Author Topic: Dividing head  (Read 77534 times)

Rob.Wilson

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Re: Dividing head
« Reply #25 on: September 29, 2013, 04:55:03 AM »
 :clap: :clap: :clap: The dividing head is looking great  Matthew , nice job doing the castings  :thumbup:





Rob

Offline mattinker

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Re: Dividing head
« Reply #26 on: September 29, 2013, 06:58:00 AM »
Thanks Rob!

Would you elaborate a bit of this split cotter design consideration? I'm familiar. with the design and have this same book and read some further info, but haven't used this method yet. Therefore I'm interested to hear reasoning about the material choices you made.

Pekka
Pekka,

my variation on the cotter is based on an article in the Model Engineer  29th of December 1965, written by Duplex, "Machining spindle locking devices". I don't know if I can provide this information to the group, for copyright reasons, (Moderator, what's group policy?) but I'm sure I can send it to you personally if you want it.

I am going to show more about the split cotter soon, but, I am making a split cotter, the locking device show in the book is a single piece cotter which locks from one side. First of all, I'm boring with the cotter in place, when finished, the cotter is cut in half, providing a sleeve at the top and a threaded part at the bottom. I pre-drilled the cotter 5mm, taping the bottom M6 and drilling the top to 6mm, clearance, M6, when screwed together the two halves pinch the shaft instead of pinching from one side, doubling the clamping surface.

In this particular case, I used cold rolled for the cotter. I have previously use brass in steel, but I was afraid that Brass in Al might give electrolytic problems. Sneak preview, I was also afraid that the steel would deviate the bore when drilling the "mixture" of metals, last drill, 25mm showed no sign of deviation, I don't think the boring bar will give problems.

I'll be back soon with more photos, regards, Matthew
[

Offline PekkaNF

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Re: Dividing head
« Reply #27 on: September 29, 2013, 03:29:18 PM »
Thank you. It's chrystal clear now. I paged GHT "The Model Engineers Workshop Manual" page 22 description of split cotter. It's rather different.

I think I read somewhere comparison of these two different locking mechanisms, but really can't remember right away.

Pekka

Offline mattinker

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The Dividing, modifications for the Emco Compact 8
« Reply #28 on: September 30, 2013, 03:01:33 AM »
Hi,

At this point, I'm about to make modifications to suit the Emco Compact eight flange chuck mount and to allow the use of the three different change gear sets that I have.



Instead of a threaded chuck mount, the Emco has an odd size DIN cone three bolt mount.



The flange is 80mm in diameter, as I don't have a lump of anything usable of that diameter, I cut a piece of 20mm hot rolled square and then chopped the corners .



Setting up in the four jaw on the Colchester.



After centre drilling, step drilling.



final hole size, 25mm.



45°chamfering for weld





I had a suitable length of cold rolled 30mm which I clocked in on the four-jaw on the Colchester. (the bore in the Emco won't take 30mm) I centre drilled both ends and one end I step drilled out to 12mm, tapping size for M14. The last 20mm were left at 12mm and the first 30mm were drilled out to 14mm, clearance for M14 thread. This is the beginning of the interchangeable gear mounting, easier to do before welding on the flange.



Reducing the Cold Rolled to 25mm Ĝ over 20mm.



45° chamfer for weld.



Assembled ready to weld.



Welded on one side. I was a touch wide and there was a piece of splatter in the centre bore.



Welded the other side.



De-stressing, the rectangular objects in there are pieces of cold rolled for another project.



So, while the shaft cooled, I set up the casting on the cross slide of the Emco, everything lined up nicely using the alignment pins.



The cold rolled for the cotter was locked into place with a hold down. Centre drilled.


The smallest bit I have that was long enough  is 8mm, and only long enough held at the very end of the shank.



Step drilling, this is the first time I used this bit that I bought for next to nothing ten years ago!



22mm



Finally, 25mm which as you can see only just made it. At 25mm the cotter was beginning to be cut. I hadn't drilled a mixture of steel an Al before and I was afraid of deflection, but there wasn't any that I could find.



I forgot to take pictures of setting up the shaft in the four jaw before turning the flange round and re drilling the centre which had been partly filled with weld!



