dangerousamateur Posted June 6, 2014 Posted June 6, 2014 (edited) A question for the rocketguys, how much tapering is necessary on a rocket spindle to pull off your motors without extra tools?I mean on long BP spindles. Edited June 6, 2014 by dangerousamateur
dagabu Posted June 6, 2014 Posted June 6, 2014 1.5° is appropriate for easily removal but even a taper of .05° is enough to ease release. There is no hard rule but friction is your enemy as twice now, someone in manufacturing popped a rocket either at my table or next to it. Afterwards, it was concluded that the motor being removed from the spindle was the cause of the incidents.
dagabu Posted June 6, 2014 Posted June 6, 2014 (edited) Whistle I believe, I know for sure one was. Edited June 6, 2014 by dagabu
dangerousamateur Posted June 6, 2014 Author Posted June 6, 2014 The reason I ask is because I have a 1lb BP tool here I got from a fellow pyro. It has a rather short spindle, 120mm, and only about 0.6°.Getting the motors of the spindle is crazy business. I now use the shortest rammer and insert it in the finished motor, with about 15mm fuel free space on the top.Then I queeze it really hard in a vice and pull at the tool with all strength... Getting the motor off is such a pain, I'm starting to my motivation.
dagabu Posted June 6, 2014 Posted June 6, 2014 Here is my solution to the exploding whistle rocket whilst being removed from the spindle. The first pic is of the spindle ready to press a motor, in the parked position. The next pic is the nozzle portion of the tooling lifter enough to eject the motor from the spindle. The last pic is a view of the ACME thread of the spindle and nuts.
schroedinger Posted June 6, 2014 Posted June 6, 2014 Can you unscrew the spindle from the base? If yes get a screw, a nut and some washers.The nut needs to be bigger than the spindle and resting on the tube itself.Add 2-3 washer (bigger than the washer )onto the screw (must be about 1/2" longer than the nut) and add this to the back of your spindle and tighten the screw.This only works if you've a spindle witch has the turnings for a srew in the bottom. If it its different maybe post a picture if your tool so we could help you.
dagabu Posted June 6, 2014 Posted June 6, 2014 The sad truth is that even the "good" tooling will fail within 100 hard pressed whistle rockets using a 1/4 screw for extraction. The threads just are not robust enough to endure such high shear forces without failure. The ACME thread is made for high shear and continuous use. The standard screw thread is made to secure static loads, not dynamic as in motor ejection.
TYRONEEZEKIEL Posted June 6, 2014 Posted June 6, 2014 From what I have heard from numerous pyros is that you really have to take the time to polish your spindle to a pristine surface. Then the motors will pop off with ease.
ddewees Posted June 6, 2014 Posted June 6, 2014 The sad truth is that even the "good" tooling will fail within 100 hard pressed whistle rockets using a 1/4 screw for extraction. The threads just are not robust enough to endure such high shear forces without failure. The ACME thread is made for high shear and continuous use. The standard screw thread is made to secure static loads, not dynamic as in motor ejection. I'm well over 100, and no issues yet (knock on wood).
nater Posted June 6, 2014 Posted June 6, 2014 A polished spindle certainly helps, the fuel you use makes a big difference too. I have much more trouble removing a sali whistle motor from the spindle than I do a NaBenz one.
WonderBoy Posted June 7, 2014 Posted June 7, 2014 I now use the shortest rammer and insert it in the finished motor, with about 15mm fuel free space on the top.Then I queeze it really hard in a vice and pull at the tool with all strength... DA, Are you just pulling the motor straight off the spindle? I have been using the LaDuke method, similar to what you're doing, but secure the base in the vice and using pliers over where your rammer is inserted, give it a quarter turn to release the motor, then it'll usually just slide off. I also like to rub some candle wax on the spindle before pressing the motor. Dag, that looks interesting, I don't quite understand it though. Is the nozzle forming portion separate from the spindle? WB
dagabu Posted June 7, 2014 Posted June 7, 2014 DA, Are you just pulling the motor straight off the spindle? I have been using the LaDuke method, similar to what you're doing, but secure the base in the vice and using pliers over where your rammer is inserted, give it a quarter turn to release the motor, then it'll usually just slide off. I also like to rub some candle wax on the spindle before pressing the motor. Dag, that looks interesting, I don't quite understand it though. Is the nozzle forming portion separate from the spindle? WB I think I know what you mean, yes. Take a look at the pic for clarification.
dagabu Posted June 7, 2014 Posted June 7, 2014 I'm well over 100, and no issues yet (knock on wood). I press to 5000-8000 LPI, if you press to lesser pressure, you may be able to get by with the 1/4" screw. I was not and stripped the hole in under 50 removals.
