Mcculloch Super Pro 125c Complete rebuild.

[Steve NW WI]

Okay...you guys that work on Macs and know them well...was that post truly a dangerous bit of advice?
I'm no saw mechanic and a lot of the guys on here aren't. Would following his advice have the potential to harm a person trying the same thing?

Bob, you don't need to be a McChanic to answer that. We test liquid tanks at work with 5 psi and that causes substantial bowing out of steel tanks. 125 is asking for it, plain and simple.

 

[Scooterbum]

Okay...you guys that work on Macs and know them well...was that post truly a dangerous bit of advice?
I'm no saw mechanic and a lot of the guys on here aren't. Would following his advice have the potential to harm a person trying the same thing?

Kinda like filling a tire with hair spray or starter fuid to seat it with a match.....................wait a minute hold my beer!!

 

[thomas1]

Kinda like filling a tire with hair spray or starter fuid to seat it with a match.....................wait a minute hold my beer, while I put my thumb next the bomb.

Fixed.

 

[Jon1212]

Fixed.

Well thank goodness something in this thread has been "fixed" properly.:msp_wink:

 

[leeha]

Okay...you guys that work on Macs and know them well...was that post truly a dangerous bit of advice?
I'm no saw mechanic and a lot of the guys on here aren't. Would following his advice have the potential to harm a person trying the same thing?

Putting a 125 psi to something unknown to me is
very dangerous. Look what happens when a truck
tire lets go that uses the old style split rim. And
they were only inflated to 90-100 psi. Many have
died. If the glue in the Mac 125 tank was a bit
stronger then whats the next weakest part. I'll
tell you what, I don't want to find out.




Lee

 

[jropo]

View attachment 254121

 

[watsonr]

Being a submarine sailor at one time, I can say that this is a dangerous idea. I know lots about pressure and 125psi even in water... although very accurate on how pressure works, that the load is spread around the tank... if something else besides the seam gives... you get an explosion! Like the cap, putting your finger over the cap was asking for trouble.

And I don't think that it actually ever got to 125psi, you may have had 125lb air to use, but internal tank pressure never made 125psi.

That math is 125psi x Sq inches of tank volume = An explosion that no cloth towel or vest would have contained and you actually put your thumb on the cap...

The better idea is to fill the tank with water and put a cap on it with no relief valve in the cap and freeze it... it will split.

 

[Jon1212]

Being a submarine sailor at one time, I can say that this is a dangerous idea. I know lots about pressure and 125psi even in water... although very accurate on how pressure works, that the load is spread around the tank... if something else besides the seam gives... you get an explosion! Like the cap, putting your finger over the cap was asking for trouble.

And I don't think that it actually ever got to 125psi, you may have had 125lb air to use, but internal tank pressure never made 125psi.

That math is 125psi x Sq inches of tank volume = An explosion that no cloth towel or vest would have contained and you actually put your thumb on the cap...

The better idea is to fill the tank with water and put a cap on it with no relief valve in the cap and freeze it... it will split.

Nice post Randy.

 

[Brian13]

Okay...you guys that work on Macs and know them well...was that post truly a dangerous bit of advice?
I'm no saw mechanic and a lot of the guys on here aren't. Would following his advice have the potential to harm a person trying the same thing?

Putting a 125 psi to something unknown to me is
very dangerous. Look what happens when a truck
tire lets go that uses the old style split rim. And
they were only inflated to 90-100 psi. Many have
died. If the glue in the Mac 125 tank was a bit
stronger then whats the next weakest part. I'll
tell you what, I don't want to find out.




Lee

:agree2:

A little hidden corrosion on the inside of the tank and it could rupture there, and I have seen quite a bit of corrosion on the inside of old mag tanks. Tanks are too easy to come by to risk it.

 

[watsonr]

Putting a 125 psi to something unknown to me is
very dangerous. Look what happens when a truck
tire lets go that uses the old style split rim. And
they were only inflated to 90-100 psi. Many have
died. If the glue in the Mac 125 tank was a bit
stronger then whats the next weakest part. I'll
tell you what, I don't want to find out.

Lee

I know of guys who have had there heads taken off by split rims, NO BS... there heads!

 

[Gologit]

Putting a 125 psi to something unknown to me is
very dangerous. Look what happens when a truck
tire lets go that uses the old style split rim. And
they were only inflated to 90-100 psi. Many have
died. If the glue in the Mac 125 tank was a bit
stronger then whats the next weakest part. I'll
tell you what, I don't want to find out.




Lee

Thanks Lee. And thanks to the rest of you guys, too. The post will be deleted.

 

[tolman_paul]

125 psi can certainly do some damage. A 2 3/8" dia circle has the area of ~4 sq in, and at 125 psi has 500# of force on it. Increase the area 4 fold over that and you have a ton of force working against that surface.

