Frankenmill: Bridgeport J head onto Victoria U2

[TomG]

What Greg said.

All machines have unique characteristics that only show up when you work to very close tolerances, and you'll know yours inside and out.

Tom

[Dr Stan]

Good job on figuring out how much to shim the plate while it was on the surface grinder.  One aspect you probably forgot is the the ability of the magnet to warp the part when it is turned on.  That's probably where the remaining little bit of out of tram you're experiencing comes from.  The next time you remove the head from the mill check the plate for flatness and I suspect you'll find a little bit of of a concave feature on the surface you ground last.

Please don't consider this a criticism, as I think you're doing one #ell of a job.

[Pete O]

You're right Stan, I did not consider the distortion of the plate by the magnet. Even though it's around 1.2" thick (no longer parallel front / back) it was shimmed at the four corners so there's bound to have been some dip in the centre, just thinking about that I think it would probably now be convex rather than concave, as the magnet will have been pulling the middle away from the grinding wheel. Will be interesting to sit it on the surface plate next time it is off.

Eit: just looked back at the third photo in post 89 of this thread, the curve in the leading edge of the fresh grind does seem to suggest that the magnet was pulling some concavity into the plate. I noticed the grind wasn't advancing in a straight line across the part, that makes sense now.

[Pete O]

I wired the machine the other day to confirm that the RPC will run both the motors. The main motor is 4hp but I expect it will not be drawing much current when used solely for the power feeds. I had a look inside the gearbox while the overarm was out and confirmed that with the high / low range selector positioned between the two gears, the oil pump still runs so I can safely use the power feeds without the horizontal spindle rotating. If I ever have reason to take the main selector panel off the side of the machine, I'll bore a 'neutral' locating hole for the gear selector. The test run was successful and the old machine is nice and quiet when running in neutral with just the feed drives spinning, but the 1.5hp motor on the J head definitely needs new bearings, running it with the belt off confirms that the noise is coming from the motor.

I extended the ram into the position for horizontal milling; it's easy enough to slide the ram for the first 6" or so but when the weight of the new hardware starts to get further out it is very difficult to slide. I moved it outward by clamping a block to the table and using the Y-axis power feed to push against one of the arbor supports. I could slide it back in manually by pushing upward and inward. Ideally it needs a leadscrew arrangement but I doubt that it will be moved often enough to justify that; perhaps if I'm running short of projects sometime.

   

[TomG]

Looks fantastic, Pete!  

It may be an obvious suggestion, but could the ram issue be lubrication related? If your mill is anything like mine, those dovetails rarely get any lubrication. Perhaps some nice, thick grease would help.

Tom

[Pete O]

I don't think that's the issue Tom although it won't hurt to lubricate the dovetails more liberally next time it is apart, but it got a thorough clean and a coating of oil when it went together this time. I think it's just the significant extra weight cantilevered that far out. Pushing upward and inward, it moved in quite freely but it's much more difficult to apply an upward vector when pulling it out. There is a gib adjustment, a parallel gib with two setscrews, I think I'll try backing that off a little next time I want to move the overarm.

[TomG]

I would try grease instead of oil. There is a lot of pressure on those dovetails with the arm extended and the oil may not be able to handle it.

Tom

[Vinny]

Perhaps a counterweight?

[EdK]

(04-30-2019, 06:44 AM)TomG Wrote: the oil may not be able to handle it.

Tom,

Do you think way oil would work? That's what I used on the ram of my mill but I didn't move the ram much at all.

Ed

[Highpower]

I use way oil on mine but I don't have all that extra stuff hanging off the front of the ram. That's got to be putting some serious pressure on the dovetails at the back of the ram (I would think) when run out that far. Lot of leverage there, no?