Rebirth of a 6 Foot Flail Mower

[awemawson]

This mornings job was to make a start on fabricating the replacement roller. This will be a piece of heavy walled tube, with stub axles welded on disks on the end, and to give a bit more strength each end will have two disks about 6" apart, one buried inside the tube, the other at the extreme end.

First thing - make the stub axles. These are 1.375" stock with the last 2" turned down to 1.25" to fit the flanged bearings. Having cut the stock I did a dummy run on the offcut as I wanted a nice push fit into the bearing inner. This let me accurately calibrate my DRO to the particular tool that I was using, ensuring the the two 'real ones' came out spot on, which they did 

I've centre drilled both ends, so that I can turn the disks down to the right size between centres when they are welded onto the stub axles.

Then the Postman arrived with the replacement taper lock bush and drive belts for the jackshaft, so I will fit those before boring the disks ready for welding.

[awemawson]

So a brief interlude from machining to fit the new taperlock bush and belts. Glad to say that my guess that they should be SPB1600's and that the originals had worn 'narrow' was correct - lucky really as those belts weren't cheap.

Set the taper lock into the four sheave pulley, and gently tightened it up while keeping an eye on the pulley alignment by the old expedient of a straight edge down the side of the pulleys (held on by magnets in picture  )

I then had to fully compress the tensioner spring to get the four belts into place, then unscrew the tensioner nut fully to transfer the spring tension to the belts. No doubt that washer I'd put under the squashing nut , which is now just sitting there, will rattle and drive me mad.

Happily the new belts sit at the correct ride height in the Vee's of the pulleys, and the swinging pivot that mounts the jackshaft is dead on the middle of it's travel - so all in looking good 

[awemawson]

So take four disks, centre drill them, wack a big hole through the middle, then bore them to size. A quick trial assembly then now it's time to crack out the welder. Sorry didn't photograph the boring, but it was boring 

We've got electricity board men in yellow coats just descended on us so I'm loath to start welding just yet as they'll be knocking on the door - they've decided to change some electricity poles in the field which they did yesterday, and have come back to dismantle the metal work from the top of the old ones - yes I've nabbed the poles themselves, I can see another field shelter coming on 


Once they are tack welded up I'll mount them between centres and check that they run reasonably square, adjust as necessary before final weld up. Then they'll get turned down to the bore size of the tube. I'll need to grind a notch in the disks to clear the tubes electric resistance welded seam which is inside the tube.

[awemawson]

Meanwhile I re-made the pivot bar that all those floppy plates hang on - just 6 foot of 14 mm bar radially drilled at both ends to take split pins so nothing high tech. Just a bit straighter than the old one that's lying beside it 

It did however get the obligatory spray of zinc rich primer and black gloss paint. Waste of time really as it'll all be rubbed off as they swing, but it goes against the grain to leave bare steel. It'll get slathered in Shell Ensis as will the plates, when they go back together again.

[AdeV]

I don't know, when are you going to repair something complicated  , enough of this easy peasy stuff already! 

Heyyyyy, I've got an idea.... how'd you fancy some Mazak skills? 

[awemawson]

Ade, I wouldn't want to deprive you of that pleasure, is it in the new building yet?

[awemawson]

Not much done this morning as I'm due at the dentist shortly 

However I did manage to draw up in Autocad the bearing baffle plates, and cut them from 3 mm zintec steel on the CNC plasma table. For some reason the cut starts are starting on the wrong side of the line giving those little lead ins - doesn't matter really in this situation but I must find some time to investigate the cause - certainly looking at Sheetcam they look good on the screen 

These baffle are to stop (or probably just reduce!) junk wrapping round the shafts and getting into the bearing seals.

[AdeV]

Ade, I wouldn't want to deprive you of that pleasure, is it in the new building yet?

Not yet.... the van's being fixed which is preventing me from moving all the smaller stuff that's right in the way... But I've moved it around loads on the computer screen I know exactly where it's got to end up...

[DMIOM]

..... I know exactly where it's got to end up...

Somewhere near Battle, East Sussex? 

Dave

[awemawson]

On with the roller today.

First job, weld up those stub axles and disks and turn them down to be a slide fit in the roller tubing. Sorry no pictures - I forgot 

Then re-fit the skids and the bearings that take the roller so that I can make an accurate final measurement for the length of tube to cut by fitting the stub axles with the disks welded on, and measure between them - 1870 mm which should leave 5 mm end float.

Then cut the tube to 1870 mm - I really do need to make a suitable trestle for the band saw - this sort of Heath Robinson affair made from paint tins and wooden wedges needs replacing 

Then chamfer the inside edge to increase the weld penetration, and  tack weld the stub axle / disk 'bobbins'  into the tube for a trial fit.

I was happy that the length would be right, but not sure how accurately the axles would be co-axial, which could only be tested putting it in it's bearings - happy to report it spins nicely with hardly a trace of wobble 

The tacks had to be light enough to be ground out if the fit was wrong, but strong enough to take the considerable weight and inertia of the assembly when fitting. It survived the fitting, but will also have to survive removal for full welding then a coat or two of paint.

[Pete W.]

It's all looking good and coming together well, Andrew.

Your projects make mine look so inadequate!!          

That off-cut of tube looks to be worth saving - I'm sure it'll be useful some time in the future.    

