indexing head lathe

[Danni BurnsParticipant @danniburns84841]

Hi there

I need some way of indexing my lathe chuck (CL500M). It would also be handy if it locked.

I’m sure this has been done many times before, but I can’t find a search function here.

Any ideas? (links/pics)? Thanks

Danni

[Howard LewisParticipant @howardlewis46836]

You could make up a form of Mandrel Handle to carry a 60T gear and some form of locking.

You could then index in 6 degree increments. (A 36T gear would give 10 degree intervals)

A  90T gear would give 4 degree intervals.

Just choose a gear to provide what you need.

If you really want get complicated, add another gear, say 59T or 61T so that you have a vernier adjustment.

Or make up a worm to suit the wheel, and use division plates. A 90T gear and suitable worm would allow you to use the dividing plates (and chart) from a Rotary Table such as the Vertex HV6 (Soba probably do a set as well)

Howard

[Danni BurnsParticipant @danniburns84841]

Sorry if my request above is a tad lacking/cryptic.

Im looking to index the chuck for manual work on a turned/chucked part.

I have just found this v-cheap plate. I am wondering if I can use this in any way; e.g. attached to the headstock spindle.

[noel shelleyParticipant @noelshelley55608]

Howards post on the use of change wheels works well, once you have made the attachment you can use which ever wheel gives you the division you need. Noel.

[JasonBModerator @jasonb]

The gear method suggested works just like that plate. Mount to spindle and index the teeth or holes with some form of indent pin. Without knowing the size of the plate hard to say if it could be fitted or not. But like the gears an expanding arbor in the back end of the spindle and a flange to mount the plate to should work.

Some people also drill a series of holes around the chuck back plate

[Danni BurnsParticipant @danniburns84841]

Thank you Howard

I should have guessed you’d have a solution right off the bat.

Do you have a link/pic?

and Thanks Jason

[old martParticipant @oldmart]

The Atlas 12 x 24 at the museum has the bull gear drilled with 60 holes and an indexing pin can lock the spindle. 60 is a useful number because it divides by 2, 3, 4, 5, 6, 10, 12, 15, 20 and 30.

A lot of users are able to drill holes around the circumference of their chuck backplate for indexing if they have the use of a mill and rotary table. The rotary table indexing discs could be attached to the left end of a lathes spindle and give a large number of choices.

[DiogenesParticipant @diogenes]

‘mood board’ articles ?

https://mikesworkshop.weebly.com/60-position-index-wheel.html

https://mikesworkshop.weebly.com/headstock-indexing-unit.html

https://www.cgtk.co.uk/metalwork/minilathe/dividingetc

..IIRC there’s probably also something here too..

http://www.homemetalshopclub.org/news/article_sort.htm

 

[Nigel Graham 2Participant @nigelgraham2]

A dividing-plate is only useful if its hole-counts give the divisions you are likely to need. Their primary purpose is for gear-cutting, when you sometimes need awkward and even prime-number tooth-counts.

Most pitch-circles and polygons in mechanical engineering use multiples of 2, 3 and more rarely, 5.  A 24-division system will probably cover most work other than 5-based and some gears (2, 3, 4, 6, 8, 12); 30-divs gives 2, 3, 5s multiples.

A 60-division reference will give all those except 8-based.

A common method uses a change-wheel on the spindle, and a detent, so you have a very wide range of possible divisions.

[John HinkleyParticipant @johnhinkley26699]

As an alternative …..

I have made a couple of fixtures to index the chuck on my lathe by one degree increments.  Two fixtures, in fact.  The first was produced using a CNC router on black Perspex® for my then lathe – an Asian 9 x 20 machine.  The build is documented in a series of four videos on YouTube, starting here.

A lot can be fast-forwarded to get the idea. (according to the stats, that’s what a lot of viewers do, anyway!)

I’ve subsequently sold both the lathe and the router, but have acquired a mini lathe for which I’ve redesigned the indexer for its smaller (100mm Ø) chuck.  This was 3D printed and the project is introduced in this ‘ere video.

Although I’ve printed it out and trial-fitted it to the lathe, it’s not quite complete, nor is it on video ‘in the flesh’ so to speak.

There are always more than one way to skin a cat and I’m a firm believer in  “why do it simply when, with a little effort, you can complicate matters beyond all reasonable grounds.”  It was done as much as a training exercise for me in the use of 3D CAD and the router and latterly, the 3D printer as much as any practical use.  Needless to say, I have never used the indexer for anything!  I just built it because I wanted to, and had the means to do it!

John

 

[Danni BurnsParticipant @danniburns84841]

Thank you Diogenes & Nigel

Thanks John

Just checked out your clips. Interesting but I don’t have as many toys as you.

I think its safe to say – it’s gonna be another painful side project, where I forget what I actually needed it for.

I see a rear-end solution on youtube (https://www.youtube.com/watch?v=xauJcjrINy0), which is what Howards etc. are referring to.

I guess the design (front or rear) comes down to where I can best/easiest attach an indexing plunger, without modifying the machine.

[duncan webster 1Participant @duncanwebster1]

There was a design many years ago which had the detent tooth half a gear tooth pitch off centre on a round plunger. This meant you could get 8 teeth division from a 60 tooth gear, 7.5 teeth per div. Seemed far too prone to errors for me. My arrangement mounts any gear on the back of the spindle and the detent is on a swinging lever. You can also set up a compound train on the banjo, I once set up my ML7 to do 125 divisions to make a leadscrew handwheel

[bernard towersParticipant @bernardtowers37738]

The one I have on my S7 bull wheel has a round bar to a 28deg blunt  point and a 28 deg female at 90 deg so you can get 120 divs from the 60 tooth wheel.

