Author Topic: Eureka form relief tool  (Read 46846 times)

Offline raynerd

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Eureka form relief tool
« on: December 17, 2012, 05:46:59 PM »
A month or so ago now I put out an ad on homeworkshop for a eureka tool and managed to pick one up. Little more to be said about the purchase other than I was a little disappointed, the parts were poorly made and the device didn`t actually work!  :Doh:

Ahh well, a lot of time has been put into correcting this and also a lot of support from a fellow madmodder in helping me get this up and running. Its seems to be working OK now. Sadly there was no eccentricity built into the gear blank arbour and so it didn`t actually turn off centre! Also the ratchet clicks were incorrectly positioned and one was the incorrect size so it didn`t count the ratchet wheel properly. Finally the ratchet wheel had been hand cut and although actually I expect this would have been OK, I have used my divider and fly cut the wheel true and even. I`m pretty sure it is now running OK. The original plans allow the eureka to be held in the tailstock with an offset (to maintain concentricity) hole in the tailstock. I might be able to turn the end down and re-spot this but for now, you can see the end spot also turn eccentrically so it can`t be supported. I`m hoping that holding the Eureka in the three jaw will be good enough support it anyway.

The proof of this is in the successful cutting of a wheel cutting blank but I just wanted to post this up as I just think the concept is incredible! Whoever came up with this just thinks on a different level!



Offline mattinker

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Re: Eureka form relief tool
« Reply #1 on: December 18, 2012, 05:40:09 AM »
Chris,

Thanks for showing this amazing device.

I didn't understand how it worked without seeing a hob in it, a little web search and I found on HSMM a thread by Charles Lessig including a video of a hob being made.

 The thread,http://bbs.homeshopmachinist.net/threads/30041-Eureka-style-gear-hob-reliever-video

The video


Regards, Matthew

Offline raynerd

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Re: Eureka form relief tool
« Reply #2 on: December 18, 2012, 08:05:39 AM »
Hi Matt
Yes, I`ve seen Charles Lessig video - he has made some adaptations to the original plans to allow the relief of hobs. I`m hoping to just use this for single point cutters.

I hope it actually works when I give it a go in the next few days!
Chris

Rob.Wilson

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Re: Eureka form relief tool
« Reply #3 on: December 18, 2012, 04:22:10 PM »


 I just wanted to post this up as I just think the concept is incredible! Whoever came up with this just thinks on a different level!



Hi Chris

I think it was original designed (the type you have) by a Mr Blazer from the USA around 1900 .
 

It is a dam clever design , I built one too  :dremel:


Rob

Offline AdeV

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Re: Eureka form relief tool
« Reply #4 on: December 18, 2012, 04:48:36 PM »
Pardon my ignorance, and possibly stupidity; but what's the purpose of the tool; or, to put it another way, what, other than making a wiggly-shaped cut on a piece of metal, what does it do?
Cheers!
Ade.
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Rob.Wilson

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Re: Eureka form relief tool
« Reply #5 on: December 18, 2012, 04:54:18 PM »
Well I am not telling you  :lol: :lol: :lol: :lol:


Rob

Offline awemawson

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Re: Eureka form relief tool
« Reply #6 on: December 18, 2012, 05:32:54 PM »
Pardon my ignorance, and possibly stupidity; but what's the purpose of the tool; or, to put it another way, what, other than making a wiggly-shaped cut on a piece of metal, what does it do?

Let Google be your friend :)
Andrew Mawson
East Sussex

Offline raynerd

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Re: Eureka form relief tool
« Reply #7 on: December 18, 2012, 08:02:34 PM »
Rob - wow! I didn`t know it was shown in books prior to Ivan Laws book. Thanks for posting the book page. I see the top of the page says: Machine Shop Chat - is that the book title, I`d be interested in reading more?
Rob, do you find yours works OK and can you see any issue I may have running mine from the 3 jaw rather than turning between centres. Mine was made with NO eccentricity on the wheel cutting arbour so the damn wheel cutting end turned concentric with the lathe! To correct it, I`d either have to remake the majority of the centre eccentric parts or, the method i used, was to turn up an eccentric sleeve to slip over the end, held in the 3 jaw which puts the eccentric motion on the wheel holding section.


Ade - imagine a 12 tooth multitooth wheel cutter. This could be easily made using the button method or similar, jabbing the correct profile into the outside of a disk of steel and then cutting the gaps to create the teeth. The problem is that there is no relief on the teeth. This tool puts the relief on the teeth. You have to set it correctly so that the eccentric motion is cutting the "back" side of the teeth and forming the relief. I.e you cut away the yellow on the image below:


 

Offline awemawson

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Re: Eureka form relief tool
« Reply #8 on: December 19, 2012, 03:29:27 AM »
Mine was made with NO eccentricity on the wheel cutting arbour so the damn wheel cutting end turned concentric with the lathe! To correct it, I`d either have to remake the majority of the centre eccentric parts or, the method i used, was to turn up an eccentric sleeve to slip over the end, held in the 3 jaw which puts the eccentric motion on the wheel holding section.



