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Dividing head question

ronan

Cast Iron
Joined
Feb 14, 2009
Location
ireland
I have a tom senior horizontal milling machine that has a swivelling table making it a universal machine. I want to buy a dividing head for it in the new year when i get some spare cash together. Does anyone (i'm thinking vertex) make a dividing head that i can gear to the table leadscrew making it possible to cut helical gears etc ?

Is this type of work obsolete now (done by other means) or still used ? I don't plan on cutting many gears, putting hex's on bolt heads mainly , but i would like the option to cut gears too.
 
I'm told Tom Senior made their own dividing head. A fairly basic device with open frame and exposed worm-wheel meshing with a two start worm. I've no idea if there was ever a factory kit to connect it to the table feed-screw but I don't recall any reason why it shouldn't be possible. If you want I can see if the ones I saw are still in local hands and verify if they are actually Senior made and if they can be connected up. My involvement came from being asked about 5 years back if I could sort out a worm (and bracket?) for a friends "box of bits" find. About a week after I'd got it all figured out I ran into the same thing in the back of of another friends shop and was told it was a Senior. That worm and bracket never did get made, so far as I know the unit is still sitting un-needed in my friends shop so could probably be got for a modest price if you have facilities to make the worm.

The Senior isn't the largest of machines, most of the usual makes are probably too big to fit easily. Not to mention very heavy. My Edgewick made Cincinatti clone is about as much as I care to fit on my Bridgeport. Elliot, Victoria et al aren't much smaller.

Clive
 
Hardinge made some of their dividing heads with shaft input for spiral milling, They have a 5C collet spindle and 3.5 inch center height, so they are suitable for mills of small to middle size. You could adapt a set of Myford change gears to drive it.

Larry
 
I played around a bit with driving a nice old Garvin head from the lead screw. In my case the head didn't come with a complete set of gears and my mill wasn't really meant for this, so I used lathe change gears for the experiment.

For me, the conclusion was that this was cool for making helix shaped stuff but a PITA in terms of actually making an accurate and smoothly machined helical gear. I don't doubt that a proper setup might still yield excellent gears, along with a somewhat steep learning curve to master all the art. In any case, for someone like myself (who might need make one or two of these gears), sending the work to a pro with CNC gear cutting machines ready to go seemed more practical. I find making something like an index plate, milling octagons, ordinary spur gears, and the like easy. Making a replacement helical gear, not so easy. In fact it's not even especially easy to measure what you've got in worn form to make something better.

You might pick up a copy of Cincinnati's Treatise on Milling (think I got that right, without looking to find my copy), to see what's involved. There are probably scores of people here who've mastered the art -- you'll have to decide if you want to tool up to be among them.
 
I have a Senior Universal horizontal mill with swivelling table similar to yours. I also had the correct Senior dividing head which came with the machine. However, the Senior dividing head is a simple dividing head and does not have the provision to gear it to the table lead screw. I subsequently sold/swapped the Senior dividing head for a Hoffman universal head which has the shaft for input from the mill table lead screw. As an exercise I made the banjo to take the change gears and cut a set of change gears to be able to drive the dividing head from the table lead screw. After all that, I have not yet had a job which requires spiral milling, or similar, though I have used the dividing head the cut numerous gears, heaxgons etc. If you wish to have this facility I would recommend that you look around on E-bay or local machine tool dealers and you should be able to pick up a Hoffman or similar universal dividing head.
 
Thanks to everyone for taking the time to reply to this thread. I have come across a vertex universal dividing head of pretty small dimensions that i reckon would match the size of the tom senior nicely. Any opinion on the vertex brand ? Any of the british or american dividing heads that appear on fleabay seem huge and far too large for my mill.
The ability to cut spirals or helix's seems to be a major feature of the tom senior so i might as well get a proper universal dividing head to suit , even if i only use it once in a blue moon.
 
Careful! The only "Vertex" (the ones made in Taiwan, rebranded multitudinously, nice quality) Universal is the BS-2. All the others are "semi-universal." In other words, the spindle swivels angularly on its base, but there is no provision for attaching gearing to allow milling a spiral. This small wording difference (which is actually very big in terms of functionality!) is often mis-quoted by resellers. The BS-2 is a direct copy of a Brown & Sharpe head; and it is BIG. It swings 10" and weighs upwards of 100-130lbs.

The Hardinge is probably the smallest made commercially that has provisions for gearing to the table. It is a very different animal, though, in terms of ratio. If I recall correctly it is 1:4. That is roughly ten or more times the ratio of a similar dividing head. Someone else will have to inform you how that affects your setup. The dividing plate holes, number of turns, and connecting gear ratio's will be strange in comparison to the tables found in Machinery's Handbook. Not to mention the Hardinge ones that are truly universal fetch crazy money ($1500+) from what I've seen. Remember there are plain Hardinge's as well which are routinely labelled wrong. Plenty more plain heads than universal heads out there. So be careful.

Believe it or not, there is a Chinese head designated FW-80 (whose mention will probably get me banned here :ill:) that is a true universal, comes with gear quadrant, tailstock, driver, the whole nine yards. It has an 80mm center height... never seen it for sale in the US directly. It is small, but all those parts still add up to "heavy to ship." Costs about a thousand bucks (plus shipping). Wish I could see how bad it is (or not) for curiosity sake... :dopeslap:
 
I have a trio of Hardinges plus an Elgin (just so they don't have to be taken off each machine and swapped around so much :D ) Unfortunately, none of mine have the gear drive input provision.

As noted, the basic Hardinge is 4:1 ratio, and with the stock size plate and stock hole & pin size*, 90 is the max, 1°/ hole (360° in four cranks, to drive the spindle once round). I find it an extremely fast and convenient accessory for routine dividing tasks, especially since it takes all the same internal and external spindle nose tooling as the lathe including chucks, faceplates, 5c collets, and 5c step chucks with external ring closers. The heads have "Zerol" gears and no backlash, so it is easy to go backwards and forwards for dividing.

