just fried my bobcat !!!!

BCboro · #1 2008-06-24, 10:02pm

well ... it's official ... my bobcat is dead (at least until I get it fixed). Unfortunately I MUST have a torch ASAP !!!

I was thinking of buying the carlisle mini cc as a stop gap until I can get the bobcat repaired ... I can't find a single bobcat for sale ANYWHERE in canada!!

How does the carlisle mini cc stack up against the bobcat ?? will it give me as much heat as the gtt ??

Feldt's Glass · #2 2008-06-24, 11:31pm

The mini cc is a nice little torch but might I ask what happened to your bobcat??

bead crazy · #3 2008-06-25, 1:09am

Mini CC has more radiant heat and a bushier flame. I think the flame if very different from the bobcat. I could not ever get used to it.

Hels · #4 2008-06-25, 1:12am

Did you try Malcolm at Artco? I think he has them in stock...

Lisi · #5 2008-06-25, 2:22am

oops...double post!

Lisi · #6 2008-06-25, 2:24am

Quote:

Originally Posted by bead crazy

Mini CC has more radiant heat and a bushier flame. I think the flame if very different from the bobcat. I could not ever get used to it.

Same here, but I like it. It's just a different kind of heat and it's great if you are doing long barrel beads and sculptural work with soft glass. Not as focused heat for melting small boro faster though. Bobcat is better for the boro.

BTW - if you happen to be using tanks rather than these concentrators/generators, then the Mini CC kicks butt with boro. Deb Crowley was making her dragons with one a few years back.

ArtcoInc · #7 2008-06-25, 9:57am

Quote:

Originally Posted by Lisi

Quote:

Mini CC has more radiant heat and a bushier flame. I think the flame if very different from the bobcat. I could not ever get used to it.

Same here, but I like it. It's just a different kind of heat and it's great if you are doing long barrel beads and sculptural work with soft glass. Not as focused heat for melting small boro faster though. Bobcat is better for the boro.

BTW - if you happen to be using tanks rather than these concentrators/generators, then the Mini CC kicks butt with boro. Deb Crowley was making her dragons with one a few years back.

As others have already mentioned, the Mini CC is a great torch, but it *is* different than the Bobcat. The Mini CC has a bushier flame, and it has more radiant heat. The Bobcat has a more focused, penetrating heat. Both are good torches, just in different ways.

If you are running a concentrator, though, do be aware that the Mini CC needs more oxygen than the Bobcat.

And yes, I still have a few 'classroom specials' left. See my website for details.

Malcolm

kbinkster · #8 2008-06-25, 3:57pm

What happened to the Bobcat? I have never heard of a Bobcat getting fried, before. How did you manage that?

BCboro · #9 2008-06-25, 4:52pm

well ... ordered the mini CC today ($185) and should have it in a few days. Hopefully it will work fine on the M15 concentrator ...

If I was back in the US I could just get another bobcat while waiting for this one to get fixed .... but I can't find a single bobcat for sale anywhere in canada !!!!!

---------------------------------------------------------

3 easy steps to fry a bobcat:

1) stop using tanks and get a concentrator (or two)

2) on your FIRST day with a concentrator ... forget to turn off the oxygen when lighting your torch

3) enjoy the "show" that your torch puts on after it bursts (or melts) it's internal seals ... quite spectacular

-----------------------------------

Diane (clarus) · #10 2008-06-25, 5:07pm

Ouch! I've done that to my Bobcat but fortunately never fried it. This was when I only had one concentrator, but now I'll really make sure it doesn't happen again.

-Diane

kbinkster · #11 2008-06-25, 9:29pm

Were you running a pilot light with the oxygen barely cracked open? Running straight oxygen through the torch wouldn't melt it down. It takes a flame to do that. Yikes!

BCboro · #12 2008-06-26, 2:20pm

Quote:

Originally Posted by kbinkster

Were you running a pilot light with the oxygen barely cracked open? Running straight oxygen through the torch wouldn't melt it down. It takes a flame to do that. Yikes!

I took a lunch break and when I came I lit the torch the way I normally would - crack open propane then light it THEN open oxygen - and completely forgot that I had 15 psi (roughly) of oxygen coming out of the torch head, since I was now using a concentrator and had left the oxy wide open when I went into the house. Lighting a torch with full oxygen coming out is ... um ... interesting. I was expecting a little propane flame NOT the big ass thundering flame that instantly came screaming out of the torch.

