stamped sheet steel / any way to duplicate with mill/lathe?

[Kermit]

What the problem boils down to is how to make 33 to 35 circular discs of 20GA steel into this pattern

I've already figured that I can drill the holes in a larger sized disc and turn down to size, and thereby open the holes out.

Do I need to have an indexable chuck, or is offset turning for the hole making something I should consider?

How would you guys approach it if you had to do it with only a lathe, or should I put this one off a little while longer and wait for a mill?

 

[Holescreek]

You did't say anything about tolerances (angular and diametral), burrs, or finish. More importantly, you don't give sizes for any of the holes.
That makes your quest rather difficult to process.

I would rough the discs to size and drill the center hole. Then create a "sandwich" placing the discs between thicker bits of metal with a bolt through the center to hold them all in place and ensure concentricity. Turn the ODs all at once.
After all ODs are to size I would set up a punch and die for the diameter of the outside holes and set the distance to the rim for a central pivot point, and another trigged out for an index pin. Punch the first hole, rotate to the index point and pin it. Punch the next, and so on. Repeat for each disc individually.

If you want to be a lathe purist, you could turn the punch and die setup on the lathe. I work in 20 gage sheet regularly. Even with a good punch and die setup you will still have distortion in the plates that will require that they be straightened. I use a flat faced body hammer and an anvil. -Mike

 

[Kermit]

always give dimensions, finish and tolerances. Got it.

(kermit makes another note on page one of his newbie handbook) lot of pages left to fill in this thing. I appreciate the time you took to help me.


I was dearly hoping that punching the metal could be avoided for exactly the reasons you talked about.

 

[b.lindsey]

Kermit,
33-35 pieces is a decent run. Not sure what your budget may be or the sizes as already noted, but this would seem to be an ideal candidate for laser cutting. Minimal deburring, minimal distortion, etc. Do you know of any local shop that may have such capability. Sometimes even community colleges, or universities have such equipment for training purposes and research projects. Just a thought.

Bill

 

[Kermit]

Diameter 4 in. 3/8 inch holes.

The true diameter if the discs enclosed the outer circles would be 4 - 1/4 (4.237) to be exact, but I'm gonna cut that away ( I hope ???)

Drilling a center hole and clamp them together was the plan, but when doing offset turning I was thinking the bolt and nuts would get in the way of a good set up and perhaps some kind of adhesive would hold the sheets together while I drilled, then reamed the holes. Then use heat perhaps to loosen the glue?

I've got an 8 inch plate with holes that I believe is used on the chuck of the lathe somehow to mount oddball setups?

 

[Foozer]

perhaps some kind of adhesive would hold the sheets together while I drilled, then reamed the holes. Then use heat perhaps to loosen the glue?

Use paper between each piece on a glued up stack would make disassemble easier. Water soluble glue to attach, do operation then drop stack in hot water to loosen glue, separates paper bond, eases glue removal. Center bolt on "sandwich" keeps all aligned. Done similar with super glue, but its the dickens to get apart

 

[Holescreek]

Back when I was in the can business we used to make some spring steel cam plates in stacks with a thick plate on each side of the stack and welds across all 4 corners. The stack was then sent to the wire EDM and all were cut at once. Seems like a long time ago now.

A stack of 20 gage will be about 1 1/4" thick plus your end plate thickness. That's not too bad for handling. Use thicker end plates around 1/4" or more thickness. Thread one plate to receive the bolt threads and countersink the other end for a flat head screw. Drill and ream the stack as you suggested then turn on the lathe. You'll still have to sneak up on the finish diameter to keep the corners on one side of the hole from deforming, and the lathe will need to run kinda fast. Good Luck!

 

[Kermit]

You'll still have to sneak up on the finish diameter to keep the corners on one side of the hole from deforming, and the lathe will need to run kinda fast. Good Luck!

Hadn't thought about that. The edges will be long tapered arcs, and very thin. You say you turned such on the lathes at work? Well, :-\ Nothing ventured nothing gained. I'll give it a go then, since it was my original plan of action. Now that I have this overlooked tidbit, I started thinking of a slitting saw.