dangerousamateur Posted June 8, 2014 Author Posted June 8, 2014 (edited) Is the spindle surface polished and smooth?Yes, perfectly smooth but not so shining like the one dagabu posted. I find it hard to polish because it's to big to put it in a drills chuck for turning. I could only do some kind of up and down polishing with my bare hands. And even if, what kind of polish should i use? I have some car stuff, but i guess that wont be aggressive enough. Edited June 8, 2014 by dangerousamateur
mabuse00 Posted June 27, 2014 Posted June 27, 2014 May I ask a question here? The sad truth is that even the "good" tooling will fail within 100 hard pressed whistle rockets using a 1/4 screw for extraction. The threads just are not robust enough to endure such high shear forces without failure.What material where these spindles made off? I bet aluminium? Besides: It has a rather short spindle, 120mm, and only about 0.6°.Getting the motors of the spindle is crazy business.Sounds like from a certain dutch shop? I think I have the same tool. That's a steel spindle.While OK overall and reasonable priced, getting the motors off is a pain. Steel has undoubted advantages, but beeing less slippery is a price to pay...For my small rockets I like it, because the tool is going to last.
schroedinger Posted June 27, 2014 Posted June 27, 2014 @mabuse Wolther uses stainless for spindles and ben uses brass and those are the better tools we talked about earlier
Mumbles Posted June 27, 2014 Posted June 27, 2014 @mabuse Wolther uses stainless for spindles and ben uses brass and those are the better tools we talked about earlier If you had bothered to actually check, you'll find that Wolter uses a mix of steel and aluminum spindles. Mostly aluminum actually. There will probably also be factors of finish placed on the material, and which grade of material used.
dagabu Posted June 27, 2014 Posted June 27, 2014 Mabuse, The spindle I had was stainless steel, I only use brass spindles for new tooling but the issue is the same, the Machinery's Handbook also calls for tightening torque of 4 pounds for a 1/4" x 20 tpi bolt. Clean and shiny spindle with sali whistle on a 3# set will make you really crank on that bolt/screw. Even a FNL grade 9, 1/4" x 20 screw maxes out at 168 inch pounds or 14 foot pounds. Guess how much torque it takes to pop off a #3 whistle rocket? I bet it's a LOT more...
MrB Posted June 27, 2014 Posted June 27, 2014 Yes, perfectly smooth but not so shining like the one dagabu posted. I find it hard to polish because it's to big to put it in a drills chuck for turning. I could only do some kind of up and down polishing with my bare hands. And even if, what kind of polish should i use? I have some car stuff, but i guess that wont be aggressive enough.I would suggest up and down motion when polishing your tool, rather then a turning motion. What ever scratches left after polishing will be in the direction of said motion, and logic dictates that a up down motion makes for easier removal. Just saying.B! 1
nater Posted June 27, 2014 Posted June 27, 2014 Dag, that last picture clears it up for me. I am guessing the bolts are the base and hold the tube / sleeve just fine? I really enjoy seeing the small modifications people have made to improve tooling. It makes me want a lathe.
mabuse00 Posted June 28, 2014 Posted June 28, 2014 @dagabu:Thank you for your expertise.How about the greater slippyness of brass, do you feel it makes a big difference comparing to steel? A thing to consider is, all reputable tooling sellers do offer these spindle removers. This type of failure cant be to common...
dagabu Posted June 28, 2014 Posted June 28, 2014 Dag, that last picture clears it up for me. I am guessing the bolts are the base and hold the tube / sleeve just fine? I really enjoy seeing the small modifications people have made to improve tooling. It makes me want a lathe. Not sure what that means Nate, the ACME rod goes all the way from the tip of the spindle to the base, the bottom nut is soldered on to the thread. No bolts on this spindle assembly. Look on Craigslist for lathes, in the Twin Cities, we allways have a crap ton of them available.
dagabu Posted June 28, 2014 Posted June 28, 2014 @dagabu:Thank you for your expertise.How about the greater slippyness of brass, do you feel it makes a big difference comparing to steel? A thing to consider is, all reputable tooling sellers do offer these spindle removers. This type of failure cant be to common... Hmmmm, Rich Wolters sets are pinned as well as screwed to the base, no such removeable base exists for 'new' tooling from him. You can buy a modification and have Rich remove the pins, use some threaded rod and a knurled grip, to pull the spindle out. Ben Smith allows for the use of his spindle removal tool (also sold separately) and yes, Ben has had sets returned because the threads have been pulled out. Ben did go to Brass spindles and I would recommend that you speak with him about inserting a helicoil and getting a longer puller screw if you are going to do this long term. I am afraid that I myself pulled the threads out of my old Firesmith set and had to helicoil the threads myself. I have done the same for a handful of others and still get the random request for help from people wondering if I could pull a stuck motor off a spindle for them. It's not legal to send the motor attached to the spindle in the mail so I recommend that they use a 5 gallon bucket, fill it halfway with warm water, add a teaspoon of liquid soap after and stir it in the water, place the set in the water overnight (be patient, people) and it all will just about fall of in the morning. If the set is still stuck, and/or the rammer is stuck, pull the motor off and send me the stuck set, I will pull it off safely and will resurface your spindle if you didn't bend it. If you did bend it, surprise! You will get a whistle spindle back from me. Wolter and Firesmith make fantastic tooling, they will repair threads at no cost and will likely help repair sets you broke accidentally but it is rather naive to think this is not an issue long term with standard thread.
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