PM Research Engine Number 1

[propforward]

Can't get that Thompson Twins track out of my head since you mentioned it Gary - at least while I'm in the shoppe. 

Not to worry, my iPhone helps with that. Either music of my own preference, or old episodes of "I'm Sorry I haven't a Clue". But that's a topic for another thread.

So, finished up the eccentric hub this morning. I wanted to ACTUALLY finish it before moving on. So I did indeed chamfer the edges of the lips, which would have been a lot easier had I left the part on the stock bar a bit longer. No matter, the little collar worked well, and let me hold it securely without damaging the lips.

Then the last thing was the 5-40 hole for a grub screw.

Getting the orientation set up using a gauge pin:



Gauge pins are excellent tools to have. I bought a set a month ago, after seeing machinists at work establish locations using them, and then following up with an online tutorial from Joe Pie. I use these pins every time I am in the shoppe.

Then, drilling and tapping as has been seen and posted about a million billion times. Possibly more than that.





And there it is, hiding among the other parts, both finished, raw, part finished and of no use to anyone.





Next up is the eccentric follower.





All I did today was a little bit of clean up, and some measurements of the casting to understand how much stock I have. I'm trying to take a bit more time to get familiar with castings before actually setting them up, and try and figure out any "gotchas", and figure out what stock there is where, and therefore how to get machined surfaces located relative to surfaces that will be left raw, to make sure visual appeal is maintained. This is all part of making an attractive engine, I think.

I did get one side flat on the sanding belt. The casting started off approx 0.005" parallel between the two sides (crude measurement), and there is roughly .1" of stock to take off, so should be plenty.

I have clamped it in place ready for a skim of the other side. Only a minimum clean up right now - so that I can hold it for drilling bolt holes and cutting it in half. I'll go to final thickness after the two halves are bolted back together, so that I can make sure the center of the lobes is centered on the finished part. That's the plan anyway.



Right now though, it's time to begin Thanksgiving day food prep, and likely a mid day bubbly. So the shoppe is closed for the day.

Thanks for looking in, and Happy Holidays and best wishes to you. 

[gary.a.ayres]

Yeah - that damn song has been reverberating in my head too... 

Great progress. Your 'family shot' is looking good.

Good point about the aesthetics of machined and unmachined casting surfaces juxtaposed. Always worth slowing down to think things through (says me, who so often doesn't...).

I can see I'll have to look into this gauge pins business - I have no idea, rookie that I am, of what they are or how they work.

Enjoy the bubbly and all that goes with it!

 

[Flyboy Jim]

I can see I'll have to look into this gauge pins business - I have no idea, rookie that I am, of what they are or how they work.

 

My set of gauge pins (mine go up to .250 in .001 increments) are one of my most useful measuring tools. Definitely one of those things that a person doesn't realize how useful they are until you have a set. I'm getting a set of the ones that go from .250 to .500 as soon as they're back in stock. Here's the set I presently have: https://www.shars.com/products/measuring/pin-plug-gages/061-250-minus-steel-plug-gage-set

Have a nice Thanksgiving, Jim

[gary.a.ayres]

Well, they look great Jim. Clearly I'm going to have to watch the Joe Pie video on them as my end-of-day viewing this evening!

 

[propforward]

There are several tools I’ve been lucky enough to acquire that are “nice haves”, but the .061 thru .500 gauge pins would come ahead of those. For both set up and inspection they are invaluable. I think the “minus” set is most important. I don’t have a plus set, and I don’t think a home shop needs both sets.

[gary.a.ayres]

Didn't manage to look at the vid last night (too knackered) but will do so.

Thanks for the info!

[propforward]

Here are some progress pics. I don't have too much to say about it. The approach was straightforward - skim both sides flat. Set up and face the three bosses, drill and tap three holes. Separate the part into two halves - open up the tapped holes in the cap to clearance holes, face bopth halves, bolt together, bore out, then skim to size. Finally, drill and tap the oiler hole.

It all went pretty much to plan. Centering the part in the 4 jaw was done crudely by aligning with a dead center. This seems to have worked well - I checked run out before boring - the inside was pretty true, the outside certainly had some visual run out, but it is not a perfectly concentric part. I decided to go with it as it was. The material removal on the ID was pretty consistent straight away, so I think this worked out well enough.



