Author Topic: Building a small and simple dividing head - CNC/Kwackers driven  (Read 37875 times)

Offline raynerd

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Building a small and simple dividing head - CNC/Kwackers driven
« on: January 21, 2012, 08:10:30 PM »
Hello,
I don`t often post before I have something to show, but I`m making an exception here as I need some advice!

I have a really lovely Rawyler Swiss made Horizontal miller that I want to use for pinion and gear cutting and I`m needing to make a divider and I will be runing this on one of Kwackers CNC index controllers that is built and ready waiting. Pictures tomorrow (well, OK, I do have something I could have shown!!).

I need to keep costs to a minimum and use things I already have as much as possible so please bear that in mind.

I intend to make something fairly simple like our very own madmodder, Dean made on his website...

I`m not showing this as an image..because IT IS NOT MY PICTURE!!, this belongs to deansphotographica: http://www.deansphotographica.com/machining/projects/divider/1stassy.jpg

I have all ready and waiting:
straight 16mm shank ER16 collet chuck
16mm ID olite bushes
cast iron block 50 x 50 x45mm which will need raising another 30mm on a ally base
120:1 suitable sized worm and wheel

Using the straight shank er16 chuck straight out of the box, if I bored he cast iron block for the bushes, I`d have an instant spindle! Then by mounting the worm wheel directly on the shaft, I could then use some mounting brackets to mount the worm above or below the wheel and I`d end up with something directly like Dean has made....

BUT  ....

.... I intend to drive this off a stepper motor. Now it only is a tiny thing with very small mounting holes, spaced in a square 31mm x 31mm. My problem is, if you look at the image above, I`d not have any material to mount the motor bracket/motor onto!

In an ideal world I`d have the motor running directly being the dividing head, inline with the spindle and table but I`m guessing that would be an aweful lot more work to rotate the worm shaft by 90 again to get the rotation back parallel with the spindle!

I`d just like any thoughts or suggestions or build ideas. Especially how to mount the motor and worm arrangement.

Chris
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Offline Scuba1

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Re: Building a small and simple dividing head - CNC/Kwackers driven
« Reply #1 on: January 21, 2012, 08:20:37 PM »
You got any pictures of the worm gear box ? As that would help a bit with making suggestions

ATB

Michael
Skype: scuba-1

Offline raynerd

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Re: Building a small and simple dividing head - CNC/Kwackers driven
« Reply #2 on: January 22, 2012, 10:34:17 AM »
Scuba, it isn`t a box... I simply have a worm wheel which is about 60mm dia, the worm which is on about a 6mm shaft and then a block for the main body...plus other materials to make brackets etc.

If you look at the picture I linked to, then I`ll end up with a setup similar to that... it is just how to mount the motor as there isn`t much material around it to locate a motor bracket onto!!

Any thoughts?

Chris
Youtube: craynerd
Projects at - www.raynerd.co.uk

Offline Raggle

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Re: Building a small and simple dividing head - CNC/Kwackers driven
« Reply #3 on: January 22, 2012, 05:01:35 PM »
This page by Tony Jeffree should interest you.

http://www.jeffree.co.uk/pages/divheadmk2.html

This version of his dividing head (there is a simpler, earlier one) has 2 modes to drive the worm, plate and arms or stepper motor. You unbolt one system and bolt on the other.

Hope this helps

Ray
still turning handles  -  usually the wrong way

Offline raynerd

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Re: Building a small and simple dividing head - CNC/Kwackers driven
« Reply #4 on: January 22, 2012, 05:31:52 PM »
Ray...fantastic!! To be honest, it is the only sort of arrangement that I was thinking about...just looked a bit too faffy in my head!! lol   That page shows that it can clearly be done!! Many many thanks!!

Chris
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Projects at - www.raynerd.co.uk

Offline John Stevenson

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Re: Building a small and simple dividing head - CNC/Kwackers driven
« Reply #5 on: January 22, 2012, 05:45:32 PM »
Chris,
What about just getting one of those cheap reduction gearboxes that fit on electric motors and bung a stepper motor on and a chuck or something up the spout.



Sort one out in a day.

