Jigging up a 6500 lb welding table.

[Portable Welder]

I just bought a welding table at an auction, its 12' long x 90" wide with a 1-1/8" top plate that has been machined down flat, so its a little less, I can still see all the machining marks, the ribbing underneath is all 1/2" x 8" flat bar running in a grid pattern.

So on the way home I dropped it off to the local boring mill shop to have 112 holes drilled in it on a 10" grid pattern.

My plans are to buy 8 slide bar clamps, cut the end off and weld a 1" solid round where I cut it off, the 1" pin will then slide in the holes of the table and when I tighten the clamp it will bind in the hole.

My question is: How much over size should the holes in the table be.

I drilled a 1-1/32nd hole in one of my tables and that worked good, however, its a little sloppier than I like.

[nfinch86]

Is it a welding table or the Titanic....... Wow.
That's one mother of a table !........ lol.

[Portable Welder]

Ya, its going to be nice having a table of this size, we are tired of using 1/2 clamps and having to grinds the welds off, $ 425.00 for the table, $ 850.00 to have it drilled and about $ 480.00 to buy ( 8 ) slide bar clamps that open up to 16-1/2" that I have to modify.
The guy at the boring mill shop said all the holes will be within .005.

I'm also going to make stops that drop into the holes that we can clamp too to keep the frames square.

[H80N]

Ya, its going to be nice having a table of this size, we are tired of using 1/2 clamps and having to grinds the welds off, $ 425.00 for the table, $ 850.00 to have it drilled and about $ 480.00 to buy ( 8 ) slide bar clamps that open up to 16-1/2" that I have to modify.
The guy at the boring mill shop said all the holes will be within .005.

I'm also going to make stops that drop into the holes that we can clamp too to keep the frames square.

What a wonderful table for chassis fab..........................

[ryanjones2150]

You can go into the battle ship making business. Dadgum that sounds like a nice work surface. I thought I was high class, just ordered a certiflat fixturing table (3'x4') to handle a good size fence panel job I'm about to start. Sounds like what you have there separates the men from the boys! On the hole size, the fixture table I ordered uses the standard Stronghand tool brand fixture tools...if that means anything to you....but the holes in the table are 16mm.

[Joe from N.Y.]

let's see photos of that table

[Portable Welder]

Joe from NY, the table is at the boring mill shop, it wont be done for a couple of weeks, that is the drilling and reaming, I need to get the clamps ordered.

[Portable Welder]

I'd really like to know how much bigger the hole is verses the pin size, I can always turn pins down in the lathe so I guess its not all that big of a deal.

[ryanjones2150]

I'm headed out for a few errands today and was gonna run by northern tool and get some fixture clamps if they have them in stock. When I get home later I'll put a micrometer on them and see diameter of the pin on the clamp and report back.

[Olivero]

That sounds like an awesome welding table. Mine is just a flat plate of steel. No fancy holes for clamps and such.

[Oldgrandad]

If 1/32 seemed sloppy to you go with 1/64, about .015 larger than the pin. With that much clearance the pins should drop right in and bind up just fine to hold whatever your clamping. Sounds like a heck of a table. Post some pics when you get it done

[ryanjones2150]

So I'm pretty useless for you today. Couldn't find any fixture clamps anywhere in this city. Grainger is my best bet as they can have them for me tomorrow. Might have to just make some like you are. Be more fun anyway.

[Olivero]

Woop, home made!

[Helios]

Sounds like it'll be a killer table. Best of luck with it.

I'm surprised that you find dropping a 1" diameter pin into a 1-1/32" hole is too sloppy on a table that's over an inch thick...I would have expected it to be too tight (1/64" clearance on all sides), but I'm more woodworker than machinist.

I bet it wouldn't take too much spatter (or rust) to gum up the works with tolerances like that!

[Portable Welder]

Helios, 1/32" over sized isn't to bad, I'm just wondering if I can go a little tighter without a problem.