First Mill Setup and Refurbishment

[kuczmarm]

I am an experienced Automation Engineer taking a leap from steady employment to independent contracting. I've spent my career in CNC machine shops and have made most of the parts for my projects myself so, while I'm no machinist, I can make my own basic parts. I purchased myself a 2J Series 1. It's mostly in good condition, it was just in a filthy garage covered with motor oil and chips. The upside of the motor oil is it is absolutely rust-free and the dovetails and sliding surfaces are very clean.

I have 2 questions:
Firstly, I have the machine bolted down to 2 4' treated 4x4s from when I hauled it. I've seen posts on this forum asking what to put the machine on instead of 4x4s. My question is if the machine is already pretty level on the 4x4s, is there any reason it can't stay on them? It's a perfect height for moving with a pallet jack and they should do a decent job protecting my concrete.
Second, everything seems like it has pretty low backlash and is pretty tight with the exception of the head tilt (L to R). There is A LOT of slop and I imagine I will have a rough time keeping my mill surface parallel with the table if I don't do anything about it. What are the recommended vendors for rebuilding parts?

 

[William Lynn]

Wooden 4x4s are not usually consistent in their dimensions. Will you need to move once it's in your shop?
The head tilt gears do not mesh tightly and their purpose is to rotate the head to the desired angle. The four nuts on the head keep it in alignment after tramming or setting to the correct angle. Do not over tighten these, as they are threaded onto T-bolts located in the knuckle casting. And be careful if you ever move the head to an extreme angle. as the shaft that turns the worm gear is a weak point in the design.

 

[kuczmarm]

Thanks for the reply. The machine is in my garage so while I have designated a permanent spot for it, I don't have the luxury of a forklift or the headroom for a hoist so if I do need to move it, it would be nice to be able to get a pallet jack under it. I also figured the 4x4s would be nice for protecting the concrete.
So how loose is normal for the head tilt gear? I'm looking at a hair under 10 degrees of slop. Is it possible that shaft is already damaged?

 

[William Lynn]

It's always possible the shaft has been stressed, but there's no way of knowing. As long as you can rotate the head, it's still in one piece. It has little to do with the slop in the gear mesh, unless the small internal key is worn. Don't worry about any slop there. It was never designed to have any finesse.

The mill can be slid on smooth concrete easily with a come-a-long and walked into position with a long pry bar.

 

[neanderthal mach]

??? For the head tilt it should be either trammed square to the table or to whatever angle your machining set up requires. At that point you use the 4 head nuts to lock the head at whatever orientation you've set it up for as William just said. Whatever backlash is present in the worm and wheel is immaterial. A small detail maybe, but important enough in my opinion is that once those nuts are tightened, is to always back either the tilt or nod worms off to a neutral or lose condition that can be moved in either direction by hand to the extent of the back lash present. That way there's no preload exerted on the head that can help move the head off a carefully set tram condition due to machining and vibration forces. It's a trick I first picked up on the forums here, and it definitely does help to keep the head in tram longer. If you think the worm or wheel might be damaged, then just pull the head using the knee and table to take the head weight. Then do a visual on both components. It's a 5 minute job. Getting it back on and trammed in will take a bit longer though. And to add a bit to what William also said, those worms and wheels are fairly delicate. For at least my BP clone, it's not pointed out that helping to take most of the head weight with your off hand when rotating the head between vertical and horizontal isn't optional. Tiny moves when doing the actual head tramming aren't an issue since the head weight is mostly centered.

Exact level with something like a Bridgeport isn't really a requirement. Ok maybe some low accuracy work could be set with a level, frankly indicators are more accurate, reliable and easier to use since your aligning the work to where the spindle C/L is located. What might be important is how much stress could be twisting the lower foot casting. That might affect the knees feed screw alignment and how much extra wear the components could see if those 4 x 4's and the floor are quite a ways out. Your on your own there about how much might be too much. But if it were me, I probably wouldn't cinch down those attachment (which I assume are lag bolts?) real tight. In fact I'd leave them a tiny bit loose and let the casting float a bit on those 4 x 4's.

 

[kuczmarm]

Great information. I think I've run into that preload on the tilt issue before, never thought of the preload being the issue. It's easier to tram resting on one side of the backlash, never thought to back it off.

I'll loosen up the lag bolts a touch. I always indicate my work so level is not an issue.