John S.
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Offline raynerd

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Re: Building a small and simple dividing head - CNC/Kwackers driven
« Reply #6 on: January 22, 2012, 05:55:55 PM »
Hey John, would certainly be a good idea if I had one lying around. I`m not sure what size they are but my little 4" rotab is too big for the machine which is why I`m having to make something smaller. I wouldn`t have thought of using one and certainly something I`ll consider doing if I ever come across one at a good price.

Chris
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Offline Dean W

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Re: Building a small and simple dividing head - CNC/Kwackers driven
« Reply #7 on: January 22, 2012, 07:07:07 PM »
Hi Chris;
You can use my pictures here, if you'd like.  Thanks for thinking about that, though!
I see you need to raise the finished divider some to work on your machine.  You mention 30mm.  I don't know how
critical that measurement is, but if you have some leeway, you could use an inexpensive 1-2-3 block and mount your
divider body to it.  That's how I do mine.  The block will also give you some mounting options for your stepper motor,
I think.  They have plenty of holes in them!

If it would be more convenient to mount your stepper directly to the spindle, you can use a simple eccentric on the
ends of the worm shaft, so it can be rotated down to disengage from the large gear.  Then you would have the option
of using the worm reduction manually, or disengage it for use with the stepper.
Just a thought.

Dean


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Offline raynerd

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Re: Building a small and simple dividing head - CNC/Kwackers driven
« Reply #8 on: February 03, 2012, 07:01:41 PM »
Made a good start. Now the near side worm mounting block is to be replaced with something bigger to allow the mounting of the stepper.

The spindle is an ER16 straight shank 16mm at was no price at all.

Squared it up as John/Bogs showed us how in his minimag build. Some of the best advice ever given.


4 jaw for boring:





Lump of ally for the base was then cut and milled to size and shape:





The picture below shows the top sitting on the base. It has now been tapped in each corner and bolted through from below.


And now with the worm wheel attached and spindle mounted. It is turning nicely so looks like it will work just fine.








Youtube: craynerd
Projects at - www.raynerd.co.uk

Offline John Stevenson

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Re: Building a small and simple dividing head - CNC/Kwackers driven
« Reply #9 on: February 03, 2012, 07:13:13 PM »
Looking good, don't forget to work out some sort of cover for the worm and wheel to stop chips jamming it.
I know it's not finished but easy to overlook in the heat of the moment.

John S.
John Stevenson

Offline philf

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Re: Building a small and simple dividing head - CNC/Kwackers driven
« Reply #10 on: February 04, 2012, 04:26:48 AM »
Hi Chris,

That looks really nice.  :thumbup:

The worm and wheel look familiar!

I'll be interested to see your first pinion cut on it.

Phil.
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Offline cfellows

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Re: Building a small and simple dividing head - CNC/Kwackers driven
« Reply #11 on: February 07, 2012, 11:51:11 AM »
Looks great, Chris.  I like the er collet chuck idea on the spindle.  One of the things I've discovered over the years is that you need to put as much thought into workholding on these things as you do the dividing mechanism.  With your arrangement, you don't need to worry so much about your milling cutter fouling the chuck.

Chuck

Offline Pete.

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Re: Building a small and simple dividing head - CNC/Kwackers driven
« Reply #12 on: February 07, 2012, 01:48:55 PM »
Looks nicely proportioned on the machine too Chris. You making a tailstock with the other block?

Offline raynerd

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Re: Building a small and simple dividing head - CNC/Kwackers driven
« Reply #13 on: February 10, 2012, 09:39:59 AM »
Hi Guys, thanks for the comments.

I`ll take some more pics tonight of the final setup as I`ve now fixed up the stepper motor and have it running with the divider but I must admit, I`ve stupidly not considered any way of locking the spindle directly. Other than the holding torque on the stepper, I`ve no way of locking the spindle up and I`m fairly sure I can feel a touch of back lash between the worm and wheel which is transfering into the spindle. I think it is pretty much neglagable, but I would quite like to add some locking mechanism direct to the spindle so that I can keep the tension in one direction and can lock up after each division.

The only option I can think of, is a simple thumb screw bearing down right on the top of the block onto the spindle but will it damage the middle of the spindle over time and is there a better solution?