[Danni BurnsParticipant @danniburns84841]

Hi bernard

i don’t understand your post. Do you have a photo.

cheers

[Danni BurnsParticipant @danniburns84841]

I bought a myford 60T gear and it is a lot smaller than I expected approx 80mm.

Does anyone have experience of sourcing map spring plungers that work well with these small gears? Can you recommend models?

cheers

[DiogenesParticipant @diogenes]

Don’t have experience with bought spring plungers, but would suggest an ‘all-metal’ assembly and ensure the size is adequate to provide a comfortable ‘pull’.

Also that another option can be to use a flat ‘leaf’ or ‘pawl’ that can be pivoted into or out of engagement.

You’ll probably need to file or shape the plunger tip, so if buying ready-made bear in mind that life might be easier if you can disassemble/reassemble the product if necessary, or that the plunger has sufficient length to modify or adapt.

[bernard towersParticipant @bernardtowers37738]

does this help?

[Les Jones 1Participant @lesjones1]

This is how I mounted  an indexing plate on my Chester DB-10G lathe.

 

It is located with a ring that fits into a machined part of the spindle pully. I leave this ring on the lathe when not using the indexing plate. The indexing plate is held to the spindle pulley with three screws. I made the indexing plate using a rotary table on my milling machine,

Les.

 

[Danni BurnsParticipant @danniburns84841]

Les. Very nice. That is the solution I was thinking of initially, but no rotary table. I hadn’t thought to just use a bolt through the holes and was expecting it to be more difficult.

Cheers for that.

[Danni BurnsParticipant @danniburns84841]

Bernard

That is a very nice plunger.

I was considering putting a second index plunger on the Gear I think that is what Duncan above is suggesting and I also discussed that with another respected engineer from here, but this does the same thing in one shot. I don’t suppose you have a drawing of that, that I can blatantly rip off (probably scale down)?

cheers

[bernard towersParticipant @bernardtowers37738]

it will be a back of the fag packet drawing as I am a luddite, just give me a day or two and I will send via a pm

[Danni BurnsParticipant @danniburns84841]

Champion.

No rush – I have DIY to do!

[jim1956Participant @jim1956]

I have a vintage Randa type lathe on which I wanted to do some simple dividing, marking out for dials or PCD holes on backplates. This is more or less my lathe, the gear train at the back sort of hangs in mid-air, not like a Myford where the casing is close to the bull gears and it’s easy to mount a detent pin.

I added a bracket on the bed to put another gear slot available in the train for left hand threads and left a protruding arm on that so that I could have a swivelling indexing arm onto the 60 tooth bull gear. It probably would have worked for factors of the bullgear although I’d held off on trying to implement it because I wasn’t clear how I’d be able to swivel it in and hold it firmly. Then I read some of the late Harold Hall’s articles about dividing using three or more gears.

I’m lucky that the Randa uses Myford size 20DP gears, albeit with a pin rather than a keyway, so I was able to add a few gears to my set to allow metric threading. I bought a set of four shop soiled with some rust (26,27,28,29) and then a couple of 21T gears. This let me do all the common metric threads to acceptable tolerances and gave me a useful range of intermediate gears for dividing purposes.

 

One of Harold Hall’s articles gave simple ratios to use three gears to get a 125 division, useful for marking out a dial for an 8tpi leadscrew, which tweaked my interest.

Indexing on any of the intermediate gears in the train would be difficult and very awkward to use. The ideal position on the lathe to index would be on the leadscrew gear, down close to the base where I could slot in a bracket to hold a detent pin fairly easily.

Of course I would want to be able to use the leadscrew to move the saddle in and out for marking while dividing. Here the pin drive on older vintage lathes proved useful. Reversing the collar on the end of the leadscrew, so that the pin faced outwards away from the gear, allowed the leadscre

gear to rotate freely. I could use a detent pin against the leadscrew gear and the rest of the gear train for dividing while still using the handwheel to move the carriage in and out driven by the leadscrew.

 

There is increased backlash as the gear train increases but even with a detent on the bull wheel I would have had to put a strap on to hold the chuck consistently against the backlash.

My detent pin needed to move in and out to accommodate different sizes of leadscrew gear. I did this by making the detent carrier out of an M12 bolt, centre drilling it for a 7.5mm pin. An M12 tapped hole in the mounting bracket allows the pin to move in at leadscrew centre height to accommodate any gear on the leadscrew. The mounting bracket also needs to move laterally one gear width since the leadscrew gear can be in the outer position for a train with a single compound gear or inner for a train with two compound gears.

I did consider making it a fixed position and always using a six gear train but on balance made it able to shift laterally because setting up one compound gear is less bother than two.

One of the difficulties is finding the appropriate ratios for any particular subset of gears (I’m missing a few from the standard sets, no 25T or 38T and only one 20T).  I wrote a small program to calculate available ratios and divides for my gear set(in Javascript, free if anyone’s interested) and found a few set-ups which will match my gear set and so all the divides I’m ever likely to want

 

Regards  Jim

 

[Grizzly bearParticipant @grizzlybear]

Hi Danni,

It’s worth doing a google search, when looking for stuff appertaining to this forum.

Bear………

[Danni BurnsParticipant @danniburns84841]

<p style=”text-align: left;”>Thanks Jim</p>
<p style=”text-align: left;”>I sis wonder what the purpose of the pins was on some gears. I chose with key when I bought.</p>
Great idea with the index. Looks like you could make/modify that to incorporate a spring to save all that winding in.

Cheers

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