Is it not supposed to be mounted in a four jaw chuck, so that the 'throw' of the eccentric is adjustable not fixed ?
Andrew Mawson
East Sussex

Offline John Stevenson

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Re: Eureka form relief tool
« Reply #9 on: December 19, 2012, 04:00:32 AM »
No the body which holds the eccentric runs true so 3 jaw, the eccentric part has an off set center in the end so although the eccentric runs eccentrically the center runs true so it can be supported.

Intersting thing with these is no matter which way the tool runs the cutter being relieved always runs forward
John Stevenson

Offline raynerd

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Re: Eureka form relief tool
« Reply #10 on: December 19, 2012, 05:04:19 AM »

Intersting thing with these is no matter which way the tool runs the cutter being relieved always runs forward

Yes, noticed that, totally amazing!



Offline AdeV

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Re: Eureka form relief tool
« Reply #11 on: December 19, 2012, 05:38:00 AM »
Thanks Chris, that picture explains perfectly what a dozen websites failed to convey  :thumbup:
Cheers!
Ade.
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Offline hopefuldave

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Re: Eureka form relief tool
« Reply #12 on: December 19, 2012, 12:06:04 PM »
That's a magical device alright... But for the truly pedantic...

 It can only relieve straight-fluted cutters! For spiral (OK, helical) flutes you're into the weird world of geared relieving attachments which work by moving the tool rather than the workpiece - for them as is unaware of such....

 Usually the spindle speed's reduced by an add-on gearbox sat on the ways in front of the headstock, driven by the spindle and with a matching spindle nose on the output side (often 6 or 8 to 1 reduction, call it 1/n);

 A geartrain (with pick-off gears) separate from the QCGB / change-gears rotates (via universal joints and a telescopic shaft) a cam which moves the form-cutting tool into the workpiece, Firm Spring Pressure returns the tool to the rest position;

The topslide (compound) is attached to a slide which is under the control of the cam.

 By varying the gearing driving the cam it's possible to get straight relief of any (practical) number of flutes by choosing integer ratios of cam to (output) spindle speed, if the ratios are non-integer then each relief starts at a slightly (or even very) different position around the workpiece, resulting in a helical relief - and a lot of calculations!

 As the spindle's rotating the workpiece at constant speed it's possible to use the lathe's QCGB to set the pitch (and handedness) of the cutter teeth for making taps etc. (but set at n x desired tpi pitch - the 1/n spindle reduction, remember! For n = 8 cutting a 16 tpi tap would need a setting of 128 tpi on the QCGB - this may explain why toolroom lathes often go to what appear to be daftly-fine thread pitches?).
 The Eureka etc. instead use a follower as in the Lessig video to establish the thread pitch, which works just fine but needs a different follower and thread prototype for every pitch... Some of the finer instrument lathes came with thread followers and sets of prototype threads as very pricey accessories!

 The lathes best suited for these attachments have "double cross-slides" that put the lower slide under control of the cam (or taper attachment when not relieving) and allow the upper slide to be used for in-feed; better yet some of the official manufacturer's attachments have a third slide between cross-slide and topslide so they can cut helically-relieved, tapered cutters and taps! Too clever for me... I've not used one, but have long ago seen 'em in action a few times, attached to older Hendey, Pratt & Whitney and Holbrook toolroom lathes making special taps etc.

 I suspect it'd be possible to home-brew a relieving attachment (assuming you have access to the quadrant gears to pick up the drive or can pick up from the spindle-speed reducing box), but a lot of work for someone much braver than me! A lathe with a taper attachment could be fitted with a cam/ follower assembly in place of the taper guide, perhaps? Of course, in these days of (relatively) inexpensive CNC there's probably an easy way to do it in software :) Sir John would probably know.


Dave H. (the other one, rambling again)
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Offline rotorhead

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Re: Eureka form relief tool
« Reply #13 on: December 19, 2012, 01:26:13 PM »
Hello Lads,

Might I be so bold, as to ask if there is a current set of drawings, or even Ivan Laws publication available among'st the fora, for this contraption.

Chris
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North Lincolnshire.

Rob.Wilson

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Re: Eureka form relief tool
« Reply #14 on: December 19, 2012, 01:55:52 PM »
Rob - wow! I didn`t know it was shown in books prior to Ivan Laws book. Thanks for posting the book page. I see the top of the page says: Machine Shop Chat - is that the book title, I`d be interested in reading more?
Rob, do you find yours works OK and can you see any issue I may have running mine from the 3 jaw rather than turning between centres. Mine was made with NO eccentricity on the wheel cutting arbour so the damn wheel cutting end turned concentric with the lathe! To correct it, I`d either have to remake the majority of the centre eccentric parts or, the method i used, was to turn up an eccentric sleeve to slip over the end, held in the 3 jaw which puts the eccentric motion on the wheel holding section.




