Tweet
It seems to be getting harder and harder to get good flex shafts so I'd like to take a shot at making my own. I don't see anyone offering stubs that are a straight 3/16 on both ends. I know that would be hard since both are 3/16 so here's my idea....procure a .150 stub. Drill the .250 side to .170ish. Turn the end of the cable down to .170ish but where you turn it down, go further than the hole is deep so the solder can be built up right there. Tin the end of the shaft. Tin the stub. Join. Then make a jig that's perfectly aligned and hart the soldered area back up, put in the matched groove of the jig aligning the cable perfectly while solder is soft. Let harden. Should be a nice straight cable? Any ideas or things I'm missing? Thx
-
32" carbon rivercat single 4s 102mph, 27” mini Rivercat 92mph, kbb34 91mph, jessej micro cat(too fast) was -
You will be starting where Ed Hughey began decades ago but, I admire your enthusiasm and drive to give it a go. You will have to use a jewelers torch and high content silver solder. I think Ed said he built them in a vertical jig??? That was over 10 years ago and I wish I got the whole procedure from him when he offered to tell me.
I believe they grind the cable smaller in a circular precision grinder so then you can get it inside a 3/16 stub. After the brazing is done, I believe they are ground again to make them smooth. There is a reason why flex shafts cost what they do.
Nortavlag Bulc -
Good stuff. Thx. I'll make a vertical jig. I can set up a grinding head on my lathe. For the first few experimental shafts I may chuck the shaft up in a drill and turn the end down against my grinder or small belt sander. Flexes don't cost that much but it gets costly when you need several. Keep the ideas coming. I'd like to do these things as true running as possible. I have the equipment to do it or I can buy what ever else I need. I just hate when I go to buy a flex and kintec and/or ose is out of them.32" carbon rivercat single 4s 102mph, 27” mini Rivercat 92mph, kbb34 91mph, jessej micro cat(too fast) wasComment
-
I have made a bunch of 1/4" shafts for our gas monos, but have not tried making a 3/16" one yet. It should be about the same though.
For the stub shaft, I use plain ole grade 8, 1/4-28 bolts! Carbon works better than stainless, cause it's a little easier to get the solder to stick to em. Cut the head off and square the end. I have a Jet 9x20 lathe, so this is a lot easier to do than if using a drill press. I chuck the cable in the lathe and use a dremel tool with a cut off disc to trim off the outer layer of wires. This will leave the core wrap sticking out. Clean the cable end 2-3 times with a solvent like acetone removing all traces of oil/grease. Measure that core, and drill a hole in your stub shaft just a few .000s" bigger in the end. Flux the snot out of it (both pieces)and heat the stub and fill the new hole about half way full with solder.
KEEP THE HEAT ON THE STUB! Try to not get the flame on the wire flex, as this will kill the temper of the wire. While you have the stub and solder hot and molten, push the flex into the hole. The solder will probably solidify, but just keep the heat on the stub and let it flow up into the flex. It will eventually remelt, and the flex will slide on in, and push out any excess solder. You may have to reflux a time or two, and it helps to have a small stainless wire brush the keep things clean.
File off any lumps and bumps, then chuck it up and while spinning (hold the end of the flex or it will beat you to death, and turn it on your slowest setting) hold the file to the new joint to true it up.AmpDaddy
don huffComment
-
Oh, well then it is much simpler.
I put a drill chuck in the tail stock and put the stub it it. Then put the flex in the lathe chuck with only an inch or so showing out of the chuck. This keeps the flex from getting too hot, but also makes it a little harder to get it hot enough.
Use the tail stock feed to put a little pressure on the joint and then as the solder melts, you can feed in more till it bottoms out. Don't push to hard or you will put a bend in the cable at the joint. Actually just a tiny bit shy of bottoming is better and gives a good layer of solder between the two.AmpDaddy
don huffComment
-
Your welcome.
I got my flex cable from the local small engine shop. The owner would let me go through his PILE of traded in and trashed weed eaters. I would pull a few flex shafts from them and cut them to length for soldering. Soak them over night in gasoline, then wash and soak in acetone. They gots to be oil free for the solder to work. I have soaked the end where the joint is made, in acid for a really clean surface. But its so hard to get all the acid back out to keep them from rusting that I don't do that anymore.
Use the right flux too, or you'll never get it to work. It's that white paste kind. I'll get the name of it if you need me to.
I've had people tell me it's a bad idea to use the carbon bolts instead of stainless, but the way I see it, they are covered in grease anyway so what does it matter.AmpDaddy
don huffComment
-
When you cut the outer layer off of the cable, do that in your lathe too. I chuck the cable up with only a little sticking out. You can use a short piece of brass tubing that the cable just fits into. Split it longways so it will close up on the cable while in the chuck jaws. This holds all the cable wires in tight. Then use the toolpost as a brace for the dremel. I use to have one of those dremel flex shafts, and made a holder that fit in the toolpost. That worked really well.
Use a fresh cutoff disc or square the edge on a stone, when you get near the bottom of the cut. Then with the lathe turning the cable, cut at the wire trying to NOT cut too deeply and score the inner wraps. I usually do not cut them all the way through, but rather stop a little shy and then break the wire the rest of the way off. You'll have to cut them almost all the way so that the wire is thin enough to break without bending. I don't want any marks on that iner wire as that's where the strength of the cable comes from. Put a little counter sink in the hole of the stub shaft to allow the non square ends of the wire to fit into. This also gives a more solder area instead of just a butt joint.
It's also important to solder the motor end of the cable too as this locks the inner and outer cable wraps together. This helps keep the cable from growing and shrinking (lengthwise) when it gets loaded and unloaded.AmpDaddy
don huffComment
-
This is a lot of good info that I really appreciate. It will use it too. I'm going to start making my own flexes when I get back from vacation. I've been using acid core silver solder to solder the end that goes in the collet, will this solder work also for this or do I need something different?32" carbon rivercat single 4s 102mph, 27” mini Rivercat 92mph, kbb34 91mph, jessej micro cat(too fast) wasComment
-
Did you figure out what you're using for flex? I'm trying to find some high quality .187 in left and right rotation, just the flex, no shafts.....curious where you're going to get it.My private off road rc track
https://www.youtube.com/watch?v=XC3H...yaNZNA&index=8Comment
-
32" carbon rivercat single 4s 102mph, 27” mini Rivercat 92mph, kbb34 91mph, jessej micro cat(too fast) wasComment
-
Well I finally got around to doing this. I made a jig so after I joined them I can hear it back up slightly in the jig and the tabs will straighten it out. I made my first one tonight. Worked like a champ and it's straighter than most flexes I've purchased. Here's what I did: I bought some octura stubs for .150 shafts from ose. Roughed up inside. Chamfered the inside and outside edges. Then found off the first layer of my flex cable. Wadduya know....the next layer is .150. Sanded down a little. Tinned it. Dropped a pice of solder in the stub shaft. Stuck the stub in the hole drilled in my jig. Heated it up, inserted flex. Cooled it. Put in jig and put some light tension on the flex with the tabs and heated it and rotated it adding solder where I needed. Cool. Rough grind it to almost flat. Then on the thin belt sander then polish it. Whew. Writing it took more time than it takes to make one lol.
The jig
Flex after I finished it. It's pretty dang straight!
32" carbon rivercat single 4s 102mph, 27” mini Rivercat 92mph, kbb34 91mph, jessej micro cat(too fast) wasComment
-
Very nice! Slightly confusing but I just woke up. Nortavlag Bulc Comment
-
Is the jig steel or aluminum? Would you give dimensions so others might make a jig?
Nortavlag Bulc Comment
Comment