Machining the inside weld I left a 45° fillet that will be covered by a spacer.



Cleaning up the other end. I have a consistent 29.94mm over the full length of the shaft. Now I can finish boring the casting.

To be continued, regards, Matthew

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Re: Dividing head
« Reply #29 on: September 30, 2013, 08:56:37 AM »
Great sequence mattinker! I really appreciate the photos and seeing how you work. Thank you!  :clap:
I love it when a Plan B comes together!
Steve
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Offline mattinker

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Re: Dividing head
« Reply #30 on: September 30, 2013, 02:05:10 PM »
Thanks VT,

I was wondering whether I was putting too many photos in! It's hard to judge when there aren't many replies!

OK, a general question, too many photos?

Regards, Matthew

Offline porker

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Re: Dividing head
« Reply #31 on: September 30, 2013, 02:58:31 PM »
Nope. Love the pictures and enjoying watching the build.

Offline doubleboost

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Re: Dividing head
« Reply #32 on: September 30, 2013, 03:11:01 PM »
The more pictures the better
Clever machining the lock with the bore
Very nice welds as well :drool: :drool: :drool: :drool: :drool: :drool: :drool:
John

Offline mattinker

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Re: Dividing head
« Reply #33 on: September 30, 2013, 04:32:00 PM »
Thanks Porker and John,

OK you asked for it, I won't hold back on the pictures!

John, more on the bore and the split cotter in the next episode!

Regards, Matthew

Offline krv3000

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Re: Dividing head
« Reply #34 on: September 30, 2013, 05:00:35 PM »
brill work once you have made that one you may as well mack me on as my lathe is the same as the one you have

Offline dsquire

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Re: Dividing head
« Reply #35 on: September 30, 2013, 07:30:17 PM »
Thanks VT,

I was wondering whether I was putting too many photos in! It's hard to judge when there aren't many replies!

OK, a general question, too many photos?

Regards, Matthew

Matthew

Keep putting pictures in the way that you feel describes the project. Your photo size is excellent and easy for all to view.  :thumbup:

There are a lot of people watching even though they haven't made a post to tell you. So far it has been seen by 1710 people. In my opinion you are doing an excellent job :D :D

Cheers  :beer:

Don

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Never let it rest,
'til your good is better,
and your better best

Offline mattinker

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Re: Dividing head
« Reply #36 on: October 01, 2013, 01:52:34 AM »
 :nrocks:
brill work once you have made that one you may as well mack me on as my lathe is the same as the one you have

Thanks for the "brill work" krv3000! It's not finished yet! No counting chickens!

Regards, Matthew

Offline mattinker

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Re: Dividing head
« Reply #37 on: October 01, 2013, 02:05:31 AM »
Matthew

Keep putting pictures in the way that you feel describes the project. Your photo size is excellent and easy for all to view.  :thumbup:

There are a lot of people watching even though they haven't made a post to tell you. So far it has been seen by 1710 people. In my opinion you are doing an excellent job :D :D

Cheers  :beer:

Don

Don,

I looked at the hits when I made a previous post that no one replied to! 200 odd hits in 24hours, so I thought "people are looking" maybe we'll hear something later. I know that I don't always reply to things that interest me so what can I expect!!

I have my camera set up to 640x480 pixels so editing is quick. I sometimes get the feeling I'm over explaining. I suppose when I don't need to make long comments, I'm saying enough.

Regards, Matthew


Offline SwarfnStuff

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Re: Dividing head
« Reply #38 on: October 01, 2013, 03:35:14 AM »
Well I am one of those who often follow posts but don't often reply. (I try not to unless I can add something to the discussion.) As to there being too many pics or too many words of explanation. They do say, 'A picture is worth a thousand words.' But I find that often the 50 or so words about the picture sure helps me understand the pic more.
John B
Converting good metal into swarf sometimes ending up with something useful. ;-)

Offline Mayhem

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Re: Dividing head
« Reply #39 on: October 01, 2013, 08:23:41 AM »
Nice work Matthew.

In answer to one of your questions: there is no such thing as too many pictures!

