Gerrit's Eureka Relieving device build

[gerritv]

It is fortuitous that Bjorn posted his build thread recently. I am in process of building a Jan Ridders Glass Cylinder engine and it requires T2.5 timing pulleys. I am not fond of spending money (it is a hereditary thing I think) so I intend to make my own pulleys. Originally I was going to use the fly cutter technique but with the tiny tip size I am concerned that the tool will not last cutting 3 pulleys.

So, I need to make proper cutters and then relieve them. As Duplex states in his original article series in ME 1949, more teeth is easier on the machine. Not wanting to cave in and use the alternatives, I need a relieving device. I researched a lot of patents, including the Hendley cross slide version but it turns out the Eureka is more feasible with the tools I have. I found Balzer's original 1895 patent for a previous version of the Eureka but the article I am basing this off is from the Centennial ME archive.

Off to the metal pile to find the chunks of steel from which to carve this thing. I opted to make the anchor and ratchet plates first so that the mandrels can be turned for a good fit. Not having a large boring head I bolted the 2 plates together after laying out and drilling a .125 guide pin hole in the centre. This was mounted in the 4 jaw and centred on the hole. A boring boring operation later and I reached the 1.500 dimension.

Off to the bandsaw for some rough trimming and then to the horizontal milling machine for cutting the  slots and cleaning up the straight bits. The round portions were trimmed on a belt/disc grinder and filed to the lines.

[steamer]

Cool!    It's on the list.....

watching along!

[Don1966]

Great start Gerrit.....


Don

[gerritv]

Feeling confident, I started on the main mandrel. This lump has 2 eccentrics and 34 diameters, of which 2 need some accuracy. The eccentric offsets also need to be accurate otherwise the relief won't be enough (or too little) and the ratchet mechanism won't index properly.

Having only metal that is too big by a margin, it was first a tedious turning exercise. I started using a carbide insert tool so that I could take .010 cuts to get the majority of the metal off. I then offset the lump 0.168, checked that several times and finished the 1.75 and 1.500 main diameters. The 1.500 was finished to a what turned out to be .004" loose fit :-( Whoopsie 1 of more to come.
The mandrel was re-centred and the 1.000, .620 and .375 sections were turned. All fine so far except the slightly loose fit above.
Then came the time turn things around and to offset the other eccentric, which determines the amount of relief. This was turned to 1.12 to be held eventually in the 3 jaw when using the tool. I also drilled the centre hole for the small end, around which the tool will oscillate. I checked this offset 5 times, perhaps in hindsight I should have only checked 3 times! After finishing this section I did some checking and found I had offset in the wrong direction! Good thing I had made that 1.12 as I had enough to turn it correctly and down to 1". Also off course I ahd to remove the incorrect centre hole from the small end, also feasible since I had left this longer than needed.
And then it happened, the cutting tool dug in and up popped the work piece. I though all was fine but realized after some other checking that the .375 portion was bent. It now sits on my desk as a paper weight!

[gerritv]

Having learned in life that learning is a good thing, I did a deep think about how to make this mandrel manufacturable. A fascination article from WWII on making the Bofors 40m anti aircraft gun ready for mass production came to mind. I also wanted to avoid producing another 5 lbs of swarf.

The result is to make the mandrel in 3 parts: the main eccentric with 0.168 offset, the main shaft with 0.030 offset and the small 0.375 shaft. this would assist in making adjustments later as well as reducing the risk of mistakes. And even better, a lot less cutting.

This resulted in proper parts and dimensions. The 0.375 hole was reamed with a .374 machine reamer, the resulting fit on my drill rod is great. I marked the 4 quadrants on the back of the main eccentric to assist in lining up with the main shaft later on. I still need to drill and tap a few set screw holes for the eccentric and the small shaft. The eccentric will also be glued using Weicon green retaining liquid (this is an affordable alternatie to Loctite, less than half price for same specs)

I also single pointed the 1/2-40 tpi thread although later realized that I should have ground the cutter at 55° instead of 60°. I turned the spindle by hand, not used to running the spindle in reverse with tool upside down yet ( a method that avoids the threading to a shoulder risks.)

[zeeprogrammer]

I'd never seen such a thing before and had no idea what it did.
A little googling got me a video of how this tool works.

Very interesting! 

[gerritv]

Yes, a fascinating device that is difficult to figure out from the drawings, it pretty much needs to be seen in a video to comprehend the motions involved. The original patent from 1895 is even more perplexing. We have so many tools such as 3D Cad to help us visualize and design, in those days it was quiet reflection and drafting skills.

