Flail Mower Weld-On Lugs Mott Hammer Knife Model 72

[racarr]

Inspecting a mower (fine-cut with 4 rows of 23 stations) purchased off Craigslist a few weeks ago, I found some of the knife stations are missing lugs. An earlier owner, instead of replacing the missing lugs, attached the knives using a bolt through one lug and several washers and a nut for the pairing blade. I have new weld-on lugs purchased from Flailmaster and hope to complete the repairs this week. It looks like I can do this with the mower tipped-back and the rotor still attached. Can the welding be done via a wire-feed welder? I have access to a dual voltage Millermatic 211. The shop is not yet wired for 230 volt, but could be.

Any thoughts or recommendations will be appreciated.

Thanks.

 

[leonz]

Hello Bob,

I want to Welcome you as the newwest Member of the Flail Mower Nation.

About your new to you flail mower......


I would much rather see you remove the rotor and then weld it ONLY because the
welding will fry and freeze the bearings (Never Good EVER) Reliable Plant and Lean Manufacturing Journal

In for a penny in for a pound,

I know but it may be a good time to buy new bearings too,
only because the previous owner did not spend the time or
money and skated through it by doing a whizz fixit.

I would so much rather see you pull the rotor now rather than
pulling the rotor later to remove the siezed and welded
bearings as you would end up smoke wrenching the bearing
mount castings off the side weldments and then grinding off the
bearing races from the stub shaft ends.

NO amount of welding the ground to the flail mower rotor is going
to help because the grease will aid in amperage and current movement.

Candidly I am unsure if gas welding would be strong enough to accomplish the
job either due to the centrifugal forces implied and created by the high speed
rotation of the flail mower rotor.


If the previous owner had broken weldments the bearings condition is always suspect.

 

[racarr]

The approach you present makes sense. I definitely do not want to make things worse. It is also possible that already-damaged bearings account for some of the vibration, so replacing them now is a good idea.

Just to be sure I understand correctly - does your statement that gas welding might not be strong enough mean that arc welding is preferred?

Thank you for the thoughtful and informative response.

 

[Arc weld]

If the bearings appear to be OK, you could weld the new lugs on with the rotor installed. You'd want your 211 on 220 volts and as hot as you can handle. If you don't have a lot of welding experience, get someone that does. I only say this because if you make a bad weld, it's a lot more work to repair and you could cause more damage. As for welding with the rotor installed, use a sanding disc or lightly grind an existing lug to attach the ground clamp to. Preferably as close to the new lug as possible. Doesn't have to be on the one beside it but close enough and still out of your way. Electricity takes the path of least resistance. Make sure you have a good clean ground and you shouldn't have any problems. I would get a bolt to go through the 2 lugs and make some spacers to go in between. This would hold the lug in alignment and also prevent it from pulling when it cools off. If you need to weld lugs near the end don't do them all at the same time to prevent any heat getting to the bearings. When the blades are installed, use the proper pins and not bolts. Mott/Alamo has special cotter pins that are flat on one side. The flat side goes against the lug and you can use side cutters to bend the other leg up about 45 deg's.

MIG welding is arc welding as it uses an electric arc. Gas welding with an oxy/acet. torch would take a very long time and be quite costly. It would also get the rotor a lot hotter than arc welding. MIG welding is fast and will cool off a lot faster. Never pour water on a hot weld though.

 

[2458n]

Thank you for your reply Arc weld. I was going to take this very question to someone who teaches at Hobart's school in Troy Ohio. I thought your suggestion would keep from arcing the bearings. I just did not know but have welded on trailers etc.

 

[racarr]

Thank you, Arc weld, for the additional information and methodology. Determining the condition of the bearings seems to be the next step. I will pursue that this week before proceeding further. I planned to add the additional electrical circuit to the shop's wiring anyway, so this project will shift that priority. I will have a friend with more experience do the welding.

Are the Mott/Alamo cotter pins available via web ordering (Messick's)? The cotter pins included in the shipment from Flailmaster do not have a flattened side.

 

[BraveheartGN]

I have had the lugs successfully welded on without any damage - don't know how my welder did it, but the bearings are fine (I also have a 72 inch Mott mower). If the missing lugs are near the center it would take a lot of heat I would think to get conducted out to the ends where the bearings are.

Definitely use the Mott/Alamo Cleve's pins instead of bolts. The cottor pins from FM used to be flat sided but the last shipment I got from them were not, but I don't think it's a big deal. Just use a good pair of needle nose pliers. I've also found the use of a scratch awl helpful in removing the cottors - slip it onto the loop of the pin and use the edge of the lug to pivot against to remove the pin (I try to flatten or cut the tails of the cottor first).

Always grease those bearings before each use, though.

 

[leonz]

Yay!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

I am glad that the surgery went well. I have to wait a bit for
the ground to dry a bit more before I bring out the lawn genie
to mow.


Happy Mowing

 

[racarr]

Thank you for confirming, BraveheartGN.

Yesterday I removed the knives from all of the stations with a missing lug, and removed the knives from the 180 near-opposite stations. Because the rows are offset, the corresponding stations removed were not in direct alignment with the stations missing a lug. Doing this made a big reduction in vibration, so I am hopeful that getting the missing lugs welded will further smooth things out.

A neighbor who welds professionally will do the welding. I hope to complete the wiring this week-end.