Chassis Frame Jig

[stevebarker]

Hi im new to welding etc, but it cant be that hard !

I would like to build a twin engine car, I am going to base it on a Vauxhall nova ( don’t slap me ).

So first things first I am going to build a Chassis Frame Jig, I have looked at the http://www.mig-welding.co.uk/chassis-jig.htm page and will loosely base my design on that.

I have ordered some mild steel box section this morning 100x60x5.

Here is a diagram of what I am planning to build

I think the most important part is to make it square and level.

For this I was planning to G clamp the 3500 lengths of box section to 160 x 160 H iron at either end. If the 160x160 H iron is flat will I need to level the frame using the “red wine level” described in the chassis-jig link above? Here is a pic.

My welder is a 180 amp MIG I have .6 and .8 wire. Will I need to space the frame I am going to weld with a root gap ? the box walls are 5mm thick.

Any input will be much appreciated

Thanks Steve

 

[peterd51]

Hi,

either a slight gap or chamfer the edges with an angle grinder to ensure you get full penetration.

Shouldn't need much taking off, down to about 70 degrees or so.

Regards
Peter

 

[malcolm]

Cool - I like jigs

One thing to bear in mind is the frame will twist very easilly - your section isn't massively stiff and the frame will be very long. For any proper setting up or checking it will need to be mounted on the floor supported by axle stands adjusted to the right height. Red wine level gauge is fantastic for setting the whole frame level so you can check the chassis.

For assembling the frame definately use the level gauge to set all the members up perfectly level before welding. Otherwise use a completely level bed plate for setting up the pieces before welding. Makes sense to start out straight otherwise the frame will try to twist the chassis when you remove big bits of the structure.

For the welds themselves Peter's chamfer would be good for a really strong weld. Though for a jig strength and fatigue aren't issues, just stiffness. I'd be inclined to butt the joints tightly together and weld as they are as that would make setting up easier.

 

[migmag]

Triangulate corner to corner too that will stiffen up the frame.

 

[scarecrow]

I have often used a water level putting up sheds it works on the same principle you just need a gallon with a long plastic tube the end of tube is Staples to a piece of timber usually a 2*1 also attached to the 2*1 is a length of an old measuring tape
you just put the gallon on something where it is fairly stable usually above the piece you want the level didn't just place the bottom of the 2*1 on the Chessie when the four corners have the same reading on the tape it it should be level red wine is supposed to be more accurate than water and will be a lot easier to see

 

[stevebarker]

Thanks for the advice so far ! I should get time this weekend to cut the box section to size and maybe play about with the level. I will take some pics and let you see how I come on!

 

[Hitch]

You shouldnt need to chamfer really, the radius on the edge of the box makes for a very nice 'prep'

 

[stevebarker]

Hi, here is my progress so far.

I cut the box using a Makita chop saw with an abrasive disc.

To make the frame level i used my digital Inclinometer instead of the red wine and tube.

So far I have spent about 10hrs on it. The steel was expensive just over £200 Inc VAT.

Now I am planning to put 4 legs on, I was thinking of mounting them next to the first set of noggins. I would like to make the height adjustable and was thinking of M20 nuts welded to the bottom and some M20 bolts about 40mm long. Then I could just use a spanner to set it up.