Rehearsal Stunt Lightsaber - "The Core" sequel

thd9791

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I decided to make a separate thread for this. With the help of Halliwax, I have worked with 2 "cores" and they both have threaded centers. My Vader ROTJ just has a hex bolt stuck in it since it's just for show, and my ESB stunt has a 3/8 16 tapped center (about 2 inches in depth). The few blades I've stuck in the Graflex handle have a threaded rod set-screwed (pinched) inside the blade, ala Episode III style. I suppose I could have gotten them stuck in the handle, and slid the blade over the exposed rod ala Ep. I style.... either way..

Anyway, Here comes the infamous Rehearsal Stunt. Pics to come, I'm headed to my small basement shop now..
 

thd9791

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Okay, so I started out with:

1) random piece of steel, same diameter as V2 steel rod. This thing is dense and has a black and light rust coating right from the metal shop, no clue what it technically is, but it's steel
2) 1.5" OD aluminum pipe, with an 1/8" wall
3) solid aluminum that I hand-sanded to fit, so it was already close. About 3.5 inches of it.
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It took a LONG time to mathematically guess the length. I was getting 10.7 or a little over 11 inches. The 10.7 was too close to a graflex, and this thing is noticeably longer, so I went with the latter. I actually had to guess the straight angle, it's not 45 degrees, and cut about 1/8 too long, in order to have enough metal to sculpt the flat lower area of the emitter. Hard to explain, but if id cut on point there would be no flat area but a gap below where I wanted. Remember, cutting this like cutting the corner of strip molding, it's going to be further from the middle at both ends.
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I then studied the profile in every good image i could find. I first cut the blunted top. Then I realized the saber has straight sides. I had to grind enough away that the profile did not curve back inwards near the top!
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see? Still too curvy on the sides...

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almost...

I had already hand sanded the round stock to slide inside (also ran a half round bastard file around the inside of the tube) so I went and drilled a hole for the steel rod 4/5 of the way through. My drill press drifted a little but it's not that far off
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Then I took to starting the countersinking. I located each one i could see in pictures and theyre not symmetrical... at all.
I did the tube first, then slid the core in and used the first holes as a guide.


I must have bad bits or a loose drill press because they rattle, scream and leave octagonal holes unless I cram it in there. I also have a dull tap so I have to get a new one, I made my arm spasm twisting the tap through little by little.

It worked though. The core can still slide around a bit and the bolt is poking through so I am going to trim the bolts a little so it pinches better
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Threw a replica clamp with gaffer tape on there... not bad!
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Mouse Vader

Well-Known Member
That's quite convincing. Good Job.

Some comments:

I'm currently working on my motorised graffy stunt. I have to get a new bit of outside tube as I cut it match a graflex tube only to later discover, while scaling for the button positions, that its 280mm & not the 275mm I cut to. I did a complete scale measure for the whole thing then. Anyway I'm getting scale measures bracketing 280mm & 11" is 279.4mm equiv. & as we are dealing with late 70's Britain they're most likely working in inches. Easy figure to work to as well. Looks like they used here as well.

Your steel is likely 'mild' steel aka EN1a ( & technically hasn't enough carbon content to be called steel - just iron, in case anyone wants to be working with iron - but gets called that anyway). It would be called black mild steels because it still has the black oxide scale on it straight from the steel mill (bright M.S. has been cleaned up to bright metal).

must have bad bits or a loose drill press because they rattle, scream and leave octagonal holes unless I cram it in there.
This is known a chatter. It's caused by harmonic vibration among all the bits involved (things not held down firmly enough, drill press to bench, vice to drill press etc. as you suggested also can do this). if you can run your drill slower or faster this should help. A drop of oil on the work area usually helps too. I often use a manual hand drill for large diam. countersinking as you can go really slow & steady.

I also have a dull tap so I have to get a new one, I made my arm spasm twisting the tap through little by little.
Are you using cutting compound with your tap? Oil will help if you don't have any. Aluminium is notoriously bad cutting, it galls - that is, sticks to other metals, you may notice it smeared all over your hacksaw blade. oil helps prevent this & makes for lighter work. Stainless steel is another galling metal especially against more stainless steel. Hence both are really poor metal choice for bearings.

Hope all that is of use. Keep up the good work!
 

thd9791

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Thanks guys! Mouse Vader that was so informative, I can't even begin to thank you. So this tang will be iron/almost steel and i should speed up my drill press. The harmonic stuff is hilarious as I already have the same sympatetic harmonic problems when I tune pianos

I plan on getting at the last 3 bolts today or tomorrow. Also, I'm reminding myself here to grind down the bolts a little so they pinch the core to the tube.

I have to lightly sand off the aluminum order # stamping too, forgot about that.

The blade.. I'm still on the fence about the outside collar, gotta find some high res versions I can blow up to see if it's a short collar or sunken into the core. I do see the two set screws though, like the v2. I may use a ski pole for this one, ther3s an ESB shot of like facing Vader and he has either this or the ANH stunt with a very thick blade.
 

