[TheForge] 3D printers

[Paul Sperbeck]

I carry my cell phone always. Never had a problem. The maximum operating 
frequency of my machine is 100,000 CPS, well below radio frequency. I 
believe Grant's machines were very similar in maximum frequency.

I use a  small coil to measure the frequency of the induction heater to 
ascertain if coils are in the correct frequency range when I wind a new 
one. Unless the sensing coils are nearly on the same axis and very close 
there is not enough coupling to register on the freq meter. You can hold 
a piece of metal on top of the coil and not even get the stock to smoke. 
Put it inside and stand back.

I have over eight years of experience with my heater, similar to Grants, 
but a different make, and have never had a problem with near field 
stuff. I don't have a hearing aid or a pacemaker though...

I don't hear any interference on the nearby AM radio unlike my VFD 
running the lathe. That makes so much racket that I have to shut off the 
radio.

Changing coils is part of the deal. Induction heaters are best suited to 
volume production. The coils are then selected to perform each stage of 
the process and changing them, which takes less than a minute, doses not 
cause any major delays. By manipulating the stock you can extend the 
range of a coil. I generally leave the 1.25" ID coil in place, it's a 
good general purpose coil.


paul
-- 
When seconds count the police are only minutes away.

Draw quickly.  Shoot carefully.  No one has been killed by a loud noise.

At the core of liberalism is the spoiled child - miserable as spoiled children are, unsatisfied, demanding, ill-disciplined, despotic and useless. Liberalism is a philosophy of sniveling brats. P. J. O'Rourke

Good judgment comes from experience, and experience....well that comes from poor judgment.

Life's tough, pilgrim, and it's even tougher if you're stupid.

No trees were killed in the generation of this message,
but a tremendous number of electrons were terribly inconvenienced




On 05/11/2015 02:44 PM, Richardson, Grover wrote:
> High Current dc sources are not as bad as high frequency sources.  Certain frequencies tend to be worse than others.  I personally have had my hand go numb in a high frequency field, and I know of another fella who went temporarily blind when he stuck his head into a field.  As with much in life, we tend to tolerate lower levels because we don't notice them, or they don't "hurt" as much<G>.
>
> Electronic computer controls only control the power and frequency.  The amount of energy radiated into the nearby area (where you are standing<G>) are a function of the shape of the coil and the shape and size  of the metal being entered into it.  Those are not under computer control.<G>
>
> Note-humor and reality at the same time.
> 900 Mhz-cell phone frequencies, are the OLD microwave oven frequency.
> 2.4 GHz-new wifi frequencies are right smack in the middle of microwave oven frequency coverage<G>.
> At least these are relatively low power, though the cell phone is held awful close to the noggin, grin.
>
> I like to measure things before I get near to them.  There is a free app for the ipad/iphone that measures magnetic fields.
>
> All the best
>
>
> -----Original Message-----
> From: TheForge [mailto:theforge-bounces at mailman.qth.net] On Behalf Of Peter Fels & Phoebe Palmer
> Sent: Monday, May 11, 2015 3:33 PM
> To: Blacksmithing List Sponsored by ABANA
> Subject: Re: [TheForge] 3D printers
>
> As i recall there are electronic/puter controls on the unit itself.
> As for personal exposure..most off us arc weld, tig weld, etc.
> Just think of all the diseases that those electrical fields might have prevented!
>
> On May 11, 2015, at 12:06 PM, Richardson, Grover <Grover.Richardson at gtri.gatech.edu> wrote:
>
> Note- no one has said anything about rfi/emi from the induction coil heaters.  The coil is an antenna.  Yes, the metal inside gets most of the power, but a coil radiates pretty well outside of the coil as well.   I worry.  Nearby electronic watchs, cell phones, could easily be overwhelmed<G>.   Has anyone done measurements of fields nearby?  We use mu-metal to shield ourselves from stray fields of high intensity.
>
> -----Original Message-----
> From: TheForge [mailto:theforge-bounces at mailman.qth.net] On Behalf Of Peter Fels & Phoebe Palmer
> Sent: Monday, May 11, 2015 2:22 PM
> To: Blacksmithing List Sponsored by ABANA
> Subject: Re: [TheForge] 3D printers
>
> I suspect it warped both our thinking and would bet blacksmiths are over represented in it's ranks.
> As an old guy, it makes it easier to deal with the roar of new tech.
> Speaking of that. Gene Olsen brought one of the induction forges that Grant S first introduced, to the Western States Conference. Sure is nifty...Fast, concentrated heat!
> The price and cooling package is coming within reach and the unit is now more portable and compact.
> I want one!
>
>
>
>