DIY Hot Wire Foam Cutting Table (not working)

[Smapa]

Hi I am trying to build a hotwire foam cutting table and my wiring and parts are working but not the way they should as the nichrome wire is not heating enough and my dimmer stops at 60 (before it stars flickering) rather than 100, my knowledge for this sort of stuff is whatever comes before beginner. My guess is I either used the wrong wire or I used the wrong type of metal at some point or my power supply is wrong, I have no idea.

There are 2 videos that I tried to go off of and theirs works. I am sure I am close. the Nichrome wire gets warm but not very hot like it should, and no other metal feels warm.

Nichrome wire (for cutting) HWCW -2, 27 gauge

http://www.jonhudon.com/hotwire/1.jpg
http://www.jonhudon.com/hotwire/2.jpg (etc)
(replace number in address above for more images 10 total)

Videos I used as reference to build:

Thank you for your time.

 

[73's de Edd]

Sir Smapa . . . . .
In looking at your set up, the situation seems that your BASIC problem is that not enough power is being supplied to your unit.
Specifically . . . . . . that PUNY little 200 ma wall wart trying to be used for your units power needs.
That 8 amp spec on the controller is fine. The interconnecting hook up wire gauge is being just marginal.so just try to double or triple up those wire runs made, so that your current capability will then be multiplied and any voltage drop minimized .
Your magnificent craftsmanship and the support arms basic mechanical rigidity is exemplary.
At the eye bolt to spring connection, scrape that clean and shiny and immediately add a thin film of silicone GREASE to create an antioxidation barrier.
Where you have to make compressed connections, be sure that they are also cleaned BARE, as well as the same treatment as above .
Also use as much bared and compressed contact area, as is being possible with the wires.
If you have the experience and capablities to do it, SILVER solder the nichrome wire end to the washer at the bottom end and the coil spring at the top end.
Now . . . . .so that you WON'T have to spends any more of yer hard earned munnies . . . . .junk that wall wart and carry the unit outside to your car and use some HEAVIER interconnecting wiring or jumper cables, to let your car battery then be a temporary evaluative power supply source .
THEN, I believe that will give you absolutely adequate AMPERIC capability to evaluate how high the controller has to be set, and let you make several satisfactory test cuts.
With it operating normally then, open one battery supply line and take DVM or analog metering in DC mode and place in 10 AMP range, so that the one open supply line passes thru your metering probes. Then load down the wire by making a fast / forced feed of the foam into the cutting wire.
That should tell you what the minumal adequate amperage that a new, heavier power source needs to be.

Thaaaaaassssssssit

73's de Edd . . . . .

Hey fellers . . . . if you're sometimes finding that there is not enough time for even a quick bath? . . . Easy Peasy . . . . just wrap yourself in DUCK (DUCT) tape and remove the dirt by simply peeling it off.

 

[Smapa]

Thank you for taking the time to look into my project! I understood a good amount of what you wrote but I am so very new to electronics that "open one battery supply line and take DVM or analog metering in DC mode and place in 10 AMP range, so that the one open supply line passes thru your metering probes." is basically entirely alien to me. Pretend I am 5 but can safely use scissors.

Would an adapter that says Output: +12V -_--_- 3A Max work? or is that still too weak?

I am ok with spending some monies to make it function. Did you mention the red wire I used is not good enough? Is there better wire for this? I have this wire should i redo my wiring to use this?

 

[Alec_t]

If I'm reading your drawing correctly, your steel rod is a short-circuit across the heating wire.

 

[Smapa]

I upped the amps and am in business, still some other stuff to do as 73's mentioned, but generally "it will cut". thank you.

 

[Bluejets]

Generally, any hot wire cutter works much more reliably with a higher voltage as well.
My system here runs at 40 volts ac.

Another bad design point is the current flowing through the spring.
Spring wire has a small resistance and will heat as well and change the spring tension.
Fix is to shunt the spring with a flex wire.

Also connection of one conductor to the clamp instead of the main riser tube underside creates a voltage drop point. You don't have a lot of leeway on this voltage as it is, let alone creating voltage drop points.