieces at that length. The red value on the far right is the total mass of the entire layer. If you get a chance, watch this video I made on how I take notes. It's from last season, but I'm doing the same things for this year as well: ruclips.net/video/6jSlhXZORMs/видео.html
The rules state that the height of the loading block must be at least 50cm from the testing surface. My builds have the height at 50.5cm to provide a little buffer
Well, you should experiment a bit with that. I would start with light for the cross members and probably medium for the source leg material. If you check out my notebook pages in this video, you can calculate exactly the density I used if you want to try and duplicate it as a starting point
Hi Balsa Engineering! Thank you for making this video for this season. I was working on making the most optimized or the benchmark tower for this year. The mass for the tower I made ended up being around 1.2 g heavier than yours. Do you know what could lead to this issue? I’m thinking it could be the amount of glue I used or something like that. Thank you!
If you check out the video at the 6:56 mark, you can compare your build to my benchmark tower in great detail. I show the mass of all the parts including the legs and the combined mass of each layer. My guess is you are using slightly heavier balsa than I used, but you can compare your build exactly if you recorded the weights for your tower pieces (which I highly recommend).
@@balsaengineering6686I’m confused as to how I made this mistake, but I made 11 crosses instead of 10?? According to the notebook page, it should be 4.6 cm from the bottom to top of each cross. The length of the stick is 52.5 cm, so how did you cover for the rest? I think I’m tripping on the math while building it 😭
@@potatoooeed7581if you re-check my notes, the first layer of cross members starts at 0.5cm from the bottom and then the spacing is 5.1cm between layers. Btw, having 11 layers is not a problem and might even be better depending on your materials
@@balsaengineering6686thank you so much! I had another question about reducing the weight, as of now it’s still heavier by about 0.9 or so even after reducing the number of crosses. Why would 11 crosses be better? Also, if my balsa is just heavier, could I just remove one of the cross members on one of the top crosses? Thank you 🙏
I think I found a part of the reason, the design I built is almost exactly like tower number 1 rather than 5. My leg masses are similar to the first one. How did you reduce the mass of the legs? Is just just by sanding it more
You can try and make a tower with square legs, but you won't be able to get flat surfaces to glue your cross members to. Some of my other videos in this series show exactly why that is the case and how you could make 60/60/60 legs.
@@balsaengineering6686does it have to be a 60/60/60 triangle? Can it be any shape as long as u can cut it so it can have enough surface to place the crossmembers?
@@butterflyindisguise3838 If you want a 60/60/60 tower like I have shown here, the legs will need to also be 60/60/60 to have perfectly flat surfaces on all sides
Does 26cm base for the equilateral triangle tower actually fits outside the 29cm circle? I have been trying to do the math and 26 cm side lengths keeps giving me the perpendicular bisector of 22cm instead of 29cm. Idk if I did the math wrong but it would be great if u could show me how u did it
I looked it up :) I can't remember exactly which source I used originally, but here is one that shows the length of a side for our case: socratic.org/questions/what-is-the-area-of-an-equilateral-triangle-inscribed-in-a-circle The formula turns out to be sqrt(3)*r or 25.11cm. You can always just draw it on graph paper and measure, that is a good way to verify it as well
@@butterflyindisguise3838 The ideal cross bracing spacing is closely tied to the strength of the legs you are using. You basically have to optimize them together and it's going to involve some trial and error. I recommend you check out my 5-part series on tower basics to see exactly what I'm talking about, specifically you'll want to watch this one carefully: ruclips.net/video/SwmINqhpHL4/видео.html
Hi, Balsa Engineering. How long does it take to build a tower? I haven’t signed up for the event yet. I’d like to know the time commitment for this event vs other events. Thank you.
