any mild steel experts?

[Danny Spencer]

sorry if this is against the rules or anything just incase but im looking for someone to weld a frame together that knows how to weld mild steel with minimal distortion. im located in Nottingham so if anyone is interested ill send pics of the frame and then get back to me with a price.

cheers

 

[Brad93]

Whats the tolerance, have you factored in the cost of jig making, post welding inspection etc. Located in Brentwood, Essex if you're ever down this way. Regularly work to and hold tolerances of +/- 0.2mm post welding.
Would need to know what the material is? Box? Plate? Tube etc,

 

[Danny Spencer]

the 2 long lengths are 10mm thick and the rest is 5mm all box 90x90mm. the bed frame is 10ft x 5ft and finish look is not an important but any warping is.

cheers

 

[Brad93]

With a build such as that there is always going to be some distortion from welding. I would recommend welding the base but bolting the runners on using shims to true it up.

 

[Kent]

Most distortion is handled at the design stage. Then the order and direction of the welds.
Anything welded will distort its all about Tollerance. First thing one looks at on a drawing, often enough you get stuff with unachievable Tollerance for the given design.
Price comes from. Seeing a proper drawing with said Tollerances.
Pm me if

 

[Brad93]

Bering in mind, likelyhood is that box will not be straight as well

 

[oilcooled :)]

front elevation. The box running from left to right in the middle of the drawing that's two pieces I'd have that as one long piece it should help getting it true and I'd have the middle vertical column as two pieces. If I was making that I'd have my cuts precisely perfect. Tack the whole lot with tig cause u can heat and sweat tacks. Put in temporary braces on the leg bottoms and weld it all in position spreading heat evenly.

 

[Danny Spencer]

front elevation. The box running from left to right in the middle of the drawing that's two pieces I'd have that as one long piece it should help getting it true and I'd have the middle vertical column as two pieces. If I was making that I'd have my cuts precisely perfect. Tack the whole lot with tig cause u can heat and sweat tacks. Put in temporary braces on the leg bottoms and weld it all in position spreading heat evenly.

im no expert on making frames this is why I need a welder who knows how these frames should go together. it doesn't matter if the tubes aint 100% straight as I will be using epoxy resin to self level but the frame needs to be perfectly square. ive not seen any steel manufacturers with a tolerance less then 2mm -/+ so I have that problem too.

 

[Welderpaul]

ive not seen any steel manufacturers with a tolerance less then 2mm -/+ so I have that problem too.

Because generally its not achievable without machining after fabrication.

 

[Danny Spencer]

Because generally its not achievable without machining after fabrication.

I mean

I mean getting the lengths cut to a zero tolerance not how flat it is

 

[Spark plug]

Usually on a fabrication Sutch as that, ware the top surface is critical you would usually see flat bar say 90x12 stitch welded on the top surface and machined flat after welding.

 

[Screwdriver]

Surely the critical components will be bolted to the good-as-it-gets framework.

Interesting project though. Be great if someone could video it. In fact, I might offer to come along and do just that if it's ok and times work out etc.

S.

 

[Revs1972]

Surely the critical components will be bolted to the good-as-it-gets framework.

Interesting project though. Be great if someone could video it. In fact, I might offer to come along and do just that if it's ok and times work out etc.

S.

Pretty sure the old plasma where i used to work had bolt on rails that were shimmed to get them level. The frame had been extended by the boys in the workshop so I would
say it was probably something like +/-3mm ( dependent on whether they were using a tape from the pound shop or a decent one)

 

[Danny Spencer]

how hard is it to stop mild steel from twisting as a beginner in welding? from what ive been reading, having the frame square is not as critical as the frame twisting ect. there will be linear rails ontop of the frame so if the frame aint true then the rails can easily be adjusted but whats more important is tubes twisting so will this be a challenge for a beginner?

cheers

 

[oilcooled :)]

how hard is it to stop mild steel from twisting as a beginner in welding?

if you could do that as a beginner you would be an expert. Every expert learned everything the hard way. An expert will know when to walk away from a job and know when to run.

