Author Topic: A Tandem Compound Mill Engine  (Read 3757 times)

Offline Ramon

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Re: A Tandem Compound Mill Engine
« Reply #60 on: February 21, 2020, 04:56:59 PM »
Nice work on that governor pulley David :ThumbsUp:

It was the likely hood of not being able to tighten the nuts inside the eccentric cut-out that was the real deciding factor for making them one piece. As someone pointed out on mine after fitting dummy bolts, once in situ they can hardly be seen anyway  ::)

Plus one on doing the straps first too :)

Regards - Tug


"I ain't here for the long time but I am here for a good time"
(a very apt phrase - thanks to a well meaning MEM friend)

Offline deltatango

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Re: A Tandem Compound Mill Engine
« Reply #61 on: March 09, 2020, 11:03:50 AM »
Thanks Tug, it's good to have you following along.

This reply has taken longer than I'd expected, a week away in South Australia and a mini CNC machine project have got in the way. I'm back in the workshop now but with two projects on the go together. On the mill engine front the crank and crank pin were the next bits. The crank starting out as the end of a bit of flat steel bar that came in the kit for the Wyvern (think it was intended to become the con rod but I fabricated that instead of carving from the solid):



After the holes were drilled and reamed the blank was roughed out using the bandsaw:




A bit of tool making followed to make a centering pin to locate the part on the rotary table and to drill and thread a hole in the RT adaptor plate for a clamp screw:



the stepper motor drive for the RT handled the rounding of the ends and I'm pleased with the finish from a 10 mm carbide end mill:



The same tool cleaned up the flat sides as well:



The pin was turned on the end of a scrap shaft from a washing machine gearbox, which I hope will be a steel with good wear properties, and then the oil holes drilled:



The two bits won't be fixed together for a long time yet but this is what they'll look like:



The two 8BA threaded holes are for fixing the bit that catches oil from the lubricator.

I feel the need to get the flywheel and crankshaft bits spinning so the main bearings and supporting cast iron will be next.

David
Don't die wondering!

Offline J.L.

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Re: A Tandem Compound Mill Engine
« Reply #62 on: March 27, 2020, 08:23:57 PM »
Beautiful photography as well as superb machining.  :ThumbsUp:

Offline deltatango

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Re: A Tandem Compound Mill Engine
« Reply #63 on: March 27, 2020, 11:18:25 PM »
Thanks John, it's good to hear from you again.

Right now I'm trying to finish off another project that has been occupying desk and bench space for too long, I'll get back to the Compound "real soon now". The other project is a miniature CNC mill based on a scrapped microscope; this provided cross-roller linear rails for the XYZ guides and a stiff frame. Adding steppers and lead screws etc didn't look too hard but it would probably have been quicker to start over, ah well...

David
Don't die wondering!

Offline deltatango

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Re: A Tandem Compound Mill Engine
« Reply #64 on: May 02, 2020, 01:25:24 PM »
The project that was holding up work on the tandem compound is showing promise of working and I'm getting back to machining. The pile of bits that might turn into a mini (micro?) CNC machine was clogging the desk and I either had to try to make something of them or chuck them out, which wasn't really an option. It's taken about six weeks to get the three axes working under the control of bCNC on an old laptop and GRBL in an Arduino Mega interpreting the G-Codes. The Dremel I tried out as a spindle proved to be useless and a real 500W spindle is currently tangled somewhere in the bowels of a very disrupted postal system. The little Frankenmachine looks like:



It may turn out to be useful but even if not I now think I understand the basics of CNC.

The flywheel and crankshaft for mill engine are sitting on the bench and I really want to see them spinning so some bearings and bed plates are needed. The bearings started as bits of some bronze flask clamps that came from my late father-in-law's dental practice. Careful marking out will allow the threaded holes to end up being machined away:



which were reduced in stages using the bandsaw and mill:





until there were two little piles of bronze blocks:



that were reduced to finished size in groups:



which hopefully leaves them all the same size. The little excursion over the marked line with the bandsaw will largely get  machined away:



To make these stacks of bits easier to handle for setting up in the 4-jaw they were super-glued together in a lightly greased nest made from a glass plate and angle plate:



Once in the chuck and centered using a dial gauge the holes were piloted with slot drills and then bored out to size:





Its good to have the engine and other workshop distractions with the world going crazy outside and I really feel for anyone who have suffered from the effects, direct or otherwise, of the pandemic. We've been keeping our heads down here along with a lot of the rest of Australia and are just starting to see some hope of positive change, we are thinking of everyone where things may be going less well - hang in there folks!

David
Don't die wondering!

Offline Admiral_dk

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Re: A Tandem Compound Mill Engine
« Reply #65 on: May 02, 2020, 09:32:05 PM »
Nice to see progress again David - though the CNC project can turn out to be very useful later  :ThumbsUp:

Best wishes

Per

Offline deltatango

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Re: A Tandem Compound Mill Engine
« Reply #66 on: May 04, 2020, 11:43:25 PM »
Thanks Per it's good to know you're following along.
The new spindle came out of the dungeon dimensions on Sunday morning - full marks to Australia Post for getting things moving - and I've pulled the CNC machine apart again to fit it in so progress on the mill engine is slowed again. When I get the spindle working in the  machine I'll know how useful it is.

David
Don't die wondering!