Harold Hall's basic dividing head

[xo18thfa]

Got started on the Harold Hall “Basic” dividing head project. This dividing head appears in the Workshop Practice Series #37 on Dividing by Mr Hall. It uses a “direct” method of indexing, namely change gears for a lathe. The change gears are from an Atlas 6”.

Mr Hall leaves the design somewhat open ended to suit your existing tooling. My dividing head will have a #2 Morse taper in the spindle for standard collets. If I ever need to mount a chuck, Sherline is the way to go I think. Sherline spindles are 3/4" x 16TPI. #2 Morse taper to 3/4" x 16TPI shanks are available.

I am following Mr Hall’s plan with only one deviation. Instead of locking the spindle with clamping splits sawed into the body, I plan to use the capture nut technique from George Thomas’ Universal Pillar Tool. My milling machine is not very rigid and probably won’t make those substantial cuts in the dividing head body. So, we will see how capture nut will work.

Here’s Mr Hall’s basic dividing head.

Here’s what’s been done so far.

Here’s the roughed out spindle. This week I’ll take it to a friend’s shop and have the #2 Morse reamed in.

The thrust collar on the spindle is pressed on. Mr Hall specifies carving the whole thing from solid. I did not want to waste all that material. The hole in the spindle is step bored to match the #2 Morse. Read somewhere that helps ensure the ream goes in straight.

Everything is coming along well so far.

 

[steamer]

The Capture nut or Cotter will work wonderfully. Best of all, make a small handle for it and you won't need a tool to fix it.. I used them on my spindle dividing attachment, as well as my bed mounted depth dial indicator.

They work great!

Dave

http://i164.photobucket.com/albums/u27/mcandrew1894/P1010195.jpg

 

[tel]

Coming along nicely! Here's a shot of mine in action - just to give you a nudge!

Oops - that's two!

 

[xo18thfa]

Thanks guys. This project is coming along quickly. Maybe done next week.

The spindle nose got reamed to #2 Morse taper. Turned out perfect. Looks like it was ground in. The retaining ring and detent thing is done too.

Tomorrow get started boring out the head stock for the spindle.

 

[steamer]

xo18thfa,

I would bore the cotter holes first. Then I would insert the cotter with a threaded stud on one side to lock them in.

THEN I would bore the hole for the spindle shaft. Once complete, the cotters will be machined complete too, and all you will have to do is remove the threaded stud from the end of the cotters

You can use two piece or one piece cotters, but I have had great luck with 1 piece cotters.

Dave

 

[xo18thfa]

xo18thfa,

I would bore the cotter holes first. Then I would insert the cotter with a threaded stud on one side to lock them in.

THEN I would bore the hole for the spindle shaft. Once complete, the cotters will be machined complete too, and all you will have to do is remove the threaded stud from the end of the cotters

You can use two piece or one piece cotters, but I have had great luck with 1 piece cotters.

Dave

Brilliant. I will do that. Just happened to bore the cotter hole first. Got started on the spindle bore, then the lathe belt broke. Must have been a reason for that.

One piece cotter bolt. I'll try that too.

Thanks, Bob

 

[steamer]

Just be sure to bore the hole for the spindle tight. Unlike the original design, you have no way to take up for a slack fit, so it needs to be a close fit. Let me know if you want some help...

Dave

 

[xo18thfa]

More progress. Used Dave’s method to turn the cotter nut while boring out the headstock for the spindle. Worked like a champ. Two parts in one setup.

Harold Hall’s plan calls for cast iron bearings in the headstock. I had some nice bronze bearings on hand, so I used them instead. They are a very light press fit into the headstock.

Spindle fits in just right and turn very smooth.

All the hard work is done. Should get this project wrapped up this week.

 

[steamer]

Cool! Glad it all came together!

Can't wait to see the finished product!

Dave

 

[xo18thfa]

Got the last of the small parts done and the dividing head is operational. Here’s the single gear set up.

The cotter nut locking scheme for the spindle works great. It does not take much turn on the handle to fully clamp down the spindle. I went with the split nut rather then solid.

Here is the multi gear set up.

There is a design fault in Mr Hall’s plan for the multi gear arrangement. The plan calls for a key slot only part way along the spindle. The key slot needs to go all the way to the shoulder in order to secure the inner gear. Rather then try to mill the slot longer, I inserted a half-inch spacer between the detent arms.

That should solve the problem. If you build one of these, be sure to mill the slot all the way to the main shoulder on the spindle.

I ordered a set of #2 Morse taper collets. Just need to make a little draw bar to fit.

Next is the paint shop and a nice storage box.

 

[steamer]

Looks slick from here Bob! What color are you going to paint her?

Additionally, put your name on it somewhere. It deserves that.

Great Job!



Dave

 

[xo18thfa]

Looks slick from here Bob! What color are you going to paint her?

Additionally, put your name on it somewhere. It deserves that.

Great Job!



Dave

Probably dark gray. That's the color of the grinding table. Stamping in the name is a good idea. That's worth ordering a set of stamps.

Spindle run out measures in at 0.0004". Sometimes it's better to be lucky then good.

 

[steamer]

Maybe mill a small pocket on the side and stamp your initials in the pocket?.....

Looks Awesome! Can't wait to see it in action!

Dave

 

[xo18thfa]

The dividing head is all done. Just so happens a set of 2MT collets came in the mail today.

And the multi gear set up.

And a handy storage box.

It looks like 2011 is the year of shop upgrades. Next up, a boring head.

 

[steamer]

Like the box! Wanta make one for my sine plate? ;D


Dave

 

[tel]

Lovely box you mean! (the D/H speaks for itself) But stopped dovetails in pinus radiata(?) - now that is skill!

 

[xo18thfa]

Thanks men.

Dave: You need a box. No problem.

Tel: The lumber came from Home Depot, a big home improvement chain in the US. Normally their lumber is the cheapest junk around. I found a one in a million board, very tight grain, highly figured, almost like bird's eye maple. What a find!! Unfortunately, the recession wiped out all the good hardwood lumber yards in Las Vegas. Crate lumber is that's left.

 

[workshopman]

I have just noticed that you have Bob made my basic dividing head and am honoured to think that it deserves a storage box as you have made, but then, you have made a much more professional looking job of the head than I have done.

I am impressed by the dovetails, have you cut them by hand or do you have a router and jig for producing them? Making them by hand would be a definite No No for me. Now that I have finished writing for MEW and my website is nearing completion, though I anticipate there will always be something worth adding, perhaps I should make storage boxes for some of my better efforts. Incidentally, cabinet making is my preferred passtime, though metalworking fills far more time. If you haven't seen my cabinet making pages have a look at http://www.homews.co.uk/page14.html and the link to page 2 from there.

I am sorry for the error in the dimension for the keyway. It is difficult to get the publishers to update such things in the books, but I will try. I have though added a prominent note on my web page for the head which may go a little to avoiding others finding out the hard way. The page is http://www.homews.co.uk/page132.html

Keep up the good work!

Harold