Mig welding over aluminium?

[bert]

I need to make some tube with a 30mm ID, I can only get hold of 29mm id so I was planning on cutting it and welding it back together with a 30mm aluminium bar inside so it gets the right internal dimension.

Will doing this with aluminium be OK as I cant find any 30mm copper bar.

Ta

 

[the snooper]

I need to make some tube with a 30mm ID, I can only get hold of 29mm id so I was planning on cutting it and welding it back together with a 30mm aluminium bar inside so it gets the right internal dimension.

Will doing this with aluminium be OK as I cant find any 30mm copper bar.

Ta

you may have an issue with the steel bar removing all the heat and using mig for alluminium is not all that easy

 

[rtbcomp]

The way I read it is that he's slitting the 29mm steel tube and then inserting a 30mm ally bar to open the tube to 30mm, then welding the steel.

 

[bert]

The way I read it is that he's slitting the 29mm steel tube and then inserting a 30mm ally bar to open the tube to 30mm, then welding the steel.

Yes thats right, i will be using mild steel wire to re-weld the mild tube together. Im hoping it wont weld to the ally and once i remove the ally bar I have a steel tube with a id of 30mm

 

[Wozzaaah]

Once you slit it, it will most likely spring open slightly so you may not need to put anything inside it. If it doesn't, just put something in the slit to prise it apart enough to get you the correct ID then tack the slit in a few places to hold it before welding it up.
Cut the slit along the seam if it has one.

 

[StickNtig]

You might struggle getting the ali bar out when the steel tube nips up as the gap is welded, like the above says though it'll probably spring open once cut

 

[bert]

i thought i may have an issue in getting it out but the tube only has to be 40mm in length and it has to be bang on 30mm id as i will be fitting a bush into it.

Ill give it a go and see what happens

 

[gavuk]

How long a tube are you thinking of Bert?,can you say what the application is in case there's another way ?......removing the aluminium could be a problem as already mentioned

 

[gavuk]

can u not turn the bush or the sleeve?......i'm not touting for work ,plenty of others here could do it ....

 

[bert]

The tube is about 40mm, I need to measure up to make sure though.

The bush is a standard size polybush and im making adjustable track control arms for a customer. Finding the right size tube has been a nightmare. I will be double skinning it to make sure its super strong though by plug welding 2 tubes together to give me 3mm overall thickness.

Ideally id like to use a tube with the right dimensions and turning/drilling the sleeve was something i thought about but as I may only sell 6 or 7 sets over a year i didnt want to have to keep getting it done

I'm still open to options before I start putting it together though

 

[Seano]

I do this on a relatively daily basis working on wheelchairs, as wozzaaah said slit it along the seam with a 1mm slitting disc, find some small scrap offcuts to hold the 3cm dimension open, put 3 or 4 tacks along the length then when cool, backstitch or tackstitch quickly along the length of the seam, unless you have workshop facilities you will have a problem with dressing the internal weld back to accept the bush, if not use a medium round or half round file to remove most of it then slot a 15cm length of 1cm round stock take some 60Gr emery tape, one end through the slot then wrap it around, using a hand drill ream it out, or get a piece of larger dia tube section it and weld it.

 

[the snooper]

The way I read it is that he's slitting the 29mm steel tube and then inserting a 30mm ally bar to open the tube to 30mm, then welding the steel.

whoops
i cant have read it properly i thought it the other way round steel tube inserted into ally and ally welding

 

[hotrodder]

If we're only talking 40mm lengths shirley it'd be cheaper to pay someone to run a boring bar through a bit of tube with a smaller ID... It won't be a (sorry, has to be said) proper bodge, it'll be round, hitting 'bang on 30mm' will be easy rather than zero chance, you won't scrap a chunk of ally on each part or (more likely) the entire thing when struggling to get the ally bar out afterwoods

34.93 OD with a 2.64mm wall exists. Obviously there'll be a tolerance but the ID will be in the ballpark of 29.65mm. If you really don't want to sub any of it out it'd probably be faster, definately be better, to buy an adjustable reamer (cheapnese start at about £25 for H12 size range) and spend the time that would have been spent splitting and rewelding the tube sweating over a reamer

 

[Hitch]

If we're only talking 40mm lengths shirley it'd be cheaper to pay someone to run a boring bar through a bit of tube with a smaller ID... It won't be a (sorry, has to be said) proper bodge, it'll be round, hitting 'bang on 30mm' will be easy rather than zero chance, you won't scrap a chunk of ally on each part or (more likely) the entire thing when struggling to get the ally bar out afterwoods

Took the words out of my mouth.

 

[johnny max]

I agree with hotrodder
Boring bar

 

[KemppiFrog]

Easier to turn down the polybush?
KF

 

[bert]

Cheers hotrodder, I will look into that and check out the costs involved. Thank you

KemppiFrog, It would be easier but if the customer wanted to replace them in the future they wont be an off the shelf item, i dont think my customers will want to have to fork out to have another set made.

 

[bert]

I gave it a go yesterday and i can confirm its not a good idea, It was impossible to get the ally bar out of the tube and was difficult to bridge the large gap with weld.

I spoke with the customer and they are happy to have the polybushed reduced in size to fit standard tube so I will go down that route.

 

[gavuk]

Have you already made these Bert?,not sure how poly bush material turns ,once a boring bar is set to turn the id of the tube a number can be run, prob quicker to turn the steel than a flexible material and may be easier to get dimensionally accurate.Are the bushes shouldered or same od across?,the bush probably needs a mandrel to hold it etc the steel sleeve can be put straight in the chuck,difficult to say without seeing though

 

[bert]

Yup I have made them already, I used a 32mm seamless tube with a 2mm wall thickness.

The bushes have a shoulder on them and a steel sleeve that passes through the centre that I believe is 14mm so may be difficult to mount, it needs about 1mm take off the OD of the bush so they press in nice and tight.

Some high quality polybushes are turned but these ones are moulded into shape.

I think your right about making the Tube the right size so in the future I may go down that route.