Braze Repair on DoAll Saw

[Don52]

In the process of moving my DoAll saw we put too much force on the table and broke the cast iron table bracket. When we inspected the bracket we could see that it was repaired by brazing in the past. The first picture shows the saw with the table askew due to the broken bracket.

1. DoAll Saw


If you look carefully at the following picture you can see the new crack next to the old repair.

2. Crack and previous repair


For the next two pictures I have removed half of the casting, so that you can see the cracked face as well as the previous repair.

3. Cracked face


4. Cracked face and previous repair


The first step was to vee out the crack.

5. Crack veed out

[Don52]

I mounted the bracket in the table to hold all of the pieces in the correct orientation.

6. Bracket in place for brazing


My friend John used one of my Oxyacetylene torches to preheat the casting to 900° F.

7. Preheating with one torch


I used a second Oxyacetylene torch to braze the joint. I used the
Lincoln pre-coated brazing rods that I picked up from Lowes. I like the pre-coated rods because it avoids stopping the brazing process to continually dip the rods into the flux can.

8. Crack brazed


I covered the brazed joint with kitty litter and let it cool off overnight.

9. Cover area with Kitty litter to cool slowly


I used a brass wire wheel to clean up the joint. Here are three pictures of the brazed joint cleaned up.

10. Inside of brazed joint

[Don52]

11. Outside of brazed joint


12. Entire bracket repaired


I decided to paint the saw. The first step was to Dual Action sand the saw to blend the paint chips. I didn't bother to use primer surfacer to make the surface completely flat.

13. Saw DA sanded


Here is a picture of the saw before painting for comparison

14. Saw before painting


Here is a picture of the saw after I primed it.

15. Saw primed

[Don52]

Here is a picture of the saw painted.

16. Saw painted


My friend John was in a GM plant downriver and noticed them scrapping a similar saw that was caught in a flood. He asked them to send him the selection dial for my saw, which the did. I don't typically use the selection dial, but it dresses up the saw.

17. Close up of Job selector dial


This saw was built in the 40's so it is older than I. It still works fine including the blade welder, but it can only weld carbon steel blades not bi-metal.

-Don

[Ltbadd]

Good work Don, saw looks great after painting

[ryanjones2150]

Excellent job Don. I appreciate the documentation process you do on your projects. I wish I had the patience for it.

I like that colchester in the background too. Great machine.

[tarry99]

All I can say is amazing , that the arm in question has been broken twice. For anyone who has not been around these machines The Doall band saws are built like a D-11 Cat dozer..........One only has to get ready to move one and they quickly find out what a heavy object really feels like.

But I'm more curious why did it brake? And if another repair along side the first one is going to solve the problem? without perhaps pinning the joint and getting into some stronger filler materials? Notwithstanding heat treating after the fact and perhaps peening the weld zone between passes.... I've done a few of these repairs over the years on different grades of cast and nodular iron and the application of heat and then cooling seems to always bring on the question of Brittlement within the weld zone ....heat-treating the component after or heat conditioning is always at question and no matter who you talk with in the industry everyone has a different method or opinion..

Great Brazing by the way and attention to pre & post heat...

[Don52]

All I can say is amazing , that the arm in question has been broken twice. For anyone who has not been around these machines The Doall band saws are built like a D-11 Cat dozer..........One only has to get ready to move one and they quickly find out what a heavy object really feels like.

I agree that the DoAll saws are robustly built. In normal operation the bracket is more than adequate.

But I'm more curious why did it brake?

It broke two time in 75 years. I can’t address the first time but the second time was due to abuse. We were tipping the saw vertical by lifting under the table on one side with a z-lift table. We got the bright idea to but a service jack under the base of the saw on the opposite side to keep it from going over center and falling down on the other side. By mistake we put too much force on the service jack, which meant that the z-lift and jack had to support the whole weight of the saw, so the bracket also had to support this additional unbalance moment. If the service jack was loose, the moment on the bracket would have been considerably reduced and I don’t believe that the bracket would have failed.

And if another repair along side the first one is going to solve the problem? without perhaps pinning the joint and getting into some stronger filler materials?

The first repair lasted ~50 years. The second crack didn’t occur on the edge of the first repair, but in a new location. The area of both failures was the high stress point of the bracket, so this is where both failures occurred. If we hadn’t abused the saw, I am confident that the first repair would still be fine. I selected the brazing process because I was concerned that if I heated it too much as required by another process, it would have melted the braze from the first repair and made it a bigger job.

Notwithstanding heat treating after the fact and perhaps peening the weld zone between passes.... I've done a few of these repairs over the years on different grades of cast and nodular iron and the application of heat and then cooling seems to always bring on the question of Brittlement within the weld zone ....heat-treating the component after or heat conditioning is always at question and no matter who you talk with in the industry everyone has a different method or opinion.

I have been lucky with all of my cast iron repairs. I have used 99% Nickel rods, 55% Nickel and Steel rods and I have used brazing rods. I pre-heat the entire area and control the cooling rate carefully. It can change tomorrow, but so far none of my repairs have failed.

Great Brazing by the way and attention to pre & post heat...

Thanks,
-Don

[Don52]

Good work Don, saw looks great after painting

Thank you.

Excellent job Don. I appreciate the documentation process you do on your projects. I wish I had the patience for it.

I like that colchester in the background too. Great machine.

Thanks, I really like my Clausing Colchester lathe and use it all the time.

-Don