Author Topic: Elmer's Oscillating Cylinder Engine #42  (Read 4968 times)

Offline Don1966

  • Full Member
  • *****
  • Posts: 6398
  • Morgan City, LA (Along the Gulf Coast)
Re: Elmer's Oscillating Cylinder Engine #42
« Reply #15 on: March 23, 2021, 01:20:35 AM »
Nice looking parts Eric.....  :Love:




 :cheers:
Don

Offline EricB

  • Full Member
  • ****
  • Posts: 76
Re: Elmer's Oscillating Cylinder Engine #42
« Reply #16 on: March 23, 2021, 02:39:59 AM »
Thanks guys. I want it to look good just in case it turns out to be a paper weight ;).

A pile of bar stock came today so now I can get on with the base and frame.

Eric

« Last Edit: April 23, 2021, 05:40:13 PM by EricB »

Offline EricB

  • Full Member
  • ****
  • Posts: 76
Re: Elmer's Oscillating Cylinder Engine #42
« Reply #17 on: March 24, 2021, 05:11:16 PM »
The plans call for the frame to be a bent strap of aluminum. All the examples I've seen (so far) use straight pieces instead so I went for the bend. I probably didn't give it enough heat so it kinked. Aside from that I was able to get the about rest right. I'll give it another try.

Eric

Offline Vilbrequin

  • Jr. member
  • **
  • Posts: 1
Re: Elmer's Oscillating Cylinder Engine #42
« Reply #18 on: March 24, 2021, 06:09:59 PM »
Hello Eric, good job. It's a good little engine that I made ,

Offline EricB

  • Full Member
  • ****
  • Posts: 76
Re: Elmer's Oscillating Cylinder Engine #42
« Reply #19 on: March 24, 2021, 06:59:08 PM »
Very nice! That's what I'm aiming for.

My second attempt at bending aluminum came out worse than the first so I think I'll mill the frame instead.

Offline crueby

  • Full Member
  • *****
  • Posts: 12274
  • Rochester NY
Re: Elmer's Oscillating Cylinder Engine #42
« Reply #20 on: March 24, 2021, 07:20:50 PM »
Were you bending around a rod, or just freehanding it? Around a rod can work much better, start it with the bar clamped to the rod in a vise or with a small clamp. That will get you the first half or so of the bend - may have to move the clamp around to finish it off.

Offline EricB

  • Full Member
  • ****
  • Posts: 76
Re: Elmer's Oscillating Cylinder Engine #42
« Reply #21 on: March 24, 2021, 08:20:52 PM »
I was bending around a 1" steel bar clamped in a vise. The stock I have is 6061 T6 so it's very hard, and I'm heating it with propane. Other than that I don't know what I'm doing. Everyone on youtube has a different story.

Offline EricB

  • Full Member
  • ****
  • Posts: 76
Re: Elmer's Oscillating Cylinder Engine #42
« Reply #22 on: April 10, 2021, 09:22:07 PM »
After much meditation, here is my current plan for carving out the frame.
https://www.modelenginemaker.com/index.php?action=dlattach;topic=10234.0;attach=124919;image

The idea is bore the inside of the curve to size and then shape the outer curve on the setup shown below. I'm thinking I should be able to finish the rest of the shape holding in the vise. It's going to make a lot of chips.

I'm considering making a single strap to hold the part on the rotary table. What would you do?

Eric

Offline crueby

  • Full Member
  • *****
  • Posts: 12274
  • Rochester NY
Re: Elmer's Oscillating Cylinder Engine #42
« Reply #23 on: April 10, 2021, 10:09:46 PM »
A couple other ways come to mind to grip the part for milling the outside - am sure that there are a number of others.
- If you have the adapter to fit your 3-jaw chuck to the rotary table (very handy item, I use mine a lot), you could reverse the jaws in the chuck and have them grip the inside walls of the bored hole. Even better would be the 4-jaw chuck, since it has a slot that can be used to clamp the chuck to the table using one of Sherline's little hold-down clamps (L-shaped with a bolt type). Milling on the outside of the piece puts force on the chuck which wants to un-screw the adapter, which would be very bad.

- Make a little arbor set like this:


The bottom plate bolts to the rotary table using the t-slots in the table. For best centering, could put a little round piece on the bottom of the bottom plate that is sized to match the hole in the rotary table.  I made a tooling plate for my rotary table for things like this. The top cap is pulled down by the center screw, and an optional little pin near the rim keeps anything from turning by the force of the end mill. The two steps on the bottom plate are to give vertical room for the hold-down bolts, and the smaller step is sized to fit the bore in the block.

With the block held in place:

Sure there are other ways too - thats half the fun of machining!
 :cheers: Chris


Offline EricB

  • Full Member
  • ****
  • Posts: 76
Re: Elmer's Oscillating Cylinder Engine #42
« Reply #24 on: April 11, 2021, 04:01:52 AM »
Hi Chris,

I like the idea of the arbor. Anything I use would need to be clear of the cutting tool so that rules out the chucks for me. I tend to autograph my tools.

For my progress today I cut down the stock to near final size and bored the hole for the inside of the curve. Lots of handwheel turning. I need a nap.

Eric

Offline EricB

  • Full Member
  • ****
  • Posts: 76
Re: Elmer's Oscillating Cylinder Engine #42
« Reply #25 on: April 12, 2021, 04:11:18 AM »
Machined the outer radius of the frame today.

First I made a long strap clamp to hold the part to my rotary table. I figured if two tiny clamps can hold my mill vise down then this strap should hold the part with no problems.

I just needed to figure out how to center it up. I was thinking about what to use to make an arbor like Chris suggested but decided to look and see if I already had anything that would work. I have an end mill holder that will thread onto the chuck adapter for the rotary table and gives a concentric bore to align the table with the mill and an outer surface to align the part with the table. To make up the size difference between the end mill holder and the part I used painter's tape.

Eric


Offline crueby

  • Full Member
  • *****
  • Posts: 12274
  • Rochester NY
Re: Elmer's Oscillating Cylinder Engine #42
« Reply #26 on: April 12, 2021, 12:21:35 PM »
Good solution!

Offline cnr6400

  • Full Member
  • ****
  • Posts: 1040
Re: Elmer's Oscillating Cylinder Engine #42
« Reply #27 on: April 12, 2021, 02:03:43 PM »
 :ThumbsUp: :ThumbsUp: :ThumbsUp: :popcorn: :popcorn: :popcorn:

Online propforward

  • Full Member
  • ****
  • Posts: 1057
  • MN, USA
Re: Elmer's Oscillating Cylinder Engine #42
« Reply #28 on: April 12, 2021, 03:33:33 PM »
Very ingenious. Looks like it worked out very well.
Stuart

Offline EricB

  • Full Member
  • ****
  • Posts: 76
Re: Elmer's Oscillating Cylinder Engine #42
« Reply #29 on: April 15, 2021, 12:43:52 AM »
Thanks everyone for the comments. I'm starting to put too much emotion into this part, but I need to keep on it.

I had left the block oversized so I could be less concerned about placement of the inside bore, and I could center on that for the next steps. In doing so it left a step on each side after cutting the outer radius of the curve that I needed to remove.

I think I will finish all the other features on this part before I cut the center out.

Eric