Hi! I would say it takes about 2 to 4 hrs to build a tower once you have the material all ready to go. It can take hours to prep the material depending on how much effort you want to put into it
@@cloudovervalley It really depends on how competitive you want to be. You can get by with 10s of hours. The top National teams will put in 100s of hours over the course of a season
I started with 36" sheet balsa, then I cut the source legs to a normalized 52.5cm (you can see this in my notebook images) to create the 60/60/60 legs. The final exact length is achieved by sanding the top off while it's in the assembly jig
@@sillyegbert-mn2zd 52.5cm You can always get this information from my notebook page shown. Check out the 6:58 point of this video. I have written for the legs (source) 3/16 x 3/16 x 52.5cm
Thanks so much for making your videos, I appreciate the amount of time you take to make them, your videos helped me medal 6th in regionals without any testing, we only build one tower and used that same tower for the competition. However, I was also wondering if you could post a video about the non-bonus tower, just like you I also neglected this part, but Troy somehow made a 4.3 gram tower nonbonus and held the full load and didn’t break, meaning that they could beat your benchmark 5.9 gram tower. So could you make a video on testing some non-bonus towers.
Hi! Thanks for the kind feedback and congrats on your results. The goal of my channel isn't to demonstrate the best possible device, just to get teams started on what would be a very good device. I didn't bother with a non-bonus build for a couple reasons. First, unless someone comes up with a non-symmetric design that works well (which might be possible), the tower would look exactly like this one with just different material choices. You can just scale my jig in the XY only to play around with that if you want. Second, I still think the bonus design has a ton more potential than I've shown with the benchmark build. Remember, my benchmark tower held 18.57 kg for an actual efficiency of 3121. That means the design could be optimized to nearly that efficiency at 15kg, which would be a ~4.8g tower or a 4100+ score. I don't expect that perfectly, but I do expect scores close to 4000 using the bonus design if you are looking for what could potentially be top 5 national scores this year. Good luck!!
Thanks for your reply, and also concerning the cross-bracing density, I can’t find websites that sell cross bracings 1/16 by 1/16 36 inches or less at the density I would prefer. Do you have a site where I can get specific densities. I already tried specialized balsa, but their sticks are way too expensive with 20 bucks on shipping and national balsa but they require 50 dollars order purchase, and I would be getting too many cross bracings I wouldn’t use(136). Do you have another site where I can get specific densities for the crossbracings that charge a bit less (not 2.25 dollars per stick, adds up with the amount of testing I do) and don’t have an order minimum.
Specialized Balsa is the only place I know of where you can specify the density. For me, buying pre-cut sticks is way too expensive. That is why I recommend you buy balsa in 4" sheets and cut your own. It will be much, much cheaper and you'll have even more control over the material. It's more work, but it's worth it. Be sure to watch my Balsa Library video if you want to see how I cut most of my sticks from sheets.
Hi Balsa Engineering,
For my last invitational, my tower weighed 6.41 grams and supported 14.1 kg. However, I haven’t been able to achieve a tower score above 3000. My best attempt so far was a tower that weighed 6.98 grams and held 16.8 kg. The tower that held the most weight was 7.17 grams and supported 19.7 kg.
I would really appreciate your advice on how to build a tower that can score in the 3000 range.
Thank you!
Hi! It sounds like you are well on your way to building a 3000+ tower. It really comes down to careful material optimization and balance. It takes just the right wood to get the perfect build. I would suggest you try and replicate my benchmark tower as close as possible if you want to hit the 3000+ mark, at least as a starting point. First, cut all the material for your next build and weigh every piece and layer like I show in my notes. Compare you material exactly with what I have to see where yours is different. Your 2865 tower is a very good competition result and if your 7.17g build had an actual efficiency of 2748, so if you properly scale that down to 15kg, that would result in a 15000/2748 = 5.46g tower that would score 3663! So you already know how to build the tower you are after, you just need to zero in on the optimal material. Good luck!!
Hello! What would be the effect if I added a horizontal cross member intersecting each x in the middle? This would halve the distance of the leg between each cross bracing, so you can use a lighter leg?
That is certainly something you can play around with, but all those extra cross members will add a lot of weight. You'll have to experiment to see if that added weight is more or less than the amount you can lower the leg mass. Another benefit of cutting everything ahead of time is that you can figure out if you can even build a tower that is overall lighter before you glue anything. I always like to estimate the final mass of the tower before actually starting construction to know if it's worthwhile or not with what I'm trying to achieve.
