Fusion Message Board

In this space, visitors are invited to post any comments, questions, or skeptical observations about Philo T. Farnsworth's contributions to the field of Nuclear Fusion research.

Subject: Home Made Spot Welder
Date: Jun 21, 8:07 am
Poster: Don Harris

On Jun 21, 8:07 am, Don Harris wrote:

I have been thinking about how I am going to
fabricate the grids in the upcoming fusor. The
following idea is where I intend to start. If
any of you guys already have experinence in this
area I sure would like to hear your comments
before I waste a lot of time and energy.

It seems to me that a reasonable spot welder could
be made as follows.

1. Use a transformer out of a microwave oven to
get the 1000 or so volts that is required. A small variac could be used to set the output level
and a mechanical stop on the variac could limit
the upper voltage level. Rectify the output and
send it to the storage/discharge cap. There can be several discharge caps for the different power
levels required. A selector switch will select
the appropriate capacitor.

2. The power supply discribed above will be discharged through the primary of a conventional
weller Soldering gun. A solid state SCR can be used to handle the discharge. The soldering gun is nothing but a voltage to current transformer. It seems that the power rating of the weller gun should be plenty to handle the short discharge
pulses from the power supply.

All that is left is some homemade copper wire holders that will hold the grid wire, provide the
proper spring preload and carry the pulse current
from the high current side (soldering iron tip holder) of the weller gun.

If the above design works, as I hope it will, then
it should be simple enough for everyone to in the
group to have their very own spot welder. All the parts should be availabe from local garage sales and flea markets. The Grid wire holder may
be a little hard to fabricate but I have seen that
some of you guys have already done that, maybe someone can post the plans to build the bussines
end of the spot welder.

If it seems I am way off track then please let me know, otherwise I will put this thing together and
let you know the results.

Thanks Its been fun

Don Harris