If you're going to pressurize something, you darn well better know if that something is rated for the pressure and you should give grave consideration about what can happen if it isn't.

 

[thomas1]

Thanks Lee. And thanks to the rest of you guys, too. The post will be deleted.

:msp_thumbsup::msp_thumbsup:

 

[hkusp9]

Its a calculated risk guys. Im not telling you to try it yourself, and im not saying that its the safest thing in the world do to, but we're all supposed to be grown men here and we can all evaluate our own decisions before making them and take responsibility for the outcome.

My tank had about a 2 inch long portion of the seam that was leaking. The inside of the tank looked to be in pretty good shape and i took a calculated guess that the pressure would start venting at that leak first. Sure enough it popped that side first and then i just jiggled the rest loose.

The epoxy holding the tank together is about 50 years old and seemed brittle when I tested it with a razorblade. I took a gamble and it payed off.

I got my second saw in today and it has a leak in the tank as well. However this leak is in the bottom corner of the tank and nowhere near the seam. On that tank, i will just be using the tank sealer and not the pressure method since it might be MORE risky on that tank.

 

[watsonr]

The only thing that saved the OP is that the tank never made it to 125psi. The relief valve in the cap lifted before it built up any real pressure and the thumb job only got him a couple more pounds. Bet you it never made ten, bet it probably never made 5.

Straight air into the tank would have blown the cap off before it blew the seams... and in this case may have been just as dangerous... flying shrapnel in the form of razor sharp pieces of hard plastic. You would have never closed your eyes fast enough.

You did have on safety glasses, standing there... right next to the bomb? You may have taken a calculated risk in your opinion... hindsight say's that the risk you took may have been your last... say your prayers, the big man was on your side this time.

 

[samdweezel05]

Its a calculated risk guys. Im not telling you to try it yourself, and im not saying that its the safest thing in the world do to, but we're all supposed to be grown men here and we can all evaluate our own decisions before making them and take responsibility for the outcome.

My tank had about a 2 inch long portion of the seam that was leaking. The inside of the tank looked to be in pretty good shape and i took a calculated guess that the pressure would start venting at that leak first. Sure enough it popped that side first and then i just jiggled the rest loose.

The epoxy holding the tank together is about 50 years old and seemed brittle when I tested it with a razorblade. I took a gamble and it payed off.

I got my second saw in today and it has a leak in the tank as well. However this leak is in the bottom corner of the tank and nowhere near the seam. On that tank, i will just be using the tank sealer and not the pressure method since it might be MORE risky on that tank.

You couldn't put the flywheel back on the first time with out miss aligning the key way and wrecking the key, flywheel and crank. What makes you the one to decide if something is a "calculated risk"? You are a danger to all the other members reading this thread who don't know any better than to think that you know what your doing. It's too bad that you can't lock your self out of the forum.

 

[Brian13]

It was less of a calculated risk and more of luck. In theory it sounds like a great idea, bet there are too many variables to make that judgement. However the the problem is somebody else could come behind you read that not knowing any better and not be so lucky.

 

[tolman_paul]

Just wondering, if you're not an engineer, how did you calculate the risk?

 

[Jon1212]

Its a calculated risk guys. Im not telling you to try it yourself, and im not saying that its the safest thing in the world do to, but we're all supposed to be grown men here and we can all evaluate our own decisions before making them and take responsibility for the outcome.
My tank had about a 2 inch long portion of the seam that was leaking. The inside of the tank looked to be in pretty good shape and i took a calculated guess that the pressure would start venting at that leak first. Sure enough it popped that side first and then i just jiggled the rest loose.

The epoxy holding the tank together is about 50 years old and seemed brittle when I tested it with a razorblade. I took a gamble and it payed off.

I got my second saw in today and it has a leak in the tank as well. However this leak is in the bottom corner of the tank and nowhere near the seam. On that tank, i will just be using the tank sealer and not the pressure method since it might be MORE risky on that tank.

Words of advice you'd do well to follow yourself, though after seeing you ignore so much advice others have given you i don't suppose you'd be one to follow your own either.

The only thing that saved the OP is that the tank never made it to 125psi. The relief valve in the cap lifted before it built up any real pressure and the thumb job only got him a couple more pounds. Bet you it never made ten, bet it probably never made 5.

Straight air into the tank would have blown the cap off before it blew the seams... and in this case may have been just as dangerous... flying shrapnel in the form of razor sharp pieces of hard plastic. You would have never closed your eyes fast enough.

You did have on safety glasses, standing there... right next to the bomb?

My money is on a stainless steel collander from his kitchen.........LOL!!!!

 

[watsonr]

Just wondering, if you're not an engineer, how did you calculate the risk?

Calculated by "WAG".....