However, it take more numbers in the plates to get all the division options from 2 - 360; and some divisions such as 125 (needed to engrave dials for 8 pitch leadscrews) are not possible no matter what count you might try to drill in a spare plate. (While a 125 hole ring would do it, I would like to see the solution to doing that practically on the hardinge-size components, or a larger plate without deleteriously modifying the mounting system)

All that said, a Hardinge with the leadscrew driving provision, is 40:1 as far as the gear ratio. The input shaft is 10:1, x the 4:1 from the hand crank shaft that it inputs to by worm drive. The actual dividing possibilities are still governed by the plates on the 4:1 shaft.

*stock hole and pin size (in the dividing plates): I do have one plate that was shop drilled for, IIRC 100 holes at the extreme rim, with a drill that is smaller than the stock pin. Presumably "whoever" used it for a certain purpose with a pin ground to match, when needed.
smt
 
Thank you for the informed details regarding the Hardinge ratio, Stephen. For the OP, for straight dividing tasks, I would encourace you to look at building a Versatile Dividing Head (VDH). It was designed by George H.Thomas and casting sets are available through Martin Model and Pattern in the States and Hemmingway in the UK. I could be wrong here, but I believe Geo.Thomas owned a Tom Senior milling machine and sized it to be a proportionate fit to both that and his Myford.

Anyway... The beauty of it is he incorporated a compounding angular dividing ability. The VDH can do all the practical prime numbers---that is, all divisions up to a very high count. That feature is not highlighted in the casting supplier listings very well. I only understood that function truly after reading the book by Geo.Thomas outlining its construction. So, in other words, it provides a solution to Stephen's issue with all inclusive divisions from 2-360.
 
The Versatile Dividing Head (VDH) is a lovely bit of kit and as Arthur.Marks says, it is capable of dividing numbers that are often not easy on other dividing heads using simple dividing via a dividing plate. It is an interesting project that provides a bit of a challenge in construction. However, I don't think this is the right dividing head for the OP because:

The OP want a universal dividing head suitable for spiral milling. The VDH is not a universal dividing head.
The VDH is very small - perfect for mounting on a Myford, but in my opinion too small for the Tom Senior. It is too delicate for serious milling work.

A Hoffman or a Hardinge universal dividing head are good choices.
Dividing heads are one of those bits of kit where the bigger and heavier they are, the cheaper they are (in UK anyway). This is my universal dividing head, which didn't cost much, but needs an engine hoist to get it on the table.
P1000304CC_zps516c0be7.jpg

This is probably too big for the OP, which is a pity because there are quite a few like this around in UK in easy reach for Ireland. They are used less and less in industry, hence prices are not OTT.
 
Thats true billmac, the larger ones are available for very little money. But they must have come out of a railway works or a ship yard , they are huge and too much for my little mill.
 
Thats true billmac, the larger ones are available for very little money. But they must have come out of a railway works or a ship yard , they are huge and too much for my little mill.

Not quite as big as that, but I agree that head is out of proportion for a Tom Senior. The Hardinge universal dividing head is smaller and a better choice for your mill. I had a quick look on UK Ebay a few minutes ago and couldn't find anything that would fit your requirements,. The Vertex BS2 is available from a lot of places but as others have said, it is probably too big. I think you will need to keep looking for a while to find a small universal head.
 
Very true -- I did not mean to confuse the VDH with being a universal dividing head. It is not and was never meant to be.
One last possibility is an Aciera universal dividing head. There is one built for the F3 that is about the overall size of the Hardinge. Quite rare, though, and assuredly expensive if one is found. You can try contacting David Samways at Anglo-Swiss Tools in Ipswich if you are interested. The Aciera one has the integral, esoteric (for most) W20 spindle nose and collet socket. 5C is far easier to tool up.
Hoffman heads always strike me as exquisitely built, but I've never seen one in person. They are far more common in Europe than in the US from my perspective. A used Hoffman is pretty rare here.

Aciera in action:
helices2.jpg

work table is 80 x 200mm size in the above illustration for scale (sorta looks like a Hoffman, doesn't it?)
 
I have a Vertex BS0 rebadged by Myford for use on my light milling machines. Not universal but very useful. Would think it is big enough at 125mm centre height

I saw it going VAT free at a Myford open day a few years ago so I got the plastic out!

Steve
 
The Aciera dividing head would be wonderful, but in buying it you would be competing with the Aceira 'completists' for an attachment that was already expensive. However,the quality will be superb. The photo that Arthur.Marks provides brings up another point worth considering - for a universal dividing head to be useful for spiral milling, you really need the full set of gears, and the gear box (as shown) or at least a banjo. If not you will need to gather a suitable set of gears and make a banjo or two. Not all that difficult, but will take time and some work. Second hand universal dividing heads always seem to lose their gears and other loose parts. Some modification will be needed to get the gears attached to the leadscrew on your Tom Senior. Again, not insuperable, but needs to be done with a bit of care.
 
Not to hijack the thread;

A while back there was another thread regarding universal dividing heads and the OP was warned that some heads are designed to sit on the Right side of the table and others on the Left. It never occurred to me that it would make a difference. Does it?
 
Not unless your specific mill's design dictates it as a problem. If you have handwheels on both sides of the table like a standard Bridgeport---no problem at all. If the mill cannot access the end of the leadscrew for gearing purposes at all on one side---big problem. That said, I cannot think of a mill I know of without some sort of access to both sides. Or why you couldn't just turn the head around to use on the side available. You're not using the dividing plates when spiral milling, so if they are inaccessible who cares?
 








 
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