Author Topic: A new compound dial for my South Bend 10L  (Read 5217 times)

Offline tvoght

  • Full Member
  • ****
  • Posts: 929
  • Indiana
A new compound dial for my South Bend 10L
« on: May 24, 2015, 04:32:46 PM »
My South Bend lathe has long needed a new dial on the compound lead screw. A previous owner has removed the proper dial, and he or another previous owner had replaced it with the wrong one, which was not only of the wrong diameter, but the wrong length. I have struggled and worked around this since I've owned the lathe. It was long past time to do something about it. Here's a short essay on my efforts. 

Starting with a length of 2" aluminum stock, I drilled and reamed for the lead screw shaft. All done with a considerable length extended past the chuck to avoid wasting stock.



I faced the end and turned down some diameter, though far from the final dimension, then began a parting operation which quickly led to chatter because of the long extension.



No matter, as I simply took it to the bandsaw to complete the cutoff. The initial lathe cutoff groove provided a good guide for the blade.




Now mounted on a purchased mandrel, it's back to the lathe in a collet where both ends end the diameter are finished square.



I had drawn a curve in CAD to somewhat replicate the dial on my cross-slide.  This dial is basically a scaled-down version of that one. I picked off steps from the CAD drawing a created a step-off chart for machining the curve.  Steps are in decreasing radii of .02 inches. here's the rough-machined curve and a shot of the chart with each step penciled out as I had finished it.




I blued up the steps as a visual aid in filing the curve smooth.  I'd read somewhere that filling a file with blackboard chalk would help prevent it filling with aluminum as filed. The chalked file is shown. The jury is out on the success of this attempt. In fact that file still has some aluminum embedded that I've not been able to get out.



Here I'm half way through the filing operation. This shows how the bluing assists in monitoring progress.



Here I've finished filing.



And here's after application of a couple of grades of sandpaper.



And now to an exercise of the new 4th axis I've added to my CNC machine.  It's a Sherline "CNC ready" rotary table which needed just the addition of the stepping motor. I had anticipated this when configuring the machine, so my electronics were already 4th axis capable. I've got an engraving tool with a 60 degree included angle point in the spindle



The photo's a little glaring, but here's a progress shot. This was not the first time the program had been run. I ran a test piece about 3 times to "dial' it in (the pun just occurred as I wrote).



Jumping straight ahead, some coloring has been applied to the engraving, and it's been drilled and tapped for a purchased thumb screw



Had to do over again, I'd use an engraving tool with a smaller included angle, so the engravings would be finer.


Thanks for looking,

--Tim

Online sco

  • Full Member
  • ****
  • Posts: 1635
  • Location: Northants UK
Re: A new compound dial for my South Bend 10L
« Reply #1 on: May 24, 2015, 05:51:34 PM »
That looks really trick!

Are saying the numbers were engraved by CNC?

Simon.
Ars longa, vita brevis.

Offline fumopuc

  • Full Member
  • ****
  • Posts: 2397
  • Munich, Germany, EU
Re: A new compound dial for my South Bend 10L
« Reply #2 on: May 24, 2015, 06:54:25 PM »
Hi Tim, thats looking nice. I love CNC machining, not always but somtimes it is a real advantage.
Kind Regards
Achim

Offline mklotz

  • Full Member
  • ****
  • Posts: 2403
  • LA, CA, USA
    • SOFTWARE FOR PEOPLE WHO BUILD THINGS!
Re: A new compound dial for my South Bend 10L
« Reply #3 on: May 24, 2015, 09:28:39 PM »
Re the aluminum "pills" sticking in the file...

Take a small piece of scrap brass sheet and push it's edge along the file teeth in the direction the teeth slant.  Very quickly you'll wear teeth into the brass that exactly match the pitch of the file teeth.  The brass teeth will dislodge any aluminum that's managed to bond itself to the file.

If you have un-reloadable rifle cartridge cases you can flatten the business end and use it as your custom file scraper.  The body of the cartridge then forms a nice handle.
« Last Edit: May 25, 2015, 03:40:42 PM by mklotz »
---
Regards, Marv


Home Shop Freeware
http://www.myvirtualnetwork.com/mklotz

Online b.lindsey

  • Global Moderator
  • Full Member
  • *****
  • Posts: 13686
  • Dallas, NC, USA
    • Workbench-Miniatures
Re: A new compound dial for my South Bend 10L
« Reply #4 on: May 24, 2015, 10:42:58 PM »
That sure looks the part to me Tim. The engraving as you say could be finer, but to my aging eyes I kind of like the way they turned out :) Nice little project and write up too!!

Bill


Offline sshire

  • Full Member
  • *****
  • Posts: 3044
    • LS Editions
Re: A new compound dial for my South Bend 10L
« Reply #5 on: May 24, 2015, 11:23:42 PM »
Damn, Tim
That looks great!
I found these when I was doing the Rider-Ericsson (all aluminum castings). They work great and I've never had a clog.

http://www.amazon.com/Nicholson-Aluminum-American-Pattern-Rectangular/dp/B006P2XB4E
Best,
Stan

Offline mklotz

  • Full Member
  • ****
  • Posts: 2403
  • LA, CA, USA
    • SOFTWARE FOR PEOPLE WHO BUILD THINGS!
Re: A new compound dial for my South Bend 10L
« Reply #6 on: May 24, 2015, 11:59:31 PM »
On the subject of chalking files to avoid pinning...

I've seen the old-timers write that one must use "railroad chalk" (their term, not mine) rather than the more common blackboard or "sidewalk" chalk.

Now, I have no idea what "railroad chalk" is; my guess is it is used to write destinations on the outside of freight cars.  Or maybe the hobos who ride the rails use it to indicate which houses will provide a free meal.