In terms of perfect straightness and squareness it's difficult to achieve. Steel doesn't come straight. And when u weld a joint molten metal flows and cooling metal shrinks in the joint basically causing a "movement"of what your making. Generally why critical stuff is machined after welding.

 

[lotus 30]

Just to say i found reading all this post fascinating as a novice you do not realise how things are made to do there job where accuracy is involved i suppose it was the same with me working on minus 100deg freezers i found i was the only one in wales and had to travel to do repairs all over wales but it became second nature once into my way of tackling the job.
andy

 

[cianh91]

As oilcooled said as a begginer theres next to no chance of understanding distortion after 14 years welding i still learn new techniques to reduce distortion .
reduce being the main word there theres a lot of weld for strenght in that job .
shimming as said already would be a far more precise method

 

[Danny Spencer]

Thought as much lol. Well as for machining then getting 3000mm lengths would cost a bomb so i will be using epoxy resin at 5mm thick which will level to a high accuracy,

 

[Brad93]

For that fab a fair tolerance would be +/- 3mm for a general steel fabrication outfit. If you pay more, take it to someone who really knows what they're doing you could *probably* get that within +/- 1.5mm. Don't expect it to be cheap. When you start getting to tight tolerances you need to start building things off layout tables for flatness, a pair of tressels off a concrete floor won't cut it. There is a lot of weld in that frame. What kind of load does it need to take. Also box section isn't ideal as you have rounded corners which means more weld metal, if you put two pieces perpendicular to each other.

 

[scott0031]

The guys here are pretty much on the money with the general comments especially Brad who clearly knows his stuff. That said, I personally would have little hesitation with a project like this because I have done this kind of work many times before producing automotive checking jigs and fixtures and other such items. Some have not been majorly crucial and some have, these have to be checked by big CMM's (co-ordinate measuring machines) and certified/ calibrated etc, prior to delivery to the plants. From this i know how good you can get larger frames with the right design, forethought, care and attention to detail ( This is the crucial bit) in manufacture. I wont quote the kind of tolerances i would expect to get if it was me making it as it will cause an argument which is not my intention, but it would be as good as it is physically possible to make it with restrictions of (as mentioned by others) the nature of materials in this case horrible black box. I would change the design and some of the box sizes in certain areas for the reasons some have already mentioned as this will alter the overall result.

I will admit i have the advantage of having Slab (as its known in the trade) A large surface table which is a big advantage most fab/weld shops do not have. This is not a welding table, this is a surface plate where you can check and know exactly whats going on with the flatness of what you are producing and it does have many advantages if you learn/ know how to use it. It's not so much the squareness of the frame that is your issue its the flatness of the important areas ie the table area and the linear rail mounting, Obviously it no good to you if you have a large disparity in those areas, of out of flat or square etc. Looking at your design I'm assuming this is a router and not plasma or such like?

Assuming your build is a router. By the book, frames like this are produced often with strips or pads in strategic areas of concern to be machined after heat treatment (as someone has mentioned). The frames are then heat treated by a process called normalising, also known as stress relieving which involves cooking the parts in question in a large oven. After this process any latent stress should be gone in the part and this will stop the frame from moving at a later date, then you machine the pads or strips to achieve flatness or what ever it is you are trying to achieve. There is another way to stress relieve but it takes a year to do. This paragraph is for information only so you know the way it should be done, but very rarely is these days even in industry and will be cost prohibitive for your project i would imagine. Lots of guys make machines like yours and by some means seem to make them work even though i have no idea how they manage to get the rails on accurately, flat, level and parallel without the thing running like a bag of nails, which i suspect they do and are also probably not cutting very square or accurately over distances. Probably fine if you are cutting wood as many do, but its that old thing of horses for courses.

As for trying it your self..... personally i would say no, but only you know what you can produce and if it will be good enough for what you want. Without a slab you will be probably looking at the worst case tolerances Brad quoted and i would suspect in reality if you tried to make it may well be a lot worse than that. Would i be right in thinking you have posted about this frame on another site?

I hope this is helpful.