[gerritv]

A bit behind in posting!
With the indexing sleeve cut off, I can now use that to machine the nut for it. I ground a 60° internal threading bit for a small boring bar and incrementally cut the thread until the sleeve just fit. The nut blank was cut off and off to the mill to machine the flats. I prefer the look of 2 flats over 6.
Then performed the stepped internal boring per drawing. It is useful to figure out which internal face is the locating one as the others then don't need as much attention for depth. In this case the locating face is at the end of the .620 bore. I thru drilled 5/16 knowing the in the end a part of it will be 0.375. Then brought the 1.500 bore to a very close fit on the mandrel. Finally drilled out the 5/16 to just under .375 and reamed with a .374 machine reamer. This was later finished reamed using an expandable reamer for a close fit on the drill rod used for the mandrel. A popping noise rewards me when putting the sleeve onto the mandrel so very pleased with the fit.

[gerritv]

Next up is the retaining ring for the anchor plate and some studs for pawls.
Nothing special here, I used 1/4-28 and 10-32 threads instead of the BA ones called out since I have those taps and dies on hand. Unlike the 1/2-40 and 5/16-40 threads, these are just generic.

It is starting to look like the desired end result. A few more parts (pawls an.ds springs) and the 12 ratchet detents before a test. I am using Weicon 306-38 retaining compound for assembly, it is an equivalent to Loctite 638 at less than half the price so the bank account is pleased.

There will be a short intermission while I install DRO's on my milling machine, I don't trust my skills in centering the sleeve correctly for cutting the detents. Too much time in that piece already to blow it on miss-location. One paper weight per project is my goal and I already reached that early on :-)

Gerrit

[gerritv]

That was a short intermission, not even time for popcorn!
The mill now has 2 of 3 DRO's mounted. Not totally sure how I want to do the last axis and don't need it for this project.

Wow, what a convenience! Trivial to centre the cutter over the indexing sleeve. I cut the 'teeth' in one depth, changing the spindle to slower speed to take it easy on the dovetail cutter. 3/32 depth of cut, a bit of oil and the teeth are done. And yes, they are pointing the right direction, not paper weight here. While it was set up I also did the wrench flats.
A bit of file work to break the sharp edges and this part is done.
That leaves the 2 pawls and springs to make and then some fitting to get things to click.

The Anchor Plate pawl was up first, a bit of work in the mill, again the DRO makes it so easy to line up holes with edges. Some band saw work and then filing resulted in an almost finished pawl.
I also cut the screw driver slot in the Anchor Plate pawl mounting screw.

[gerritv]

I used some old school lay out methods for the arcs. Its great to have lots of different sized stock on hand for marking out.

[zeeprogrammer]

One paper weight per project is my goal and I already reached that early on :-)

I'm still targeting 3. I've got a ways to go to match your goal. 

Following along. It's an interesting tool. 

[Don1966]

Looking good Gerrit and pretty close to finishing.....

Don

[gerritv]

It's alive. Still have to add a spring for the lower pawl, finish cleaning up surfaces and securing various parts (the mandrel is 3 pieces instead of original 1) but the ratchet works.

<a href="https://www.youtube.com/watch?v=Eou5lnRIGSE" target="_blank">http://www.youtube.com/watch?v=Eou5lnRIGSE</a>

Gerrit

[Steamer5]

Hi Gerrit,
That's cool to watch! I hope once you get it up &  running that you will show us it doing it thing!

Cheers Kerrin
 

[steamer]

It's alive. Still have to add a spring for the lower pawl, finish cleaning up surfaces and securing various parts (the mandrel is 3 pieces instead of original 1) but the ratchet works.

<a href="https://www.youtube.com/watch?v=Eou5lnRIGSE" target="_blank">http://www.youtube.com/watch?v=Eou5lnRIGSE</a>

Gerrit

Put her to work!!!!   Looks good from here!

Dave

[gerritv]

I'm working on a mandrel to make the cutter blanks, then the drill guide and the first form bits. First up will be a cutter for T2.5 timing pulleys.

Have to get this done before May as that is when I am expected to build a new 12x16' multi-level deck for summer enjoyment. :-)

[zeeprogrammer]

That's cool to watch! I hope once you get it up &  running that you will show us it doing it thing!

I couldn't have said it better.