(^ Mostly I'm wondering what they are and how they are held and what el$e I have to have to use this new thought. What else I have to have I ask... Some TALENT for starters ;D

And a new brain, this one is kinda worn out,
Kermit

 

[RobWilson]

HI Kermit, looks like your building an armature ?
Regards Rob

 

[Kermit]

Okay, You can take a seat and I'll take the podium for this one. (BAck in my element )


Making the rotor assy. The coils will be wrapped around the outside and will share each opening. A total of sixteen coils. I'm making a 4 pole motor/generator this time. Coils will be preformed on formers and placed and wired in parallel to give two phases. I'm trying, in a fashion, to replicate a design I found in an old book. I've got access to much better wire for winding the motor than was available in the past, so for the amount of room available I will be able to put much more copper into the motor than was possible when it was first designed. Cotton covered wire, double cotton covered and silk and varnish covered; all of these were used and lots of productive area inside the motor was wasted by these things.

The need for the segmented metal core is for the reduction of heating through an effect called magnetic hysterisis and from 'Foucault Currents', or the flow of electricity in a closed circuit inside the metal of the rotor. The larger a conductive area that is exposed to the rotating magnetic field, the more of these electric currents will rotate and heat the iron or steel of the rotor. Segmenting limits these currents so none of them can join together to create a LARGE current which would heat up the rotor to dangerous levels. The surface oxide layer of each piece of steel acts like a limiting resistor to the electricity and prevents them from forming one large steel conductor with a large current to heat it up. Some manufacturers also put leaves of insulators between the metal, but to much insulation between steel sheets reduces the amount of magnetism you can 'fit' into the rotor area.


Did any of that ^ help?

 

[arnoldb]

Hi Kermit.

You could also spray the plates with a thin layer of clear lacquer before assembling; this acts as isolation to limit the eddy currents. That might work better than to rely on metal oxide to provide a barrier. Old-timers used shellac for this.

Regards, Arnold

 

[Kermit]

I forgot all about varnish, although, in my defense, I did say 'insulator'. Thank you Arnoldb.

;D You guys are wonderful. Between the members, nothing gets missed. Advice is complete and experienced.

I love big families, until christmas shopping time,
Kermit

 

[thezetecman]

Hi I have stainless bits like this made by a laser cutting company www cut-tec .co.uk

Obviously you want them made in soft steel they should be able to do that.

No connection etc etc.

But you probably want the satisfaction of making them your self.

I would ruff cut the discs about 5mm bigger tack weld or soft solder together

Drill the center hole use this as the mounting point(via a suitable bolt) on the rotary table drill the outer holes then turn away the outer edge on the lathe.

By which time I would have wished I had had them laser cut out.

 

[Kermit]

Ya know. I'm finding the amount of work required to do what most would consider the 'simple' stuff, to be quite exhausting.

Love requires much sacrifice I suppose

Again thanks for the added suggestions. I now have added solder, or 'tinning' to my list of possible ways to glue the discs together. Also the welding suggestion. I have a small welder, good for 1/4" steel supposedly. Of course, I haven't used it. : ??? It seems to be a theme in my life. Owning tools that I haven't used, but intend too.

So much to learn

 

[RobWilson]

Hi Kermit i can see this being an interesting post,hope you put more photos on this time :big:
any drawings of what your building?

 

[Kermit]

Hi Kermit i can see this being an interesting post,hope you put more photos on this time :big:
any drawings of what your building?

So far just these

 

[Kermit]

Got 11 steel panel blanks(unpainted). I suppose this means I have a date with a bandsaw now.

Thanks to everyone for the helpful suggestions,
Kermit

Continued as a new post in Works in Progress
http://www.homemodelenginemachinist.com/index.php?topic=5313.

 

[Dhow Nunda wallah]

Just a tip re indexing:
cheap circular saw blades are accurate enough for a job like that.
If you can find one with the right number of teeth, or a multiple, job done

Just set up some sort of arbour and a click stop (bit of springy steel)

Rgds,
Lin