109 replies to this topic

[Bill from NH]

I have an indexing & dividing attachment to use with the Unimat I've had since the early 70's.

[dc-65x]

Time to build a chassis for this motor. I've build both pin tube and piano wire versions for 705/706 motors but I wanted to do something different.

I've always thought this Cox brand brass chassis for the Pittman DC-65 looked cool:

 

 

I've decided to pattern (NOT clone) my chassis main elements after it. My milling machine was used again to make the motor mounting brackets. These will be screwed into the holes I drilled and tapped into the motor side plates:

 

 

The Cox chassis has slots cut into 5/32" brass tubes that are soldered to the side plates. I'm did the same thing:

 

 

A hand saw, band saw or cut off disc could be used for the slot but I used my milling machine again. I made this slitting saw mandrel when I was an apprentice. A keyway with a key isn't needed to keep the blade from slipping in light applications):

 

 

Here's the slitting saw in action. It made a perfect cut dead center in the tube:

 

[SpeedyNH]

nice setup! i'd forgotten about those tubes slit for the plates. 

[dc-65x]

Thanks Steve. I also needed to drill a hole in those tubes for the drop arm hinge. I used that as an excuse to buy a sensitive feed drill chuck that I've been wanting from the Little Machine Shop.

 

Here's a link:

 

Little Machine Shop

 

The chuck uses your finger tips to grab the large ring and pulling down to feed in the drill:

 

 

Because the wider rail spacing I decided to add a 5/32" tube brace the Cox chassis doesn't have. I used a 5/32" end mill to cut the birds mouth notch to fit the main rails:

 

 

Then I changed my mind and went with a square tube:

 

 

I also had to cut a birds mouth notch into the 1/8" main rails that attach to the axle tube. This time I used a round file:

 

 

Here are the main chassis parts along with the taped up motor:

 

 

Final test fitting in my Rick's setup jig:

 

[SpeedyNH]

yeah, i want one of those feeding chucks too. 

nice work, as always. 

[dc-65x]

In the build jig with all the soldering done:

 

 

All cleaned up and ready for a drop arm:

 

[Larry Horner]

Simply amazing as usual!   Can't wait to see it with the uber cool motor installed.

 

Rick, someday you need to do a post strictly on your cleanup techniques. No matter how hard I try, I still end up with a few file marks and your's always come out pretty much perfect every time. How do you do that?

[dc-65x]

Thanks Larry, I'm looking forward to getting the roller together and testing it too.

 

Filing, done "korrectly", is really an art and since I'm not an artist I try to avoid it.      File marks can run pretty deep especially if the file gets clogged (called "pinning").

 

Instead of filing I most often wrap sandpaper around a file or a 6" machinist scale. The coarsest I use is 320 grit then finish with 400 and 600 grit.

[dc-65x]

I've been scratching my head to come up with a drop arm design.      I know I'm going to use an early Cox guide and instead of "combing out" the stiff braid I'm cheating and using some softer stuff:

 

 

Finally I decided to combine brass strip and brass pin tube. I drilled holes in the strip because the builders in the old magazines were always drill holes in things    and I think it looks cool    Here are all the parts ready to go into my Rick's jig:

 

 

And all soldered up except for the hinge tube. That needs another step:

 

 

The cleaned up arm needed a notch cut into the pin tubes so the hinge tube would be flush with the brass strip. I used my jig's dowel pins with some axle spacers slipped over them to act as a bearing/guide for a round file to cut the notch:

 

 

As soon as the file kissed the brass strip it's done:

 

 

The hinge tube and drop arm in the jig for soldering:

 

 

All finished up except for a down stop. I'm still not sure about that. Lots of older cars just used the lead wires.    I'll come up with something:

 

 

 

 

 

 

 

 

 

[Isaac S.]

I would just solder on a piece of rod or piano wire like this. I would just shape it to the brass sheet. It also would look really original with that chassis. Looks really great so far! 

[dc-65x]

Thanks for the suggestion Isaac, that would look cool. I haven't posted a picture of the drop arm in the chassis yet. But it won't work on this chassis because my drop arm is flush with the bottom of the chassis. It's not sitting above the main rails like the Cox Gurney Stocker. A stop that would allow some drop arm movement would drag on the track. 

[Isaac S.]

Okay, that would make a ton of sense. 

[dc-65x]

While ruminating on the drop arm down stop I went ahead with the body mounts. I'm using the cool Kemtron "body mounting brackets" on the rear. They wrap around the frame rail to strengthen the 2-piece rear pin tubes:

 

 

All soldered up in the jig. The front pin tube was bend downward to act as the drop arm upward stop:

 

 

The chassis all buffed up and ready for that drop arm:

 

 

Here's that Kemtron piece in place:

 

[don.siegel]

Wait, a strange Kemtron accessory I've never heard of?? Where do you find these things Rick? 

 

Excellent idea in fact, and it looks very good. 

 

Don 

[Martin]

Nice solution to the body mount pin tube U brackets, they look strong.

 

Is the wheelbase still adjustable at this point or does the hinge hole lock it in to a fixed position?

[dc-65x]

The wheelbase was fixed early on back at this step Martin    :

 

 

You know I like the weirdo old stuff Don.    In fact in my quest for a drop arm stop that didn't look like it came off of a rewound Mabuchi era "jail door" chassis, I turned to the old stuff for inspiration............a pile of vintage doodads, doohickeys and gizmos:

 

 

I couldn't find anything I liked for the task so I made something up on my hobby lathe out of 3/16" bar stock:

 

 

Now to solder it on the drop arm........

[Martin]

I should off seen that.   Your slip joint is so clean it did not look soldered.

[Isaac S.]

Don, I agree absolutely! I thought had seen most everything but I have not seen that! 

 

Rick, you teach me so much here is a thank you. 

[dc-65x]

We all learn from each other's builds Isaac. This is a great forum to build and share our projects. Here's that installed drop arm stop and my finished chassis:

 

 

 

 

 

It looks so simple but it took me forever to figure it out.   

 

 

[don.siegel]

Beautiful job Rick... as usual! 

 

I see what Martin meant by asking if you forget to solder the adjustable wheelbase part - really looks like no solder in there yet! 

 

And your drop stop looks very Art Deco! 

 

Don 

[Isaac S.]

Great! Looks really strong and that can be a very good trait. But also fairly light. 

[Regis4446]

I like coming here, you see unfamiliar tools , slot parts that I have never seen elsewhere.

 

And in addition there are beautiful constructions and beautiful photos.

 

Thank you Rick for sharing

[dc-65x]

Thank you guys. 

 

I've been a bit sidetracked but I'm back working on my King Cobra. I've decided on good old Russkit set screw rear and threaded front wheels:

 

 

For the front tires I epoxy bonded Revell Dunlop fronts and ground them to 1" :

 

 

For the rear's I'm trying Smilin' Ray's urethane repops of Russkit Dunlop tires (shown ground to 1.020" on the right):

 

 

I'm still waffling between Russkit Cooper and Monogram Scarab wheel inserts while I build up the roller........

 

 

[dc-65x]

The roller is finished:

 

 

 

 

The body is next.........

[don.siegel]

Wowie Kazowie Rick! Nice shiny brass. After all that fun, now you have to pay for it by doing the body... 

 

Don