Hi Balsa engineering, I was wondering what is the best method to store a tower to it doesn’t get heavier overnight, as that has happened to my towers. Maybe it’s from moisture? Thanks!
Hi! I like to use a dry-box to keep all my devices in a controlled environment. I made a video awhile ago showing this process in a lot of detail and the benefits that you might want to check out. I'm showing bridges in the video, but it applies to everything: ruclips.net/video/6zOvHMZLaNE/видео.html
Hi Balsa Engineering! I was wondering what the measurements are for this tower's cross-legs. Thank you so much for these videos!
Hi! You can see those dimensions in this video when I show my notebook page, for example at 6:53 Check out the blue numbers on the right side of the page. The bottom layer is 25.5cm (6 pieces), the next layer is 23.2cm, all to way to the top layer which is 7.4cm. Hope that helps!
@@balsaengineering6686 Thank you so much!
how far apart did u make the crossing layers.
You can see that in this video when I show my notebook pages. For example, at 6:58 The bottom horizontal layer is at 0.5cm and each layer after that the spacing is 5.1cm.
Hello Balsa Engineering. Thank you for these amazing videos. We wouldn't know where to start with the triangular legs without these great tips. Can you kindly let us know the density of the balsa wood you used in the benchmark build? What is the density of the legs (3/16 x 3/16) balsa sticks and what is the density for the cross members (1/16 x 1/16)? We read through all your responses to the comments and figured the density for the legs should be medium and for cross members it should be light. Is my understanding right? Appreciate your response.
Thanks! Yes, if I recall, the source legs were in the "medium" density range at around 11 lbs/ft^3. I don't have the value for the cross members off hand, but you should be able to compute it exactly from the masses I've shown in my notebook page. They are definitely in the "light" range.
@@balsaengineering6686 Thank you so much for taking time to respond to our question.
Based on my calculations, your source wood at a length of 36 inches had to be around 3-3.5 grams, right?
That sounds about right. Probably closer to 3.5g, although I didn’t keep track of that. I did record all the 52.5cm source legs though and they ranged from about 1.9 to 2.2. Only the final sanded weight matters though, so that is the library of material you want to build up to choose from
@@balsaengineering6686 Thank you. I've been at it for the past hour, trying to find the right weight wood. Been getting wood too light, but never too dense, but just finally struck a 3.3. Hopefully I can get more!
Hello! What are the units for the lengths of the legs and cross members?
Those measurements are all in cm
hi balsa engineering - for the bottom part of your tower, for your triangular legs, how do you ensure that the tower is standing straight on 3 flat surfaces? Do you sand the bottom of the triangular legs until they are flat and level? thank you!
Hi! I've found in my recent years of building a lot of towers, that it isn't necessary to have the bottom of the legs sanded flat. I always just leave them at an angle and it works fine. That being said, you need to be pretty deliberate to get the legs perfectly aligned from the start. If you check out my assembly video at around the one minute mark, I show how I tape the legs in place on the jig while using a very flat build surface. This works well to make everything nearly perfect: ruclips.net/video/TkUS4W4bOZM/видео.htmlsi=w-yEqXui0G-rYRWH&t=70
@ oh i see! thank you so much!!
Hey balsa engineering, i tried to 3D print the STL jigs that were in the description, but all the actual tower pieces contact the base of my 3D printing machine at only one point, making the print fall over. Are the files supposed to be like this? What should I do to fix the positioning of the prints?
Hi! You may need to rotate the STL files before printing. Your slicer program should be able to do that easily. Just select the object and rotate it, probably just 90 degrees in one direction so it is flat on the printing surface. Good luck!
Hey balsa engineering! I was wondering what kind of glue you use for your legs to minimize weight and whether you have a strategy for adding minimal amounts of glue?
Hi! The short answer is I like to use 50 cps CA glue. The long answer, including techniques, is the dedicated video I made on that topic: ruclips.net/video/55lb2KzSiwg/видео.html
What glue do you recommend for a strong tower?
The short answer is 50cps CA glue. The long answer is to watch my 25 minute video I made on this exact topic: ruclips.net/video/55lb2KzSiwg/видео.html Good luck!!