 

[gerritv]

A design for the mandrel on which I will shape and face the cutter blanks, hope to get this piece done on Monday:

[gerritv]

The mandrel is finished, mostly per my drawing. I used a 5/16-18 SHCS as it provides for more oomph should I need it to grip the cutter blank better. 6 slits of 0.5mm width and an internal taper of approx. 10°. I added 17mm wrench flats because it is a common size on my lathe.

The mandrel is used to face the cutter sides, do the rough shaping and then the actual shaping before cutting the gashes and relieving. By using it in my ER32 collet chuck I get predictable concentricity every time.

Presently making cutter blanks from 1.250 drill rod that I happened to have 3' of.

[gerritv]

I made 3 cutter blanks with another 4 in the wings. That should be enough for a while....

I centered the drill rod in 4 jaw, getting good at this with all the recent practice. Drilled and bored out to just under .5, then used a .500 reamer to finish the hole.

A cutoff operation, supported by dead centre (yes a live centre is on the -to-buy-real-soon list). Then onto the mandrel for facing both sides and trimming to .250 width.

With the blanks made I decided to see if the device actually would relieve cutter teeth. To my relief it will relieve!

There are 2 more tools to make, a holder for drilling the 12 holes (might do this in the mill with dividing head) and a jig to assist in cutting the teeth gashes (might do that in the mill with slitting saw and dividing head as well). And of course whatever form tools to make the actual tooth shape.

There will be another intermission as yard work is kicking in, have to sand and treat 4 new Muskoka chairs. And have to work on our pond. Plus this coming weekend we (wife ands I both) will be at NAMES.

Gerrit

[mike mott]

This is really interesting, it is similar to the way that some of the watchmakers made their single cut milling cutters work. I made some 48DP cutters by turning the gear blank eccentric to the shaft, then notched the gear at the extreme point of the sweep so that I can sharpen the cutter on the one face and the cutter always has some relief.
I am not in the shop at the moment because I am recovering from emergency appendicitis and on some heavy painkillers. I will look for a picture of the cutter. I know I have them somewhere.

Found them


Mike

[gerritv]

Hi Mike,
Yes, Dean made a mandrel to assist in making 4 tooth ones. I am fascinated by tooling, sometimes I think making an engine model is just an excuse for me to make tools.

Gerrit

[gerritv]

Those look professional Mike, and a proper stand for them as well.

Gerrit

[mike mott]

Gerrit I agree the whole notion of making tools is one of the best parts of these hobbies. Thanks for the kind words about the cutters.

I used them to make these gears



I need to get back to this engine http://www.modelenginemaker.com/index.php/topic,4423.msg90810.html#msg90810

Mike

[zeeprogrammer]

I find this very interesting and I'm certainly enjoying the learning.
Very nifty thread.

@Mike - I hope you have a speedy recovery and get off the painkillers soon.

[90LX_Notch]

Gerrit-

I have been watching this thread with great interest. 

-Bob

[Dave Otto]

Gerrit I agree the whole notion of making tools is one of the best parts of these hobbies. Thanks for the kind words about the cutters.

I used them to make these gears



I need to get back to this engine http://www.modelenginemaker.com/index.php/topic,4423.msg90810.html#msg90810

Mike

That is a great project Mike, I would love to see more progress on it.

Dave

[gerritv]

I found Eureka's little brother at NAMES. 1/4" shaft instead of 1/2" for the cutters. Being used to make cutters for 72 pitch and smaller gears.

[gerritv]

Finally updating my posts, been a bit busy with stuff.
When I last posted the main part of the tool was complete and I had made some cutter blanks.
Next was making the drilling jig. While it is possible to drill the 12 holes in the blank using a dividing head, the jig means it can be done on the drill press without complex setups. The dividing head comes into play just the once to make the jig. Another bit of single point threading to make the 1/2-40 spindle and a trip to the blow torch for hardening.

[gerritv]

The next jig enables aligning the cutter blank to cut the gaps for teeth. A simple gadget, just s .500 rod in a flat to be mounted in the tool post. A .125" pin holds the blank from turning. The teeth are cut out using a slitting saw on arbor in the chuck.

[gerritv]

Of course once the teeth are cut you need to have a way to sharpen the teeth. For that I looked to the web to glean what the correct adapter is for my 1910's Cincinnati T&C grinder looks like. There happened to be one for sale on eBay so I captured the phots and made a work-alike in a somewhat less grandiose style.
I subsequently bought a CBN wheel which fits better into the tooth gaps. After hardening the cutter a few trips around the grinding attachment results in a sharp cutter. The first one resulted in lovely T2.5 teeth on the 3 pulleys I needed for my Ridder Glass 2 Stroke.