oversized holes not a problem

[slowcoach]

Thought I would share this video with you all. I found it quite interesting.

Rob 

[Majorstrain]

That's neat Rob,
But now I feel like I've rubbed sand in my eyes.

Cheers,
Phil

[slowcoach]

You too  I'm still walking around bumping into the furniture at home 

Rob

[Chazz]

Cool, the shop my Sense runs repairs Diamond Mining equipment and they have a similar automatic internal bore welder that actually more than paid for itself on the first job!

Imagine a $850,000.00US scoop tram (think low profile front end loader designed for underground mining) that the operator ran into a solid granite rock face at an angle, cracked both sides of the fork box frame that holds the bucket and bent the holes that hold the bucket bushings.  So, the manufacturer says for about $250,000.00 we can replace the front bucket-fork assembly, however, there will be about a 2 year wait for your order.  So, plan 'B', outsource to China, well they can make the same assy for about $160,000.00 BUT a 9 month wait (not including shipping costs and time), so the guys here said they'd do the job for $100,000.00 and in 3 months.  The job was actually complete in 6 weeks, 2 weeks to get the welder in and about 4 weeks to do the work!

Cheers,
Chazz

[John Swift]

Hi Rob

looks like the welder is worth its weight in gold as they say, just  being able to make the repair quickly on site

just two questions

1 )  how do you re bore the hole  as in Chazz's example ?

2 ) do the make another version to rebuild damaged spindles ?

    for instance I'm thinking of the damage done by a failed roller/ needle  bearing  (the type runs directly  on  the spindle , with  no inner !)

    I  assume just adding metal fee hand with a mig welder would result in a bent spindle


   John

[Bernd]

How do like that, a "put on tool". 

Neat Rob, thanks for posting.

Bernd

[Noitoen]

I friend has a set-up like that. It's actually a machine that fills an then machines the holes so that you can fit new bushings on loader's buckets.

[Ned Ludd]

I am sure I have seen a You tube video of a similar machine but used build up worn shafts.
Ned

[John Stevenson]

How do like that, a "put on tool". 

Neat Rob, thanks for posting.

Bernd

Here's a cheaper version [ patented  ]



It's just a knurl wheel fitted with a bush mounted on the wrong end of a boring bar.



One end takes it off, 'tother end puts it back on 

John S.

[Blade]

2 ) do the make another version to rebuild damaged spindles ?

There are lathes set up with metal spray torches for fixing the outsides of worn shafts.

[John Swift]

Hi Blade,

Not working in any mechanical engineering industry , I did not know about metal spraying !

but having read your reply I quickly found this  :--


http://www.metalspraysupplies.com/videos/metallisation-flame-spray.htm


with the metal spray equipment and the borewelder  It should be more often economic to repair / refurbish equipment than just buy new all the time

then there is the maintenance of historic machines


    John

[PekkaNF]

IMHO, quite a few wearing pars can be metalsprayed or welded very sucesfully. Sometimes they will outlast original. But there are quite a few places that are outright dangerous to weld/bush/fill/spray to make bearings fit. Specially modern machines are designed to get the last margin out with FEM and such. There may have been very careful consideration over materials and methods. The funny outcome is that then you have to buy spare from the original supplier....there is somewhere in the manual note that certain bearing surfaces should not be tried to be fixed.

To my knowledge most fo the brake disks (I'm talkking industrial here) should not be fixed...even skimmed, they might be pretty close to minimum thermal mass and shape to keep brake pads happy just that odd situation once a ash wednesday they might be needed....

PekkaNF

[dickda1]

I worked in a steel rolling mill in Detroit long ago.  Steel was rolled from a 160 ton ingot into a continuous slab about 5cm thick and 3 meters wide.  The rolls were cylinders of alloy steel about about a 0.8 meter in diameter and 4 meters long.  Needless to say the rolls experienced extreme abrasion at high temperatures.  The rolls were removed about every 3 weeks and resurfaced with an automatic welding machine that put on an extra 2 cm of metal on the outer diameter - later trued up on lathe.  As I recall the surfacing took the welder almost 8 hours to complete the task.


-Dick

[Bogstandard]

John S,

I regularly do a bit of outside expanding using a straight knurl, I never even thought of using one on the inside.

A couple of thou expansion can be obtained with basically just touching on. What you have shown there must have done a real lot more, I suspect somewhere between 0.005" and 0.010". Usually more than enough to get part to fit again.

Nice one


John

[John Stevenson]

I love metal spraying   it earns me pounds because they use it where it's not suitable.

True story:-

One day the rewind company roll up just as I was leaving to go on site with a large armature, one bearing journal was very badly damaged and it was wanted immediately.
I told them that I could do it first job the following day but not that day. This wasn't good enough so it went somewhere else. They metal sprayed it and turned it back to size and returned it. Motor was rebuilt and sent out and fitted to the job which was a large travelling crane.

Motor fitted and at switch on massive bang that removed about 10 foot of very heavy bussbar from the roof and sparks galore from the motor.

Turns out they had not screened the armature when metal spraying and some of the dust had gone up the vent slots and shorted the comm out from the inside.

Bottom line was one team had to go in, remove the motor and rewind the armature working all thru the night and the following day, not an easy task as most big DC motors do not use wire but copper strip which takes a lot of bending without destroying the enamel.
Another team had to work all night to replace all the burnt out bussbars.

To add further insult about three weeks later I got the same armature back and the bearing was rattling about on the shaft but it couldn't be removed as it had hammered the metal spraying out both sides to resemble a dog bone.

I had to turn the dog bone off, remove the bearing, remove all the metal spraying as you can't build up on this stuff, then rebuild with solid weld and turn back to size.

I have had plenty of other shafts that have done exactly the same, hammered the metal out from under the bearings.

John S.

[Weston Bye]

How do like that, a "put on tool". 

Neat Rob, thanks for posting.

Bernd

Here's a cheaper version [ patented  ]



It's just a knurl wheel fitted with a bush mounted on the wrong end of a boring bar.



One end takes it off, 'tother end puts it back on 

John S.

Aw, come on John, you ain't putting it back on, youre just fluffing it up.

[Ned Ludd]

Hi John S,
Methinks that the metal sprayers in your little story failed on two accounts, one the over spray and two the wrong powder/process. As you know there are two main processes, one metal spraying and two Powder welding. With powder welding you don't get a lot of over-spray, so I assume they used metal spraying.

With metal spraying you effectively spray a ring on a shaft, the two are not necessarily fused together, which leads to its bad reputation on things like crankshafts.
With powder welding the process is more akin to MIG and the weld is definitely fused to the job. The advantage of powder welding is that you can select different powders to achieve different purposes, much like you can with different rods when stick welding, but with powder welding the heat input is much less, so tempering might not be effected. Some of the powders are so tough that they can only be machined by grinding, but that might be over-kill on an armature.

Yes folks, I did the Eutectic powder welding and spraying course, but about 25-30 years ago and haven't done any since.
Ned