hot wire varivac

[TWsup]

HI,

Been out on swaylocks forum, but thought i would ask here too.

Need to make a hotwire for shaping a 16ft sup blank. Dont want to do the home-made approach to power supply because i know nothing about electricity, my electrician friend won´t let me do anything that violates swedish electrical safety codes and i´m generally afraid of electrocuting myself. 

So i plan on investing in a Varivac - This one: is it the right spec ??


Input voltage: 230V
Output voltage:  0-260V
Frequency: 50-300Hz
Load:  max 6 A cont. 5 A
Weight: 6.8 kg
Encapsulation class:  IP00
Ambient temperature:  max 45°C
Insulation test:  2.5 kV
Design:   - Autotransformer wound with double-varnished wire.
 - Winding and carbon brush mounted on a robust frame.
 - Knob with scale 0-100 supplied.
 - Easily replaceable carbon brush.
 - Extra carbon is supplied.
Mounting: Panel or chassis mounting with four screws.

[TWsup]

Or this one- it is for table mounting, dont have to make my own box. But costs another 50 USD ( I´m in Sweden- everything is expensive)

Input voltage:  230 V
Output voltage:   0-260 V
Frequency:  50-300Hz
Load:   max 4.0 A  cont. 3.8 A
Weight:   6.9 kg
Encapsulation class:   IP20
Ambient temperature:  max 45°C
Insulation test:  2.5 kV
Design:  - Primary connection with appliance cable stand, appliance socket as per EN 60320/C13.
- Secondary connection to terminals, red for regulated output voltage, connection for external protective earth.
- Indicator light for mains connection.
- Fuse 5x20 mm, 5 A, mounted in appliance socket.
  - Autotransformer wound with double-varnished wire.
 - Winding and carbon brush mounted on a robust frame.

[DurhamSUP]

I'd go with the first one. Depending on wire thickness, you will need about 3 amps. The first one gives a little more headroom for amperage to be safe.

[Dwight (DW)]

If your're not electrically inclined, I'd search for one ready as-is. Not one that needs a housing and wiring installed.

Mine is this one http://www.weisd.com/ProductView.php?PN=PHI48-1205

It's made in China. This one seems to be sold about everywhere. Shipping cost can be high. They are very heavy.

[TWsup]

Thanks guys-

I can get a fully encapsulated and ready-to-go in 5 amp too.

T

[supuk]

You can buy hot wire bows all reedy to go literally just plug in the wall there not super cheap but it so easy to use the amount of time you will save having to build it will more than pay for it mine is adjustable from 2-4' wide and 1-2' deep and used it to cut my 18' blank no worries. it would be nice to have a variac but this thing is so simple you cant go wrong. i think its similar to this

 http://compare.ebay.co.uk/like/230704360788?var=lv&ltyp=AllFixedPriceItemTypes&var=sbar&adtype=pla&crdt=0

[TWsup]

supuk,

thank you ! the 2/4 ft bow cutter is international and will cost less than me buying power source and all the parts.

what do you use for gluing the foam blocks that can be cut by cutter ?

[supuk]

i just use pu foaming wood glue its a little slower to cut than foam but it does cut. that cutter realy is just plug in and go, im not sure where mine came from but the chap i got it from had extra wires and stuff with it im not sure if they were extras or not though. it may be worth searching the internet for other companies that sell the same one i know it was a uk based company

[supuk]

that link doesn't actually show the correct cuter any longer but i believe they actually originate from these people

 http://hotwirefoamfactory.com/home.php

[TWsup]

yes, I found them.

the uk source of the foam fusion glue only has a 16 oz bottle. I'll be gluing foam blocks 100mm thick- meaning gluing 3.5m2 area of glue...
how much do I need for that ?
do you know of any other glue or adhesive that works and is cuttable.?
otherwise I will have to experiment.

thanks for your help

[supuk]

this is the sort og glue i use, just go to a builders centre that specialises in wood and they should have something similar. it sounds like you are having to make you blank up? have a good search around for eps suppliers were you could get it in block form. you could probably get a block shipped for one blank quite easily as it can not be any harder than shipping a board. if you are stuck with 100mm thick sheets once you get it thinned out at the nose and tail you can bend more rocker in if you need to. i managed to shape two boards from cheap builders foam and they go fantastic.

http://www.beatsons.co.uk/building-chemicals-c40/adhesives-c332/wood-c333/lumberjack-5-min-pu-wood-adhesive-liquid-750gm-p3688?utm_source=google&utm_medium=cpc&utm_term=everbuild-lumberjack-5-min-pu-wood-adhesive-liquid-750gm-weight-0-75-weight-0-75-eve-5minpu7-eve-5minpu7&utm_campaign=product%20listing%20ads#4575

[Dwight (DW)]

yes, I found them.

the uk source of the foam fusion glue only has a 16 oz bottle. I'll be gluing foam blocks 100mm thick- meaning gluing 3.5m2 area of glue...
how much do I need for that ?
do you know of any other glue or adhesive that works and is cuttable.?
otherwise I will have to experiment.

thanks for your help

I use a tiny amount of glue. I just squirt a few streaks down the face. The glues expand. I use Gorilla Glue. You just want enough to tack and hold the blank together for shaping. Minimal use of glue is what makes the hot wire cutting no issue at all. Too much glue and the hot wire cut will get messy. Also, the glue doesn't shape well. I try to only glue near the core, so my shaping tools don't hit the glue spots.

[TWsup]

Hej DW and SupUK! you guys are a great help.

yes I have to glue together 100 mm thick sheets I can get in 1000 x 2000 size. nothing else available in Sweden.

I'll get some of that pu glue, it's available here. seems that the gorilla glue is same kind of glue. never seen that brand here.

I was thinking of spreading glue over entire surface, but if trying to keep it at the non cutting parts works, I'll do that. I've shaped kiteboards with glue lines and it was a problem at glue lines.

on the hot wire bow: I have 2 options.
1. order the big bow from hotwirefactory. will end up costing me 300+ bucks after shipping and sales tax.
2. buy laboratory DC variable power source for 120usd, 10 meters of nichrome wire for 10 usd and some wood bits & hardware for 20 usd, some electrical connectors for 10 usd. total 160 usd. DC power is 0-30 volts and 5 amp max. easy to make big and small bow.

leaning towards option 2. don't have to decide until 2 weeks, still making my shaping stands and setting up my side lights in the shop.