{"id":2739,"date":"2017-03-19T16:42:07","date_gmt":"2017-03-19T20:42:07","guid":{"rendered":"https:\/\/volareproducts.com\/blog\/?page_id=2739"},"modified":"2017-03-19T16:42:07","modified_gmt":"2017-03-19T20:42:07","slug":"how-to-make-a-superior-prop","status":"publish","type":"page","link":"https:\/\/volareproducts.com\/new2024\/how-to\/how-to-make-a-superior-prop\/","title":{"rendered":"How To: Make a Superior Prop"},"content":{"rendered":"

The other day, Andrew Sego asked: “Can you share how you let-in the plywood on your prop? Was it before or after carving?<\/span><\/span>”\u00a0 Well, you can’t start in the middle of something like that, so I went into the workshop and got the nose off of my Elmendorf Special Greve Racer.\u00a0 The existing prop had some issues over the past season, so I decided to replace it and record all of the steps.<\/p>\n

STEP 1<\/strong> – I weighed the nose assembly.\u00a0 Why?\u00a0 Because this prop flies the plane well and if I swap out the prop, I need to replicate the overall nose weight so that I don’t disrupt the general stability of the model.\u00a0 So, 6.9 grams will be my target weight for the finished new prop.\u00a0 Note, I am only replacing the prop, not the entire assembly (although the prop shaft had to be replaced, too).<\/p>\n

\"NewProp01\"<\/p>\n

Step 2<\/strong> – The old prop was a 6″ Superior Prop; I can’t remember exactly, but I am sure it was a 7″ cut down to 6″. \u00a0 I am replacing this with a 7″ cut down to 6.5″, so I start with a Superior Props 7″ blank.\u00a0 This has a 1.3:1 Pitch, so it was cut to 9″ Pitch.\u00a0 This is how you receive the product from us – most of the wood cut away, true pitch cut into the back side, and blades slightly tapering from a thick hub to a thin tip.\u00a0 IMPORTANT NOTE:\u00a0 we always mark the TOP or LEADING EDGE of the prop.\u00a0 It is important that you remember that and know which side of the prop you are working on.\u00a0 The blade faces you can see when looking down on these markings are the back side of the prop blade – you will sand and shape these faces, but NOT the other faces (the ones you can’t see here).\u00a0 Those faces are the working faces – where the pitch has been cut.\u00a0 you must only lightly finish-sand those faces or you will change the pitch.\u00a0 THIS IS CRITICAL.<\/p>\n

\"NewProp02\"<\/p>\n

Step 3<\/strong> – Lay out your favorite prop blade shape.\u00a0 This is a 7″ Chinese prop (which weighs 4 grams by itself).\u00a0 I make sure the blade is aligned properly then trace around it with a pencil.<\/p>\n

\"NewProp03\"<\/p>\n

Step 4<\/strong> – This is the part Andrew asked about.\u00a0 After locating where the hub would be (front to back), I located and drew a line about 2″ long and 1\/4″ up from the prop base.\u00a0 Do this on both sides.\u00a0 If you use an Xacto, slowly cut over the line repeatedly, switching sides after each pass – and being careful to keep parallel to the base (or perpendicular to the prop shaft).\u00a0 This time, I tried doing that with the balsa stripper seen here.\u00a0 It worked fine – probably better than guessing at parallel.\u00a0 You do have to be careful with the stripper, too, as you can gouge the blade surface (see the gouge to the left of the cut line).\u00a0 Cut this slot all the way through, but only as long as the line.\u00a0 The idea here is to strengthen the prop hub so it doesn’t break as easily.<\/p>\n

\"NewProp04\"<\/p>\n

Step 5<\/strong> – cut a piece of 1\/64″ plywood the same length as the slot (2″ in this case) and wider than the blade (1\/2″ in this case).\u00a0 You want to center this ply in the slot, leaving excess on either side.<\/p>\n

\"NewProp05\"

1\/64″ plywood spine<\/p><\/div>\n

Step 6<\/strong> – Test fit the ply into the slot.\u00a0 Be careful and take your time.\u00a0 You will probably need to do this two or three times as the slot is not the same thickness as the wood.<\/p>\n

\"NewProp06\"<\/p>\n

Step 7<\/strong> – Soon you will be able to insert it completely.\u00a0 Test fit to insure you know how you want it to end up.\u00a0 That is, centered end-to-end and fore-and aft, so that equal amounts of the ply are visible on either side of the prop blank.\u00a0 Make sure you can slide this in and out relatively easily – like a drawer.<\/p>\n

