My big and heavy table out of 25mm plate

[Ed.]

Well I got my 3mt x 1.2mt x 25mm plate for free from a friends neighbour so here is how I built my new welding table and moved it, it was badly bent in a couple of corners so they had to be straightened first

Pic 1.

Grooves cut about 8-10mm deep into the plate and 4-6mm wide, to be filled with a very hot weld to try to pull up the plate into being straight as the weld pool cooled, all 4 corners had bends in them, 25mm, 8mm, 10mm and 2mm out of flat, although it might not look it, that corner in this pic was bent about 25mm out, the straight edge was resting on a power cord at the other end but I didn’t notice it till after I finished taking the pics, trickiest part was working out where to put those grooves and I think I got lucky as it didn’t come out too bad.

Pic 2.

The grooves are welded and plate straightened as best I could and a piece of 200mm x 75mm channel welded to the top center. This was welded to provide a support for the 2 long T pieces of steel made from cutting a universal beam (30cm x 16.5cm) in half. This gave me a vertical wall of 165mm x 12mm thick plate

Pic 3.

As I cut the Universal I beam the internal stresses from when the I beam was formed, released and the 2 halves curved slightly outward. So I welded the two halves to the channel and the plate, and then used strong clamps to force the ends in till they mated with the smaller I beams on the ends, also clamped the ends down to the plate as well.

Some of my welds weren’t the best as the plate was very badly pitted and the pits full of crap, I didn’t want to spend a week grinding it all out, so just ground out what I could within reason and then blasted out the crap with the arc.

Pic 4.

The I beam cut in half and two smaller pieces slotted to fit together to try out before fitting and welding to the plate.
The frame support T beam and I beam welded together.

Pic 5.

Support frame fully welded

 

[Ed.]

Pic 6&7

A couple of welds holding the top plate to the support frame

Pic 8

200mm x 75mm Channel welded to the frame for legs, (10mm flats were welded to the bottoms and a couple of 75mm SHS spreaders between the table legs which aren’t shown here)

Pic 9, 10, 11

Winched up the table on to the trailer using a 2000Kg winch and short lengths of 32mm pipe underneath it to make it easier to get on and off the trailer. Positioned it near where I wanted it to be near the garage allowing for the flip over distance.[

And this is where the stress starts. Using large leverage bars to raise the top up slightly whilst pushing steel and timber supports between the edge of the ground and the plate. Raising the table slightly each time until it was high enough to use a 1200kg trolley jack. Clamped a piece of heavy angle to the top edge of the plate with two clamps. Put the jack under the raised angle edge and jacked it up bit by bit. When it got about 300mm of the ground I used a 2mt long piece of 100mm x 50mm RHS wedged in to the base of the top plate and the earth, tied that at the top and then to my clumping bamboo with 12mm rope and tensioned it. Also put a metal stand against it but as the angle increased it became less usefull. Then used different lengths of pipe between the trolley jack and the clamped angle steel to get the increasing height till I finally flipped it over

This was in case the table slipped off the jack, the idea being, it might give me a slight degree of safety, and should make the table slide forward away from me. Well at least that was the theory. Tensioning the rope each time I raised it up a little. Getting the table up from upside down flat to on its side was the hardest and the riskiest, from on its side up to completely right way up was relatively easy.

Once it was right side up it as just a matter of putting a couple of pieces of steel underneath it and levering or jacking up the ends, putting a set of skates under the legs and then using those large levers of mine to lever it into the garage. Had to put steel under the skates as my driveway is gravel.

 

[Welderpaul]

Not the sort of work for a hot day Old road plate there?

Looks like you've done a decent job there. Tidy welds. What are you planning to use the bench for?

 

[Ed.]

So all up, it took about 8 hours spread over 2 days to move it into position from under the carport and into the garage, and 5 days to recover from all the effort. Probably didn’t help due to the fact that I had a kidney stone removed in hospital 2 days earlier.

Anyway it’s in now. Just have to add a few more things to finish it off, build a shelf underneath it for tools and so forth and also put up some support plates to attach my large vice to it.

The top surface is also pretty badly pitted, so I might fit a 4 or 6mm plate as a skin to it, and I managed to get 2 corners flat and the other two corners within 1-2mm. But I am also contemplating building a machine to face mill the entire top to make it completely level, smooth and flat.

As I have always wanted something like that and this gives me a reason to do so. But unfortunately it will take a long time for me to work out how to do it and also squeeze that in with all the other things I have/want to do. But at least I have just bought the motor for it which should arrive next week, a nice 3 phase 4HP 2800RPM unit. Thinking of using a 3” face mill as the cutter. Just have to spend a lot of time working out all the details on how it will go together, what features I would, like such as angle milling etc., and work out everything in my head what I need to make it all happen before I start it.

Ah!! Too many projects and not enough hours in the day to do them all, I still haven’t finished off my other welding table I started before Christmas.

 

[Ed.]

