Exhaust modification

[scsmith42]

In the 11 years that I've owned Tom, the Baker sawmill, I've had to repair or replace the rain cap on the exhaust several times.

Last week when repairing the hydraulic pump I noticed that the rain cap was cracked again so I decided to go to plan B and do an exhaust pipe modification to eliminate the rain cap.

I was able to source a stainless steel exhaust pipe donut in inch and 3/4 on eBay that I could cut up to make the revised rain protection.

Hopefully this solves the problem for good. The exhaust is directed off the side of the mill and towards the front so as to keep it out of my face.





I don't take the Sawmill mobile anymore so the exhaust opening facing forward should not be an issue. If I do need to, I can simply take it up with some duct tape while on the road.

[Ben Cut-wright]

Good job.  Wouldn't the first 90 have been enough? 

I actually prefer flappers on diesel exhaust. What caused yours to be replaced? 

[scsmith42]

Good job.  Wouldn't the first 90 have been enough? 

I actually prefer flappers on diesel exhaust. What caused yours to be replaced? 

Ben, I've gone through several flappers on Tom in the past 12 years.  They have cracked through, welds broken, bushings worn through the bolts, etc.

When I went to source a replacement flapper, I figured that I'd try a different style.  Turns out that every flapper available in the USA for 1-3/4" exhaust is made by the same company, and it's the same style that I keep having problems with.

This particular setup has a muffler mounted directly on top of the exhaust mainfold, going straight up.

If I had only put in a 90, then any blowing rain that entered it would have gone down the muffler, through the exhaust manifold and straight into the cylinders.  

IF I put in a 180, then the fumes would be coming back into my face.

Hence my design.  Any blowing rain would have to go a few inches up before it could enter the main exhaust pipe.

[Dave Shepard]

The flapper on my LT40 Super rattled horribly at idle. It got thrown on the ground next to the first support leg, and shoveled up with the sawdust. A five gallon bucket works very well in its place.

[jpassardi]

Yes the flappers can be very annoying at idle. I have one on my boom lift and it rattles at idle.

[Dave Shepard]

I had a 90⁰ turnout, but it didn't like tarps.

[YellowHammer]

That looks pretty cool, it reminds me of a striking cobra snake.

[Magicman]

There has gotta be something wrong here, or at least cheating or something.  

A reverse P trap on an exhaust ?? 

[customsawyer]

I wish you would quit making my welds look so bad.

[Peter Drouin]

A little Hot Rodding on the mill. Looks cool.

[scsmith42]

I wish you would quit making my welds look so bad.

Jake, there's a reason why the photo's of the welds are fuzzy.... 

Welding stainless is always interesting.  When I want a pretty weld, I'll do it in a gas-down box flooded with argon, or seal the ends of the tubing and flood the inside with argon.

In the desire for full disclosure, in this instance, I took a shortcut and just used the mild steel wire that was already in the MIG. 

Between the alternator boss breaking off of the front cover 3 weeks back, and then the hydraulic pump blowing an elbow out, the darn sawmill has been down for 2 of the last 3 weeks.  My mother-in-law's well pump also died during this same time so that cost me a day to repair.  Not to mention all of the other fun farm maintenance needs that are always cropping up.

By the time that I fixed the exhaust I just wanted to get it back in service and keep it that way.  So up close the welds on this tubing are not my best...

I really do know how to weld though....  Honest!  .

Here is one of my aluminum TIG beads from when I built the slabber 12 years ago.



And here is a (6010 or 7018 - forget which) bead from when I did some repair work on one of my trailers.




Re the broken alternator mount that I referred to above, here is a "work in process" photo of the alternator bracket "fix" that I made.  The end result was much nicer with all milled corners, radiused, etc.  The blue portion in the middle was the piece that broke off of the Kubota front cover.  Basically I made a saddle that encompassed the broken section in it, and reduced the stress on the OEM design.




And here is the installed, finished product.  You can see the break at the bottom of the blue painted original boss.  The alternator pivot bolt is now supported with a bracket on both the front and rear of the front cover.  Hopefully this improves the design so that I don't need to replace the cover or remove it and weld the old boss back on.



At 19 years of age it's to be expected that some repairs will be needed.  It sure is sweet though when equipment does not break down and you just get to use it (and enjoy the service from something that was paid for a long time ago).

[scsmith42]

There has gotta be something wrong here, or at least cheating or something. 

A reverse P trap on an exhaust ?? 

That's a pretty apt description!  

The last time that the rain cap broke I didn't discover it until after we had a hard rain.  Fortunately the engine wasn't hurt but that was part of my motivation to come up with a redesign that would last and be weather proof.

[doc henderson]

reminds me of an expansion chamber on an old school dirt bike.

[fluidpowerpro]

Couldn't one just add some weight to one end of the flapper so it wouldn't rattle at idle?

[doc henderson]

unless the restriction made the system hotter and warped valves and stuff.  but we used to add steel wool to quiet things down and did fine, so prob. not an issue. .   or squelch the movement some so it does not move a little at idle.

[customsawyer]

I don't claim to be a good at welding, so I weld a lot.
Reminds me of the old joke. Do you know the difference between a welder and a farmer? The welder doesn't think he can farm.

[jpassardi]

Just tell everyone: grinder and paint makes me the welder I ain't... 

[fluidpowerpro]

We are all Welders. Just some are better at it than others.

[scsmith42]

Couldn't one just add some weight to one end of the flapper so it wouldn't rattle at idle?

That would have been an option, but the funny thing is that the sawmill does not spend a lot of time at idle, because of the centrifugal clutch that Baker uses.

At idle, the hydraulic pressure is very low and so the hydraulics move slowly.  This is annoying when you're trying to crank out production.  If I idle up 35% or so the pressure comes up, but then the clutch is slipping and wears out prematurely.  So the engine is basically at either idle (less than 1% of run time) or full throttle - or at least enough throttle so that the clutch engages.

I don't mind fixing something *one* time, but when I fix the same problem multiple times it's time to do something different.

Hence - as Lynn would say - my P trap exhaust mod!

[doc henderson]

If it was an expansion chamber, then the rattle would not really bother you anymore.  

[Ben Cut-wright]

"And here is a (6010 or 7018 - forget which) bead from when I did some repair work on one of my trailers."

My money is on 6010 and well done.  Ran my share of root welds with them.

"Couldn't one just add some weight to one end of the flapper so it wouldn't rattle at idle?"

Gas or diesel, the exhaust flappers are *balanced to prevent excessive back pressure while ensuring closure.

Open exhaust pipes can be an invitation to many varmints and pests.  Straight up covered with an aluminum can at shut-down is a good option if the noise or wear is intolerable.  A very light weight short-cut can will easily blow off when the engine is started.  A heavy can will muffle the exhaust so much the operator would have to be deaf to ignore the difference.  Performance will suffer enough to alert the operator.

The older Onan's had beehive style spark-arrester mufflers.  I've transferred a pair of those through three engines so far.  The exhaust stream is a nearly 180 degree wide cone of fast moving exhaust air when the engine is at full RPM's.  Creates a slight dust hazard in forward travel in the cut.

If I fabricate a straight up exhaust I will have to take my own advise and....use a can on both mufflers.  Mounted sideways as they are, they prevent water intrusion.  Mounted straight up they will permit rain or dust when the engine isn't running.  Moot point, as I normally have the entire saw head covered when it isn't in operation for extended periods of time.  

[scsmith42]

Re the can's, one of my challenges is that we frequently get high winds and they will blow the can / bucket off the exhaust.  That happened to me last winter the last time that the cap broke, and I ended up with some water in the exhaust.