# Headlight Reflectors (Metal Spinning)



## Slipped Eccentric (Jan 2, 2008)

A request was made in my other thread to show how I spun the reflector for my headlight. I took some pictures and some video that I hope will show the process.

A quick disclaimer: I'm writing this with the assumption that you are familiar with the safe use of a lathe and are comfortable using one. There is always a chance of injury when getting your hands close to a spinning lathe chuck.

With that said, the hardest part, for myself, was learning when to stop and straighten out the disc when it started to feather. I'll explain that further shortly. Aslo, there are some other videos on TouTube that show actual spinning lathes that were very informative.

First up is the mandrel. It's just a piece of aluminum round stock shaped to the inside profile of the reflector. The step on the side proved useful as it allows for a strngthening lip to be added to the edge of the reflector.









Next, the actual materials. In this case a 1-1/2" diameter disk of anneald brass and a round stub with a center-drilled end. Both sides need to be square and I used a piece of 3/16" thick wall brass tube.









Solder the stub to the center of the disc. I used silver bearing solder in case the parts heated up.









Then mounting the disc-stub assembly in the lathe. The center-drilled end of the stub rides on a live-center in the tailstock, and the tailstock is extended to push the disc against the madrel


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## Slipped Eccentric (Jan 2, 2008)

Now on to the actual spinning.

4 things to take not of in this picture. First, the vertical toolpost. This is circular which allows the bar you're shaping with to rotate freely. Second, the horizontal toolrest. This is also circular for the same reason. Thirds, the bar used for shaping is round. This helps prevent and scratching or gougine of the disc. Fourth. Note the the way the shaping bar is resting. This puts the bar under the rotation of the spinning work and greatly reduces the chance of the chuck hitting it and pushing it towards you. The carriage needs to be locked in place for all of this work.










The next picture is of the finished piece on the mandrel. I honestly forgot to take pictures while spinning but hope the video is kind of clear. Tere would have been more video, but my camera was being temermental.










And the video


http://www.youtube.com/watch?v=_5naRMpGYDM
Don't know how to embed.
(Here ya go, just use the 'Embed YouTube Video' button on the tool-bar








and then paste the copied embed HTML code in the yellow area at the top of the dialog,SteveC mod.)[/i] 

In the first part I am straightening out the edge. While you are pushing the metal around the edges will start to roll around. If you continue to just keep pushing on it it will pleat it's edges forming creases that are very difficult, if not impossible, to get out. Better to stop often and straighten them out that to ruin a part. This was the hardest part for me to learn. You'll see the round bar being used to get the shape down. At about 1:40 i switched to a square bar with smooth edges to form the lip by pressing against the step in the mandrel. The res is straightforward lathe work with the caution to use very light passes as the isn't a lot holding the workpiece on the madrel. You can actually see the part stop spinning a few times.










Questions orcomments are welcomed.


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## Dan Pantages (Jan 2, 2008)

I had asked for pictures and how you did it. Very good demonstration, thank you. I think the hardest part would be making the form. Thank you for the demonstration.


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## Semper Vaporo (Jan 2, 2008)

What was the thickness of the metal you used?


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## David Leech (Dec 9, 2008)

Hi Justin,
Okay:-
1) How thick a material can you 'easily' spin, assuming that it is well annealed?
2) Do you need to re-anneal at all?
3) Are you sure that that is a 'perfect' parabolic shape????? 
4) Have you tried plating the reflector to get a better beam?
Cool stuff
All the best,
David Leech, Delta, Canada


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## rkapuaala (Jan 3, 2008)

SE, 
That is one smooth way to make a reflector. It sure beats the H out of the way I've been doing with a dapping block and a hammer. Thanks for sharing


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## Slipped Eccentric (Jan 2, 2008)

Thanks Steve. I can work metal and machinery much better than I can work a computer. 

Dan, glad you enjoyed it. Hope you found it informative. The hardest part about the form was getting the shape just right and it was a little fussy. A lot of hand work with a file. 

Semper, The material is 0.010" K&S brass sheet. 

rkapuaala, You're actually the one who inspired me to do this instead of turning a refelctor out of a solid block. I think I remember you plating a headlight of your own, but can't seem to find the thread. 

David, 
1) How thick a material can you 'easily' spin, assuming that it is well annealed? *I don't really know. Depending on your tooling possibly some fairly thick plate. I've only tried this so far, but may try some thicker stock to make stacks. I'm using a 10" lathe.* 
2) Do you need to re-anneal at all? *I didn't re-anneal. I actually had problems re-aligning the stub when I tried to re-anneal the first workpiece which ruined it when I mounted it back in the lathe.* 
3) Are you sure that that is a 'perfect' parabolic shape????? *I'm actually pretty sure it's not! I just drew an ellipse in CAD that fit the space constraints that I had and ran with it under the assumption that some form of parabola was better than none at all. I also only aligned the middle of the flame vertically and let it sit where it may in the fore-aft direction. As it is I can get enough light at about 5' to make out rough shapes in total darkness. I'm not expecting to light up the night, but it looks good (I think) and does cast a fair amount of light.* 
4) Have you tried plating the reflector to get a better beam? *Have not gotten that far yet. I will polish the insides and I've been researching plating methods.*


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## rkapuaala (Jan 3, 2008)

SE, I am flattered and converted at the same time. Are you going to plate this beauty like I did? After reading this thread, I'm not hammeingr those suckers out ever again.


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## Slipped Eccentric (Jan 2, 2008)

Thank you again for the inspiration! If you can point me in the right direction on how to plate I sure am! After annealing and beating/shaping boiler plates, I can't imagine shaping a reflector like that. Actually, I did try, but this was MUCH easier and I got better results. I'll be interested to see what you come up with. I think my next project will actually be some 7/8" scale dome tops and bases.


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## Dave Sykes (Jan 3, 2008)

I can state with knowledge that when you get a rag that close on a spinning lathe 
it should be a MUCH smaller piece. 
So if it catches it won't take as big a piece out of your hand. 
78 and still learnig.


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## rkapuaala (Jan 3, 2008)

SE, 
I bought mine at Caswell Platings site. I use the 1 gallon kit, but there are others available. The one thing I do know is that you want the electro less plating, (No electricity) This is a much easier process with just as good of results. 
Be very careful though that when using the mix over your fluid levels are right on. Ask Mark Shrivner , he'll tell you what a disaster I had forgetting to do that.


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