The stuff I use is about one inch diameter and seems soft compared to blackboard chalk but, hey, I'm no chalk connoisseur.  It sort of works but, like Guy Lautard and some others, a thick coating of oil seems to work better.  My idea is that, hey, it's a cutting tool and we use cutting oil when we use cutting tools on the lathe so...
---
Regards, Marv


Home Shop Freeware
http://www.myvirtualnetwork.com/mklotz

Offline sshire

  • Full Member
  • *****
  • Posts: 3044
    • LS Editions
Re: A new compound dial for my South Bend 10L
« Reply #7 on: May 25, 2015, 02:03:39 AM »
Best,
Stan

Offline tvoght

  • Full Member
  • ****
  • Posts: 929
  • Indiana
Re: A new compound dial for my South Bend 10L
« Reply #8 on: May 25, 2015, 03:37:29 AM »
Thanks for the comments fellows.

Simon, yes the numbers were engraved with CNC. It's hard to imagine how I myself could have accomplished such a neat looking job any other way.

Achim, I agree most wholeheartedly. The engraving came out great due to the wonders of CNC. On the other hand, using the step off chart to cut the curve manually on the lathe was the better approach and it was fun.

Marv, I had heard the trick with brass, but probably didn't understand it. I tried just filing a piece of scrap brass afterward with little joy. I'll read what you wrote over and try again.

Bill, thanks and my tired eyes are fine with the thick lines as well. I think they will be just as effective from an accuracy standpoint.

Thanks to you too, Stan. I've seen those aluminum files in the flyers and forgotten about them. I probably should get some. Wonder if they have them with a half round side?

Rather than being 'railroaded' into buying yet more chalk, I think I'll try some of the other great suggestions you guys have made.

Thanks again!

--Tim

Offline fumopuc

  • Full Member
  • ****
  • Posts: 2397
  • Munich, Germany, EU
Re: A new compound dial for my South Bend 10L
« Reply #9 on: May 25, 2015, 04:28:08 AM »
http://www.dick.de/en/files-and-rasps/:

Only if somebody would like to learn more about files.
There is a download cataloge availalble also.

Caution, you can get confused easily by the amount of available tools.
Kind Regards
Achim

Offline steamer

  • Global Moderator
  • Full Member
  • *****
  • Posts: 10328
  • Central Massachusetts, USA
Re: A new compound dial for my South Bend 10L
« Reply #10 on: May 25, 2015, 12:19:15 PM »
Nice Tim!    having the larger "ticks" isn't so bad once the eyes start to go....the SB lines are really fine and hard to see......at a certain age.... 8)


Dave
"Mister M'Andrew, don't you think steam spoils romance at sea?"
Damned ijjit!

Offline tvoght

  • Full Member
  • ****
  • Posts: 929
  • Indiana
Re: A new compound dial for my South Bend 10L
« Reply #11 on: May 25, 2015, 02:17:51 PM »
That's a good link, Achim. I've already learned things about files I didn't know.

Dave, as another of the benefits to using CNC for the engraving: now that the code is locked down and proven, if I don't like the graduations I can turn another of these out in a morning's work.

--Tim

Offline mklotz

  • Full Member
  • ****
  • Posts: 2403
  • LA, CA, USA
    • SOFTWARE FOR PEOPLE WHO BUILD THINGS!
Re: A new compound dial for my South Bend 10L
« Reply #12 on: May 25, 2015, 03:22:46 PM »
http://m.grainger.com/mobile/category/ecatalog/N-1z0ccca
Here you go. A lifetime supply

Thanks for that, Stan.  But I still don't understand what makes it "railroad" chalk.  Any guesses?
---
Regards, Marv


Home Shop Freeware
http://www.myvirtualnetwork.com/mklotz

Offline mklotz

  • Full Member
  • ****
  • Posts: 2403
  • LA, CA, USA
    • SOFTWARE FOR PEOPLE WHO BUILD THINGS!
Re: A new compound dial for my South Bend 10L
« Reply #13 on: May 25, 2015, 03:48:34 PM »
Marv, I had heard the trick with brass, but probably didn't understand it. I tried just filing a piece of scrap brass afterward with little joy. I'll read what you wrote over and try again.

I was picturing myself doing it and didn't think to make the description sufficiently clear.

Hold the brass sheet at an angle of about 45 degrees to horizontal and push its edge along the teeth in the direction the teeth run, i.e., NOT perpendicular to their edges as in normal filing but rather parallel to the edges.  Because the brass is soft and the file teeth are dead hard, the teeth will quickly wear their profile into the brass and the edge of the brass will begin to look like a saw blade with teeth whose pitch perfectly matches the pitch of the file teeth.
---
Regards, Marv


Home Shop Freeware
http://www.myvirtualnetwork.com/mklotz

Offline sshire

  • Full Member
  • *****
  • Posts: 3044
    • LS Editions
Re: A new compound dial for my South Bend 10L
« Reply #14 on: May 25, 2015, 03:59:03 PM »
Here's everything I know.

Railroad chalk was originally produced to mark RR cars before barcodes and the electronic ID tags now in common use.

It is cast (the tapered shape is for easier removal from the mold) rather than extruded (as is blackboard chalk).

RR chalk uses a less frangible binder than blackboard chalk. I assume because it was designed to mark rougher surfaces with less degradation.

Sidewalk chalk may be a closer alternative to RR than BB chalk as its name suggests.

Both RR or BB chalk can be made "dustless" by coating it with lacquer.

As Tom Lehrer wrote:

"Who made me the genius I am today,
The mathematician that others all quote,
Who's the professor that made me that way?
The greatest that ever got chalk on his coat."

Best,
Stan