welding steel base or just getting aluminium extrusion

[reefy86]

was ordering the steel from metals4u.co.uk cut to size, i forgot to ask that question as well so thanks for that boyan, I do not have access to a welding table and i do want to try and keep the cost down so what would you recommend welding the frame on? i was thinking of doing a cheap wooden frame and make sure its level and use a sheet of mdf on top for flatness

[Boyan Silyavski]

I welded it on the floor, using the larger beams themselves for base. Basically the correct way will be to spot weld the outside frame. Then make sure all is straight and knock here and there with the big mallet. Then weld. Then insert inside beams, use scrap or washers to adjust to a tight fit so after welding it does not contract.

Do not worry, first frame ever i welded with stick welder and was welding for first time.


The main thing to understand when welding is very simple but crucial: "You are making a molten pool and moving it around" . All else serves for that to happen, that means you must think only about that, not thinking angles of electrode, this and that. See that pool, maintain it and move it around or up and down. That's it. I believe many welders do think of other stuff than the pool when welding. I am talking about DIY welders like us.

[reefy86]

thanks boyan, about the frame do you think i am on the right track with the frame design? i just want to get the design nailed so i can crack on with pricing and getting required tools ect.

[m_c]

Weld it on as flat a surface as you can.

If I was going to do something like that, I'd be buying a big spirit level to ensure the main frame was set as level as possible to welding, and a big set square for ease of checking things are square during initial setup (I'd also be measuring corner to corner to check squareness after the initial tacks are in place).

If you order metal pre-cut, you may still have to grind it to length, as cut tolerances can be quite big (typically -0mm to + several mm).

As for welder, I'd go for something in the 150-200A range. You won't need that much capacity, but at that rating you shouldn't need to worry about duty cycle. Ideally gas MIG is better, but the cost of gas can mount up if you're using disposable bottles, and the rent on full size bottles is quite costly. There are suppliers where you can buy bottles, but you really need to find one locally, and check to see how much the gas works out to per litre (some of the schemes where you buy bottles don't fill bottles to that high a pressure, so you don't actually get much value for money).
Other option is gasless MIG using flux cored wire, but then you have to deal with flux/slag cleanup afterwards (best way to describe is, is it's pretty much ARC welding, but with a roll of wire instead of rods).

[cropwell]

was ordering the steel from metals4u.co.uk cut to size, i forgot to ask that question as well so thanks for that boyan, I do not have access to a welding table and i do want to try and keep the cost down so what would you recommend welding the frame on? i was thinking of doing a cheap wooden frame and make sure its level and use a sheet of mdf on top for flatness

Reefy, have you tried Nottingham Steel at Colwick, they will cut to size and they are probably cheaper !
Weld UK at Pinxton have got some heavy duty clamps at £60. I called in in person for one and asked how much they could do two for cash and it was a good discount !
https://www.welduk.com/product/sip-0...rs-angle-clamp

[reefy86]

No not tried them mate, i will give them a call tomorrow so thanks for that

[Boyan Silyavski]

Do not try to make all like 2000mm, for example. make it 2003mm but parallel and square. Hence you don't need the pieces to be super precisely cut. You will definitely need a box of washers though, to fill the cracks. Remember that your final epoxy cast below rails will be 40mm wide, and rails are 20mm wide. The ???what was the name of it, the epoxy that lifted to the sides due to attraction will be 3-4mm each side, so basically you will be able to position the rails within that margin of the rest 10mm. hence do the gantry when you have finished and measured your final base frame, not at the same time.

And as you have been told, not bigger stitches than 2 inch at a time and place, and no higher overall temp of the beam than 60C. When you reach that temp, leave to cool before continue.

You will be tempted to hurry, but take your time and do it properly, you are not welding a typical welders job. I would go as far as to say that i will not trust a normal welder to do that job, as the moment i turn my back he will make 2 meter stitch

PS. best is to use hard stop ruler or a contraption to make all exact same distance

[reefy86]

Do not try to make all like 2000mm, for example. make it 2003mm but parallel and square. Hence you don't need the pieces to be super precisely cut. You will definitely need a box of washers though, to fill the cracks. Remember that your final epoxy cast below rails will be 40mm wide, and rails are 20mm wide. The ???what was the name of it, the epoxy that lifted to the sides due to attraction will be 3-4mm each side, so basically you will be able to position the rails within that margin of the rest 10mm. hence do the gantry when you have finished and measured your final base frame, not at the same time.

And as you have been told, not bigger stitches than 2 inch at a time and place, and no higher overall temp of the beam than 60C. When you reach that temp, leave to cool before continue.

You will be tempted to hurry, but take your time and do it properly, you are not welding a typical welders job. I would go as far as to say that i will not trust a normal welder to do that job, as the moment i turn my back he will make 2 meter stitch

PS. best is to use hard stop ruler or a contraption to make all exact same distance

cheers mate, How do you know what temperature you are at?

[Boyan Silyavski]

cheers mate, How do you know what temperature you are at?

I have laser thermometer, but when it starts to feel too hot to the touch, thats it

[reefy86]

thank you