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Quetico Bob
05-22-2008, 03:40 PM
Need some advice on what to look for in a used universal dividing head. The fellow I purchased my mill from about a year ago offered it to me at the time time for additional cost, wasn't in the budget at the time nor did I really look at it.

Called a few weeks ago and am going to the city tomorrow, would like to check it out.

To be honest I don't know what I am looking at or how to judge the condition or what it should come with. And unfortunately I can't tell you what make it is. He dosn't know either as i asked when I last talked to him, he did tell me there was plates with holes in them, a chuck and a few other things??. All I can tell you is that it was awful big and heavy looking, which I guess describes most pieces of equipment.

Don't get to town very often (200km drive one way) (thats metric) maybe once a month or two but would like to pick it up if its in reasonable condition.

Cheers, Bob

Alistair Hosie
05-22-2008, 03:43 PM
you must make sure it's not too big for your milling machine and is there a tailstock etc don't rush it you might end up with something of no use to you .Alistair

Quetico Bob
05-22-2008, 04:01 PM
How does one know if its too big? If memory serves correct I believe the pivot point to be 8" to 10" diameter. What is the tail stock? Similar to a lathe?
Have an older bridgeport mill.
Cheers, Bob

pcarpenter
05-22-2008, 04:08 PM
The tailstock is for holding work between centers. Given your interests, this is something you might use if (for example) you wanted to flute rifle barrels.

A lot of these heads are fairly large, eating up work envelope. A typical bridgeport table is flexible out at the ends that are unsupported, so having to have a 200# head sitting out at one end might be a recipie for deflection. Even a fairly small one can be a bit heavy and rigidity is nice, but the really big ones are real gut-busters.

Me--I am still shopping. I want a smaller one so I can use it on several of my machines...maybe even my 12" Sheldon shaper. I still have this vision of being able to cut a gear with a form tool ground from a $5 HSS blank. I don't have any project in mind with that...just that it might be useful some day.

Paul

wschoenbeck
05-22-2008, 04:26 PM
I have an Ellis dividing head that is 6 1/2" swing. According to the brochure I got on the net it weighs 80 pounds. Mine has a 3 jaw set true chuck on it that feels like it must weigh as much. :eek: It does fit on the table (6"x24") of my Clausing 8520 mill just right. I only have one plate for it though and only one set of jaws for the chuck. No tail stock either but it would be easy to build one. Looks like this.

http://i20.photobucket.com/albums/b222/bill8410vna/Shop%20Shots/ellisonclausing.jpg

Malc-Y
05-22-2008, 05:06 PM
I have a 10" swing (5" centre height) Elliott universal dividing head that I use on my Bridgeport, it has a tailstock and a full set of change gears for differential indexing and spiral milling. It is very, very heavy and I have to use a half ton chain hoist to lift it on and off the mill table. The Bridgeport seems to be quite capable of taking the weight and I have used it with success to cut gears.

Malc. :cool:

Quetico Bob
05-22-2008, 05:18 PM
Know what you mean by gut buster, the mill came with a 6" Kurt with rotating table. Constantly moving it between mill and drill press. Found out recently this is a pretty good quality vise. Maybe the head is of the same?

From what i remember the body is not cast like that, it looked more like one machined part fitting into another. When i saw it the chuck was not on it nor did i see it. Hard to judge the scale of size but think it's a fair bit bigger.

Also need to know if I should be checking for wear in certain areas if this is a concern.

I will find a picture of my mill, its a 9 x 40 something, havn't thought about the bed size since I it got home. Has always been big enough so far.

Cheers,Bob

Quetico Bob
05-22-2008, 05:19 PM
How many gears is there Malc?

Malc-Y
05-22-2008, 05:47 PM
How many gears is there Malc?

There are 10 gears as follows: 24, 28, 32, 40, 48, 56, 64, 72, 86, and 100 teeth, they are 14 DP, not sure of the pressure angle but machine tool gears usually are 14 1/2 degrees (at least they are in the UK).

