welding steel base or just getting aluminium extrusion

[reefy86]

i ain't saving any money lol not when you take into account that i need welding equipment/free standing press drill/new angle grinder/clamps/straight edges but on the plus side ill be adding to my new workshop full off tools that will be needed in the future anyway. the frame as it stands in materials is costing me £725 and thats for 90x90x5mm mild steel

[reefy86]

any tips on the frame guy's? also have a few question's

1. what welder do you recommend for welding 90x90x5mm steel
2. do you wait until all the frame is together before you drill holes and fill with sand
3. best method used for drilling and tapping for the linear rails

cheers

[Boyan Silyavski]

My 8x4 had roughly 700kg in it , which translates to 800 euros, 100 euros for gas, 60 euros for MIG wire.1 day receiving and cutting the material, about 2 full days of welding it alone by myself. Yes i moved it alone around here. Managed to do it at around 1mm precision or less.

250Amp MIG which cost me around 350 euros and 300e Rage Saw were previous investment, when i decided i will fabricate things. And 500kg welding table / which i made later/

I will charge at least 2000 at the blink of an eye for that job, especially having in mind that i welded it slowly so it's not under stress.

Similar frame will cost more than 2500 in aluminum and will take same amount of time to put together. A week.


My advice is to go 100x100x3mm if you do it at home, as bigger is no good to cut by any means. Best will be if you speak with someone local and design your frame with bigger beams as possible, say 200x200, which will greatly simplify things. You will have to find someone who does metal structures , for them these beams are small in their mind. They may even have some scrap enough to build a house.

[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).

[JoeHarris]

If you don't want the cost of mig I had pretty good success with a cheap Clarke stick welder from machine mart. No gas to buy either. Defiantly get an auto darkening visor though and some decent rods. For a welding table i bought a massive lump of 12mm steel plate from a guy in Telford for about £20. I found welding very satisfying!


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[JoeHarris]

Helpful video:


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[JoeHarris]

Ps I find it hard to comment on a frame without seeing it in context with the rest of the machine but on the face of it it looks pretty solid


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