@@balsaengineering6686 Thank you! Do you prefer thick, medium, or thin 50cps CA glue.
@@madisonwhite7811 50cps is what defines the viscosity. 50 is somewhere between the typical "thin" and "medium" ratings
Hello balsa engineering, I noticed that this year you didn’t list the densities for the wood to the left of the tower. You did last year,is there any way you can provide me with those numbers?
Preferably for the 36in and 48in sticks, thanks!
@@demonplayz857 I have the mass listed for the entire layer of cross members, so some simple math will get you source stick mass. For example (6) @ 25.5cm at 0.491g is 153cm or 60.236 in. For a 36" stick, that is just 36/60.236 or 0.598*0.491g, so 0.294g for a 36" for that layer. You can then compute the actual density if you want by knowing the volume, just make sure you get your units correct.
@@balsaengineering6686for the legs are they actually 52.5 cm long or will it be 51.5cm long? I know you say the little space between the first layer and the ground is around 0.5 m, and from there each section is 5.1 cm long, doing the math it would be 51.5 cm? But on the 5th design you said it was 52.5 cm long?
Hi Balsa Engineering, first off I wanted to thank you for making these videos! I found them really helpful last season and I was able to get second place at states thanks to you! For this seasons build I was wondering which type of balsa sheets (dimension's and density) you used for you benckmark build. Thanks!
Thanks for the kind feedback and congratulations on your success last season! If you check out 7:45 of this video, you can see my notebook page for the benchmark build. There I show the sizes and masses of everything I used from which you can calculate the density. To save some time, I believe the source legs (3/16 square) were about 11 lbs/ft^3 which is in the "medium" range. The cross members were all 1/16 square. I didn't calculate the density, but I'm sure they were in the "light" density range. You can see the mass of the entire layer on the far right side of my notebook page in red. For example, the bottom layer had (6) pieces that were 25.5cm each and the total mass was 0.488g. Good luck this season!
@@balsaengineering6686 how were you able to sand the legs down into the triangular shape you needed? should i just wing it from a corner until it hits the proper length of the tower jig's side?
@@ame9792 You are in luck!! I made an entire video on how I created the legs! Check this one out when you get a chance: ruclips.net/video/MTHygxUS3YU/видео.html
So, I got Balsa Wood of 1/8" × 1/8" and 1/16" × 1/16' and 1/4 ×1/4" can I make a tower from this measurements
Sure. You'll just need to make your own sanding jig to make triangular legs out of 1/4 x 1/4 sticks instead of the 3/16 square sticks I used
Hi Balsa Engineering! My 3D printer has a base of 220 mm, and it is not big enough to print the bottom layer of the Div C bonus jig (260 mm across). How much impact on the construction of the tower would it be to split the bottom trapezoid and print the two halves separately? (cutting through the middle of the triangle parallel to one of the sides)
That should be OK. Just tape the two pieces together as tightly as possible and it should work fine. Good luck this season!
Hi Balsa Engineering the program im using doesnt support zip files so do you have the same jigs but as a stl file(divison B)
Hi! Just use Windows (or MacOS) to unzip the file first. All the stl files are included in that single zip package
Hey balsa engineering thank you so much for making videos like this. But I had a confusion on what the size of the base is for for the jig.
Thanks! My overall approach video shows all the details of the jig design and dimensions. Let me know if you still have questions after watching this: ruclips.net/video/_QTOCIHE_1w/видео.html
@@balsaengineering6686 Thank you so much for the help much appreciated. I think I just missed this video when watching this series thank you so much for highly informative videos every year for such build events.
Hi Balsa Engineering! How are you doing? Thank you so much for making these videos and sharing your resources, I really appreciate it! I wanted to ask you what software / app you use to slice the jig? I am asking this because the Tower Bottom STL file is too big for my 3D printer to print so we are trying to split the bottom and print the two halves separately except we don't know how to do that or if we even have access to free resources to do so. Any suggestions? Do you think you could help? Thanks for your time.
