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Frank Hoppe
09-06-2011, 12:55 PM
I've been trying to spin copper and aluminum on my wood lathe for the past few days without sucess...Not sure what the problem is....In general it just wrinkles and tares as soon as I try to work it...The speed is at 1500 rpm...Using lub and a wood mandrel...Just can't seem to get it to form properly...Tried annealing with heat and seem to help some...Any suggestions??? I made the forming tool from a steel rod and rounded the end...

Frank

Carld
09-06-2011, 12:59 PM
I think the rpm's are to high. Do you have a book showing how to spin metal?

Metalmelter
09-06-2011, 01:22 PM
Terry Tynan does it all and here is his site: http://www.metalspinningworkshop.com/

I wanted to get into this but it's on the back burner for the moment. He's got videos you can purchase or you can rent them through here: http://smartflix.com/store/search
Just do a search for metal spinning.

I don't know if that helps you but it can surely get you in the right direction hopefully ;)

Oh yea - welcome to the group!

Dr Stan
09-06-2011, 01:25 PM
How thick of material are you using? I've played with spinning a little and have toured plants that do spinning on a production basis. It's more art than science, so don't be too discouraged.

PTSideshow
09-06-2011, 01:53 PM
Terry vid's are great, Rent them from smart flix then buy them they are great. Yes you are too high of speed, All metals needs to be annealed before starting and during the spinning. You can't really spinning any sheet metal. Thickness, dia are important, speed will be dependent of them. The amount of pressure that is applied to the disk and the type of tool rest, and the metal. Also the dia and shape/profile of the turning tools aren't what they appear in photos and drawings in the books.

If you are air spinning, trying to shape the disk with no form behind it you will not have any success.
Principles of metal spinning, by C. Tuells.--Tools and methods used in metal spinning, by W.A. Painter (http://www.archive.org/details/metalspinning00tuel) 1912 internet archive

Metal spinning by Crawshaw Fred (http://www.archive.org/details/metalspinning00crawuoft)1909 internet archive

Are two of the best out there downloadable in E book or PDF or online. Since basically nothing has changed in the metal spinning world since that time, and as been stated. It is an art more than a basic science, they are topical as you will get. Besides the first one is by the publisher of Machinery Handbook, and the second by Popular Mechanics.

I know they have cleared up a bunch of questions along with the dvd's that I had and with both I feel that i will be making progress this winter when I start spinning.

jugs
09-06-2011, 05:18 PM
I've been trying to spin copper and aluminum on my wood lathe for the past few days without sucess...Not sure what the problem is....In general it just wrinkles and tares as soon as I try to work it...The speed is at 1500 rpm...Using lub and a wood mandrel...Just can't seem to get it to form properly...Tried annealing with heat and seem to help some...Any suggestions??? I made the forming tool from a steel rod and rounded the end...

Frank

Speed's OK (abit slow for small stuff)

Tools need to be ground & mirror polished, - (you can also use a ball race bolted on "a stick", :D the OD rolls the metal rater than rubbing)

Copper & Alu work harden very quickly when spinning, so you may have to re-anneal several times (you'll get a feel when you need to do it) DON'T be tempted to "just do that next bit" it always ends in tears. :mad:

jugs
09-06-2011, 05:40 PM
Here's some VIDIOS (http://www.youtube.com/results?search_query=metal+spinning&aq=f) to start you off

& using SPLIT MANDRELS (http://www.youtube.com/watch?v=DGszBVy3cgU)

have fun :D

Frank Hoppe
09-06-2011, 06:51 PM
Guys....

Thanx for your insight....I figured it was work hardening....What is your suggestion for annealling....I heated it with a propane torch till the copper turned dark red and then quenched it in water...Is this OK????

The copper I'm using is 0.025...The aluminum is 0.011...It's basically roof flashing stock material.....The copper looked like the right alloy according to what I read........I think the aluminum was too thin....

I retreved the books off the internet you suggested...HAve some reading to do tonight...

Anyone need scrap copper and aluminum....Got quite a bit at this point...Maybe I'll make some teabag cozies???

Thanx again..

Frank

Stepside
09-06-2011, 07:27 PM
If you are not trying to spin a real deep shape you could try hydraulic forming. 1) you will need a hydraulic press. I built a frame from 2 x2 x 3/16 steel tube. I used a twenty ton jack because I did not have access to a hydraulic press. 2) make a model of the part you want. I have used wood, Urethane castings as well as machined aluminum parts. The model has to withstand the force of the press. 3) On a steel plate first place your model and then a piece of annealed metal and then a large stack of rubber or Urethane . I cannot remember the actual durometer of the rubber, but a stack of truck tire innertube pieces would work. On top of the rubber place a thick steel plate that is bigger than the part. 4) press and then take apart to check the results. You might have to anneal and press a second or third time. With real thin copper and a twenty five cent piece you should be able to read the mint mark.

Questions?

Pete

hornluv
09-06-2011, 08:40 PM
I think it may be a thickness issue on the Aluminum. The copper is probably a work hardening issue. I take it that it's tearing right at the end of the mandrel? If so, you have to lay a bit down on the mandrel before trying to spin the rest of the blank. Have a block in the tailstock the same diameter as the end of the mandrel so the disk is well supported and spin around 3/8" or so tight to the mandrel. That keeps the disk from twisting. Then you can go to bringing down the rest of the disk to 45 degrees and laying a bit more down on the mandrel with each pass. Don't go back over what you've already laid down as that can wear it too thin. Also, with metal and wood turning, you're keeping the tool at the center line and moving horizontally. With spinning it's more of a downward motion. Definitely rent or buy Terry Tynan's videos if you're really interested in this.

darryl
09-06-2011, 09:15 PM
Could be wrong, but I think the aluminum flashing is the wrong alloy for spinning. You would want something more ductile.

bborr01
09-06-2011, 09:36 PM
Frank,

I have no experience spinning metal but have seen some videos of spinning.

I am wondering if a roller on the end of your bar might help. I saw a video of a guy spinning a dome that was probably 5 or 6 feet in diameter and it seems like he had a bearing contacting the metal. The friction of a bar without a bearing may be causing the wrinkles.

Brian

etpm
09-08-2011, 07:46 PM
Guys....

Thanx for your insight....I figured it was work hardening....What is your suggestion for annealling....I heated it with a propane torch till the copper turned dark red and then quenched it in water...Is this OK????

The copper I'm using is 0.025...The aluminum is 0.011...It's basically roof flashing stock material.....The copper looked like the right alloy according to what I read........I think the aluminum was too thin....

I retreved the books off the internet you suggested...HAve some reading to do tonight...

Anyone need scrap copper and aluminum....Got quite a bit at this point...Maybe I'll make some teabag cozies???

Thanx again..

Frank
Greetings Frank,
With the light down low, or in a shadowed corner, heat the copper till red. Not just dull red but not as bright as cherry. The low light level really helps judge this. Then plunge into cold water just like you were doing. Spinning a shallow shape is easiest. The first thing I tried to spin was a silver shot glass. This was a bad choice. So use a form that's shallow for the first try. Use lube that can stand up to the pressure. Look online for all sorts of formulas for spinning lube. Try to deform the metal as fast as possible. This means using plenty of pressure. Trying to go slow just lets the metal work harden. If it starts to wrinkle you should probably take it out and anneal it. After you get a shallow bowl shape you can anneal and re-spin on another form, or just mod the first form, that is deeper and narrower. It takes practice but is lots-o-fun.
Eric