How to cut woven fiberglass sheathing?

Question

I got the heaters for my roller project from McMaster-Carr.

Also I picked up a bit of woven fiberglass (neat-resistant) sleeving.

The reason for the sleeving is that the heating rods may need to be supported along the length, and I didn't know if the nichrome was surface-conductive or not.

What is the best way to cut the fiberglass sheathing to keep it from unraveling? I tried sticking it into the flame on the gas kitchen stove and it burns down a bit that way.... I have an oxy-acetylene torch around (which of course will do it) but wondered if anyone who worked with it a lot knows of a better method.

David Billington · Accepted Answer

Which elements did you buy. The ones I'm used to have an outer metal sheath which is insulated from the internal heating element and it's advisable to ground the outer sheath in case of a short, rare but it does happen. For item such as glass annealing ovens this also saves having to have an isolation switch to turn off the power to the elements when the door is opened which would be required for safety with bare wire elements.

Jim Wilkins · Answer

I pasted the sheath of a thermocouple with wood stove cement (sodiumsilicate) to keep it from unraveling. It worked until I overheated thefiberglass and made it brittle.jsw

DougC · Answer

I got two of these-part#   3540K3636" long x .260" dia - 120VAC 750W - 36.45 eachI just poked around on them with a voltmeter and the outside is isolated. Testing against one end and the sheath = open circuit, while across both the ends is 19.7 ohms.I saw the ceramic end caps and just assumed it had to be mounted only by them.

David Billington · Answer

I have real trouble loading any details linked on that site as it wants me to give a user name etc, I did get details recently but can't currently other than the item being a "tubular bendable immersion heater" so it sounds the same as what I use in which case the outer sheath is insulated from the inner heater with MgO IIRC. When I go to

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and enter a part number it just sits and spins and is really annoying, it can be tricked into giving the details sometimes. Maybe it's because I'm in the UK. If they were UK based I would not do business with a website like that but I suspect that is not the problem.

Usual suspect · Answer

Are you familiar with Sauereisen cements? I have used it to mountheating elements in devices.

DougC · Answer

The site does require that javascript be enabled. If you had that blocked, almost nothing there will work.

David Billington · Answer

I have javascript enabled but if I put your part number in the search box it goes to the page briefly and then switches to a page requiring me to log in. Oddly if I search on "immersion heater" I can then go to the bendable immersion heater page. They look like the ones I'm used to but worthwhile getting a technical spec from McMaster as their description is a bit vague. The ones I have are Incoloy sheathed and the details say they can be brazed IIRC and that the Incoloy sheath is insulated from the heater wire core.

How to cut woven fiberglass sheathing?

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