Hi Chris


Yes there a few versions of the reliving attachment going back yonks , The book is "Shop Kinks by Robert Grimshaw  1911"  I can scan the pages if you wish ,there are only two covering this, or you may fined the book on line or some company do print on demand (mine is an original copy)  .

Yes my relieving attachment  works well , I did case harden some of the components and add oiling holes .

Here it is made about 20 odd years ago .


Only made about 10 cutters on it ,here are a couple .


IF I were to make another I would   make it double the size  :dremel:


Holding in the three jaw would be fine ,I personally would remake the faulty part Chris  :poke:


Rob


Rob.Wilson

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Re: Eureka form relief tool
« Reply #15 on: December 19, 2012, 02:53:37 PM »
Hello Lads,

Might I be so bold, as to ask if there is a current set of drawings, or even Ivan Laws publication available among'st the fora, for this contraption.

Chris

Here you go http://www.amazon.co.uk/Gears-Gear-Cutting-Workshop-Practice/dp/0852429118


Rob

Offline philf

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Re: Eureka form relief tool
« Reply #16 on: December 19, 2012, 04:11:22 PM »
Rob, Chris,

The Stephen M Balzer attachment is a different beast to the Eureka. It uses gears. It was patented in 1895. You can view the patent application here:

https://patentimages.storage.googleapis.com/pdfs/ec8d3eb4c5ebb85c2ce3/US535127.pdf

In 1906 Charles G Taylor patented another relieving attachment which looks a little more like the Eureka:

https://patentimages.storage.googleapis.com/08/e4/92/3588edcf0129bc/US817885.pdf

I have a book dated 1916 with another variation looking even more like the Eureka but it allows cutters with 9, 12, 18 & 36 teeth to be backed off.



I've attached a pdf of the article including an explanation. It's much easier to understand if you've got one mounted on the lathe in front of you as Craynerd knows.

Rob - what material did you use for your cutters? I'm thinking of using O1 tool steel. (By the way Rob - I've just remembered that I promised you a stereo microscope!)

Phil.
« Last Edit: January 12, 2023, 06:00:19 PM by philf »
Phil Fern
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Offline rotorhead

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Re: Eureka form relief tool
« Reply #17 on: December 19, 2012, 04:26:46 PM »
Hi Rob,

That's great stuff, went straight there and it should be here Friday, with '1 day click'

I'll save those very nice pics of yours too, and later I'll look for that other book you mentioned.

Thanks for that Rob, a scanned page or two would be appreciated, as the more cross referencing of the same principle would help towards stress relieving my brain cells.

Whilst typing this missive I received another posting notice, thanks go to Phil as well.

Chris
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North Lincolnshire.

Rob.Wilson

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Re: Eureka form relief tool
« Reply #18 on: December 19, 2012, 04:29:14 PM »
Hi Phil


Nice patent finds  :thumbup:

 If you have a look at the photo I posted in shows a ratchet and pawl and re reading the text it dose not mention gears on this device .


I used gauge plate to make my cutters .


Rob

Rob.Wilson

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Re: Eureka form relief tool
« Reply #19 on: December 19, 2012, 04:32:02 PM »
No worries Chris  (rotorhead)


I take it your planning on making one ?


Rob

Rob.Wilson

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Re: Eureka form relief tool
« Reply #20 on: December 19, 2012, 04:49:55 PM »
Here you go lads , scan from book attached .


Rob

Offline philf

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Re: Eureka form relief tool
« Reply #21 on: December 19, 2012, 05:14:13 PM »
Here you go lads , scan from book attached .

Rob

Rob,

That description is more comprehensive than the one in my book but seems to describe exactly the same tool.

Phil.
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Offline Simon0362

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Re: Eureka form relief tool
« Reply #22 on: December 19, 2012, 05:34:42 PM »
There was a simplified version published in Model Engineer (according to my hunt, 1987, issue 3794, 3804 and 1988 issue 3820).
I extracted the 2 issues a couple of years ago with the intention of making it - and then moved house which delayed all construction projects and has left the 2 issues 'somewhere'...
Having a CNC mill, it looked like it was crying to be made using that - perhaps in combination with water jet cut blanks - any takers?

Simon

Offline John Stevenson

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Re: Eureka form relief tool
« Reply #23 on: December 19, 2012, 05:40:10 PM »
Made one a few years ago, in fact got paid to make it as we needed it to make some special cutters.
Scaled everything up X 2 so it used 1" bore cutters, made out of bright mild steel plate but everything was Cyanide hardened professionally.

Made loads of cutters but ironically never made a gear cuter on it.
John Stevenson

Offline BillTodd

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Re: Eureka form relief tool
« Reply #24 on: December 19, 2012, 06:06:18 PM »
Presumably, the relieving tool has to have the same profile (or at least a mirrored/ double sided profile - IYSWIM) as the originating threading/forming tool - does it?


Bill
Bill