Thanks Welderpaul. I don't know where my friends neighbour got it from, but he originally was going to do the same and make it into a welding table but ran out of either time or enthusiasm so it sat outside on the ground in his backyard for years till I came along. I have a feeling it may have had a lot of slag on it at some stage, possibly from arc gouging over it or something as it was a pain to grind off. I didn't need a table that heavy but wanted the size , as my smaller table is always half covered with bits and pieces and tools etc leaving almost no room to do anything on it. As the plate was free, the total cost was about $100 for the I beams, grinding disks and channel.

 

[Shox Dr]

Very nice, I bet the old butt was nipping a bit while you were, jacking it up

I've got a plate 2400x1200x12mm thick to make a Hydraulic table out of, luckily it's flat as... On the back burner at the mo, like you, more projects than NASA.

Keep us informed on finishing the top, though I would have though Grinding it would have been easier?

 

[Ed.]

Thanks Shox Dr. I definetly was feeling it. It's something that I forgot about, whilst 25mm is great for not bending or deforming easily, once it does you normally have to apply some pretty massive forces to straigten it back. At least with 12mm or so you could straighten it if neccessary by clamping it to a rigid frame. But not this 25mm stuff. If I had to do it again I would also use 12mm.

Grinding would not work, it took me something like about 8 hours in total of grinding to prep it for welding and clean up the surfaces of it, and even then I did a lousy job of it. The surface has really got heaps of nasty pits in it.

 

[Rubber Duck]

Holy Moly that's a big table.

It would make a nice coffee table in your front room!

 

[Sphinx]

That welding is super neat!

 

[Wedg1e]

That welding is super neat!

Hear hear.

 

[jugs]

. I have a feeling it may have had a lot of slag on it at some stage, possibly from arc gouging over it or something as it was a pain to grind off. I didn't need a table that heavy but wanted the size , as my smaller table is always half covered with bits and pieces and tools etc leaving almost no room to do anything on it. .

You'll just end up with a larger table, always half covered with bits and pieces and tools etc leaving almost no room to do anything on it

Nice welds

But I am also contemplating building a machine to face mill the entire top to make it completely level, smooth and flat.

As I have always wanted something like that and this gives me a reason to do so. But unfortunately it will take a long time for me to work out how to do it and also squeeze that in with all the other things I have/want to do. But at least I have just bought the motor for it which should arrive next week, a nice 3 phase 4HP 2800RPM unit. Thinking of using a 3” face mill as the cutter. Just have to spend a lot of time working out all the details on how it will go together, what features I would, like such as angle milling etc., and work out everything in my head what I need to make it all happen before I start it.

A 3” HSS face mill needs to run @ 114 rpm, Carbide @ 290 rpm

I have a feeling it may have had a lot of slag on it at some stage, possibly from arc gouging over it or something as it was a pain to grind off.

The hard spots will smash the cutters
You have a toolpath 54m long on a bad surface, you'll get through a lot of cutters, & unless you make the machine very rigid & heavy (a couple of ton ) the cutter will chatter giving you a bad finish & damaging the cutter

SO

Make a gantry grinding machine,
tack some outrigger arms under table on 3m sides, weld 4m guide rails (3" box, one flat & other on corner so you have 1 vee guide ) onto arms.

make gantry to bridge table (2 parallel beams 600mm apart (3" box. one flat & other on corner so you have 1 vee guide ) fixed to sliders on 4m rails.

make grinding head to fix on your motor shaft ,See section 76 below (your motor will run a 300mm wheel)

devise a screw mechanism to raise/lower motor & grinding head. If you are clever you can make it do angles
fix this to gantry so you can adjust & lock (across the plate)

devise a mechanism to power gantry along 4m rails (I used a shaft at each end, 1 with 2 pulleys & 1 with 2 drums, thin ropes fixed to side of gantry 2 turns around drum down 4m length around pulley back to gantry each side. 1 shaft driven by worm drive motor (reversible), crude but it worked

TAKE LOTS OF LIGHT CUTS - should do it in a day or less depending on condition of plate.

Before starting, talk to grinding wheel suppliers in your part of the world

& Read ALL this http://www.liv.ac.uk/safety/Hazard_A_to_Z/safe_use_of_abrasive_wheels.pdf
See section 76

Or find someone with one of these -
http://www.directindustry.com/prod/...y-surface-grinding-machines-20586-233306.html

good luck

 

[Ed.]

Hi JUGS, thanks for the info. Damn, and I thought I might get away with it, I was actually intending to gear it down quite a bit as 3" a cutter at 2800rpm would be more than 1000fpm which would be way too fast.

Grinding is not an option, I would not even contemplate it due to the noise, time involved, mess and the cost of replacement grinding wheels.

I had envisioned a setup similar to a cross sliding power saw obviously significantly overbuilt with 2 x 75mm or 100mm SHS 8mm walled beams ( or universal beams) for the slide either one per side or both on the same side, bearings where neccessary on each beam, with the main cutting going across the width rather than down the length. That way it should be able be easier to construct. After the first pass, then move over 3 inches down the table, lock in place and start again. The cutter "Holder" would be either slide across using a large threaded rod or via chain connected to a geared down motor and cog setup to drive it. Circuit breakers to stop the motors when it reached the end so I could leave it cutting and do something else.

