dividing head /indexing

[mark smith 20Participant @marksmith20]

Hi Just wondered if any one has built their own dividing head??

Ive been watching too many you tube videos of self built dividing heads and thought it would be an interesting project for use on a mill. Most nice ones i see are huge and i try to avoid the Asian imports if i can.

Im wanting something of about 4" centre height.

Any good sources of worm gears and wheels that good be adapted?

What about using an old lathe headstock, it seems handy because it already has a nice spindle and probably MT and thead for a chuck.

Ive seen worms and wheels on ebay for belle cement mixers ,but no idea of their size and quality.

**LINK**

**LINK**

Also a guy is selling lots of bronze steel and tufnol worms and wheels on ebay ,are these too small?

**LINK**

Any advice appreciated as im still trying to get my head around ratios etc.. i know most are 40:1 for some reason .

Thanks

Edited By mark smith 20 on 14/11/2016 12:22:27

[mark smith 20Participant @marksmith20]

[John CoatesParticipant @johncoates48577]

Harold Hall built one. It was a series in MEW and then a chapter in his book "Milling: a complete course"

[mark smith 20Participant @marksmith20]

Yes ive watched Harold`s video explaining his design,he uses Myford gears??

I thought this guys design looked useful although a bit small.

**LINK**

[Trevor Drabble 1Participant @trevordrabble1]

Mark,

I believe Hemmingway can supply dividing head kits.

Trevor.

[John CoatesParticipant @johncoates48577]

Well the main concern will be the centre height of the dividing head if you intend to use it on a lathe. Less of a concern if for use on a milling machine.

I plan to make Harold's design when time allows. My gear wheels are larger than Myford ones but part of the challenge will be to follow Harold's principles but adapt for my machinery.

I will have a look at the Youtube videos when I get home from work tonight

regards

John

[Roderick JenkinsParticipant @roderickjenkins93242]

Hi Mark,

I made the Timmins head, drawings and casting available from Blackgates.

The plates and fingers for dividing via the worm are borrowed from my George Thomas Headstock Dividing Attachment. What you can't see from the photos is that the bore for the head was machined by lying the casting on its back on the lathe cross slide and boring between centres. The head can therefore be used on the lathe or, more usefully, on the mill as shown, with an increased centre height. You have a choice of using a Myford 60T changewheel and adjusting the angle of the worm shaft to suite or buying a helical wheel (which I did) and having the worm shaft at right angles.

Cheers,

Rod

Edited By Roderick Jenkins on 14/11/2016 14:43:08

[steveteeParticipant @stevetee]

A bit like 20 shillings in a pound 40 is a number with a lot of factors. When you consider you can divide that 40 turns up into many more smaller increments , for example a plate with 25 holes 25×40 =1000 . 40 also divides into 360 4×9=36 . I don't consider myself a mathematician , someone else will come along shortly and explain it much better, I'm sure.

[mark smith 20Participant @marksmith20]

Roderick m thanks for the post never heard of that one but im only just learning.

Its not too easy line boring on my south bend as the cross slide isnt t slotted like boxford which is something i find to be a pain.

I want one for specifically mill use really .

An old lathe headstock casting and spindle looks ideal to me for the main casting .

Steve, thanks for that im trying to figure it out , my small rotary table has a ratio of 72:1 ,so does that mean the worm wheel inside will have 72 teeth???? Also divides into 360 .

[John Stevenson 1Participant @johnstevenson1]

Mark,

How about starting off with an off the shelf electric motor gearbox such as this one.

Ignore the fact it's stepper driven this is for a hobbing machine.

These boxes can be bought for far less than a set of castings and you get a bronze worm wheel, hardened worm, 4 bearings and all in a sealed and lubricated box.

They come in all sizes from about 3" square upwards and all different ratio's.

Ebay Link

This is only 30:1 but a look round will find others

[Anonymous]

Posted by stevetee on 14/11/2016 15:21:23:

………. 40 is a number with a lot of factors.

Errr, 40 only has two prime factors, 5 and 2, so not ideal for direct indexing because there is not factor of 3. Without looking I think that the direct indexing ring on my dividing head has 56 slots on one side and 60 on the other.

Mark: Yes, 72 teeth if the worm is single start. My rotary table has 90 teeth on the worm, or 4 degrees per turn of the handle, which is another common divisor.

Andrew

[BazyleParticipant @bazyle]

The Timmins and Thomas versions are oriented to Myford owners with MT2 bore and thread. It would be a great advantage to match your SB with MT3 and UNC thread. (and mark it as such to avoid the next owner getting confused when his Boxford chuck doesn't fit).

A full headstock would likely be big but you might find a tailstock which when off its adjusting base is a nice height. Otherwise see if you can get a new tailstock barrel to give you the MT3 and shrink on a flange for the thread. A bit of a cheat for a DIY job but the sets of plates and fingers sold for rotary tables are very good value and nice and shiny.