Hi! Thanks for the kind feedback! I used a free Microsoft tool called 3D Builder to cut the STL into pieces which worked really well: apps.microsoft.com/detail/9wzdncrfj3t6?hl=en-us&gl=US Some people have said it's not available anymore, so maybe it's a Windows 10 only tool, I'm not sure. I have also read that Meshmixer can do that task as well, but haven't used it for that myself: meshmixer.en.softonic.com/ If neither of those work for you, just google "split stl file" and there are plenty of things to try. Good luck!!
Hi, I am trying to use the link that you inserted in the caption to get info on the jig, however when i click on the link and try to download the files its saying no file to preview and i am unable to get anything off that link. Do you have any idea why this is happening or how i could get the date of the link?
I just tried it and it's still working. It should auto-download a zip file which contains all the stl files. Once you click on it, go to your downloads directory and see if you have it
Hi, balsa engineering! Thank you for the video. Can I just order triangular leg, not sanding the square leg? Because it can make some errors or mistakes.
Hi! I don't know of any place where you can buy 60/60/60 legs. If you find somewhere, please let me know!
I checked with National Balsa and they do not unfortunately produce such legs.
@@completeandabsolutenerd Yeah. Specialized Balsa sells pre-cut 45/45/90 legs, but that's not ideal for our use case either
@@balsaengineering6686 I hope we can find a vendor who will do that because that will save a lot of time and effort, as well as wood waste.
@@completeandabsolutenerd It's not too hard to make them. I found it was about 2-5 min per leg depending on your technique. It will definitely be much cheaper to make them yourself as well
Hi balsa engineering. I was wondering where I can buy the balsa sheets? Also, How did you cut them? Thank you.
I like to buy my balsa sheets from Specialized Balsa: specializedbalsa.com/products/balsa_sheets.php To learn how to cut them, please watch this video: ruclips.net/video/bLsTOpmozGI/видео.html Good luck this season!
Hello, is there a reason why you added a horizontal bracing to the top and bottom of the tower?
not 100% sure on the reason for the bottom but the bracing on the top helps with dispercing the weight since the it gives more surface area for the loading block to lay on.
Actually, the block doesn't sit on the horizontal pieces at the top, so that's not the reason. Because the base is much wider with this bonus design, the bottom is pretty much in pure tension, for which a horizontal piece can help a lot. The top piece, I just decided to go a little conservative to make sure the legs didn't fold in on themselves. I would recommend you experiment with removing both for your builds and see how it goes! They may or may not be necessary depending on your cross bracing! Good luck this season!
How long did your 3d printing take. My printer is small and had to slice everything for the tower in half and building the jig by pieces. Thank you for all you do for these kids. Very methodical process you have that these kids need to learn it.
Thanks for the kind feedback! I don't recall the exact print timing right now, but they take a long time. On the order of 10-20 hours per piece
Hey Balsa Engineering, I am competing in tower for the first time and would like to play with this design. Where can we find the lengths for tower 5 as this was the most optimized one. The lengths of the cross structures and the legs would be helpful. I was also wondering where you got the specific balsa wood sticks. I would like to get the same ones so that I can minimize any flaws.
Hi! You can find the detailed information on each of these tower builds right in this video. For #5, check out my notebook page at the 7:44 mark. Everything in blue on the right shows the lengths of the pieces in cm. The red is is total mass for each grouping. You can compute the exact density by know the size which is also shown (1/16 square for the cross members). I like to buy all my balsa in sheets from a place called Specialized Balsa. It's not that the wood is better, but it's the only place I know of where you can specify the density range when ordering. I would highly recommend you check out some of my general videos to learn more about getting great material to use. Here is one to get started: ruclips.net/video/bLsTOpmozGI/видео.html
@@balsaengineering6686 Thanks, I'll take that into account. Our club itself has some Balsa wood sticks, I'll see if it matches the density of it. If not I may need to order myself from Specialized Balsa, do you know the rough estimate of delivery time?
I also just want to make sure, the height of each leg is 52.5 cm, the increment for where each cross member needs to go is 4.6 cm. And the length of the cross members itself starts from 25.5 cm and goes till 7.4 cm., dimensions of each balsa stcik is 1/16 x 1/16 inch. the top has 3 (4.5 cm ) sticks.
