Hi Chris. You could use 3" or 4", that would be fine. I like to overbuild everything anyways. You can reinforce it with whatever you feel will suit your needs best. If you are going to buy a couple lengths of channel, you can use that for the center beams as well. I would notch them out with a torch so they fit snug inside the box of the frame. You could do mitered corners, so it has a clean look to it. If you want to have bottles on it, determine where you want them & DO IT WHEN YOU BUILD IT!!!!! I didn't & got stuck putting them in a not so great place. Plan it out well, maybe even draw it up. I know it's kinda corny, but I really try and think everything thru before cutting a single piece first. I'll set & stare at something & figure on it for hours sometimes, when it's a big move or a serious amount of labor to make the setup for the job.

I try to imagine every scenario first, so when I go to work, I've explored all the options first & have a confident idea what's going to work the best. That's a lot better than having to rework & repaint a job when you thought of a better way....As soon as the paint's on it! Believe me, I'm no expert fabricator, but I don't like having to do things twice. I this case, I've learned a great deal since I put the trailer together 7 years ago. I would even look at rigs online & here to get a wide range of ideas. That way, you can use the best of what you like for your setup. I would just buy tool boxes. I was originally going to make mine, but the Greenlee box on my rig was only $185 on sale. I couldn't even think of building it for that. Sure, if I had access to a huge sheetmetal shop & machinery. Otherwise, you'll be cutting sheet with a Metabo, or a plasma & trying to square it all up, etc will be absolutely no fun at all.

You can pick up an axle for reasonable if you look around. Mine's a solid one, but you could make one too & just weld a set of spindles on. Use sch 60 min pipe if round. I would most certainly go with 3500# springs, EACH SIDE. That way, you won't be in a bind if you add another box, or something else. I went 7000# total on mine & it sits & rides nice. I probably have 3500# on it at the very most. As for countersinking the machine, it can be done, just figure you have a 1500# machine & you want it to sit as close as possible to the axle. That would be a lot of tongue weight if it's too far forward. Go too far back, and you'll be popping wheelies. :-) Which way are you going to orient it? parallel with the trailer, or perpendicular? You'll have to take that into consideration too.

As long as you have access to the right side (facing the machine) you will be able to change the oil, no sweat. Some guys cut a hole in the door, but I'm not into that. finally, if you intend to TIG weld the main channel & supports, just remove the scale on the steel surfaces to be welded first. I'm sure you know that, but I just thought I would mention it anyways. I would probably stick weld it myself if I couldn't get it in my garage to weld on it. I think you'll come out good. keep me posted on it. S.W.

"I am not a number, I am a free man...." (Patrick McGoohan, The Prisoner)

Looks good Steve

Yes, two b's I know that grill thing dangit!! And no one else EVER spells it right.

My Dad, and his folks came over from England, so not so sure... but cool none the less.

"It's merely a flesh wound" Monty Python, but also ME last night- as I got ten stitches in my fingers :O hee hee (thought I'd throw one back at ya!!!!)

Jenn