Offline mattinker

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Re: Dividing head
« Reply #40 on: October 02, 2013, 03:46:01 AM »
Hello again,



I should call this drawer my kennel, the dogs came with a cabinet that I bought from a machine shop closing down.



I made this boring bar a long time ago, before I had either a mill or a shaper, I haven't used it for about ten years, I had my doubts about it when I dug it out! Well it's too short, so turn a cone on one end to weld a bit on.



Turning a stub extension. I love working between centres.


Ready to weld.



I would not recommend this construction, it chattered at all speeds, I think I last used it with one end in the chuck, but it was so long ago I just can't remember!

To make things clear, I started machining about twelve years ago, I hadn't done any since I was 14 years old, I made a centre punch and a hollow handled big screw driver on the lathe. So my first machine tool was a home made lathe that looked as though it had been made in the 1950s. I bought a shaper as I thought I could learn to make parts for the not very rigid lathe. I started getting the hang of the Elliot M10 shaper which was nice and tight and produced use full bits. Then nine years ago I bought the building I now live and work in, I bought a slice of an industrial building, 12m x 14m 6.25m to the eves with a nearly flat roof. I built my home on a 70 square metre "upstairs" that built. The building work and life have taken up a lot of my time and I'm only just getting back into machining. I've bought machines since I've been here, A 1944 Colchester Master on eBay UK, a H. Ernault SOMUA mill, a Clarkson MKI tool and cutter grinder (the only tooling were a pair of centres) a Denbigh piller drill (a camel back of 1960s construction) and relatively recently an Emco 8 x 18 Compact 8 brand new (1989, still had the protective gunk on it) but missing the motor and drive pulley. I've been working in metals most of my life, ten years as a mechanic, steel construction, building, trained as an electrician, the list is long. Anyway, this is why I have tools that I've built but can't remember much about them! I have only had thread cutting capacity a few months!

So it's time to build a real boring bar 40cm 25mm hot rolled was cut off and centred and centre drilled on both ends in the four jaw on the Colchester.



I milled a flat in the middle.




Centre bored it and drilled 6mm.



Using the the 6mm bit I eyeballed it 90° to the first hole to drill a 5mm, m6 tapping size hole.






I didn't get past centre drilling, I forgot to tighten the vices, Ooops, so I drilled it from the other side.



Tapped M6.



I cut the ends of a  suitable broken 6mm Ĝ tap for the bit.



Mounted in the universal vice on the Clarkson Cool & Tutter grinder to grind a flat face that will serve as a reference to grind the tip and orientate the tool in the boring bar.



Grinding one side of the point. I seem to have forgotten to take a pics of centring the point and giving it some front rake.



Grinding the top rake.



So far, I'd bored out to 25mm, I wasn't going to be able to fit a 25mm boring bar in without some drilling. A 27mm to see how it went through the cotter. No apparent deviation and a very nice finish.



All's well, so I thought I'd run a 28mm through to give more room for chip clearance.




First test cut.



In use.



I don't trust my cheepo digital callipers, so I bought myself some bore gauges.



Without trying I hit 28.5mm.





To adjust the boring bar I used this tool that I think is in the Gingery Lathe book.



The feeler gauge is put in the tool and the set screw, once the tightened, you take out the feeler gauges and adjust the tool up to the set screw.

While I was doing the last cut, over confident, I wrote down the figures, calculated a it less than half the diameter I wanted, remounted the bar and didn't do a test in the bore, over confident, I bored away until a little before the cotter, took out the bar to make sure there was no chip build up before cutting the steel, measured, oversize! ****! Reset the bar, took a small cut, remeasured, another cut, and the last third was perfect! I still don't see how I did it, The only thing I can think of is I absent-mindedly set it twice. I can always make a sleeve so it'll be OK.



I didn't have a Morse 3 fly cutter, so I threw together a quick one, A piece of cold rolled brazed to a broken milling cutter shank, a grub screw and the tool from the boring bar.



The first cut revealed that when I set up the casting on the boring table I didn't put it far enough back so it misses the the front bottom corner of the casting. I decided that as it wasn't critical I'd just file that off rather than move the part.



Here it is spindle in place, I'll do some more work on the spindle before I sleeve out my mistake!