Chris
Youtube: craynerd
Projects at - www.raynerd.co.uk

Offline Fergus OMore

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Re: Building a small and simple dividing head - CNC/Kwackers driven
« Reply #14 on: February 10, 2012, 10:08:10 AM »
Insert a slug of copper into the clamping end of the locking bolt

Offline raynerd

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Re: Building a small and simple dividing head - CNC/Kwackers driven
« Reply #15 on: February 10, 2012, 12:27:31 PM »
When you say a slug, so you mean so basically your screw is actually pushing down on a copper piece that is actually locking onto the spindle?

only problem I`ll have is that the spindle is 12mm and it is running in bushes that are 16mm. The is a slight gap between the front and rear bush, therefore the location of the locking screw will probably end up in the middle, meaning there will actually be a 2mm gap between the the spindle and the wall of the block...I guess this just means that the copper slug would need to be a minmum of 3mm or so, so that it doesn`t fall out of position.  Would copper be best or would brass do.

Chris
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Projects at - www.raynerd.co.uk

Offline Fergus OMore

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Re: Building a small and simple dividing head - CNC/Kwackers driven
« Reply #16 on: February 10, 2012, 12:54:47 PM »
Literally bung something tightly into the drilled end of the stop which is not going to bruise your spindle. Copper or brass or aluminium at a pinch.

As you rightly remark, it is only to lock the spindle-- without causing damage.

A lot of us use a detent which is a plunger to fit into the index wheel which is graduated into 24 holes. So you can do multiples of 15 degrees without have to screw down to lock the spindle. Myford super 7 owners often do this on the bullwheel which is 60 tooth so that you can get 120 divisions- using the bottom and top of the teeth.

You can also put division plates on the bullwheel with a worm  but also a micro-attachment which will do things which the plates don't cover.

'Fraid your machine is too complicated for an ancient geyser to play with.

However, enjoy it!

Offline andyf

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Re: Building a small and simple dividing head - CNC/Kwackers driven
« Reply #17 on: February 10, 2012, 01:21:04 PM »
Hi Chris,

Rather than trying to clamp the spindle itself, could you arrange some sort of a clamp screw which pushes a concave brass pad down on to the collet chuck, just forward of the two flats on it?

Andy
Sale, Cheshire
I've cut the end off it twice, but it's still too short

Offline Fergus OMore

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Re: Building a small and simple dividing head - CNC/Kwackers driven
« Reply #18 on: February 10, 2012, 01:36:04 PM »
I always risk getting 'chopped' but my versatile dividing head is a George Thomas affair- which uses a pair of split cotters and a ball handle for fast tightenning and subsequent quick release. I fitted the same sort of thing to my Quorn tool and cutter grinder.

You could fit a pair of split cotters of brass- with a ball handle.   

Put gilt on the ginger bread? :poke:

Offline Anzaniste

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Re: Building a small and simple dividing head - CNC/Kwackers driven
« Reply #19 on: February 11, 2012, 04:30:34 PM »
I find that a hole in the end of a locking screw to take a domed copper rivet is a nice simple solution.
Scrooby, 1 mile south of Gods own County.

Offline Pete.

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Re: Building a small and simple dividing head - CNC/Kwackers driven
« Reply #20 on: February 11, 2012, 04:48:37 PM »
If you make a split clamp that 'pinches' one side of the spindle it won't have a tendency to try to turn it when tightened.

Offline raynerd

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Re: Building a small and simple dividing head - CNC/Kwackers driven
« Reply #21 on: May 04, 2012, 04:38:46 AM »
Still not finished it, but it is looking better:

Motor attached and although isn`t hooked up here, it is turning nicely using the Kwackers indexer cnc controller.




As John stevenson said, I now need a cover for the gearing and also some slots milling for clamping down.

It seems like it is going to be a good size for my horizontal miller! Now need a matching tailstock!

Chris
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Offline Pete.

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Re: Building a small and simple dividing head - CNC/Kwackers driven
« Reply #22 on: May 09, 2012, 04:31:19 PM »
Looking very nice Chris - hope to see a nice pinion from it soon!

Offline krv3000

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Re: Building a small and simple dividing head - CNC/Kwackers driven
« Reply #23 on: May 09, 2012, 05:44:01 PM »
well dun chris

Offline raynerd

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Re: Building a small and simple dividing head - CNC/Kwackers driven
« Reply #24 on: May 10, 2012, 07:03:46 AM »
Looking very nice Chris - hope to see a nice pinion from it soon!

Lol, you provide me with a clock pinion cuttor and I`ll be right onto it  :drool:

Thanks guys, worked out very well for the price!
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