Mouse Vader

Well-Known Member
That's OK. It's basic workshop stuff I was taught by a former engineer for British aerospace when I worked for him for about 18 mnths.
The metal is almost always called mild steel - it took me many years, when I was trying to find some plain old iron, to find out mild steel is pretty much pure iron. Useful if your trying to make an iron age sword repro for instance.
Speed up or slow down your drill. I usually slow down or, more often, use a hand drill. That said Aluminium usually requires higher cutting speeds than steel (iron) but defo use oil, ally gets 'stickier' the hotter it gets.
 

thd9791

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Oh yes forgot to ask. How do you use you tap? You should have at least a second & a plug.
I've been buying Irwin tap sets because they have the straight area to start with at the tip. My 1/4 20 is part of a large OLD tap set that was colored black and just has conical tips that are already worn down. I tried once to use a drill press but couldn't coordinate my hands pushing down and twisting the chuck by hand, so I just twirl them in with a tap handle. WD-40... I used a LOT of it the other day while I was drilling and tapping!

I should really do this, how hard is it? To make the downward curve in the handle.
Surprisingly not that hard, but it was artistic, doing it this way. I didn't make a drawing and dremel out the shape. I did what they probably did, and started by

1) hacksawing the tube at that sharp angle
2) hacksawing off the pointy tip - it arises from cutting a tube at an angle (you get a pointy oval cross section)
3) Laying a metal file against the the oval, and tilting up the file so that you carve a "flatter" portion to the bottom of the cut
4) grinding down the upper corners of the blunted tip you made
5) continuing to work on the upper corners and the flat bottom until you get this shape. Sometimes you have to smooth out the transition from the flat bottom to the sides. Not too right-angly an not too diagonal. See? To get what they did, it wasn't precise by any means :D

Eventually your sides will not curve inwards. I had 4 photos printed out in my basement to eyeball as I carved. I held my saber at the angles in the photos to better understand the profile too
 

thd9791

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I should also say I used a half-round bastard file for most of it, and then sandpaper. Sometimes I rotated the file and slid it lengthwise at the same time to make curved parts
 

Mouse Vader

Well-Known Member
Not quite sure your using these right. There are 3 taps in a set - a taper , 2nd & plug. The taper, as the name suggests, has a tapered tip (teeth ground down) the 2nd has less taper & the plug none. You use them in that order. Taper tap until the going gets difficult, then swap to the 2nd, until the resistance gets more, then plug. If the you need a deeper thread start again with the taper etc & repeat until you have the depth required.

To be honest I (& many others) just alternate between the 2nd & plug tap. This gets harder to do the larger the thread size & the taper tap becomes more useful then (I'm talking 1/2" +). Tapping with a plug tap only is very hard work as you know (your 1/4"), it also makes for a poor quality thread & decreases the life of the tap. It's a drag I know but you soon get used to swapping taps about & overall not that much longer to do & certainly not such hard work.

I'd use a heavier (thicker) oil if you can. WD40 is sure better than nothing - you're using so much of it because it's so thin. If you can get some cutting paste for tapping, even better.

If you can learn the knack of starting a thread in the drill press, do - esp. on round work such as this. As you know it makes sure you're cutting the thread on the same axis as the hole, always a good idea. If you're threading into a flat surface you can make yourself a guide. It's just a hole in a thickish piece of metal (or plastic I suppose) drilled with a clearance drill for the size of thread your using. Place the guide hole over the thread hole & the tap in the guide & away you go.
 

thd9791

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I finished drilling and tapping these holes yesterday. I learned some things again.

I did change the speed of my drill press but what made the most difference in reducing chatter was having the first bolt tightened in place. Once I got a new tap and cleaned up the hole and bore a little it tightened down and the other 3 holes came out very clean.
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I did start by trimming all the bolts by like 1 thread, measuring by the front hole.
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But wait! My drill press drifted so the hole is not centered. That means the bolts in the back have to be shorter. Hard to see here, but they stick out further.
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Next, judging by eye I think my core is 1-2 mm deeper than the real prop. Even so, the countersink for the left upper bolt is awfully close to the edge. Mine pokes out a little. Maybe this is why they added a thin layer of filler, as well as blocking extra light reflected from the aluminum?
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Anyway, I have to trim2 of these bolts a little more, maybe get different steel or use this rod.
I did spin some sand paper around it to get the order printed letters off and give it the ringed finish I see in photos, almost like they sanded it on a lathe.
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Next up is the blade.. another ski pole? This blade is looong and thick
 

thd9791

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Also, I should say, the only taps I've ever used are the Irwin sets that include the accompanying drill bit. Lately I just buy the single tap and use my DeWaldt black drill bit set and look up the accompanying drill bit size on a chart. I've neve4 heard of multiple step taps!

If we find good foam strip....
 

Dann

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Good job!

And yeah, to reduce chatter, "decrease speed and increase feed" is what you learn in machine tool school. Gotta know your speeds and feeds! Or at least print out a chart and hang it on the wall for easy reference. Just look up "speeds and feeds" and I'm sure something will come up.

And yeah, of course ALWAYS have everything you're working with locked down. If you don't have a file card, get one. Aluminum, like folks have said, is soft and gummy and will make filing MUCH more difficult if you don't clean your files often.

Bottoming taps are great to have, to get those threads as close to the "bottom" of the hole as possible. You can always MAKE one from a taper tap in a pinch. I'll use a bench grinder or belt sander to flatten the nose (a Dremel would work, just be careful), then de-burr and dress the edges, like you're shortening a screw's threads to make a shorter screw.

Anyway, yeah I think you're doing a great job on this one!
 
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