@@niranjankothandaraman They are a small family-run business, so their delivery speed changes a lot depending on how busy they get. My experience has typically been about 1-2 weeks or so.
@@niranjankothandaraman That is mostly correct. The cross-member layer spacing is 5.1cm (the first one starts at 0.5cm from the bottom). Also, don't forget about the bottom 3 horizontal pieces that are 26.0cm each.
Hi Balsa Engineering! Should I use light-density balsa or medium-density balsa for the main legs?
Hi! I think if you do the math to calculate the density of the source sticks I used for the legs, they are around 11 lbs/ft^3 which put it more in the "medium" density range
@@balsaengineering6686 Hey balsa engineering this might be a weird question but im trying to build 5 towers, and im buying balsa sticks that are 36 inches long, how many sticks would I need to make 5 towers (for cross members only). Im thinking of buying 50 sticks but i dont know if thats enough or too much :(
@@steamedfrog8386 Math is your friend :) If you check out at the 9:06 point in this video and see my notes, I show the lengths of all the cross members and horiz members. It adds up to 1055.1 cm which is 415.4 in which if you had perfect utilization would be 11.54 sticks at 36" each. That is not possible though, so add a couple sticks extra for each build. 13-15 for each tower is probably a good estimate. BTW, I recommend buying sheets of balsa and cutting your own sticks, it's much cheaper that way. Good luck!!
How do you calculate the 11lbs for the legs?
@@sillyegbert-mn2zd From the notes in my video, we know the source sticks were 3/16" x 3/16" x 52.5cm. First we can calculate the volume of that in cubic feet. Converting to inches, it's 0.1875 x 0.1875 x 20.669" = 0.7267 cu in. Divide by (12*12*12) to get to 0.000421 cubic ft. Next we know the source stick mass is roughly 2.1g from the video notes. Convert that to lbs and you get 0.00463 lbs. Our final answer is then just 0.0046297/0.00042052 = 11.01 lbs/ft^3. Hope that helps!!
hey balsa engineering, should I order 1/16 * 1/16 inch and 3/16 * 3/16 inch cross members and legs?, also could you tell me what the numbers at the right of your notebook drafts mean?
Also, you didn't make the cross bracing triangular, did you???
@@nooby8828 No, the cross members are normal square pieces. The blue numbers are the cross members lengths and the (6) means 6 pieces at that length. The red value on the far right is the total mass of the entire layer. If you get a chance, watch this video I made on how I take notes. It's from last season, but I'm doing the same things for this year as well: ruclips.net/video/6jSlhXZORMs/видео.html
So what’s the height it’s supposed to be?
The rules state that the height of the loading block must be at least 50cm from the testing surface. My builds have the height at 50.5cm to provide a little buffer
Hello balsa engineering,
Should I get light or medium weight for the legs and cross members?
Thanks!
Well, you should experiment a bit with that. I would start with light for the cross members and probably medium for the source leg material. If you check out my notebook pages in this video, you can calculate exactly the density I used if you want to try and duplicate it as a starting point
@@balsaengineering6686 thanks!
Do you recommend your three legged tower or is a four legged tower good? For division c
Please read the rules carefully. This year, it needs to be a 3-leg tower for Div C.
Thank you very much I think I never read that part
Hi Balsa Engineering! Thank you for making this video for this season. I was working on making the most optimized or the benchmark tower for this year. The mass for the tower I made ended up being around 1.2 g heavier than yours. Do you know what could lead to this issue? I’m thinking it could be the amount of glue I used or something like that. Thank you!
If you check out the video at the 6:56 mark, you can compare your build to my benchmark tower in great detail. I show the mass of all the parts including the legs and the combined mass of each layer. My guess is you are using slightly heavier balsa than I used, but you can compare your build exactly if you recorded the weights for your tower pieces (which I highly recommend).