[awemawson]

Thanks Pete for the kind words 

I've a 5.5 metre long 'offcut' of that tube if you need a new gatepost 

[sparky961]

For some reason the cut starts are starting on the wrong side of the line giving those little lead ins

Are you sure it's at the start of the cut?  Hard to tell whether your outside profiles had the same problem as the inside ones. 

With inside profiles especially if it's set to do any kind of lead-out at the end, it can result in a similar notch.  What happens is that the slug falls out but the plasma is still on due to the lead-out settings.  It has no choice but to complete the ground circuit through the part, thus burning away a section you'd rather be left there.  Best settings for lead-out are nil, or better yet turn off about a 1/2 kerf width before the end of the profile.

Best lead-in is arguable and dependent on material thickness also.  Perpendicular straight lead-in at least twice the size of the initial pierce hole seems to work well.  Tangent arc is ok for some smaller holes, but lead-out needs to be tweaked accordingly due to the tapering thickness of material near the end of the cut.

Or just get an industrial fibre laser and don't worry about it.

Or who knows, maybe you just picked "outside" when it should have been "inside", totally a user error... ;)

[Will_D]

Love the way you managed to colour match our dancing bannanas

    

[awemawson]

Depends which bit you look at Will, that yellow doesn't cover well even with two coats 

Today's job was to finish off the roller. So I took off both skids, lowering the roller to the floor and dragged it into the welding shop. It's blooming heavy and I was anxious not to bend those delicate tack welds.

Not the easiest thing to get at for welding - it ended up propped up against the bench at about 45 degrees, with a couple of clamps strategically placed to stop it rolling away as I welded and dressed back the welds. I reckoned that the smoother it is the less tendency there will be for bits to get wrapped up in it.

Then it was up onto a pair of trestles, masking tape over the bits of axle that go in the bearings, and a coat of primer. A bit of cooking with a fan heater and it was ready for a coat of black top coat. This will probably all roll off when it's first used but should keep the rust at bay until then.

[awemawson]

Can't do too much today due to livestock commitments. Off to the feed store first thing for a load of pig and chicken feed, then while waiting for help with the sheep managed to get the bearing cover, jackshaft cover and belt cover back into place.

Getting close to finishing thank goodness - just need to re-fit the roller, make up the rubber curtain that hangs at the rear, fit the three point lifting tubular framework and those floppy plates. Only thing left to source is the PTO shaft - the one that came with it seems reasonable but it's safety covers are a write off, but I want to get the flail on a tractor and prove that the 48" length of the original is correct before spending out on new covers or maybe a new PTO shaft.

But now it's off to get the flock in, sort out some Ewes that are limping, and select six lambs for tomorrows trip to the abattoir.

[modeng200023]

It looks too good to use now 

[Spurry]

Another magnificent job Andrew.    It will be too nice to leave outside though, even when you have used it once or twice.
Pete

[awemawson]

As it happens I have a planning application in for a Tractor Shed at the moment - 40 foot x 45 foot so it should fit in there nicely if the permission comes through 

[awemawson]

The 'other half' is out playing her Oboe for the British Legion, so by bribing the dogs with a stoked up fire and some classical music I was able to sneak out and get a bit more done 

Got the Three point lifting frame back in place and bolted on. The original 'brace that stops it rotating on the mounting bar had got damaged when I was a bit too enthusiastic with the 'gas axe', but as luck would have it, I had a brand new heavy duty tractor 'CAT 2 Top Link' that I'd bought for that Hedge Flail mounting project, but it had proved too bulky to fit the tractor lift eye. No such problem here, it could have been made for the job 

All this wasn't accomplished without loss of blood, but Ghoul Ade will be pleased to hear this time I took a picture for him 


.... the final jobs are getting crossed off the list 

[awemawson]

Back from the Abattoir early doors, (why do I ALWAYS seem to get held up by a train at the level crossing both going AND returning  ) so quickly loaded up some sheep that a friend's taking to Ashford market for me, and was able to get back in the workshop 

Put the roller back without loosing much paint (or blood!) and hopefully that should be the final fitting, it can now stay in place. Delighted to see that the end float is pretty much exactly the 5 mm I'd decided on - didn't want it too floppy but certainly not tight. In practice the end float is equally distributed each end, then the bearing collars locked onto the stub axles with Allen grub screws.

I also refitted the little straps that I presume are intended to give the bearings a little protection. I reckon a pressed cup design would be much better !

[AdeV]

Hehe 

[awemawson]

I finally got round to sorting out those flappy plates. They'd been soaking in Citric Acid for quite some time, so the rust had all gone. To neutralise the citric acid they got a brief dip in caustic soda, and a good scrubbing in very hot water, before blowing them dry with a hand hot air drier.

Then a fairly heavy coat of zinc rich paint both sides, trying to get it down the pivot hole, followed by a spray of black on both sides. These are aerosol spray can paints as they are very fast drying, but I'll leave them over night before further assembly.

 

[vintageandclassicrepairs]

Hi Andrew,
Great project,
Its too good to go cutting grass with now 

Regards
John

[hermetic]

Lovely job Andrew! Has been an interesting thread! I could do with one of them, or maybe a Topper to put on the back of my Fordson Diesel Major as we have 4 acres of East Yorkshire to keep under some sort of control! Cracking rebuild!
Phil