Manual Lathe Job, Start To Almost Finish

[Wreck™Wreck]

The site Owner would like some input from experienced machinists, I do it for a living so will document a rather tedious job that I began today. Can not show the finished product however.

The blanks are 304 SS, laser cut from 1/2" thick plate, 23 5/8" ID X 25 1/2" OD +- 1/8". The finished parts are roughly 23 7/8" ID X 24 3/8" OD.

They bought a 34" DIA X 3/4" thick 6061 aluminum disk to hold the parts, this I will bolt to a 22" faceplate in a lathe on top of eight 4 1/2" long by 2 1/2" Dia stand offs and secured by 5/8-11 fasteners. I had to take the gap out of the lathe which is every bit of 18" long leaving the toolpost 12 or more inches away from the faceplate hence the standoffs.

I began by laying out the faceplate hole positions and drilling eight 15/16" holes in the disk using an enormous Cinci/Bickford radial drill press, this is not an enjoyable machine to use.



Then laid out the holes for 12 clamps inside and 12 outside then drilled and tapped them 3/8-16 with a manual Bridgeport knee mill whilst someone on another mill was making the clamps out of 1" X 5/8" X 2" long CRS with a 3/4" long slot for the fasteners and a 1/4-20 tapped hole near one end, we used SHCS with the heads bearing against the fixture.

It now lookd like this when I left a 3:00 today, tomorrow I will attach it to the lathe faceplate and begin turning, this setup does not inspire confidence.

More to follow, wish me luck

 

[sgisler]

Pix are absent


Stan,
Sent from my iPhone using Tapatalk

 

[ch2co]

I got Pix just fine. Good luck on this one. I can't add much other input, this is above and beyond what I even pretend to know about.

Chuck the grumpy old guy

 

[Chippy]

Looks like it will hold. If I'm seeing it correctly, maybe you could add some alignment pins in the clamping bars, see skecth.

 

[sgisler]

I got Pix just fine....

Weird, maybe a tapatalk thing


Stan,
Sent from my iPhone using Tapatalk

 

[pepi]

I say not your typical hobby build.... that my friend is some massive stuff. Thanks for showing that giant...

 

[joshua43214]

That drill press looks like something that could be used against a Terminator...

 

[Wreck™Wreck]

I say not your typical hobby build.... that my friend is some massive stuff. Thanks for showing that giant...

Not hobbyist sized work but scalable, one would have to use the same methods to do a 12" part in a 13" lathe.

 

[Wreck™Wreck]

Looks like it will hold. If I'm seeing it correctly, maybe you could add some alignment pins in the clamping bars, see skecth.

Good idea.
If it were more then a handful of parts I would do that however it's not worth the extra work for this job.
This morning, drilled the standoffs in a #5 Warner & Swasey Turret lathe then faced them to length in a chucker CNC lathe, eight parts 2 1/2" Dia X 4 1/2" long.

Bolted the fixture to the face plate, I had drilled a 3/16 hole in the center with a hand drill in order to use a rod with a point at one end held in a drill chuck with the tail stock in order to get the fixture close to center, this worked a charm.


Clamped a piece of steel to the compound to hold an indicator, did not indicate the fixture as it was close enough. I do not experience what some call "indicator sag" (-:



A boring bar was used to bridge the gap for turning and facing, not having a LH bar I used a RH bar upside down running the spindle in reverse, in order to get the tool this far from center turn the toolpost and put the holder on the outside.
Turned the OD and 3/4 of the face, a lot of tool overhang across the gap but it worked well an the finish was excellent, 25.250 ±.015 on the drawing measured with an extremely cumbersome and heavy 40" Mitutoyo vernier.



Moved the clamps to the outside, rotated the bar right side up and did the rest of the face and ID, I milled some 1 X 1/4 rectangular bar with slots to be screwed 90° apart against the finished ID so that when flipped to do the other side I can hang it on them and it will be very close to center when re-clamped. I put pieces of aluminum shim stock under the clamps, this customer is very fussy about finishes.



It has been easy so far, the work sheet gives me 24.7 hours to make 4 parts including making the fixture, removing the gap and related setup.

 

[Silverbullet]

Big plus the sheet of aluminum made up to use again on other jobs.