I don't know exactly what happened to the innards of my torch ... I'm sending it to GTT to get fixed and will find out when they get it. The torch is unusable as it is. The pilot flames are constantly deforming in different ways. You can't get a focused flame for more than a 2 or 3 seconds before it starts acting crazy again.

Hopefully an M15 running a mini CC will keep me in business this summer.

Andrew · #13 2008-06-26, 4:54pm

wow badluck sounds strange though for a surface mix torch. Shouldnt of caused any internal damage. A premix i could understand. The main reason for Flash back arrestors.

I have a mini cc which i love and have just ordered a bobcat and a cheetah. I cant vouch for a bobcat just yet but cant see you having any gripes about the mini apart from hot knobes. Since i always run my concentrator at max now and adjust flame size with propane i notice the torch is much cooler until you use a tiny flame for detailed work.

Hope it all works out for you.

Regards
Andrew.

tiggybubba · #14 2008-06-26, 5:08pm

I do that every time with my bobcat and have never had a problem. I dont start it with the propane cranked tho...

Mr. Smiley · #15 2008-06-30, 7:04am

It may have had an internal leak... this would cause a premix situation inside the torch... when you lit it, it would create combustion inside the torch and the chambers in there aren't designed for that. That's my guess if it went all wacky after the incident you described.

I'm sure GTT will fix it for you. They have good service when something goes wrong.

kbinkster · #16 2008-06-30, 9:38pm

Quote:

Originally Posted by BCboro

I took a lunch break and when I came I lit the torch the way I normally would - crack open propane then light it THEN open oxygen - and completely forgot that I had 15 psi (roughly) of oxygen coming out of the torch head, since I was now using a concentrator and had left the oxy wide open when I went into the house. Lighting a torch with full oxygen coming out is ... um ... interesting. I was expecting a little propane flame NOT the big ass thundering flame that instantly came screaming out of the torch.

I don't know exactly what happened to the innards of my torch ... I'm sending it to GTT to get fixed and will find out when they get it. The torch is unusable as it is. The pilot flames are constantly deforming in different ways. You can't get a focused flame for more than a 2 or 3 seconds before it starts acting crazy again.

Hopefully an M15 running a mini CC will keep me in business this summer.

Well, thanks for explaining the situation. I think I know what may have happened.

You left your torch thinking that just the oxygen valve was open with the oxygen running through. If that were the case, and you returned to re-light the propane with the oxygen already on, all that would have happened when turning on the propane and lighting it would have been a loud pop and an instant blue flame. Depending on how open the oxygen valve was, your blue flame would either have stayed lit or blown out. Willy and I do this all the time when lighting my torch, since I, too, run on concentrators.

For there to have been a problem like you described - walking away and coming back to relight the torch - only to get a thundering flame "show" instead of a regular blue flame - very specific things had to have happened.

You said that you turned off your torch, but left your oxygen on. It sounds like you may not have shut your propane valve off all the way and left a tiny blue flame behind. These flames can get so small that they are just blue specks at the tips of the jets - it would not even be a visible flame. At this point, ignition is taking place right at the tips of the tubes. Gas is still trickling out, and is ignited, and the oxygen is just going out and around it, with enough reaching back to the end of the gas tubes to keep it blue and hot at the tip of the tubes. Even with the propane valve on the tank turned off, there could be enough gas in the line bleeding out for the small amount necessary for the tiny blue dot flames. If run long enough, this can (1)overheat the tubes or (2)erode them back below the surface of the torch face.

(1) When the ignition is right there at the tip of the tubes, instead of pushed further out like on normal flame settings, the tubes overheat. The heat transfers back up the metal of the tubes and can overheat the whole torch. If it overheats enough, you can melt the internal parts of the torch.

(2) If erosion occurs, the center jet would most likely be the first to erode back because it sits by itself and nothing is there to pull the heat away from it. If that center jet is eroded back, the metal starts overheating and the oxygen kicks in and starts melting the tubes down like a cutting torch would go through metal. This would explain the "show."

