LumberJocks

Table saw trunnion crack

  • Advertise with us

« back to Power Tools, Hardware and Accessories forum

Forum topic by Gaffneylumber posted 12-04-2016 07:42 PM 749 views 0 times favorited 17 replies Add to Favorites Watch
View Gaffneylumber's profile

Gaffneylumber

98 posts in 668 days


12-04-2016 07:42 PM

Topic tags/keywords: tool

So I was helping a friend tune up an older blue Jet contractor saw he bought recently off of Craigslist. As we were aligning the blade to the miter slots I noticed that the motor seemed a little unstable. This is before we even loosened the trunnion bracket bolts. I looked around inside with a flashlight and found a crack in the trunnion at the front of the blade. The crack is all the way through and you can pull the pieces of cast iron apart. It is right beside where the tie rod goes through the trunnion. What would have caused this? Has anyone seen this before? What is the best option to repair?

-- Grayson - South Carolina


17 replies so far

View Loren's profile

Loren

9633 posts in 3487 days


#1 posted 12-04-2016 08:57 PM

contractor saw trunnions are often pot metal,
but whether they are that or iron, the trunnion
can be welded by a shop that does such work.

As an alternative you may be able to find a
trunnion from a scrapped saw on ebay.

View crank49's profile

crank49

4026 posts in 2810 days


#2 posted 12-04-2016 09:09 PM

If it’s cast iron the best bet may be to braze it. A good welding shop would know.

View Gaffneylumber's profile

Gaffneylumber

98 posts in 668 days


#3 posted 12-04-2016 09:15 PM

Thanks Loren it may very well be pot metal. What would be your thoughts on using an epoxy like jb weld in the crack? I know that stuff is supposed to be pretty strong and will adhere to metal. I could get complete coverage in the crack with the liquid version. My friend only has $140 in the saw and is trying to get out as cheap as possible.

-- Grayson - South Carolina

View Loren's profile

Loren

9633 posts in 3487 days


#4 posted 12-04-2016 09:18 PM

I’ve had mixed results using JBWeld in stress
areas but it may be worth a try, especially
if you can drill and tap a couple of holes
for a steel mending plate somewhere along
the crack.

View knotscott's profile (online now)

knotscott

7789 posts in 3215 days


#5 posted 12-04-2016 10:24 PM

The older Jet contractor saws were made by Mao Shan, and were nearly identical to the older Grizzly, General International, Omega, Ohio Forge, King, Bridgewood, PM, and many others. Maybe you can find an old donor saw on CL.

-- Happiness is like wetting your pants...everyone can see it, but only you can feel the warmth....

View Carloz's profile (online now)

Carloz

984 posts in 431 days


#6 posted 12-04-2016 10:27 PM

I would not advice anyone using a table saw which was glued together.
At least “your friend” learned what craigslist is.

View splatman's profile

splatman

586 posts in 1238 days


#7 posted 12-04-2016 10:31 PM

Mending plates or, if you could drill thru the entire part, (1.) perpendicular to the crack, apply epoxy, then run a bolt thru the hole and tighten it down good.
Might not need to drill through the entire part; (2.) only drill though one 1/2, and an inch or so with a smaller bit into the other 1/2, then thread the smaller-diameter hole.
Apply epoxy to the crack and the repair hardware to make doubly sure this will not come apart again.

View MrUnix's profile

MrUnix

6012 posts in 2038 days


#8 posted 12-04-2016 10:41 PM

Lots of ways to fix cracked parts pretty easily, but before doing anything, you need to figure out what it’s made out of and go from there. Maybe post a picture or two as well :)

If it’s cast iron… it’s easily welded, which is the preferred method.

Cheers,
Brad

-- Brad in FL - In Dog I trust... everything else is questionable

View corelz125's profile

corelz125

314 posts in 815 days


#9 posted 12-04-2016 10:41 PM

It’s not going to be cheap to weld it. Cast iron is tough to weld and some people don’t know how to weld cast. My trunion cracked on my saw when I first brought it home but it was brand new and was covered under the warranty.

View MrUnix's profile

MrUnix

6012 posts in 2038 days


#10 posted 12-04-2016 10:53 PM

It’s not going to be cheap to weld it.
- corelz125

Hmmm… around here, a welding shop would charge maybe $25 to braze a small crack. Certainly cheaper than trying to source a new bracket for an old machine like that. I’ve even fixed cast iron a few times using standard ER70S wire in a mig welder, which basically cost me nothing but about a half hour of my time. YMMV.

Cheers,
Brad

-- Brad in FL - In Dog I trust... everything else is questionable

View SignWave's profile

SignWave

440 posts in 2874 days


#11 posted 12-05-2016 02:37 AM

I’ll echo that brazing is the best choice for a crack like you describe. Brazing works best when you have a good size surface that mates together properly, and it sounds like you do. It isn’t all that difficult and should end up at least as strong as the original part, and it will be permanent.

If you use adhesives like epoxy, it will probably fail eventually if it works at all, and it will prevent a proper repair later.

Before I had a welder, I had a couple of small jobs done at a local muffler shop (not a chain). The cash price was very reasonable.

-- Barry, http://BarrysWorkshop.com/

View Gaffneylumber's profile

Gaffneylumber

98 posts in 668 days


#12 posted 12-05-2016 02:42 AM

Thanks guys for all the insight and advice. If it were my saw I would probably go the welding route but my buddy sent me this pic and said he decided to epoxy it. Thanks Loren and Splatman for the mending plate idea. He said that he will add one for extra support.

-- Grayson - South Carolina

View bigJohninvegas's profile (online now)

bigJohninvegas

383 posts in 1301 days


#13 posted 12-05-2016 03:07 AM



It s not going to be cheap to weld it.
- corelz125

Hmmm… around here, a welding shop would charge maybe $25 to braze a small crack. Certainly cheaper than trying to source a new bracket for an old machine like that. I ve even fixed cast iron a few times using standard ER70S wire in a mig welder, which basically cost me nothing but about a half hour of my time. YMMV.

Cheers,
Brad

- MrUnix

I agree with Brad. $25 at a weld shop for sure. Don’t give up if the JB weld fails.
Scary fix, good luck.

-- John

View corelz125's profile

corelz125

314 posts in 815 days


#14 posted 12-05-2016 03:08 AM

There’s a difference between welding and brazing strength.

View SignWave's profile

SignWave

440 posts in 2874 days


#15 posted 12-05-2016 02:02 PM

Sometimes you have to just choose a path and run with it. I hope it holds well.

-- Barry, http://BarrysWorkshop.com/

showing 1 through 15 of 17 replies

Have your say...

You must be signed in to reply.

DISCLAIMER: Any posts on LJ are posted by individuals acting in their own right and do not necessarily reflect the views of LJ. LJ will not be held liable for the actions of any user.

Latest Projects | Latest Blog Entries | Latest Forum Topics

HomeRefurbers.com