This winter's project. A transmission for the 302 engine

[gbritnell]

Here's the last 4 pictures for today.

The first is just a progression from the last one. Just a tiny bit more stock removed. Once you get the high spots knocked off it's time to go to the files. I have several rifflers with a round cross section. They are a little over .125 at the big part and taper down to about .04 at the tip all the while curving back like a shepherd's crook. I use a #0 cut for roughing and a #2 for finishing, at least on aluminum. The flat surfaces are filed with several flat, curved rifflers, a couple with blunt tips and others with a semi pointed end.

Once the filing is complete or at least seems finished I start sanding with emery paper wrapped around some maple sticks of different shapes, flat, square, rounded etc. Once you start to smooth things out with the emery you always see cutter marks to then you have to go back in with the files and touch them up.

I save all my small pieces of emery and use them wrapped around pieces of stock for getting into pockets and corner.

As can be seen from the 2 finished pictures there's a couple of dimples in the surfaces. I have to say that when you're making several hundred cuts on a part, going up and down in -Z- it's almost impossible to not make an oops. These dimples are probably no deeper than .002 but they show up like a sore thumb. If I was totally anal about the whole affair I could drill them with a small drill, put in a piece of aluminum wire and refile them but with all the work that lies ahead on this project I'll worry about that somewhere down the road.

George

 

[Lakc]

I dont know where to find the jaw-dropping smiley but that looks fantastic!

 

[Deanofid]

George, these last few posts today are some of the most informative I've read in some time. For the
great majority of us who've never seen this actually done, this is as good as things get!
Thanks very much for taking the time to explain these finishing steps.

 

[ozzie46]

Thanks for the post George. Thats very good info. Thm: Thm: Thm: Just what I needed right now as I am trying to profile my locomotive wheels.

( see reply #39)
http://www.homemodelenginemachinist.com/index.php?topic=8358.30#lastPost

I have some cheapie riffler files. They seem to be ok for aluminum but nothing to write home about. I will find out how good they are on cast iron when I try profiling the steam cyls.

I don't have any burrs at the moment. Need to look into them.

Ron

 

[Metal Butcher]

Hi George, the sculpturing is coming along real nice. The light weight flex shaft attachment you use is on my wish list. The weight of the rotary tool becomes an issue for me and adds to my control problem rather quickly. I haven't used my Dremel much for that very reason.

Great work George! Your project is taking shape much faster than I anticipated, I can't wait to see it up close and in person. ;D

-MB

 

[coopertje]

George, many thanks for the detailed explenation how to profile the outside of the gearbox. I hope to be able to use your method in a model in some time, if I can reach 20% of your result I will be a veay happy man!

Thanks again for sharing! :bow:

Regards Jeroen

 

[gbritnell]

This part of the build is finished. Other than some clearance issues that might occur when I start putting the gears inside I am done. I didn't know if it was wise to wait until the end to tap the 1-72 holes along the top rail but they went in without a hitch.
Thanks to everyone who followed along and added their comments. It makes the extra work worthwhile when others can enjoy it.
George

 

[stevehuckss396]

Holy smokes G you truely are the man.

Any way you could snap a shot with the full size case behind the mini one?

 

[kustomkb]

A beautiful piece of work George, very well done!

Thanks for all the detailed posts.

 

[ChooChooMike]

th_confused0052 th_confused0052 th_confused0052

As usual, AMAZING work George !!

<whimpering on the corner of my desk>

Mike

 

[steamer]

Awesome build George!....can't wait for the "stuffing" in the form of gears!

Dave

 

[Deanofid]

It's beautiful, George. Certainly, your time in making this thread is worthwhile, considering how
many of us will learn from it. Thank you, again.

 

[RichD]

Well,
I'm late in finding this thread, but I just want to add my compliments to the rest..."Beautiful Work" George!
Rich

 

[Ken I]

What a pice of craftsmanship - I am in awe.

If you only screw up one cut in 100 then your chances of pulling off 100 operations without mishap is only 36%

You are a Jedi Machinist.

Thanks for all the postings and information on how to..

Regards,
Ken

 

[b.lindsey]

Very timely, not to mention informative post George. I will need some of these finishing techniques shortly on my current project, but in the mean time am thoroughly enjoying your progress on this awe inspiring project!!

Bill

 

[gbritnell]

I know it's been quite awhile but I have been working on the Galloway engines. I took a break from them and put a little bit of time back on the transmission. I had the tailshaft housing cut to size just sitting on the bench so I grabbed my drawings and planned an attack.
I started out by drilling the shift shaft hole and the mainshaft hole. From there I did the counterboring with a few end mills and finally with my boring head. My setup was to clamp the block to an angle plate for these operations but to cut all the angles I wanted to use my rotary table. The trick was how to do it. I couldn't clamp on top of the block because I had to cut that surface. I then remembered that I had a pair of pinch down clamps or toe clamps or whatever they are called. I hadn't used them in years but thought I would give them a try.
I was just a little skeptical with the block being so tall. After I snugged them up I gave it some pretty good hits with my hand and it seemed very secure.
The first pictures are of the roughing out of the cavity. This was done with the drills, end mills and boring bar. I then stepped of the cavity with a .50 ball mill.
George

 

[gbritnell]

The next 3 pictures are of my setups. One with the angle plate and C-clamps, the other with the pinch clamps on my rotary table. I had bought these clamps way back when I was in the pattern shop and don't remember what I paid for them. After seeing how well they worked I pulled out the tool catalogs to see if they were still available. Sure enough, they still make them except you need to take out a loan to buy them, $52.00 each. I'll try and make do with the 2 I have.
George

 

[gbritnell]

Here's the final 3 pictures. These show all the detail machined, the ribs, bosses and flanges. I won't do any bench work in this are until I get the whole thing machined. The last picture shows the .531 through hole. I could only drill so deep from the front side and had to finish it up from the back. I'm happy with how well the 2 holes lined up.
George

 

[stevehuckss396]

Very cool G!! I was just thinking about this last week hoping for some kind of update. Thanks!!

 

[crankshafter]

Hi George "the wizzard" ;D
Have waited a long time for a update on this topic. Loged in, and man what a update, you make me th_confused0052 First class work. Keep it coming :bow:

I can see you are still using your round columb. You mentioned that you where getting you a new mill, have you desided for what mill to change to?

Best regards
CS