Search found 879 matches

by Rich Feldman
Mon Jan 15, 2018 5:41 pm
Forum: Images du Jour
Topic: Arc polarity for fusing wire?
Replies: 5
Views: 185

Re: Arc polarity for fusing wire?

Not so fast, Rich! The wire-negative balls are brittle & can't be beaten into pinheads. Maybe the copper is oxidized, or contaminated with metal from the other electrode. Back to wire-positive, I bypassed the thumbtack & let the arc go straight to the thick copper baseplate. Ran the variac up to 140...
by Rich Feldman
Mon Jan 15, 2018 6:59 am
Forum: Images du Jour
Topic: Arc polarity for fusing wire?
Replies: 5
Views: 185

Re: Arc polarity for fusing wire?

Thanks for the reminder about high frequency, Michael. I want to form balls about 2 or 2.5 times the wire diameter. Concentricity with the wire axis is more important than roundness. A first step toward making a few of what might pass for copper rivets, about 2 mm long. First trials with NST and var...
by Rich Feldman
Sun Jan 14, 2018 3:39 am
Forum: Images du Jour
Topic: Arc polarity for fusing wire?
Replies: 5
Views: 185

Arc polarity for fusing wire?

Posting here at IDJ because this is ephemeral, and not a mainstream fusor question. Pictures to follow, but the microscope camera is at work. I've been forming balls on the end of 28 AWG (about 0.35 mm) copper wire by putting the wire in a torch flame. Not unlike the method used on a much smaller sc...
by Rich Feldman
Tue Jan 09, 2018 10:32 am
Forum: Advanced Technical Discussion Area
Topic: Alternative Reactor Design
Replies: 13
Views: 2803

Re: Alternative Reactor Design

There are some world-class accelerator based neutron sources that get pretty darn close (as laboratory beamlines for studying materials or basic physics). When high neutron fluences are needed for production processes, whether breeding fuel or doping silicon ingots, the work has to be within or very...
by Rich Feldman
Sun Dec 24, 2017 8:27 am
Forum: Fusor Construction & Operation (& FAQs)
Topic: Vacuum Chamber Construction
Replies: 9
Views: 690

Re: Vacuum Chamber Construction

Can one use a torch to locally anneal work-hardened places in a SS workpiece?
For applications (such as fusor chambers) that don't demand the best mechanical, chemical, electrical, magnetic, or aesthetic properties.
by Rich Feldman
Sun Dec 24, 2017 7:55 am
Forum: High Voltage - Fusor Input Power (& FAQs)
Topic: A Festive High Voltage Load
Replies: 2
Views: 164

A Festive High Voltage Load

Finally made & tested a 51,000 ohm 175 watt ( 3000 V x 58 mA ) resistive load concept. It started out as a string of 25 C9-size Christmas lights, bought for under $10 at a clearance sale last January. DSCN0015.JPG These screw-base lamps are generally wired in parallel, an option sadly overlooked in ...
by Rich Feldman
Wed Dec 13, 2017 7:51 am
Forum: Images du Jour
Topic: Loads on roads
Replies: 4
Views: 320

Loads on roads

Don't know if I'd ever seen one of these on a highway, before last week.
DSCN0929.JPG
Please excuse me for taking a picture while driving. A thing I do maybe once every year or two, knowing that it's not very safe behavior.
by Rich Feldman
Sun Nov 19, 2017 6:28 pm
Forum: Vacuum Technology (& FAQs)
Topic: Will a Sprengel Pump Work?
Replies: 19
Views: 688

Re: Will a Sprengel Pump Work?

Rex, I think we both hit Send at about the same time. I wasn't responding to your answer. Didn't figure it out myself, or find that dimensioned diagram, until seeing the first answer (which is correct size for 4 metric tons). The most recent round is doubly relevant at fusor.net. The big boys at Oak...
by Rich Feldman
Sun Nov 19, 2017 2:05 am
Forum: Vacuum Technology (& FAQs)
Topic: Will a Sprengel Pump Work?
Replies: 19
Views: 688

Re: Will a Sprengel Pump Work?

Silviu Tamasdan wrote:
Sat Nov 18, 2017 9:04 pm
1t=1000000g; divided by 13.53g/cm3 makes 73909.83cm3. V=pi*r^2*h; if h=d=2r, then V=pi*r^2*r/2=(pi*r^3)/2
r^3=2*V/pi, solve for V=73909.53, r=36.1cm or d=h=72.2cm.
Is that your final answer? :-)
Capture.JPG
by Rich Feldman
Sat Nov 18, 2017 6:17 pm
Forum: Vacuum Technology (& FAQs)
Topic: Will a Sprengel Pump Work?
Replies: 19
Views: 688

Re: Will a Sprengel Pump Work?

Silviu did post that video link first, and I'm sorry not to have noticed sooner. Here's my account of cleaning "dirty" mercury, obtained through craigslist from a local resident about 5 years ago. Since then the street price has gone way up. I think after a USA-and-Europe export ban, to discourage u...