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Engineering help!


Medic1281
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I’ve got a lawn mower that needs attention on the drive roller. It appears the drive from the pulley to the roller goes via a shaft with flats that sits inside the bracket pictured. The trouble being, the bracket I’ve got has worn badly and the oblong hole is now nearly round. As this is an obsolete part so difficult to get hold of , I’m looking at trying to repair it. 

 is there any way to build it up and then file back to shape. Either weld it, but I don’t know what metal /alloy I’m welding. Or build up with a type of resin? I don’t really want to have to take it to be milled, so anything I can do in my garage would be my plan. 

Any suggestions gratefully received!! 

F6333A53-2660-4DDF-B1BF-07EF6F61B76E.png

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Is there no wee agri welders or fabricaters or blacksmiths  round about u??? Esp if they also sell/fix lawnmowers

 

I take it its not possible to sandwichich penny washers either side? Possibly rivet or weld on?

Thhat JM glue/resin stuff is prety good and for metals/alloys.

Either that or just make a brand new part. Even use mild steel just need 3 holes drilled for ur self tappers and ur main hole

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    anyone with a tig welder can add metal so you can file back to the required size and shape there will be someone that can rebuild worn areas for you    a google search of aluminium welders / fabricators in your area    any epoxy repair will make it really difficult to repair properly  in the future  when you file back to fit the tighter the fit the better as a rattling good fit leads to excessive wear       there may be someone on here who can weld it up for you for a jolly

Edited by Saltings
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If you want to repair it yourself.

Test with a magnet. If magnet sticks and feels "heavy" it is likely to be mild steel. If you can scrape it with a penknife, non-magnetic and feels "light", likely to be an aluminium alloy.

If steel, invest in a MAPP torch and some coated brazing rods and build up the inside surface with a thin layer of braze.

If aluminium, use the MAPP torch and Lumiweld. 

Then use fine Swiss files to dress the hole to the exact size.

It will take a while to do it right, but it is very satisfying to repair rather than scrap.

Or, if you want a temporary bodge job, just pack the sloppy fit with chopped up shim steel from a cheap feeler gauge.

Edited by amateur
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Good advice above but i know the local welders/agri engineers to me wouldn't charge much to fix it or fabricate a new 1.

If u don't already have the tools it'll probably cost more to bu the tools than get the part made. But it is nice to fix something urself

 

I'd almost bet 2 of them would do it FOC as a goood will gesture as they selll lawnmowers and chainsaws etc, hoping to get some ustom of u in future

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Thanks for all the advice, I think it’s fair to say I’ve got “all the gear, but no idea!” Most of the tools needed I’ve got. And I’d like to attempt to fix it if possible. The part shown is the centre from the pulley. I can still buy the complete pulley if needed but seems a great waste as I only need the centre, and it’s £40! So, don’t think I’m losing much by having a go at fixing it myself. 

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8 hours ago, amateur said:

If you want to repair it yourself.

Test with a magnet. If magnet sticks and feels "heavy" it is likely to be mild steel. If you can scrape it with a penknife, non-magnetic and feels "light", likely to be an aluminium alloy.

If steel, invest in a MAPP torch and some coated brazing rods and build up the inside surface with a thin layer of braze.

If aluminium, use the MAPP torch and Lumiweld. 

Then use fine Swiss files to dress the hole to the exact size.

It will take a while to do it right, but it is very satisfying to repair rather than scrap.

Or, if you want a temporary bodge job, just pack the sloppy fit with chopped up shim steel from a cheap feeler gauge.

good adfvice  there.........or silver solder with the right flux.....dont buy a jar as it is £25 quid plus......PM me and i will send a small packet to you...

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23 minutes ago, ditchman said:

good adfvice  there.........or silver solder with the right flux.....dont buy a jar as it is £25 quid plus......PM me and i will send a small packet to you...

 

Thanks all for the advice. I’m taking it all on board. 

Hi Ditchman, what would be the right flux? I’ve got a rothenberger plumbers touch and silver solder. I’m wanting to try sorting it myself if possible. Just need some tips or guidance. Time to watch some YouTube I think! 

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1 hour ago, Medic1281 said:

 

Thanks all for the advice. I’m taking it all on board. 

Hi Ditchman, what would be the right flux? I’ve got a rothenberger plumbers touch and silver solder. I’m wanting to try sorting it myself if possible. Just need some tips or guidance. Time to watch some YouTube I think! 

if your torch is butane it might not be hot enough.............the flux must be for silver brazing...i will let you know 2moz when i get back in the shed

 

if i was to do it i would...

  1. drill out the hole
  2. round off a bit of steel
  3. put it in the hole
  4. silver solder
  5. drill out
  6. shape internal with file

:good:

Edited by ditchman
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Looks cast to me - drill it out to accommodate the biggest bolt you have and tap it to that size - Loctite the bolt in and trim it flush - drill thru the centre the AF size then take it to your nearest machine shop and have them slot the hole with an end mill - might cost you a tenner but that should sort it.

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When I look at your picture I see a round hole with 2 pretty good flats and what seems like minimal surface wear. That doesn't chime with the description you have, or am I missing something obvious?

In any case I agree that it would be pretty easy to make from scratch.

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2 hours ago, Bazooka Joe said:

(When I look at your picture I see a round hole with 2 pretty good flats)

Yep noticed that, is that a stock picture off the web? 

If not are you sure it's not just the shaft that's worn.? 

Yeah this is a pic taken from the internet. I’m not home again until midweek, but when I am I’ll put up a picture of the actual thing. All the advice has been good. Id happily build it up with weld once I’m sure that it’s steel and not some fancy alloy. 

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Well today I took this part out of the pulley it was mounted in, and it subsequently fell into 4 bits! So that’s the end of that. It’s very light material and non magnetic so it’s some sort of aluminium or alloy. Either way it’s scrap now! 

So I had a look around the garage for some spare plate to make a new part from. The only thing I could find was an old lawn mower blade. So I set about cutting, drilling, filing and tapping it to make a replacement part. Fitted it tonight and I works a treat. It’s no masterpiece of engineering, and I’m too embarrassed to post any pictures as ditchman might see it. But it’s doing the job so I’m happy. 

Thanks everyone for the offers of help, and pm’s offering solder and the like. It’s most appreciated! 

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