Malc. :cool:

Quetico Bob
05-22-2008, 05:52 PM
In everyones opinion, what would be the maximum size dividing head suitable for this machine? Couln't find any recent pictures, just started tearing it apart here to give it the once over.
Cheers, Bob

http://i303.photobucket.com/albums/nn142/Queticobob/BridgeportMill.jpg

Herm Williams
05-22-2008, 09:19 PM
It should run smoothly in both directions, have the fingers for hole spacing, three plates, the most common #2 with 23,24,27,29,31,33 #1-15,17,18,19,20,21 #3-37,39,41,43,47,49 that is the circle numbers for my index head, I have the tail stock and chuck, 40 to one ratio, K&T about 75#, five inch capacity. Also there should be someway to adjust for backlash.
re

Greg Menke
05-22-2008, 10:05 PM
Sorry the pic crops a bit, but this is my 6" Yuasa/News head (I think its a B&S clone from way back in the day). Its a good size for a regular sized Bridgeport- when set to vertical theres still a bit of envelope for drilling (but not much- bigger drills need to go into collets). Chuck on mine is a 5" or so Buck.

As far as condition, try to ensure you have plates- they can be a nuisance to track down. I had to convert a plate from a different head- bushing for the center hole, plug the existing screw holes and drill new ones in the right place. Annoying but simple enough.

I guess checking mechanical condition is obvious enough. Backlash and engagement are adjustable on mine- quite handy.

Ensure there is a means to lock the spindle- which is how you'll prevent backlash from letting your work flop back & forth under the cut, starting the chuck loosening on the spindle. Don't ask... But speaking of which, if you really need to lock up the work, put a length of threaded rod through the spindle bore (long studs from a Brigeport holddown set, for example), then a nut on each end, compressing the chuck against the spindle so it can't unscrew. Don't ask...

Also ensure you have or can easily get tooling for the spindle- chuck would be nice, collets if possible, etc. A tailstock would be nice but lacking one shouldn't be a deal-breaker if the other stuff is there.

Consider an extensive disassembly and cleaning, mine was full of old grease that had hardened to something like epoxy.

http://pounceatron.dreamhosters.com/shop/dividing-head/dividing-head.jpeg

Regards,

Greg

J Tiers
05-23-2008, 12:08 AM
Size...........

If you can't tilt it up as shown, you will want to have a rotary table as well.....

For regular stuff, like gear making, with it in horizontal mode, you need daylight of AT LEAST 2x center height, PLUS the total height of spindle tooling (cutter, etc) from table to spindle.

If you can work from the side, you can cut that down some, but then you need a lot of travel on the cross-slide.

To tilt it up, for minimum daylight you need to add the total height, plus the height of workholder (chuck, etc), plus work, plus spindle tooling.

It gets to be a lot, at the end of which it would be far more solid to have a rotary table.

Malc-Y
05-23-2008, 05:30 AM
In everyones opinion, what would be the maximum size dividing head suitable for this machine? Couln't find any recent pictures, just started tearing it apart here to give it the once over.
Cheers, Bob

http://i303.photobucket.com/albums/nn142/Queticobob/BridgeportMill.jpg

My Bridgeport is the same size as yours with a 42" x 9" table and I have found that the 10" swing Elliott dividing head is the optimum size, any bigger would be too big!

The Elliott comes with two division plates with holes as follows:-

Plate No.1:- 15, 18, 20, 23, 27, 31, 37, 41 and 47.

Plate No.2:- 16, 17, 19, 21, 29, 33, 39, 43 and 49.

The worm ratio is 40 to 1.

Malc. :cool:

Quetico Bob
05-23-2008, 08:21 AM
Thank you all very much, will let you know how I made out.
Cheers, Bob

Quetico Bob
05-25-2008, 08:25 AM
Passed up on the deal. No gears, only one plate, no handle and the end of the tailstock beaten up pretty bad. Couldn't find a name on it as it had been recently painted fluorescent green.:eek: Thanks again for the pointers folks.
Cheers, Bob

pcarpenter
05-25-2008, 01:29 PM
YOu are going to find that most dividing heads are not universal and as such do not use gears. The gear drive is off the x feed screw for the table of a mill and as such you were generally talking about a dividing head made by the same maker as the mill. The "works" had to be there to drive the head. The premise of these gears was to allow you to cut spirals...something that could be handy, but which is not that common.

