Chassis Jig Frame Table discussion

[javajoe79]

 We are nearing completion on our own chassis jig or frame table if you prefer and I thought that a discussion on the subject might help us and others. I have built a number of cars but never to this level of needing a chassis jig. A few months back we had a little talk on the chat line about this and it helped us move in the direction that we did.

 What I am after is any suggestions, ideas, comments etc.. that will help make our jig better and or help others build a nice solid chassis jig.

 I will share some pics and details and I hope some other folks will too. I know that there is some serious know how and experience on this site and I would love to hear anything you folks have to say.

 So for starters, my jig is basically on long I beam (20') with outriggers at the wheelbase of our car(1993 Firebird). We have removable casters at all four corners so we can move it around as needed and we have leveling screws along the length of it. At this point we are planning on adding leveling feet to the outriggers, connecting the outriggers and end beams with square tubing that we can adjust in and out and eventually make removable plates to fill in the spaces in between the outriggers and center beam. So far we have about $500 in materials. We got the caster on craigslist for $200 and the I beams at an auction for a few hundred.

 Here are some pics to get things started and please let me know what you think or anything that you think can make it better.

Pics coming shortly   

[javajoe79]

[javajoe79]

[gearheadeh]

Good thread idea, I would like to know if a table made with 2 main rails like a rectangular box would be more ridged?

[maj]

Great timing for this sort of thread
i am just about to build a jig for a partially built motorcycle streamliner i want to make some changes on .

Was thinking of a square frame like 4x2 rhs with risers to the suspension pivot points
 
I like the rotisserie idea

Javajoe do you get much flex from the i beam or is the floor true enough to rely on the wheels on the ground

[tauruck]

I have a jig table for car chassis and a purpose built jig for rigid bike frames. The car deal is for one off stuff so it's flat, level and square, the bike jig is for "production" not that 1000's of frames were built but it is adjustable. It rotates. I built it from square and rectangular tubing and has a few machined components that clamp the pipes. I build frames for custom Sporty based bikes and I can go from a Bobber to Pro Street to a long chopper frame all off this one jig. The best tools I have for getting things spot on are a Bosch tripod mounted laser level, tube notcher and white marking pens. I think the trick is not to get the welding wrong. Have all the frame components in the jig and move around when welding. I think of cylinder head torque when I'm welding, going from one area to another but not trying to weld the whole frame in one go. The same thing goes for the car chassis. I'm not chassis builder of the decade but if you take your time building the jig and keep it flat all else built on it should be the same. Good clamps and patience. I modified some G clamps by tacking half round pieces of tubing onto the threaded ends. Clamping round tubing with a normal clamp sucks especially when you work alone. I've marked the pic where my bike jig swivels off a bushing. Clamping pressure comes from the bolt that threads into it but I prop it up with a pipe for insurance.

[javajoe79]

Great timing for this sort of thread
i am just about to build a jig for a partially built motorcycle streamliner i want to make some changes on .

Was thinking of a square frame like 4x2 rhs with risers to the suspension pivot points
 
I like the rotisserie idea

Javajoe do you get much flex from the i beam or is the floor true enough to rely on the wheels on the ground

 As it sits right now, the central I beam will twist easily if you lever on one of the outriggers. The wheels are only to move it around. Once we are using it, we will unbolt the wheels and sit it on the ground. We are adding leveling screws to the outriggers too, so once it's set on the ground we can adjust all the leveling screws to make it sit level and solid.

[maj]

Do you need to bolt it down so it can't pull diagonally ?
and would a raised platform make it easier to work on ?


MTA i agree it has to be stiff or there is not much point in building the frame
your c channel looks much more solid than i was originally thinking i needed , time to recalibrate the thought process
 
the liner bottom half is like 1/2 an octagon and i find it tapers too fast, my shoulders are too tight , Kim fits fine
and the motor has the same problem at the crank centreline
so i intend putting a new bar pretty much from the feet area all the way to the back about 4" lower than the current wide point
this will mean all the vertical and angle braces on the sides will be cut and replaced over a ~8 ft length
and i think he jig should have the capability of alternate suspension mount points as i am rapidly running out of room
working with Jon on an overdrive has just eaten up another foot of engine bay

so now as i want good access without the jig blocking anything but still very stiff , in the air on a rotisserie
i am picturing a perimeter box frame  braced , with adjustable supports along the sides to secure the position of the upper and lower frame rails when i release them

sometimes wonder if i should start again and sell the existing frame to someone smaller with a narrower motor

[javajoe79]

 We are adding braces across the outriggers and at an angle from the outriggers to the I beams on the ends. We decided on the height it is, planning on having the car floating maybe 18" above it. That way it's not too tall to get to the top of the car and we will be able to access everything on the bottom side too.

[wheelrdealer]

Joe:

Looks like a good platform to start with. It is hard to tell how high it is off the ground. But some heavy wall nesting pipe with holes and pins like the old round jack stands. Then some big 1" bolts to use as leveling feet welded to the bottom of the nested tubes. I would add some tube gussets to X brace the out riggers.

BR

[Dean Los Angeles]

Notice that the Bloodhound jig is built out of rectangular tubing and the top was machined flat.



The ultimate in jig fixturing is to use a granite surface plate.
I found a 240" x 72" x 30" on Ebay for only $12,500!!! 52,000 pounds. How strong did you say your garage floor was?

[javajoe79]

Only $12,500???    Seriously though we have joked about having this one ground flat on the top. It's pretty flat and square but not perfect. Would love to know who has a surface grinder that big and how much that would cost though. No doubt it's ALOT!

[Tman]

I have used perimeter jigs made out of rectangular tubing as well as one with a long Ibeam down the center. I prefer them to be waist high and we tack smaller Ibeams to the top in an outrigger fashion.


Here is one a pal of mine built, different style

http://www.jalopyjournal.com/forum/showthread.php?t=577892&highlight=frame+table

[bearingburner]

How much sag do you get in the center of the 20' I beam? We used a 26' tapered ex steel sq.tube light pole and had to put a jack in the center to take out about 1/2" sag.

[javajoe79]

I have used perimeter jigs made out of rectangular tubing as well as one with a long Ibeam down the center. I prefer them to be waist high and we tack smaller Ibeams to the top in an outrigger fashion.


Here is one a pal of mine built, different style

http://www.jalopyjournal.com/forum/showthread.php?t=577892&highlight=frame+table

 That is frickin beautiful!!