Author Topic: Dividing Attachment Idea help needed  (Read 6328 times)

Offline jcrous

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Dividing Attachment Idea help needed
« on: September 29, 2012, 03:59:21 PM »
Hi,



I am now drawing an Indexing tool for my mini mill, based on the Harold Hall Design, but I will make use of what I have available in my garage,
It will be a direct indexing one with five sets of holes in one plate, 90, 80, 72, 60 and 48.
The main body will be of aluminum. the base plate of bright mild steel, as well as the spindle.
The indexing plate will be of brass and there will be 80mm chuck added.
the green handle will be the spindle lock - forcing a brass pad against the spindle (I am still learning the CAD program so please excuse the bad design).
The plunger will have to penetrate the indexing plate from the left (back) of the picture because there is not enough space to penetrate from the right to the left. The innermost set of holes will be well between the plate and the main body. The operator must turn the spindle by grabbing the Index plate as a handle after the lock has been disengaged.

The spindle is now bored through 8mm, and I will see if I will add a MT 1 hollow.

My question is to find a simple plunger design that will work with this design. I don't mind to make use of a screw-in type of plunger. This will most probably more sturdy than the type that is spring loaded (and easier to make).
Regards

Johan

Offline Lew_Merrick_PE

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Re: Dividing Attachment Idea help needed
« Reply #1 on: September 30, 2012, 12:50:33 PM »
Johan,

The devil is in the details and the image is not clear on some of them.  Does the index plate spin with the spindle (i.e. the index pin is stationary) or is the index plate fixed (i.e. the index pin rotates with the spindle)?  Each approach has its advantages and disadvantages.

My view is that speed of indexing trumps effort of construction.  If locking the indexer takes 30 seconds/indexing operation and you are indexing (say) a 200 tooth gear (as I did a couple of weeks back), then that is 100 extra minutes to complete the task.  If you can lock the indexer in 10 seconds, then that is 33.3 extra minutes.  It does not take too many saved seconds of index locking to pay back time & materials.

It would probably be simpler if the index plate rotates with the spindle.  It is then only an issue of allowing the index pin to span the various index hole circles.  I would certainly make the effort to have the index pin be spring loaded with (say) a half-turn hold at retract to make it easier & faster to find the next index hole.  Do you need an example of such a mechanism?

Offline BillTodd

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Re: Dividing Attachment Idea help needed
« Reply #2 on: September 30, 2012, 02:21:34 PM »
Quote
It will be a direct indexing one with five sets of holes in one plate, 90, 80, 72, 60 and 48.

Without  taxing my brain-cell too hard, there looks to be a lot of redundant factors in those hole numbers. I wonder if you could improve the range with different numbers?

Bill
Bill

Offline jcrous

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Re: Dividing Attachment Idea help needed
« Reply #3 on: October 01, 2012, 12:25:26 PM »
Lew_Merrick_PE:
The Indexing plate will spin with the spindle. There will be nut covering the screw thread showing extruding through the indexing plate. The indexing plate will only be able to take a maximum of 90 holes, maybe up to 100.
I decided on the numbers with the aim to make a few once-off gears for the future (90, 60, 40 and 30 wheels for worms).
As this is a device that I will not use so often I don't mind the time.
BillTodd: I think the number choices make sense for me now with what I plan for the future. At a later stage I will make a full dividing head as a project.
Regards

Johan

Offline raynerd

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Re: Dividing Attachment Idea help needed
« Reply #4 on: October 01, 2012, 06:31:12 PM »
Or stick a stepper motor on the back and fit Kwackers indexing attachment... you can`t go wrong. Any division 0-999 in a click of a button!  (http://madmodder.net/index.php/topic,6672.0.html)
Sorry, couldn`t help myself... I love these devices so much!!

Offline Lew_Merrick_PE

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Re: Dividing Attachment Idea help needed
« Reply #5 on: October 02, 2012, 01:07:13 PM »
Johan,

Take a look at http://www.reidsupply.com/products/tooling-components/spring-loaded-devices/hand-retractable-spring-plungers/ as these should give you some ideas as to how to make your index "plunger" mate & retract with respect to your dividing plate.