[Stephen BensonParticipant @stephenbenson75261]

I have the original Geo H Thomas one brilliant little dividing head now made in the far east but Hemingway's do still have the drawings and castings

Seen here cutting a clock wheel

[mark smith 20Participant @marksmith20]

John, interesting idea ,i`ll keep an eye out , don`t fancy ordering from china though.How would you put a spindle in there?

Bazyle , another interesting idea ,you can often find some old hefty tailstocks on ebay.

Can you fit any type of plates to these things as long as they fit the worm spindle and plunger etc made to match?

[mark smith 20Participant @marksmith20]

The george thomas ones look nice but are pretty expensive. Looks massive compared to the cowell mill.

[mark smith 20Participant @marksmith20]

THis one would be useful if it were 90 degree drive instead of inline.

**LINK**

[Thor 🇳🇴Participant @thor]

Hi Mark,

I have made my own dividing heads, one using a purchased MT 2 spindle, but none with a centre height as high as 100mm. I have also made an indexer using a Mini-Lathe spindle, but the centre height is only 85mm. It should be easy though to increase the centre height by 15mm and add a worm and worm wheel to make a proper dividing head.

Thor

[Chris Evans 6Participant @chrisevans6]

Harold Halls simple dividing head in his book "Dividing" looks to be a doable workshop project. You can adapt the sizes to suit what is to hand.

[Alan JacksonParticipant @alanjackson47790]

Hi Mark

Here is my version. made from mild steel and uses a 40 tooth spur gear ( an old lathe change wheel) Has had much use and works well. Centre height is set to suit my lathe centreline when it is mounted on the cross slide. More photos in my album.

Alan

[Michael GilliganParticipant @michaelgilligan61133]

Posted by mark smith 20 on 14/11/2016 16:40:58:

The george thomas ones look nice but are pretty expensive.

.

It's worth having a look at what Hopper is doing … **LINK**

http://www.model-engineer.co.uk/forums/postings.asp?th=113571&p=9

… He's building a fabricated version.

Also worth getting GHT's book [or the original ME articles] … just for the 'Masterclass' … even if you don't work exactly to his design.

MichaelG.

[mark smith 20Participant @marksmith20]

Thor, very nice and simple thanks for the link.

Chris, i`ll have another look at Harolds, it seemed pretty fiddly to adjust but maybe easier if scaled up.

Alan, very nice and simple ,is the spindle just floating in the steel body ?

Michael i do like the GHT design but maybe alot of work and im pretty much a beginner to machining other than basic turning and milling.

I do want the project to be an exercise in machining though ,so i can learn s i go along.

I did a 5 yr sheet metal apprenticeship on leaving school but didnt do much machining as such ,more manipulation of sheet material and welding. Made some very intricate stuff out of sheet metal .Basically most of the stuff in the textbook Geometry of sheet metalwork by A Dickason.Ive now forgot most of what i learned back then.

Lots to think about .

One question i see worms being used with normal change gear wheels in a lot of the designs ,do these mesh properly with a worm gear.

Also is 40:1 the best ratio ,i saw one guy making one using a 360 t wheel it must take forever to turn through 360 degrees. Is a 90:1 ratio theoretically more accurate than a 40: 1 ratio worm wheel/gear combination.

 

Thanks

Edited By mark smith 20 on 14/11/2016 19:25:53

Edited By mark smith 20 on 14/11/2016 19:28:18

Edited By mark smith 20 on 14/11/2016 19:31:10

[Michael GilliganParticipant @michaelgilligan61133]

Mark,

Here's another one [by Tony Jeffree] that might provide some inspiration: **LINK**

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

MichaelG.

[BazyleParticipant @bazyle]

A bit large there is a thing called a Spindex that does 1 degree increments as standard. Over on HSM forum someone did a conversion to add a worm wheel.
Your earlier questions: Not often seen big tailstocks on ebay – you need to look for a 12 in lathe being broken for parts which is less common.

When a worm is used on an 'ordinary' gear the axis of the worm has to be canted over – you will see this in some pictures.

[Anonymous]

Posted by Bazyle on 14/11/2016 20:03:42:

When a worm is used on an 'ordinary' gear the axis of the worm has to be canted over………….

….ideally by the helix angle of the worm at the pitch circle diameter. The contact area between a worm and a spur gear, or helical gear of matching helix angle, is a point, so not ideal.

Andrew

[Michael GilliganParticipant @michaelgilligan61133]

Posted by mark smith 20 on 14/11/2016 19:25:25:

One question i see worms being used with normal change gear wheels in a lot of the designs ,do these mesh properly with a worm gear.

.

Not 'properly' but probably 'adequately for the job' … provided that you angle the worm to match the helix angle of the thread.

MichaelG.

.

[beaten to it]

 

Edited By Michael Gilligan on 14/11/2016 20:59:53

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