Frankenmill: Bridgeport J head onto Victoria U2

[Pete O]

I got the lathe work on the nosepiece done.
The 'B' side first. I have some precision ground round stock in various sizes, the largest being 20mm so I poked a 20mm hole in the centre to use that as a spigot. There will be a circle of 8 bolts mounting this to the front plate.
   

Flipped it over and put the necessary features in the front face, as well as the recess for the tilt scale around the outside. The centre recess takes the worm gear for the tilt adjustment. I left a few thou on the main mating face, it will be finished in the surface grinder after the T slot is milled.
   

Drilling and tapping all the mounting holes will take care of any free time I get before my T-slot cutter arrives. I'll have to mount the good old vertical attachment to do the slot.

[Pete O]

I've been busy with other things over the past couple of weeks, but having ticked a few jobs off the list I could justify spending my days off this week back on the frankenmill project.
I finished the jobs that needed the shaper vice to hold the overarm in front of the spindle again, getting the remaining 5/8 NF holes drilled and tapped in the front end of the cheek plates and the front plate. I decided that the most suitable place for the remaining bolt holes was right where I had put the dowels, so I drilled and reamed some new dowel holes before doing the bolt holes. The top two holes in the nosepiece bolt circle / top of the front plate have to be drilled all the way through the 5.2" width of the top plate, two 5/8 NF x 8" long bolts will come all the way through into the top of the nose piece. I found a long 5/8 drill bit on ebay, it arrived today so I can finish those holes.
   

The bottom edge of the front plate was protruding a little below the dovetail and preventing the arbor supports sliding on, I shaved .040" off the bottom edge so they clear.
   

I've been mulling over how best to mount the nosepiece on the rotary table to do the T-slot, decided to use the front plate as a fixture. I needed to spigot the front plate to the RT so I mounted the nosepiece in the lathe and trued it up in the 4-jaw chuck, then bolted the plate to the nosepiece and bored a place for a spigot  that fits the centre bore of the RT.
   
   

I mounted the assembly on the RT and set about makiing it look like the front of the original BP knuckle. First the well that allows the T-slot cutter (and the bolt heads) to access the slot. It's .800" deep, so I plunged with the largest centre-cutting endmill I had (16mm) and then opened it out with an insert endmill. I did this blind, going round the block with the DRO in .100" deep steps, as the well was full of coolant the whole time.
   

I made a beginning on the vertical slot for the T; using a 10mm carbide endmill, got two passes done at .150" depth. This slot needs to be about an inch deep before the T-slot cutter does it's thing. Each lap was taking about 45 minutes. Cranking the RT around for 45 minutes at a time sure gets old. I can see a motor-drive to the RT happening at a future date.

   

[f350ca]

Coming along nicely Pete. 45 minutes seams long to make a pass, I generally feed a bit on the hard side to keep the chip load up, if too slow the cutter is rubbing and it dulls quicker.
Can see the need for a powered feed. Used a gear head motor I think from a blue print machine to drive the rotary table on one long cut.

[Pete O]

Thanks Greg, I'm very inexperienced cutting slots. Taking in all the advice I can get.
Your jury-rigged motor drive has got me inspired, I have a geared motor a friend gave me from some x-ray equipment, been sitting on the shelf for years waiting for its time to shine. I'll dust it off and see if I can put it to work. For the number of laps I need to do here, it should be worth investing a little time.

[Pete O]

The little geared motor is unfortunately a non-goer, I wired it up this morning and ran it on the bench for 5 minutes and it was too hot to touch. Not going to risk it.
Following the wise advice from those on this forum, I swapped out the carbide end-mill for a HSS one of the same size, decreased DOC to .020" and cranked faster (in fact I cranked from the main shaft instead of from the reduction drive, cranking much slower but turning the RT much faster). Making progress, I've got .500" to go to reach depth, plus say .050 for some clearance under the T-slot cutter, not to mention the same number of passes again on each side of the slot to bring it out to full width. Good news is each lap is now taking six minutes.
   

Tomorrow is Monday for me, and my days off next week are not looking favourable for time on this. I'm going to be sweating on that T-slot until it's done.

[Dr Stan]

Are you counting them as part of your 10K steps today?

BTW, lookin' good.

[Pete O]

Used up a few hours today getting the slot ready for the T. I opened the top .600 of the slot out to the full width, then ran a 12mm endmill around inside it in .050" deep steps until I had the full depth plus .120" under the T-slot cutter. Nothing left but to cross the T tomorrow. Wish me luck.
   

[Vinny]

Good luck!

[Highpower]

Luck!

[Pete O]

This is what success looks like.
   

   
   

The T-slot cutting went off without a hitch. I honed the 6 teeth of the cutter with a diamond hone, touched off on the top surface (don't worry, the surface will be ground yet), brought the knee up by the calculated amount and aimed a jet of coolant at the cutter. Didn't take any photos during the cut, didn't want to get distracted and there was nothing to see anyway as the slot was full of coolant. It cut like butter, very pleasing. The only real difficulty was clearing chips from the last section of the slot- piling chips up in the slot behind the cutter means that the first part of the cut piles the chips up in what will be the last part of the cut. I solved that by putting the air nozzle in there and blasting coolant and chips out of the slot and onto everything else in the shed.

Next job will be to mount the worm wheel for the tilt adjustment. This means drilling a few holes in the centre so I'll do it with the vertical attachment before removing the assembly from the RT. A previous user has done serious damage to the gear, presumably by trying to 'undo' the drive pinion without loosening the locking bolts. The pinion shaft and worm were cactus; thankfully the nod adjustment parts are identical. I'll  drill another hole for the locating dowel and install the gear 180 degrees rotated so the damaged teeth (facing the camera here) won't be used unless I decide to use the head upside-down. The two 1/4" bolts and the 5/16 roll pin had been sheared off and the hole for the roll pin damaged, must have really been committed to getting that thing undone!

   

That can wait until next week though, I think that T-slot earned me an afternoon off.