Plates, on the other hand, are typically used to establish fixed index units. I have heard that there are a few that only used maybe one or two plates for the most common index numbers as they were pretty dense (Cincinnati comes to mind). Yet another Cincinnati dividing head used none as I recall....it had some sliding (rotating) scale deal that actually allowed for some totally outlandish number of possible divisions.

I was just giving you that as background in case you were interested in finding another one some day. Still, it sounds like you made the right decision in this case.

Paul

Quetico Bob
05-25-2008, 03:22 PM
Thanks Paul,
Not sure if this was set up to use gears or not, but spiral cut is something I want to try someday, like what you would see on the bolt of a benchrest action.

This head was very similar to the one Greg added a picture of although it did not have the index plate below the chuck, just a hubbed bolt flange. It did have a plate on the horizontal shaft with a G-zillion holes in it. The opposite side of this shaft had what looked to be a female MT4 as well as a fixed shaft 5/8" dia. (best guess) with a retainer bolt in the end which was positioned part way down the base. It also had a rotary base which the whole affair sat on.

Certainly want to find one, right now the only way I can make a radial bolt pattern is to plot 1:1 and use a centre punch, then off to the drill press. Starting to get into designing and building stuff like this and there's got to be a better way not to mention having a little accuracy behind it. Designed this one for 48VDC, worked OK but wanted more production. Tried 120VAC through a bridge rectifier, that's when things went bad. Very very bad.
Cheers, Bob

http://i303.photobucket.com/albums/nn142/Queticobob/DSC_0052.jpg

Malc-Y
05-26-2008, 06:27 AM
YOu are going to find that most dividing heads are not universal and as such do not use gears. The gear drive is off the x feed screw for the table of a mill and as such you were generally talking about a dividing head made by the same maker as the mill. The "works" had to be there to drive the head. The premise of these gears was to allow you to cut spirals...something that could be handy, but which is not that common.

Plates, on the other hand, are typically used to establish fixed index units. I have heard that there are a few that only used maybe one or two plates for the most common index numbers as they were pretty dense (Cincinnati comes to mind). Yet another Cincinnati dividing head used none as I recall....it had some sliding (rotating) scale deal that actually allowed for some totally outlandish number of possible divisions.

I was just giving you that as background in case you were interested in finding another one some day. Still, it sounds like you made the right decision in this case.

Paul

Gears are not only used for spiral milling with a drive from the table lead screw, they are also used for differential indexing to obtain divisions not available using the standard hole plates. My Elliott instruction manual gives the gear trains for up to 382 divisions and there are probably a lot more if you care to do the necessary calculations.

Obviously the Elliott dividing head is designed to be used with Elliott milling machines having a 1/4" pitch lead screw for the table. As I use mine on a Bridgeport I would have to make an adaptor to replace the left hand table ball handle with a gear. I am not sure what the pitch of the Bridgeport table lead screw is without going out to the workshop to check it, but if it is other than 1/4" pitch then a fresh set of tables will need to be calculated to use the dividing head for spiral milling, cam milling etc.

Does anyone know what the pitch of the Bridgeport table leadscrew is?

Malc. :cool:

fasto
05-26-2008, 10:57 AM
Bridgeport table leadscrew is 0.200/rev.

Interestingly enough, my B&S horizontal has 0.250 lead on the table "x" screw, which is where the dividing head goes when doing spiral milling. I wonder if there is some magic about 0.250 lead that makes the geartrain calculations easier? :confused:

aboard_epsilon
05-26-2008, 12:25 PM
In everyones opinion, what would be the maximum size dividing head suitable for this machine? Couln't find any recent pictures, just started tearing it apart here to give it the once over.
Cheers, Bob

http://i303.photobucket.com/albums/nn142/Queticobob/BridgeportMill.jpg

Think I'll put a welsh flag on mine ...and call it a Pontporth :D

all the best.mark

oldtiffie
05-26-2008, 12:39 PM
For a good read and a bad head-ache, read "Machinery's Handbook" items" "Helical milling", "Milling Machine Indexing"; "Indexing" and "Helical Gearing".

Frankly, its too easy to make a mistake and better left to CNC.