@@balsaengineering6686I’m confused as to how I made this mistake, but I made 11 crosses instead of 10?? According to the notebook page, it should be 4.6 cm from the bottom to top of each cross. The length of the stick is 52.5 cm, so how did you cover for the rest? I think I’m tripping on the math while building it 😭
@@potatoooeed7581if you re-check my notes, the first layer of cross members starts at 0.5cm from the bottom and then the spacing is 5.1cm between layers. Btw, having 11 layers is not a problem and might even be better depending on your materials
@@balsaengineering6686thank you so much! I had another question about reducing the weight, as of now it’s still heavier by about 0.9 or so even after reducing the number of crosses. Why would 11 crosses be better? Also, if my balsa is just heavier, could I just remove one of the cross members on one of the top crosses? Thank you 🙏
I think I found a part of the reason, the design I built is almost exactly like tower number 1 rather than 5. My leg masses are similar to the first one. How did you reduce the mass of the legs? Is just just by sanding it more
hey, so i had a question the legs, I got the square ones is it okay or i have to cut the quarter to triangles
You can try and make a tower with square legs, but you won't be able to get flat surfaces to glue your cross members to. Some of my other videos in this series show exactly why that is the case and how you could make 60/60/60 legs.
@@balsaengineering6686 Can you please tell which video excatly
@@YanaPandit-b2f This one tells about how I created the triangular legs: ruclips.net/video/MTHygxUS3YU/видео.html
@@balsaengineering6686does it have to be a 60/60/60 triangle? Can it be any shape as long as u can cut it so it can have enough surface to place the crossmembers?
@@butterflyindisguise3838 If you want a 60/60/60 tower like I have shown here, the legs will need to also be 60/60/60 to have perfectly flat surfaces on all sides
Hi, where can i find the stl files that you used for the main three-legged jig? Thank you!
You can find the main jig files linked in the description of this video: ruclips.net/video/_QTOCIHE_1w/видео.html
Does 26cm base for the equilateral triangle tower actually fits outside the 29cm circle? I have been trying to do the math and 26 cm side lengths keeps giving me the perpendicular bisector of 22cm instead of 29cm. Idk if I did the math wrong but it would be great if u could show me how u did it
I looked it up :) I can't remember exactly which source I used originally, but here is one that shows the length of a side for our case: socratic.org/questions/what-is-the-area-of-an-equilateral-triangle-inscribed-in-a-circle The formula turns out to be sqrt(3)*r or 25.11cm. You can always just draw it on graph paper and measure, that is a good way to verify it as well
also how do figure out how to space your trusses out and how many of them you want?
@@butterflyindisguise3838 The ideal cross bracing spacing is closely tied to the strength of the legs you are using. You basically have to optimize them together and it's going to involve some trial and error. I recommend you check out my 5-part series on tower basics to see exactly what I'm talking about, specifically you'll want to watch this one carefully: ruclips.net/video/SwmINqhpHL4/видео.html
Hi, Balsa Engineering. How long does it take to build a tower? I haven’t signed up for the event yet. I’d like to know the time commitment for this event vs other events. Thank you.
Hi! I would say it takes about 2 to 4 hrs to build a tower once you have the material all ready to go. It can take hours to prep the material depending on how much effort you want to put into it
Thanks for responding. Do you know the estimated hours for the whole process?
@@cloudovervalley It really depends on how competitive you want to be. You can get by with 10s of hours. The top National teams will put in 100s of hours over the course of a season
Got it. Thanks.
Hello!
I see that the jig included in the shared folder is the Bonus one. Are there any plans to share the non-bonus version? Thanks in advance!
Nevermind, just saw the approach video! Idk how i missed that lol.
What glue u use?
The short answer is 50cps CA. For the long version, please check out this video: ruclips.net/video/55lb2KzSiwg/видео.html
Are you starting with 36 inch long legs?
I started with 36" sheet balsa, then I cut the source legs to a normalized 52.5cm (you can see this in my notebook images) to create the 60/60/60 legs. The final exact length is achieved by sanding the top off while it's in the assembly jig
Thanks. So are the weights listed the 36” or the 52.5cm?
@@sillyegbert-mn2zd 52.5cm You can always get this information from my notebook page shown. Check out the 6:58 point of this video. I have written for the legs (source) 3/16 x 3/16 x 52.5cm
Is there a design log bonus this year similar to last year, or was that removed?
I believe the design log multiplier was removed for this year, but double check the latest official rules to be sure