\"NewProp07\"<\/p>\n

Step 8<\/strong> – Pull the ply out so that just the edge is in the slot.\u00a0 Lay a bead of medium CA on the top and bottom of the plywood.\u00a0 Then carefully press the spine back into the slot, aligning so that it matches how you had it set up in Step 7.\u00a0 Use a stick of balsa to wipe off the excess CA after you slid it in.\u00a0 On the other side, run some thin CA along the top and bottom intersection of the ply and the balsa.\u00a0 Do this because it is likely that the medium CA did not go all the way into the wood.\u00a0 Thin CA from the other side should seep in and complete the gluing process.<\/p>\n

\"NewProp08\"<\/p>\n

Step 9<\/strong> – Using a SHARP knife, carefully trim off the plywood that sticks out of the prop blank.\u00a0 Take your time and be careful – avoid a slipping knife that gouges the balsa.<\/p>\n

\"NewProp09\"<\/p>\n

Step 10 – Once you have the plywood trimmed close, use a sanding stick to sand the ply down to the surface of the prop blank.\u00a0 You will probably need to sand the plywood more later when you shape the blade, but this is a good start.<\/p>\n

\"NewProp10\"<\/p>\n

Step 11<\/strong> – Using your sharp knife, cut NEAR the pencil line.\u00a0 Try to keep the blade perpendicular to the surface of the balsa; it is not super critical, but will help with the blade shape.\u00a0 Carve down to about 1\/16″or 1\/32″ close to the line.\u00a0 You will sand down to the line in the next step, so removing most of the required wood with the knife will make sanding a little easier later.<\/p>\n

\"NewProp11\"<\/p>\n

Step 12<\/strong> – Using a sanding stick or board, sand away the remaining excess balsa.\u00a0 Again, try to keep the sander perpendicular to the surface of the blade.\u00a0 In this photo, you can see the edge in the upper right has been sanded and I am now working on the other side.\u00a0 I use up-and-down sanding here to rough in and then side-to-side to smooth the line.<\/p>\n

\"NewProp12\"<\/p>\n

Step 13<\/strong> – This photo is just to show the blank after the blade shape sanding is completed.\u00a0 Note that this is a strange shape of prop since I could not have any blade behind the nose bearing – downthrust was already hitting the long vertical nose.\u00a0 So all of the prop blade in front of the hub and base makes these blades look strange.\u00a0 The cutout will be covered by the spinner and this is where the Nason clutch will be installed.\u00a0 Nason clutches are great for use inside a spinner since they automatically catch the prop shaft and require no manual setting (like the Garami clutch sometimes does).\u00a0 This prop could work as it is, but there is much to be done to finish it.<\/p>\n

\"NewProp13\"<\/p>\n

Step 14<\/strong> – Remember when I said it was critical to know the side of the blade to carve and the side that must be left alone?\u00a0 (If not, go back and read Step 1.)\u00a0 Now is when you need to know that.\u00a0 These blades are way too think and you must carve and sand them down to their final thickness.\u00a0 It only takes minutes once you know what to do.\u00a0 Remember – LEAVE THE WORKING SIDE ALONE – only work other surface – the one that you can see when you look down on the prop from the front.<\/p>\n

Using your sharp knife, carefully cut off the corners, beveling that edge.\u00a0 Be careful the direction you cut – sometimes the knife will get into the grain and split the wood – that is bad.\u00a0 Always cut across the grain to avoid that.\u00a0 Once you have beveled those corners, use the knife to thin the tip.\u00a0 You only need to do a rough job here because sanding will take care of the rest.\u00a0 Also, don’t over cut with the knife or you will cut away wood that should remain.\u00a0 Use your sanding board to bring the thickness of the prop down to where you want it to be.\u00a0 It takes a couple of props to get better and better, so don’t be discouraged if your first prop isn’t as good as you would like.<\/p>\n

\"NewProp14\"<\/p>\n

Step 15<\/strong> – Here is the prop sanded to (nearly) final shape.\u00a0 Remember, do all of your work on the back side – only lightly sand to clean up the surface of the working side.\u00a0 Superior Props as cut to true pitch at all stations and any aggressive sanding on that working face will change the blade.<\/p>\n

At this point, the prop is read for your favorite sealing or finishing process.\u00a0 I use thin CA.\u00a0 I lay a couple of beads on one surface of one blade and rub it in evenly with my pinky finger.\u00a0 I make sure it is as smooth as possible.\u00a0 Then I use my sanding stick to sand down and smooth out that layer of CA.\u00a0 I do it again, this time with less CA.\u00a0 Then I sand that surface again with a finer grade of sander, removing all high spots.\u00a0 The finished prop has a satin finish that is harder than the balsa.\u00a0 That process on this prop added 0.4 grams of weight.\u00a0\u00a0 This provides basic protection only.\u00a0 The blade can still nick or crack or break, but it is better than bare balsa.<\/p>\n