Setting up for the bosses.



I checked relative height of each side boss by touching off with the tool tip, and it was within 2 thou, as shown by the DRO in the pic after next.





Boss face clean up:





Getting ready to split. My prior set up was not thought through well enough, so I had to do a new set up to saw the part.



Obtaining center by using the saw, feeler gauge and DRO.







Clean up:



Ready for boring (probably what I'm doing to anyone looking at this thread)



Alignment:





After boring and facing:



And last but not least, the oiler hole:



I did a test fit on the eccentric hub, and annoyingly it is tight. However, I am suspicious of burrs on edges. I'm going to give both parts a deburr session and try again, but I may have to go back on the lathe and skim out a thou, which never works well. Hopefully deburring takes care of it.

Still, not a bad day. Cheers!

[crueby]

Wow, nice results! That indexable cutter you used on the mill gives a great finish, looks different than the ones I have seen, with a more shallow relief on the inside of the tip, towards the screw.

For the tight fit on the eccentric, is it a small enough difference to use some lapping compound on it rather than try and center it on the lathe again? If its just a thou or so, some Timesavers powder mixed with oil will take that down and give a smooth running fit.

[propforward]

Thank you! I am very pleased with this part. I think I have done a reasonable job this time of getting the machined surfaces balanced to the location of cast features, resulting in a decent looking part as well as functional. I must say I like your suggestion of lapping very much - that is the way to go. If I chuck this up I know I will take too much off. The two halves come together over the eccentric hub without needing to crank the screws hard, so it is a minimal anount to take off.

The insert is one specifically made for aluminum and non ferrous metals. In researching inserts recently I happened uon these, and thought I would try them. While I was making a test cut on a piece of 6061 I was blinded by the reflection of my little LED light, the surface finish was so good. Very impressive, and cutting dry too. No more expensive than a TiN coated carbide insert. It’s an APKT11T308LH insert.

[Flyboy Jim]

That came out great Stuart. Well done. I worked a little on the same part on my PMR #5 today.

Jim

[propforward]

Well I did a little close up investigation, and re measured OD of the hub and ID of the follower, and discovered that within the measuring capability of my calipers, ID and OD are identical. Couldn't have achieved that if I'd tried for it. I can get a 2 thou feeler gauge in this gap, and freely rotate the hub.



So I gave the follower a polish on the ID, and the hub a polish on the OD, and after that they go together nicely and the hub rotates freely in the follower. Sort of disappointed, but polishing those two diameters to a better finish is not a bad thing anyway I guess.





The photos tend to exaggerate surface roughness, but even so I could have done better on the face of the hub with the offset boss on it. Should have done a skim after making the offset boss. Live and learn.

After that, I didn't make any new parts, but spent the day reorganizing the shoppe to better arrange tools. I made a Version 3 roly thing:



It's just one of those cheapy wire carts, but with solid infills on all 3 shelves, and anti slip mats on the lower 2. Top one deliberately has no lip. Also added a backboard out of some scrap polypropylene sheet that was thrown out from work years ago. This serves as a clip board for prints and a white board for notes as needed. This is so any metrology tools don't sit on the top with other tools and bits of material, where they have a habit of working their way towards edges. Middle one is for said metrology tools, so that they can't be knocked off during normal use. Top is for whatever selection of tools I need for whatever I'm doing. Lower one actually now has my gauge pins on it for ready access. Quickly thrown together though this is, it's rather handy.

And then I allowed myself a look at the next engine project, for inspiration.

[crueby]

Came out great!
And next to the new cart, see that you have a comfy chair for sitting back and admiring the progress - very important!

[propforward]

Very, very important!

Sometimes it's necessary to sit in a contemplative manner. Either to plan what's coming up, or figure out what just went wrong.

Or just nap. Let's not forget that, either.

[gary.a.ayres]

Great work on that follower.

Very nice shop! Looks more comfortable than some living rooms I have seen in my time.

[gary.a.ayres]

Is that next project a PMR #4?