Thread: Welding question

You should be able to drill and tap the weld provided you haven't used a high tensile welding rod - not knowing what your machine is made of - some parts may be cast iron and you would need a cast iron welding rod and it helps to pre-heat the part with a gas torch etc, reduces the risk of it cracking.

Cant put in some sort of bushing?

I'll go with Harrys' thoughts, normal practice for oval worn components is boring and bushing, when bush wears again just replace

Of course !.....Why didn't I think of that .......thanks fellas...

Bushing is the only way to go

However check that the pins arn't worn & are round.
Second you will need to drill or bore for preferance the two bush holes in one pass to ensure they lign up exactly other wise they will cause stress someware else
Bushes should be bronze or if possible self lubricating fibre but this does take special turning techniques
You can make wooden bushes then you can replace them often at a small cost but choose your wood carefully lignum vitae is perfect and will last when used with a silicon grease.

With bronze bushes it would pay you to introduce grease nipples and drillings to suit & then you only do the re bushing once


A picture is worth a thousand words, and so it should be it takes up a thousand times the memory

Thanks Ashore,,,,,,,I'll save your letter,,,,lots of good stuff....
Before I was reminded on bushing,,,,I planned on using bearings,,, the focus for me was to avoid wear so I only ever have to fix it once.....

If interested the idea was to use those small bearings that come out of the scooter wheels that every kid seems to ride nowdays ( a broken one comes into the local op-shop every week for $2).. outer diameter was 7/8" and they fit snuggly into this steel pipe out of the scrap pile......I was going to make a new crankshaft (about 8" with one bearing each end) by cutting 2 waffers off the pipe to be housings for the bearings and welding one to each end of a steel bar ( with concave half-circles cut each end to meet the housings),,,bearings held in with grub screws ,,,, and then just using the pins that came with the scooters bearings as new pins for the fretsaw......thats why I was thinking about welding up the old holes in the fretsaw and redrilling for the new pins to take the new crankshaft......the wear would be in the easily replaceable (and very cheap) bearings.......

But then ......bushings......... it would be easier,,,just using old crankshaft..

But where I'll probably get unstuck,,,come to think of it now,,,,is that its an old rickety machine to begin with ,,,,,,the reason why its all so loose might be a necessity to accomidate for everything being out of alignment to begin with .....

I've heard of lignum vitae,,,,well read about it,,,,,, Is it hard to get in Australia ?

Your original idea appears ok but those bearings are designed for rotation not oscilation and may not stand up to it too well
For steel pipe to be used as a bearing holder should be cold rolled seamless pipe as normal steel pipe has a joint though you proberly can't see it
Also have found that small sections op pipe when welded tend to deform and after being welded are no longer round enough to fit bearings
You however will proberly be a better welder than I am. I usually either silver solder or braze thin walled pipe but this has limitations on strength.

Lignum Vitae: As an old Marine Engineer I have seen it used in large cargo ships stern seal bearings though it is only used in small boats now happen to have a couple of discarded bits (fell off the back of a ship )
I believe however if you contactid a fishing boat Marina / repair yard you would be able to get some
The only thing to watch is that whan you turn it use a negative rake tool
and let it cool down 20/40 mins before taking your final measurements.
Because of the oscilation movement you can cheat with bushes and rotate 60 degrees twice before changing bushes.
With bronze bushes you need extra grease holes

thanks again ashore.....I didn't know about the pipe deforming...that and the bearings not being suitable so I'll give it a miss and go with the bushes.....ta