| View previous topic :: View next topic |
| Author |
Message |
PARATECH1
Expert
Joined: 19 Mar 2008
Posts: 112
Location: ALABAMA
|
 Posted: Mon Mar 24, 2008 9:59 pm Post subject: Cotter Pins (Cotter Keys) VS. Ceramic Insulators |
 |
|
| Quote: | | "You also don't need the ceramic insulators for the Hardibacker 500 oven, because the Hardibacker itself is a fine electrical insulator. I'm using $10 worth of cotter pins and small washers instead, with little loops of stainless wire to connect the nicrome coil to the heads of the cotter pins. (You do need to put something across the back of the board, to keep fingers and things out, because the cotter pins are electrically live. But that's way cheaper than the ceramic insulators from infraredheaters.com.) That should shave tens more dollars off the price." |
Ceramic insulators can cost a bunch of money. Unless you get them out of waffle irons or other stuff, a bag with a quantity of 25 can cost you over $20.00 after shipping. Depending on the size of your oven you can end up needing several bags.
You can get a 555 PC.COTTER PIN set with a case included from Harbor Freight for $2.99 ( Sometimes Cheaper ).
Sizes and quantity of each:
1/16'' x 1'' (150),
3/32'' x 1'' (150),
3/32'' x 1-1/2'' (100),
1/8'' x 1-1/4'' (75),
1/8'' x 2'' (50),
5/32'' x 2-1/2'' (30)
Here's the link:
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=41875
After you mark out you oven route for the nicrome wire drill your holes for your appropriate size cotter pin. Slip the pin over the wire and then the pin through the hole. Flatten out the cotter pin iin different directions on the other side of your oven. You can then put a bead of DAP high heat mortar to cover each of the cotter pin sides that you have flattened. You can then cover the extra space from the drilled holes. After this is done you can use the rest of the tube to seal cracks in your oven. All of this will help keep the heat inside the oven where it is supposed to be. DAP high heat mortar can withstand temperatures up to 2000 degrees. This mortar can sometimes be found for less than $2.00. It comes prepackaged in a tube. It goes on kind of like a tube of silicone. You can get it from most of the bigger hardware stores in the silicone section. I've seen it at both Home Depot and Lowes.
Here's another link:
http://www.castlewholesalers.com/DAP-18854-High-Heat-Mortar-10-Oz-.html
If you spread/trowell a small layer throughout the inside of your oven prior to drilling your holes it can help cracks and falling dust later on when you make your projects.
For added safety make sure you build your oven sides approximately 1/2" above (over and under table) or below (side by side table) the portion of your oven where the flattened/mortared cotter pins are. Secure your lid ( made of hardibacker ) on this side.
Doing the above method is a whole lot cheaper and hold the heat in better. It can also possibly hold the wire just as good if not better than the ceramic insulators.
All this is just an idea. Remember "SAFETY" is the key. |
|
| Back to top |
|
 |
ANH trooper
Master
Joined: 20 Oct 2005
Posts: 305
Location: UK
|
| Posted: Tue Mar 25, 2008 4:43 am Post subject: |
|
|
I agree, it's a lot cheaper.
I have used the cotter pins rather than insulators. I went to the local store that sells every kind of fastener, and I ask for 100 1/8" cotter pins and suitable washers (although I probably only needed half the amount, better to have more) and the guy said they have a £10 minimum charge, and gave me them for free!
I installed them onto my hardibacker floor plan and strung the wire. I used hardibacker for the oven walls and sealed the joints with high temperature sealant. I didn't seal the cotter pins, no need I don't think, but you can if you prefer.
One thing to check though, is that the pins don't touch each other underneather where they have been split. It happened to me me once and I only noticed because one part of the oven wasn't getting as hot as the rest. When I check the back side of the oven, two of the split pins were touching. I turned to oven off and twisted them apart, turned the oven back on and everything was fine. I suppose sealing the pins would stop this happening but it only happened once. |
|
| Back to top |
|
|
PARATECH1
Expert
Joined: 19 Mar 2008
Posts: 112
Location: ALABAMA
|
| Posted: Tue Mar 25, 2008 7:30 am Post subject: |
|
|
Covering the back of the pins with the fire resistant mortar is more of an electrical conduction safety issue (from the cotter pin/nicrome wire contact). This goes hand in hand with the higher walls behind the spread pins. The hardibacker lid on top of that makes everything nice, safer, and neat.
Hopefully it shouldn't be a problem for anyone, but have you had any probem with your pins getting to hot and breaking? |
|
| Back to top |
|
|
PARATECH1
Expert
Joined: 19 Mar 2008
Posts: 112
Location: ALABAMA
|
| Posted: Tue Mar 25, 2008 9:58 am Post subject: |
|
|
| I also meant to thank you on the tip about making sure the cotter pins don't touch. I didn't even think about adding that above. If seperate pins touch it can create an electrical arc and stop a portion of your stove from working right. |
|
| Back to top |
|
|
ANH trooper
Master
Joined: 20 Oct 2005
Posts: 305
Location: UK
|
| Posted: Tue Mar 25, 2008 11:06 am Post subject: |
|
|
I suppose the pins get hot, but they don't glow red hot or anything like that. In fact, the nichrome wire that I used to attach the coils to the cotter pins don't even glow, just the coils. I only made a dozen or so pulls so far, and did that in two sessions, so the oven has only been on for a maximum of an hour at a time. I can't see the cotter pins ever being a problem.
I like the idea of putting a lid on the back of the oven to hide everything and keep it safe. The back side of my oven is over the top of my head, so I would have to reach up and put my hand up there to cause any kind of problems (which I wouldn't do  ) but still, better to be safe than sorry so I'll get a lid on there soon.
Hey, no worries about the tip, that's what were are all on here for...to share ideas and help each other  |
|
| Back to top |
|
|
fast_monte
Novice
Joined: 17 Aug 2005
Posts: 40
|
|
| Back to top |
|
|
thebluecanary
Expert
Joined: 02 Feb 2006
Posts: 123
Location: St. Louis, MO
|
| Posted: Wed Mar 26, 2008 1:43 pm Post subject: Re: cheap ceramic insulators |
|
|
I wonder if you could remove the pin for a screw or bolt? |
|
| Back to top |
|
|
Fredo
Master
Joined: 21 Mar 2007
Posts: 251
Location: Kingdom of Nye Area 51
|
| Posted: Wed Mar 26, 2008 10:36 pm Post subject: |
|
|
| The pin is a double headed 16 penny nail with a rubber washer. They are used on wood fence posts, the double head and rubber washer let you snug it up to the post with out breaking the insulator. Its not attached to the insulator, it just goes through the hole..........Fredo |
|
| Back to top |
|
|
fast_monte
Novice
Joined: 17 Aug 2005
Posts: 40
|
| Posted: Thu Mar 27, 2008 6:45 am Post subject: |
|
|
| Fredo is correct. The nail comes out and the the hole will fit a 1/4"X20 bolt. I used pieces of threaded rod to go through them. I only used four on my project to insulate the Calrod holding bars from the frame. |
|
| Back to top |
|
|
|
Log in to check your private messages
Log in
Register
