Eureka Tool

[Donald MayesParticipant @donaldmayes16231]

I would like to know if anyone knows when the Eureka tool plans were

published in Model Engineer mouth & year. I have the book Gears & gear cutting by Ivan Law and on page # 125 it shows the large eccentric to be .168

off center and i don't see how that could be enough.

I though that if the Model Engineer that had the plans in it was still available

may be order it and see if there is a different spec.for the large eccentric.

Thanks Don

[Donald MayesParticipant @donaldmayes16231]

[JasonBModerator @jasonb]

It was in several issues, put Eureka in this index search and it will list the mags

[Brian WoodParticipant @brianwood45127]

Hello Don,

The article was published in 2 parts Volume 158 # 3794 6 february 1987 and # 3796 6 March 1987.

The plans were given the number WE88

I recommend a few improvements;

1. Make a holder for a 4 jaw chuck to grip a boss for turning the eccentrics on the mandrel, a much more satisfactory way of holding things for intermittent cutting than between centres using a catch plate and drive dog. It also makes offsetting for the throws so much easier. Drive the whole thing from that boss when in use for gear cutter making.

2. Fit brass bearing surfaces to both the anchor plate bore and those of the indexing sleeve, furthermore lubricate with EP80 gear oil [don't ask!]

3. Harden the pawls and fit each one with its own individual eccentric mounting, setting up the timing later is a lot easier

4. Notch the indexing teeth on the sleeve to help hold the indexing pawl engaged when operating, it tends to jump out on notches cut as shown.

Those were the main improvements I found helpful. I attempted to make standard size gear cutters using the device, but sadly it wasn't up to that duty and eventually found another way but I imagine it would work for the size of cutter [1.25 inch diameter] Ivan Law built it for.

I hope that experience helps you.

Regards Brian

 

Edited By Brian Wood on 05/05/2014 09:35:32

Edited By Brian Wood on 05/05/2014 09:36:37

[davebParticipant @daveb17630]

Plans are in Ivan Laws book, Gears and Gearcutting, Workshop practice 17.

Sorry, you already know this.

Edited By daveb on 05/05/2014 09:41:25

[John Stevenson 1Participant @johnstevenson1]

Donald,

Can't answer you question on the 0.168 measurement but never seen a query before and it's only enough to put back relief on. Any greater and you will have a conflict in how soon you get retract from the relief move and get back to the cutting edge.

Brian raised some good points.

I built one some years ago scaled up by 2 to make full size cutters which it has done many, ironically no actual gear cutters but many special profile cutters. Because I was paid to make mine I used 1/2" gauge plate and had it all hardened afterwards professionally.

Without dragging it out of it's custom made felt lined box [ perks of working at a piano company ] to look I made the boss end eccentric as well so I could just pop it into a 3 jaw chuck to relieve a cutter.

A very unusual feature of this design is that it works correctly no matter which way you drive it. Sound like Brian had some problems like me getting the pawls correct so it didn't miss teeth but I found that running backwards cured all this and it never misses a tooth going backwards.

Very very hard to explain, as is how these work, you have to see one in action to appreciate it.

**LINK**

Not a good clip but you see how it does back off.

[Neil WyattModerator @neilwyatt]

One day I will make one of these!

Neil

[John Stevenson 1Participant @johnstevenson1]

They are a right of passage attachment. A bit like a quorn without the ball handles.

Main difference is there are not so many un-started or un-finished kits under the bench.

[Brian WoodParticipant @brianwood45127]

Hello Donald,

John's comments remind me that I made the same observation, the thing runs happliy when driven backwards, a curious effect.

I think my trouble was due to amateur hardening, I folded up one pawl, and seized the running surfaces of the anchor plate which stopped it dead and tore up the drive boss by overcoming the grip in a 3 jaw chuck. That was the story behind fitting brass running surfaces and the use of gear oil with the extreme pressure additives it contains.

My alternative method worked for me, I estimated torque loadings of about 30 foot pounds on the drive when shaping the flanks of the embryo cutter [the maximum loading condition] which was then all manual, it regularly bent a 5/16 inch tommy bar. Some day I may put pen to paper toi record it all.

Regards Brian.

[BazyleParticipant @bazyle]

Unable to run John's video on my corporate computer but found a youtube video.
Could do with a better view and slow motion capability.

Hasn't there been an alternative design recently with gears instead of the eccentric that enables different numbers of teeth to be worked.

[Neil WyattModerator @neilwyatt]

I haven't made one of these, but I have made other cutters. The described drill and double saw method of making the teeth in the blanks is very involved. A much easier way is simply to index the cutter around and run a suitable size end mill in to make each gullet. simples!

Neil

[Roderick JenkinsParticipant @roderickjenkins93242]

Here's some more video:

Don, I've sent you a personal message.

Cheers,

Rod

 

Edited By Roderick Jenkins on 06/05/2014 20:13:47

[BazyleParticipant @bazyle]

thanks, Rod. nice detail will be a great help for anyone making one

[BazyleParticipant @bazyle]

I mentioned a geared version of a relief tool earlier. I have now found the article in issue 57 of MEW "Gear hobbing in home workshop" by Dr Parkes. It possibly started in issue 56 but I can't find that one at the moment. I was looking for something different of course – very distracting thumbing through back issues on a wet Saturday.

[IanTParticipant @iant]

That's a really nice video Rod.

I've previously read the Eureka article and looked at the drawings but a (moving) picture is certainly worth a good deal more than thousand words in this case!

Thank you & regards,

IanT

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