I had thought about connecting that main motor to a reduction gearbox such as a 10: 1, but whilst that would work for a 3" carbide insert cutter it would not be much good if I decided to put a 1" or 1/2" fluted mill into it as it would be too slow, so pulleys may have to do or even a combination of the two.

The main beams would or could bolt to the side of the table as there is a 12mm x 165mm flat supporting the table and legs and running the full length. I would like to shave it down about 2mm as that would remove most of the pits and make it flat. Even chatter marks would be preferable to the condition it is in at the moment. Doesn't have to be perfect or anything, just flat and the crud removed. After all it is a welding table and will get worked on, just don't want to turn it into a very time consuming and extremely expensive exercise, The cheapest option would be to just put a 4mm plate of new steel over it, but then, where is the fun in that and I would still want to make something to do some facing.

Decisions , decisions. Too many wants and desires versus actual needs. As I said before, this will require a lot of thinking involved

 

[Shox Dr]

The problem I see, with using a face mill is the mill scale will kill, cutter tips in no time, because of the light skim you'll be taking, I'd really would be looking at using large cup grinders. Possibly diamond ones, plenty on fleabay for not alot of coin

 

[Ed.]

I've have got a pile of roughing inserts which are really tough that I could use, about 50 of ceramic and the other are carbide, I will probably have to make a face cutter to suit these inserts but they should last the distance before I run out, at least that is what I am thinking. Using any form of grinding is out, I would rather cut the metal off than grind it off.

 

[Shox Dr]

Well if you have the bits already there is no harm in using them. better than buying stuff.

Thankfully the plate I have is in very good nick, so I'll just run over it with a grinding pad, to clean it up. oh and its (5/8") 16mm not 12mm as I first posted. cira 429lbs it weighs. But at least 2 people can just about pick it up

 

[Ed.]

Nice! You will have to post up pics as you do the build.

 

[Shox Dr]

I will, I going to bore holes in a grid 200mm square so I can use stops and bench dogs for clamping stuff down, as it will be used in the main for building/mod'in Motorcycle/trike frames. I was going to build a table but they are never at the height you want them, so a hydraulic version seams to make sense, as well as making it easier to get bikes on and off

 

[ghound]

I have a 3x2mtr table, fine when your using it, but it just seems to end up cluttered with cr4p most of the time, i'm thinking of making adjustable feet so as i can pull it out into the yard when i don't need it?#

 

[Ed.]

You'll just end up with a larger table, always half covered with bits and pieces and tools etc leaving almost no room to do anything on it

Oops.... I hate to admit it, but it has started already, looked at it the other day and yes, it 1/3 covered already. Bad habits are hard to break although in my defence I have actually started to clean up the garage and so I picked up a lot of stuff off the floor and on to it till I work out where to put it!

 

[jugs]

Hi JUGS, thanks for the info. Damn, and I thought I might get away with it, I was actually intending to gear it down quite a bit as 3" a cutter at 2800rpm would be more than 1000fpm which would be way too fast.

Grinding is not an option, I would not even contemplate it due to the noise, time involved, mess and the cost of replacement grinding wheels.

I had envisioned a setup similar to a cross sliding power saw obviously significantly overbuilt with 2 x 75mm or 100mm SHS 8mm walled beams ( or universal beams) for the slide either one per side or both on the same side, bearings where neccessary on each beam, with the main cutting going across the width rather than down the length. That way it should be able be easier to construct. After the first pass, then move over 3 inches down the table, lock in place and start again. The cutter "Holder" would be either slide across using a large threaded rod or via chain connected to a geared down motor and cog setup to drive it. Circuit breakers to stop the motors when it reached the end so I could leave it cutting and do something else.

I had thought about connecting that main motor to a reduction gearbox such as a 10: 1, but whilst that would work for a 3" carbide insert cutter it would not be much good if I decided to put a 1" or 1/2" fluted mill into it as it would be too slow, so pulleys may have to do or even a combination of the two.

The main beams would or could bolt to the side of the table as there is a 12mm x 165mm flat supporting the table and legs and running the full length. I would like to shave it down about 2mm as that would remove most of the pits and make it flat. Even chatter marks would be preferable to the condition it is in at the moment. Doesn't have to be perfect or anything, just flat and the crud removed. After all it is a welding table and will get worked on, just don't want to turn it into a very time consuming and extremely expensive exercise, The cheapest option would be to just put a 4mm plate of new steel over it, but then, where is the fun in that and I would still want to make something to do some facing.

Decisions , decisions. Too many wants and desires versus actual needs. As I said before, this will require a lot of thinking involved

Sorry ed, but grinding is the ONLY option for what you are proposing. to construct a milling machine capable of doing that job is going to be very expensive & it will be big & heavy, 1ton maybe more. you would also need lifting gear to handle it.

You mentioned noise - Don't confuse surface grinding with angle grinding, surface grinding is much quieter,

The milling frame you propose will be very noisy as the tool will chatter, bounce & smash.
If you do use that frame I think you will be limited to a 8 or 10mm cutter ( = 400 meter tool path ) 3/4 - 1 hp will do.

You need a big stiff rigid tool