Stump Grinder

[BobRip]

I was cutting a few small stumps today and the stump grinder disc came off the motor. I figured I had lost a bolt and worst case I needed a new bolt and a key for the keyway. I went home and took a closer look and there was a break on the blade outside of the hub weld. Initially it looked like the weld was broken, but it was acutally the disc. The blade and hub are still intact, but loose. I have attached pictures and would appreciate any suggestion on how to weld it back. Please note, I have a gas welder.

Should I grind into the crack or just fill out the weld from the hub to outside of the crack.

Or maybe you have a better way.

 

[J_J]

I was cutting a few small stumps today and the stump grinder disc came off the motor. I figured I had lost a bolt and worst case I needed a new bolt and a key for the keyway. I went home and took a closer look and there was a break on the blade outside of the hub weld. Initially it looked like the weld was broken, but it was acutally the disc. The blade and hub are still intact, but loose. I have attached pictures and would appreciate any suggestion on how to weld it back. Please note, I have a gas welder.

Should I grind into the crack or just fill out the weld from the hub to outside of the crack.

Or maybe you have a better way.

Bob, I would take it to a good welder and let him weld it.

 

[BobRip]

Bob, I would take it to a good welder and let him weld it.

That's an excellent suggestion and probably the best I will get. How about another. Here is a good chance to test and improve my welding skills. I hate to have someone else fix my stuff. That attitude forces me to learn new stuff, but is not always the best short term solution.

 

[J_J]

That's an excellent suggestion and probably the best I will get. How about another. Here is a good chance to test and improve my welding skills. I hate to have someone else fix my stuff. That attitude forces me to learn new stuff, but is not always the best short term solution.

Bob, I have learned years ago, that I can not fix everything that I use. At my age, I don't have the time to become qualified or certified in all aspects of the things that I use. I was a qualified electronics technician at one time, but I would not attempt to touch any of the new electronic stuff around today. I am getting better at my welding skills, but I know what satisfaction is, and I am not there yet.

 

[Barryh]

That's an excellent suggestion and probably the best I will get. How about another. Here is a good chance to test and improve my welding skills. I hate to have someone else fix my stuff. That attitude forces me to learn new stuff, but is not always the best short term solution.

That´s the sprit Mr. Bob, you think like myself. It doesn't have to be real pretty as long as it´s functional. I like to do my own work (if I can.... and have the equipment.) Not to take away from J.J.'s advice. It´s always well thought out but, if your weld does not hold, then you can always go to plan B just my 2 cents. Of course. I know you will show us pictures ?.

 

[BobRip]

Bob, I have learned years ago, that I can not fix everything that I use. At my age, I don't have the time to become qualified or certified in all aspects of the things that I use. I was a qualified electronics technician at one time, but I would not attempt to touch any of the new electronic stuff around today. I am getting better at my welding skills, but I know what satisfaction is, and I am not there yet.

I am an electronics guy to. A lot of today's stuff is not designed to be fixed. But you and I and a lot of other people on TBN keep trying new stuff and after awhile we accomplish a lot.

 

[BobRip]

Here is what I am thinking of doing. I will drill a series of 1/4 inch holes around the hub at the crack, right through the crack. They will be spaced about 1/4 inch apart. Then I will weld into the holes and extend the existing weld from the hub to about 1/4 inch or a little more past the crack line. Actually I already drilled the holes. Comments please or other suggestions.

 

[woodlandfarms]

My only concern is about the physics you are working with. I don't think this could come apart and kill (god I hate the safety police) but I do think that unless the weld is done right, and ground properly, you could end up with a balance issue that will eat the motors bearings at the very least...

 

[BobRip]

My only concern is about the physics you are working with. I don't think this could come apart and kill (god I hate the safety police) but I do think that unless the weld is done right, and ground properly, you could end up with a balance issue that will eat the motors bearings at the very least...