It sounds like the damage was done by the time you came back to the torch (that big flame that came rushing out shows that - a whitish flame with sparkles shooting out of it, I'll bet).

Just running straight oxygen through the torch and loading up the gas chamber with oxygen would not hurt a Bobcat. You would get a loud bang on the initial lighting and the flame may or may not stay lit. By the second lighting attempt, the flame would be back to normal. You would get a normal blue flame. You would not get a "show."

You are describing a meltdown and meltdowns are caused by pre-mixing. But, pre-mixing can have different causes (tube erosion, internal leaks, etc.). I do not believe that the Bobcat pre-mixed due to an internal leak. You make no mention of any previous problems with the torch. No previous bangs or pops, no acting up with flames going off, no problems starting up, etc. It is highly unlikely for a torch to go from functioning normally straight to meltdown mode.

Heat is the enemy of a torch. Heat in the body of a torch is usually what causes internal leaks in the first place and GTTs are internally cooled. The internals are not exposed to the heat that would cause a leak.

BTW, I have watched a competitor's torch go into meltdown at a show. It was due to pre-mixing from an internal leak, and the torch was shut down before any serious damage occured. Meltdowns don't just happen for no reason. A torch will usually let you know there is a problem. Usually, you would have time to shut off a torch before it goes into meltdown mode. Here is the pre-mix with meltdown scenario:

First, there is a crack/bang like a firework. The flame usually blows out at this point. Then, you will hear a whistling or stuttering (a fast series of popping). After that, you had better be shutting the torch off and hoping that the flashback arrestors catch it. But, if you were to let it go and the flame were still on and had not been blown out, the flame would turn yellowish/whitish with sparkles from the metal particles shooting out. You would know that there was something wrong by the way the flame looked and you would then shut it down. At this point, the damage would still be minimal. The tubes would not be eroded back far if caught fast enough (like 20 seconds or so).

kbinkster · #17 2008-06-30, 10:03pm

emphasis mine

Quote:

Originally Posted by Mr. Smiley

It may have had an internal leak... this would cause a premix situation inside the torch... when you lit it, it would create combustion inside the torch and the chambers in there aren't designed for that. That's my guess if it went all wacky after the incident you described.

I'm sure GTT will fix it for you. They have good service when something goes wrong.

Actually, the chambers of the Bobcat (and all GTTs) are designed to withstand full explosion from ignition - with either the gas chamber fully loaded with oxygen on ignition or the oxygen chamber fully loaded with gas on ignition.

It's not the chambers that become the problem from pre-mixing, it's the site of the pin-leak where the gas meets the oxygen. It is at that point where pre-mixing, if not caught early enough, will cause the metal to burn away and open the leak up more. Then, you have a bigger leak. The leak would have to be catastrophic to cause meltdown. Pin leaks are usually just pesky. They certainly need to be addressed before they get bigger and cause problems (ignoring them can be dangerous), but pin leaks in and of themselves do not cause meltdowns.

GTTs are rigorously tested for internal leaks before they ever see the outside of the shop. Each torch is tested no less than three times during production. If there are any internal leaks from manufacturing, they are caught. And, like I said before, because of GTT's internal cooling system, the internals of GTTs are not exposed to the heat that would cause internal leaks to form like in other torches (like from cracks in the joints, stress, etc.). Since GTT began, there have been less than ten torches to come back due to a leak, and those all occurred in the first four years. That's a pretty good track record, in my opinion.

Andrew · #18 2008-07-01, 3:21am

A good read nice clear info. Almost sounds like you are part of the business and watch them getting built

. Makes me feel somuch better about the ones i have on order.

Regards

Andrew.

mdimatteo · #19 2008-07-01, 5:27am

I love my Bobcat. When I first started I was hopeless but got lots of help from Willy and Wally and Flame Tree Glass. I had no one to help me start and they did it long distance. I finally found out that the people who sold me my oxycon (on the web) sent me an old outdated model they don't even make parts for any more (beware 5 year guarantees). Once I found that out, lucky me it broke down in 14 days, and got a new one everything smoothed out and now I've worked on two other type torches (at B&B) and was soooo glad to get home to my Bobcat!!
A big thank you to those guys....they are really wonderful!!
Mary in Florida