ok, so our school finally has a running FSAE program, and we have ordered the 4130 tubing and are ready to start building when it gets here. only problem is, any jig we have ever made here hasnt been the most accurate/consistent (read: plywood and 2x4's) and i would like some advice on making or purchasing one.

also, what would be the best filler material for welding the 4130. Im assuming the backfilling gas would be the same argon or helium we are using as a shielding gas?

thanks a ton guys,
Parker

 

if this is your first year for the school doing SAE my advice would be just to try your best with everything, most schools, such as mine, have been doing this for a long time, so basically everything is all spelled out already, and since you guys are starting new you are just building the blocks which your future cars will come from.

very good luck to you, post pics if you wish. i myself am doing SAE mini baja, but hopefully next year and my 5th year senior year ill do formula for my senior design.

try making the frame from metal instead of 2x4's, and be as accurate as possible.
also get a ton of sponsors lined up and keep harrassing them for free stuff.


good luck

 

To make your jig, just remember, you can never go to heavy duty. Make 4 legs out of 6"x6" square tube. And then either use I-Beam's or a flat plate steel for the top...if you use the plate steel, be sure it is thick enough to span the distance without sagging in the middle. A lot of bracing is always a good idea.
As for the filler rod, for 4130 you want to use ER70-S2. Now some may get on here and tell you to use ER80-S2, but it doesnt flex like ER70-S2 does. 80-S2 has closer characteristics as the 4130 itself, therefore doesnt give much at all, instead it cracks when forces are applied to a welded joint. By using the 70-S2, you will get more flex out of it, so that it will rebound back to its normal state, instead of cracking.
4130 DOES NOT need to be backpurged. Just clean the joints to be welded up really good, and take your time around each joint...it will turn out fine. Also, dont let anyone tell you anything about preheating and post-heating and yada yada yada...it doesnt need to be done. Just weld it like you would weld mild steel, no difference in welding charcteristics.
GOOD LUCK!
Kyle

 

exactly what blue oval said no such thing as to stiff...Hopefully you have access to some machining equipment (i would assume so if your doing Formula) and just machine some jigs ver carefully...also you wanna make sure the LAST thing you do is weld the suspension pickups, or at least thats how we do it to avoid the inevitable very slight chassis warping doesn't affect the geometry

 

I appreciate the advice guys. we have had a formula team before, but their execution of the project was poor at best.

I was always under the impression that welds on 4130 need to be annealed to properly stress relieve them. we have access to an autoclave to do it in if need be.

We have done Mini Baja several times, but we have never really had the funds to do Formula. its like pulling teeth to get any money from the school, and even then its only like $600 per semester.

 

I made my frame Jig out of 6x8 15lb I-beam. There are four cross braces and the legs are made out of the same stuff. My jog weighs over 400lbs. It is as flat as I could get it with several high dollar levels and angle finders. I can weld to it or drill it and bolt to it which ever. If need be I can also add more crossmembers.

4130 does not be anealed if you weld it with a mild steel rod. It does need to be anealed if you use a 4130 rod.

I dont have any pictures of the jig itself.