\"NewProp15\"<\/p>\n

Step 16<\/strong> – Every Superior Prop comes with a 3\/32″ hole drilled in the center for a prop shaft.\u00a0 I have had problems with this area in the past – after a few flights, my aluminum tube bushing wears the soft balsa and the prop gets a little wobbly.\u00a0 The new spine is just one of the things that I am hoping will fix the problem.\u00a0 Of course, the spine did not have a hole drilled in it.<\/p>\n

Use a piece of 3\/32″ OD aluminum tubing to act as a drill guide.\u00a0 And use a 1\/16″ drill.\u00a0 I do this next step by hand.<\/p>\n

\"NewProp16\"<\/p>\n

Step 17<\/strong> – Using the tubing as a drill bushing, gently drill through the plywood with the 1\/16″ drill.\u00a0\u00a0 Again, I just do this by hand, without even a pin vise to hold the drill.\u00a0 Just be careful – don’t stress the sides of the balsa hole.\u00a0 Remove the tubing and do the same process again with a 3\/32″ drill (without the tubing this time).\u00a0 Again, be careful not to disturb the existing balsa hole.<\/p>\n

\"NewProp17\"<\/p>\n

Step 18<\/strong> – Eventually, you will be able to fit the 3\/32″ OD aluminum tube all the way through the prop.<\/p>\n

\"NewProp18\"<\/p>\n

Step 19<\/strong> – The second part of strengthening the hub for the tube bushing is to glue small plywood washers on the front and rear of the prop hub.\u00a0 It is my hope that this will anchor the tubing in three strong places – the front and back and the center spine.<\/p>\n

I insert extra tubing, put medium CA around the hole on the prop, and slip on a washer.\u00a0 I press it down into the glue and rotate the tubing so that it doesn’t get stuck.\u00a0 I don’t use too much glue – just enough to hold the ply washer in place – final gluing will come later.\u00a0 Do that front and back.<\/p>\n

\"NewProp19\"<\/p>\n

Step 20<\/strong> – This is the final tube bushing installation.\u00a0 I insert the tubing so that about 1\/32″ is sticking above the surface of the ply washer on the other side.\u00a0 Then I mark about 1\/32″ excess on this side, scribing a mark with a knife.\u00a0\u00a0 Remove the tube and cut the tube to the newly defined length.\u00a0 Similar to the plywood spine gluing in Step 8 above, I just start to insert the new tube into the hole and apply medium CA around the tube.\u00a0 I press it into the prop, making sure to leave some excess tubing on each side.<\/p>\n

I let that CA set up and then I put just a drop of thin CA on the washer so the CA flows under the washer and at the tubing and washer junction.\u00a0 It should wick into the assembly and hold it firm permanently.\u00a0 Note – this is why the aluminum tubing was a little long – so the thin CA didn’t get inside the tubing.\u00a0 Be very careful with that part.<\/p>\n

Once the CA is set, use a coarse sanding stick or a fine file to grind down the excess tubing.\u00a0 It should be flush with the ply washers.\u00a0 On my Nason and Garami clutches, I use a 1\/16 OD thin-walled brass tube inside the 3\/32″ tubing.\u00a0 This should be cut to nearly 1\/16″ longer than the aluminum.\u00a0 This tubing will accommodate an 0.047″ prop shaft wire.<\/p>\n

\"NewProp20\"<\/p>\n

Step 21<\/strong> – Here is the nose block with the new replacement prop.\u00a0 The new prop was slightly heavier than the original.\u00a0 I did have some clay in the nose, so I just removed that until I replicated the original nose weight.\u00a0 A spinner will be added once I have re-trimmed the plane for flight.<\/p>\n

This process took a few hours; maybe 4 or 5.\u00a0 But much of that time was taken planning and taking the photos.<\/p>\n

\"NewProp21\"<\/p>\n

\"NewProp22\"<\/p>\n","protected":false},"excerpt":{"rendered":"

The other day, Andrew Sego asked: “Can you share how you let-in the plywood on your prop? Was it before or after carving?”\u00a0 Well, you can’t start in the middle of something like that, so I went into the workshop … Continue reading →<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"parent":1107,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-2739","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/volareproducts.com\/new2024\/wp-json\/wp\/v2\/pages\/2739","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/volareproducts.com\/new2024\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/volareproducts.com\/new2024\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/volareproducts.com\/new2024\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/volareproducts.com\/new2024\/wp-json\/wp\/v2\/comments?post=2739"}],"version-history":[{"count":0,"href":"https:\/\/volareproducts.com\/new2024\/wp-json\/wp\/v2\/pages\/2739\/revisions"}],"up":[{"embeddable":true,"href":"https:\/\/volareproducts.com\/new2024\/wp-json\/wp\/v2\/pages\/1107"}],"wp:attachment":[{"href":"https:\/\/volareproducts.com\/new2024\/wp-json\/wp\/v2\/media?parent=2739"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}