Frankenmill: Bridgeport J head onto Victoria U2

[TomG]

Looks good Pete!

Is your T-bolt going to be able to make the turn into the outer ring? Never mind, I see it already has in the first pic.

Tom

[Pete O]

(04-04-2019, 11:55 PM)TomG Wrote: Looks good Pete!

Is your T-bolt going to be able to make the turn into the outer ring? Never mind, I see it already has in the first pic.

Tom

The bolt heads are square, so they move outward and then sideways into the ring without rotating. I brought the cutter about 10 degrees past the starting point and then back as I finished the cut, to ensure there was no chance of a little apex protruding into the slot at the start / finish point. Probably not necessary but didn't want to take the chance.

[Pete O]

Got some more done on the frankenmill:
I drilled the two long holes through the top plate for the 5/8 nf x 8" bolts. I did the first one in my crappy drill press, which has about 40mm quill travel. Then I realised I have a drilling machine with a fair bit more travel than that:
   
The long drill did not make for a very straight hole over 5 1/2", fortunately I had a 5/8 straight reamer that cleaned them up enough for the bolt to go through.
   

Next job was to grind the front surface of the nose piece, this was referenced to the depth of the step where the tilt gear mounts, to ensure correct mesh of the gear set.
   
Gotta love the surface grinder; correct depth to within 0.01mm and this finish.
   
I removed the vertical attachment (REALLY for the last time...I hope!) and re-inserted the overarm with the cheek plates, then bolted the top plate on
   
Assembled the nose piece to the front plate
   
and mounted the nose assembly
   
I seem to have miscalculated something here, the 8" long top bolts bottomed out. Easiest thing will be to make some thick washers I think.
   
I filed the damaged teeth of the tilt adjustment gear so they won't bind if I ever turn the head upside down. I've rotated the gear 180 degrees so undamaged teeth will be in use. Mounted the gear, which also serves as the spigot for the J-head. Roll pin not installed yet.
   

then at about 4pm this afternoon, schoolgirl-like giggling could be heard coming from my workshop...
   
   
   
   
   

Lots of work to do yet, I have not taken any tram readings at all but I expect there'll be quite a task to get the tilt set up accurately. Then everything will be disassembled again and painted. And there's the VFD and the mach tach to set up.

[TomG]

Very nice Pete. A perfect example of form follows function.

Have you considered taking a grinder to the outside corners to make them look more casting like before paint? That, and sharp corners always seem to attract elbow and head collisions.

Tom

[Pete O]

Thanks Tom, yes I was looking at all the sharp corners and edges today as I was assembling things, wondering about the best way to deal with them. I think I may have a suitable radius horizontal milling cutter to go around the edges of the front plate and the top plate too, I guess an angle grinder would be an option...come to think of it I have a 12" disc sander that might even be a reasonable tool for the job.

[TomG]

You can do a pretty decent job with just an angle grinder, followed up with sanding discs. I built a safe once out of 1" plate and used an angle grinder to radius the welded corners that turned out quite well.

Tom

[Pete O]

Had a few other things to do today but I took some time to grind my tramming ring, checked it on the surface plate and it's within .0001" all around. I set it up on the mill and adjusted the tilt to within one division on my .002mm DTI, then checked the nod and found it to be 0.1mm over the diameter of the ring which is about 160mm, so about .004" in 6 1/2". I'm having to mix metric & imperial measurements due to what equipment I happen to have, I'm actually more comfortable working in imperial with fine work, even though Australia went metric when I was seven years old.
   

The geometric relationship between the spindle and the front plate was too much to try and figure out late in the day so I decided to use trial and error to get the shim thickness required, which will translate into the amount of taper that will be ground into the front plate. I tried shimming the front plate by .005", that got the nod error down to .025mm, found a bit of .006" shim stock and that got the tilt to within one division on the .002mm DTI, probably near enough for the bush.
   

I'll disassemble back to the front plate and grind it to a .006" taper, that should get the nod about right.

[Dr Stan]

Lookin' good

[Pete O]

I managed to get a couple of hours on this the other day but I've been too busy to post. I had been at a bit of a loss as to how to measure the lateral alignment of the head, i.e. in the left/right plane as opposed to 'tilt' and 'nod', and how to correct any misalignment. I came up with a way of measuring it; extended the quill with the head tilted to one side, and swept the front of the quill with an indicator mounted to the table:
   
Then tilted the head to the other side and moved the table across to sweep the quill again
   
I forget what the difference was; from memory it was about .006". I added shims to one side in addition to the shims I'd already put in the bottom, to get the reading zeroed in both axes.

I dismantled the nosepiece and front plate, then shimmed the front plate on the mag chuck of the surface grinder to the same tilt in both planes. That took a bit of doing, I ended up clamping an indicator vertically on the grinder head and running it around the plate to get the correct distance between the four corners, then started grinding away. The fresh grind marched diagonally across the surface.
   

To the left of the plate, on the mag chuck in the above photo, you can see the base of the wheel dresser. Because I had a fair bit of material to remove (in surface grinder terms) I mounted it on the mag chuck next to the workpiece, so I could dress the wheel part-way through the job without disturbing the setup; just lift the spindle, pull out the table stop and move the dresser over to do it's thing, then move the dresser out of the way, lower the spindle and keep grinding.

I reassembled the parts, trammed the tilt and took the nod and lateral measurements again. The nod has gone from .004 forward, to .0008 backward; with the twist, I can't recall where it started but I ended up with .0015" over the width of the sweep which was about 12".

I made a couple of spacers for the long bolts whilst they were out. I think I'll keep an eye out for some capscrews to replace them with.
   

I was hoping to get it wired up but I don't have any suitable cable and the electrical supplier was closed for the Easter break.
Also I'm tossing up where to mount the VFD, I'm open to suggestions on this but I'm thinking I'll mount it on the wall behind the machine and make a small control panel to go on the opposite side to the DRO.

[f350ca]

I must say you've got amazing determination to stick with this build and get the results you have Pete.
I put the VFD for my drill on the wall, figured it might have less chance of stray chips getting to it.
Thanks for posting.
Greg