UGEARS Engine 3D Wooden Puzzle Brain Teaser Construction Set for Teens and Adults

I give the model 5 stars because it is involved enough to hold an adults attention, but not so complicated that it could not be completed in a single evening. I believe a teen could get it assembled but would need to be mechanical minded to get it to run well. The manual could use some trouble shooting tips....I have built Ugears kits before and I build a bit different than most people and even differently than the manufacturer recommended...here is how I got it to run Very well:There are a couple critical parts of this model that need special attention, the number one issue is the spacing and tuning of the upper piston, it is the smaller one with 2 pistons and it is actually the air diverter valve the controls the air flow AND timing to the larger power piston ( lower). When you fit the piston and housing on to the lower base the slot in the bottom of the piston assembly fits over the middle rail in the base...the rail is longer than the piston assembly and this allows you to Correctly "Time" your Engine! It is crittical that the upper piston is centered in the jug as you rotate your flywheel...the pistons should travel to just sub-flush with the jug at top dead center on the left and bottom dead center on the right!...you need to remove the last plywood round ring on the left to view this correctly! Roll the engine over slowly, then if the upper piston sticks out at the end of it's travel either on the left or on the right...gently lift the entire assembly and slide it left or right until both pistons come just flush or better yet just sub flush...if the piston travels to far to the left it will tap the last ring of plywood, cause your engine not to run...if to far to the right it will leak to much air and the engine will have poor performance.The second adjustment is my piston rod (the big one that goes from flywheel to lower power piston) would touch the axle the Tachometer needle rides on if I fully seat the piston/cylinder assembly all the way down on the middle ridge...carfully observe it as you roll the engine over slowly and if it touches then slightly raise the assembly until it no longer touches!Than recheck timing in upper cylinder...if still well centered the engine should run well with just your breath, try not to get moisture in your engine!The other area I differ from manufacturer recommended assembly is rather than lubrication from wax I use graphite, just an ordinary #2 pencil, I rub both the bore and the pistons all very well with the pencil lead until they are completely silver gray, this has a burnish effect making the grain of the wood very smooth and slippery from the graphite, this is much smoother than sticky wax...I also use it on the toothpick axles and also the holes the toothpicks ride in...my engine will coast for nearly 4 seconds with only one finger flick!I do sand the little nubs off the parts but no more than the nubs! The Pistons are undersize for free running and therefore leak Some air...if you sand to much you engine will leak excessive air and have poorer performance.A final optional tip...as you build the jug out of the layers of plywood...lightly sand the flat sides with a fine sanding block, this removes the little wood fuzz and causes the engine to seal better...I went one step further and rubbed a smooth even light coat of wax on the flat sides of the layers as I assembled...the soft yellow bee's wax acts as a seal or gasket between the layers for nice air tight fit.Lastly the flywheel takes some fiddling to get it to run true and smooth, select your best toothpicks for axles!!....spin them in your fingers to be sure there straight!!...time spent here will reward you with a beautiful running engine...I wrote this review because I enjoyed this kit very much and hope it inspires others to get there Engines running well.PS: the flywheel and pistons are blurry in my photo because my engine is coasting!

Model was fun to build, but doesn't hold pressure in the piston; won't work :( I'm a meticulous adult modeler, so I lean towards kit problems more than build problems. Others might have more luck.

Not as easy to assemble as I had hoped. Directions are pictures with symbols. Smaller pieces break easily. Bought for my 11 year old future engineer and he broke one of the pieces. I made another with the scrap wood left from the cutouts and made it work. Make sure you find the section that explains the symbols before attempting to put together. The second time around was easier once we had this info. All in all it was a great bonding/teaching moment for him and I. Neat little toy. I work on a power plant, which is why I chose this one.

Definitely an awesome project for an evening. The main thing to keep in mind is have plenty of wax on the areas it tells you to apply and realize you may need to do minor tweaking once it is all assembled for a very smooth operation. My tweaks were minor.....I removed the upper piston assembly back out because it was slightly binding when I rotated it very very slowly but when I spun the engine fast I did not notice. Once I removed it I sanded it even smoother and added more wax, definitely helped. Also, when I placed the engine assembly to the stand it was a little lower than it should have been by a fraction of an inch which was also letting the upper piston slight bind. You could tell by looking at the angle of the toothpick for the upper piston. Once I raised it ever so slightly and the toothpick was totally horizontal the engine performed fantastically! Take your time and read every direction a couple times! I made a few mistakes and wasted a few toothpicks but thankfully they have some spares with it. Cannot wait to do my next Ugears model.

Piece of garbage. Not difficult to put together, all the parts move with no issue, but it doesn’t work. No matter how much air is forced through, it doesn’t run. I’ve sealed each piece with glue even and still it doesn’t maintain air pressure. Waste of time and money. Oh also it doesn’t come with a balloon.

I was expecting a lot of difficulty based on some of the other reviews, however, I was able to put this model together without any problems. If you take your time and are careful removing the pieces, you should be fine. I did not break one single part. They are attached with just enough wood left to hold them in place and came off cleanly for me. A couple of hints. Work the pieces from both the top and bottom until it loosens, then you'll see the best way for it to pop out. For those that ended up with a non functioning model, make sure everything moves freely. This means that it must rotate several times when you flick it with your finger. Mine did not work the first time even though it seemed to move freely. I thought freely meant I could rotate it with my fingers. I found the two large back wheels were binding a bit and squeezed them together so there was no friction at the two ends. After that it moved very freely and would rotate 6-8 times on a single flick of my finger. Once that was fixed I gave it a flick to start it and simply blew into the opening and it ran as fast and long as my breath would hold out. Though I didn't have a balloon, I have no question that it would work fine with that as well. All in all I thought this was a very well made model and was a lot of fun to put together.