Rotary Head/Dividing Head Question

[chucketn]

About a year ago I purchased a Vertex 4” Rotary Table without the accessories for dividing, or the tail stock. It was an expensive investment, and as of now, I haven’t used it much. I have made a copy of my lathe spindle nose, mounted on an MT2 taper and can mount the lathe faceplate, and 3” and 4” chucks on it.
I’m studying gear cutting, and dividing and such and realize I need to be able to index and divide accurately to make gears. I have found several examples of homemade ones, and priced the accessories made for my RT.
My dilemma is, do I Spend as much as the RT cost to get the indexing accessories, or make my own dividing head, al-la Gingery, or some other style? Do I make a tail stock? Do I really need a tail stock?
So, my question, plea, request is: Has anyone made their own dividing head, tailstock? Or has anyone made their own indexing accessories for their RT? Any plans out there?

Chuck in E. TN

 

[portlandron]

You can cut gears with out a tailstock. However you run into problems with getting the cutter to clear the chuck or what ever you use to mount the arbor that holds the gear blank. If you make the arbor long enough to clear everything then you have to worry about deflection.

I faced the same issue a few years ago. Found a used dividing head with out any plates or tailstock for a very good price. It was not low end made in Chine one. About a year ago Enco had a sale on the "cheap" dividing heads with plates and tailstock with free shipping so I ordered it. I kept the tailstock, plates and fingers and sold the "cheap" dividing head to recover some of my cost. Ending up paying about $60. for all the parts I kept.

It would not be that hard to make a tailstock For the plates keep an eye open on e-bay I have seen them listed there many times.

 

[mklotz]

If you have some patience, any RT can be used as a dividing head without the attendant hole plates. Use my ROTARY program to print out a table of the settings for your desired number of divisions and enter them manually using the table handwheel. (Here's an example output...)

Number of divisions = 13

DIVISION   degdec   deg   min   sec
    0   0.0000    0    0    0
    1   27.6923   27   41   32
    2   55.3846   55   23    5
    3   83.0769   83    4   37
    4  110.7692   110   46    9
    5  138.4615   138   27   42
    6  166.1538   166    9   14
    7  193.8462   193   50   46
    8  221.5385   221   32   18
    9  249.2308   249   13   51
   10  276.9231   276   55   23
   11  304.6154   304   36   55
   12  332.3077   332   18   28
   13  360.0000    0    0    0

Remember, any error you make entering the angle will be reduced by the gear ratio of the table. For instance, on a 90:1 ratio RT a one arcminute error on the handwheel will be only 1/90 arcmin = 2/3 arcsec error at the workpiece. To put that in perspective, making a 2/3 arcsec error pointing your rifle at a target 100 yards away will cause a miss of only 0.012".

 

[rhankey]

I suspect you will find that you will need a tail stock, as you will likely find it hard to adequately support the workpiece while still having sufficient access with the cutting tool.

However, I don't think it is completely necessary to buy a set of plates or a dedicated dividing head. Sure, if you are dividing all the time and have the budget, then absolutely get a divding head or plates for exisitng RT. However, you can use Excel to quickly produce a list of additive angles from zero for each tooth of the gear you are cutting. Then it is a simple matter of carefully dialing the next angle from your Excel print-out, locking the table, and making your cut. In the meantime, you can keep en eye out for a good deal on a set of plates or a used dividing head while you assess just how much dividng you infact are doing.

Robin

 

[Maryak]

Chuck,

Yes a tailstock is a good idea. When you need one.................you really need one.

I made my own, nothing fancy, the main thing is that it matches the centre height of the RT. There was also an article a few years back in "Model Engineers workshop" with plans for a homeshop tailstock. Helps me out here guys..........sometime in the 1990's :-*

Hope this helps

Best Regards
Bob

 

[moconnor]

Hello Chuck,

If you would like to build your own indexing and dividing head, a real nice one was published inThe Home Shop Machinist magazine back in 1988 by Philip Duclos. It was reprinted in The Shop Wisdom of Philip Duclos as well.

Here are the issues:

"Model Maker's Dividing Head"
Part 1 HSM Vol.7 No.6 Nov/Dec 1988
Part 2 HSM Vol.8 No.1 Jan/Feb 1989
Part 3 HSM Vol.8 No.2 Mar/Apr 1989

The D/H uses a stock set of 40:1 Boston Gears and has a center height of 2.250" or 4-1/2" swing. It looks like a smaller L-W Dividing Head that is very much sought after by owners of smaller milling machines and which usually commands high prices on eBay. Mr Duclos used a 1"-10 TPI spindle nose with a No.2 Morse taper to allow the use of his chucks and tooling from his 6" Atlas lathe. This could be modified to match the spindle of whatever small lathe the constructor might own. I just purchased a set of Boston gears in order to construct one and I plan to use a 1-1/8"-12 BSW Thread to match the spindle of my Myford lathe.

He also details the construction of a footstock (or tailstock), driving dog and describes several methods to generate the index plates which is one of the more daunting aspects of building your own dividing head. It is a full featured tool that is well within the capabilities of any model engineer that can build a working miniature engine.

Here are the specifications for the worm and worm wheel which are not clearly stated in the article:

Worm Wheel
Boston Gear Part No. G1036 (Bronze)
40 Teeth / 14-1/2 degree P.A. / 24 D.P. / P.D. 1.667" / 1/4" Face / 1-25/32" O.D. / Style: Plain
1/4" Hole / Hub: 5/8" Dia. x 5/16" Projection

Worm
Boston Gear Part No. GLUH (Steel Hardened & Ground Threads)
14-1/2 degree P.A. / 24 D.P. / P.D. .500" / Single Lead / 13/16" Face
1/4" Bore / Hub: 3/8" Dia. x 1/4" Projection

When I did a search for the gears to find a place to purchase them, I actually found them on Amazon.com and bought them there. The worm wheel was $37.50 and the worm was $47.50 which I thought was very reasonable.

Regards,
Mike

 

[ShopShoe]

I made a tailstock a while back. You can see it in this post:

http://www.homemodelenginemachinist.com/index.php?topic=10987.msg120191#msg120191

I had purchased indexing plates: I only use them occasionally, but when you need them, you need them. If you use only one or two standard intervals, you could make your own just for those.

--ShopShoe