Good point. I will try to balance the weld. Since the welding is near the center of the disc, I don't thing a little unbalance will cause much vibration. I have attached a picture of holes that I drilled in the crack.

 

[MrJimi]

Another point, make sure you weld at opposite sides to avoid warping, tack welds is what I do to eliminate warping

 

[BobRip]

I finished the welding and ground about 5 stumps. It ground well, but there is a little wobble when not grinding. It's nothing like the vibration you get during normal grinding, so I guess it's OK.

Just some additional comments. I talk to Jim at J & S Enterprises about how to do this. He is the tech support for the DHC 2000 (Henrob) gas welder and also the president. He confirmed drilling the holes, but suggest that I taper them. I used a step bit to do this and wound up drilling out about 80% of the metal at the crack (no pictures of this, sorry). He also I suggested that I support the center hub as well as the rim of the grinder blade during welding. Gas welding has advantages for this type of work because you end up heating the entire piece and there is not as much stress built up. So hopefully there will not be future cracks. During the welding I preheated the center of the assembly out to a radius of two inches. When I actually welded even the undrilled out sections melted, so hopefully I will have a long lasting weld. On the other hand, I am still learning this welding process and I hope I got things hot enough. And yes, I welded on both sides. The most difficult part was getting the grinding wheel back on the motor shaft. I beat it with a hammer and I do not feel it is fully seated. I used lock tite on the 1/4 20 by 1 inch bolt which holds in it place and the hex head screw (is that the right name) which pushes against the woodruf key.
I have attached some pictures of the welds for your entertainment. Please feel free to laugh.

Thanks for all of the help and comments. Oh, I talked to Keth at PT and he said worse case send it to them and they will weld it. It probably needs sharpening as it is seven years old. Also the key in the shaft is a woodruf key 1/4 by 1 inch. I got one at Lowes.

 

[J_J]

Bob, I believe the word you were looking for is called a set screw.

 

[BobRip]

Yeah, set screw. I could not think of the English word. Must be the pace maker.

 

[J_J]

Bob, I believe the British call that screw a grub screw.

 

[BobRip]

And in Japanese a flat bladed screw driver is a "-" and a Philips is a "+".

 

[Rivco]

Bob,
How old is your stump grinder ?. I can now understand why the earlier blades can't be reversed because of the hub configuration. The blade I had on my 180 grinder was attached to a 5 bolt hub ( if my memory is working ),
which allowed me to reverse the blade.
Don't worry about anyone laughing at your welds!! , if we never take the opportunity to learn something new we will always be back seat drivers. I'm always willing to try my hand at a new skill, as long as the project is for my own personal use, that way if things don't go as planned I can only yell at myself instead of getting yelled at from a client.

 

[BobRip]

Bob,
How old is your stump grinder ?. I can now understand why the earlier blades can't be reversed because of the hub configuration. The blade I had on my 180 grinder was attached to a 5 bolt hub ( if my memory is working ),
which allowed me to reverse the blade.
.

I purchased the stump grinder in Feb 2000, so it's about 7.5 years old and has been used a lot (for a home owner). I done neighbors stumps and friends stumps as well as mine. I have also pushed it hard, sometimes taking off big chunks of stumps. I think this is pretty good life. I have also had to replace the shaft seal on the motor twice, from getting vines and a strap in the seal. If it gives too much more trouble I will probably buy a new one, unless I can repair it as easily as this time.

I am not too concerned about laughing at my welds, I just wish they were better. I am going to an Auto Show in Charlotte NC this month and Jim from J & S will be there. I hope to learn more techniques there. His support has been outstanding.

 

[sandman2234]

Isn't a Woodruff key one of those half moon shaped ones? I don' know what a straight one is called, other than a keyway or square key for the actual key.
David from jax

 

[BobRip]

Isn't a Woodruff key one of those half moon shaped ones? I don' know what a straight one is called, other than a keyway or square key for the actual key.
David from jax

Yes, it is half moon shape.