Cheers, Matthew


Offline hanermo

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Re: Dividing head
« Reply #41 on: October 02, 2013, 04:23:44 AM »
Lovely.
Well done.

I really enjoy it, here from Barcelona.
.hannu (hanermo)

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Re: Dividing head
« Reply #42 on: October 02, 2013, 12:33:42 PM »
That surely is a Gingery boring bar gauge! I used the same to set the bar for my tailstock and headstock bores. It works very well.  :thumbup:

Besides a measurement mistake, sometimes when boring aluminum castings you can pick up a bit of aluminum swarf, friction welded to the tip of your cutter, and it will enlarge the bore -- the same way it happens on a regular lathe tool. I don't know if this happened in your case. Coolant helps prevent this, but I've learned the hard way that It's best to sneak up on the final bore in home cast aluminum by stages and measurements.

Thanks so much again for all the pics, and for openly talking about mistakes -- we all make them, and it helps to see how to fix them, and also reminds us to check carefully when doing similar operations.  :thumbup: :clap:
I love it when a Plan B comes together!
Steve
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Offline mattinker

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Re: Dividing head
« Reply #43 on: October 02, 2013, 04:01:55 PM »
Thanks Hanno!

Vt, I'm pretty sure that it's a short circuit between the ears! I kept the bore pretty full of WD40. The noise didn't change and the surface finish was extremely good, a chip stuck on the tool would have left scores in the bore. I can sleeve the bore and I won't have lost anything.

Thanks for confirming it is a Gingery gauge, it's a nice simple idea.

This an interesting learning process, taking the photos and writing up the build is a good way of seeing what I've done and how to go forward from here.

Thank you both for your replies! Regards, Matthew

Offline doubleboost

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Re: Dividing head
« Reply #44 on: October 02, 2013, 04:15:48 PM »
Hi
Shame about that like you say a slive will sort it
That is why I bored mine first then did the mandrell
Coming along very nicely
John

Offline mattinker

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Re: Dividing head
« Reply #45 on: October 02, 2013, 04:22:54 PM »
Thanks John,

at least, of all the things that could have gone wrong, that's the easiest thing to correct. I just have to make sure that I never go without checking, measuring the cut when so close to the end! Over confident!

regards, Matthew

Offline Chuck in E. TN

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Re: Dividing head
« Reply #46 on: October 02, 2013, 06:17:46 PM »
Mathew, Don't give up! You're doing great. I'm watching your build closely as I hope to make the same DH. Bought the book, followed John's build and following yours. I'm still at the point of building my foundry to make the casting, so am way behind you and John.
Chuck
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Offline mattinker

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Re: Dividing head
« Reply #47 on: October 03, 2013, 12:01:29 AM »
Chuck,

thanks for the encouragement, I never even thought about giving up!

Regards, Matthew

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Re: Dividing head
« Reply #48 on: October 03, 2013, 08:54:36 AM »
Matt, just a point of interest about the Gingery boring bar gauge in case anyone reading wants to make one -- I was just looking again at your picture and noticed that you are using the head of a bolt for contact with the feeler and cutter. I think the original used the other end of the bolt, rounded slightly to give a distinct contact point for the feeler gauge and cutter for highest accuracy.

However that assumed a square cutter, as shown in the Gingery lathe book, which couldn't rotate in the square hole filed into the boring bar. With a round cutter in a round hole which might rotate slightly during adjustment, I guess you need a flat end for the gauge anvil.

If so, It might help to keep the flat as small as possible, though -- it doesn't have to be a greater diameter than the cutter is. It would probably be helpful to machine that flat to make sure it absolutely square and smooth with the bolt axis. Bolts on this side of the pond have raised letters and grade symbols formed on the top of the head, and you'd want that off, and the surface to be really true as well, since you rotate it to make an adjustment. Half a thou difference side to side in the bolt head could mean half a thou difference in depth of cut.
I love it when a Plan B comes together!
Steve
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Offline PekkaNF

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Re: Dividing head
« Reply #49 on: October 03, 2013, 02:18:15 PM »
How about flat/domed point set screw for adjustement screw?

PekkaNF