The coefficient of resistance wire isn't as linear as platinum but it's
stable. You can design the current regulator to maintain a set temperature
once you've calibrated it.
Come to think of it, this will be an average over the length of the wire, so
if it's not all being used in cutting the foam, the temp wouldn't be
inaccurate. So if you string the wire on a tension mount with insulators,
then bring the current in with copper wire and clips. Then you put the
length of the resistance wire doing the cut in the controller, or the
controller could measure it if it was cold. Should get an even temperature
across the wire that way.
Just thinking out loud...
toggle quoted message
Show quoted text
On 9/5/06, Graham Stabler <eexgs@...> wrote:
--- In CAD_CAM_EDM_DRO@..., "turbulatordude"
<dave_mucha@...> wrote:
Hi all,
Is there a formula to help select the proper voltage and current for a
foam cutter ?
Any special wire ?
Dave
I don't know of any formulas but power disipated is I^2.R and the R
will be a function of temperature itself so it might be a bit
complicated. I suspect it is a rule of thumb situation.
How long a wire do you need for cutting? A review of RC websites
might give you an idea of the currents, its not more than a few amps.
, lots of people seem to use 12v transformers driven from dimmers. A
current regulated supply might be better.
The best wire is nichrome, it has a high resistance and is very
strong. I do manual cutting with a 0.25mm wire which is rather thin
but reduces my "recast layer" meaning there is no melted surface on
the foam. In CNC I think they tend to use the wire in a non contact
mode so they always have this melted on layer which is fine if weight
is not the issue and it can give a nice finish.
Graham
Addresses:
FAQ:
FILES:
Post Messages: CAD_CAM_EDM_DRO@...
Subscribe: CAD_CAM_EDM_DRO-subscribe@...
Unsubscribe: CAD_CAM_EDM_DRO-unsubscribe@...
List owner: CAD_CAM_EDM_DRO-owner@..., wanliker@...,
timg@...
Moderator: pentam@... indigo_red@... davemucha@...
[Moderators]
URL to this group:
OFF Topic POSTS: General Machining
If you wish to post on unlimited OT subjects goto:
aol://5863:126/rec.crafts.metalworking or go thru Google.com to reach it
if you have trouble.
I consider this to be a
sister site to the CCED group, as many of the same members are there, for OT
subjects, that are not allowed on the CCED list.
NOTICE: ALL POSTINGS TO THIS GROUP BECOME PUBLIC DOMAIN BY POSTING
THEM. DON'T POST IF YOU CAN NOT ACCEPT THIS.....NO EXCEPTIONS........
bill
List Mom
List Owner
Yahoo! Groups Links
