Hulett Ore Unloader in 1:32th

[SandiaPaul]

Great work! I am VERY anxious to hear about the rivet machine! So you went from "I'm not doing rivets" To a dedicated machine for rivets!

Also what is the "special cutter" you mentioned?

[Lawton Maner]

The start on the towers looks good.  Gusset plates with rivets will make it spectacular.

Some wise soul once said "a task of a million rivets starts with just one".  Once you've done the first one the other 500,000 will seem easy.  Be thankful that the peer pressure from this group didn't have you make them from hot metal and air powered hammers.   

[finescalerr]

Your etched parts are gorgeous. Please add that to the other compliments. -- Russ

[1-32]

Bernard.
Spectacular that is all I can say.
Cheers

[Bill Gill]

Terrific start of construction!

[Bernhard]

Thank you all for your interest!

@Paul:
The special cutter is a double-edged solid carbide tool with no twist. The tool is very stable. Because of the lack of twist, the sheet metal is not pulled upward during milling, and it does not tend to vibrate. This is especially useful for large thin sheets, although I always stick them to the MDF with double-sided adhesive film to be on the safe side.



@Lawton
You are absolutely right. However, I won't be able to punch all the rivets because I can't get the parts into the press. I will have to put model rivets in such places. There's a lot of work waiting!

Bernhard

[Lawton Maner]

Bernhard:

I use s straight flute drill bit to drill out the side frames of O scale plastic trucks to insert Celron bushings from Foothills Model Works when I convert them to P:48.  This lets them roll better.  Twist drills of the same size might catch on the plastic frames and destroy them.  Straight flute bits can be found at most machine tool vendors, I buy mine from the local Granger's (no affiliation only a happy customer).

One challenge of making rivets from brass rod inserted into holes drilled into the 2 or more pieces being joined is to work out the assembly sequence to get them where a sub-assembly can be accessible for milling of the head early on in the process.  I have been working on a 1:48 scale model of the EBT's Scale Test Car off and on for the last 3 years between trips to the full sized RR to help restore a 140+ year old passenger car.  Getting it right is a 3D puzzle.  Your loader is a puzzle on steroids.

[Bernhard]

Lawton, these drill bits also have the advantage that they are more stable than those with twist. For the same reason, I only use single tooth cutters below 1.5 mm.

When joining several parts with model rivets, there is another problem: the holes in all parts have to be very exactly on top of each other. I will therefore only drill the holes in the outer parts to fit exactly. In the inner parts, however, I will make them slightly larger.

Bernhard

[Lawton Maner]

Bernhard:

Good trick to know. 

On some of the parts I've found that assembling braces onto the ends of the cross bearers prior to drilling for the rivets goes a long way toward getting the parts right.  The ends are soldered prior to inserting brass rod with the hidden end rounded over before soldering leaving only the outer end to be milled later.  The closed weight box on top will be easier to add rivets onto because it is closed and there will not be any way to see inside.

Of course using solder powder mixed into its flux and of decreasing melt temperature makes adding each subassembly easy.  At each stage a torch makes the soldering go quite fast. 

[Ray Dunakin]

Impressive work!

[Barney]

It Just gets better and better - Mind Blowing precision
Barney

[Bernhard]

Thanks for your interest!

Today I want to show you how I made the curved angles on the front and side plates of the towers (green in the picture below).



The angles have a size of 4 x 4 x 0.5 mm and cannot easily be bent into the desired shape. Therefore, I milled them out of a 4 mm thick brass plate.
In the first step, the contour is pre-milled to a depth of 3.5 mm.



This results in a total of 20 parts, and a lot of chips.

[Bernhard]

Now 532 holes with a diameter of 1.1 mm have to be drilled into these parts for the rivets.

[Bernhard]

Now I could actually finish milling the angles out of the plate. Nevertheless, that's when the disaster happens: for some reason the machine loses the zero points in the X and Y directions! And of course it doesn't have reference point switches, which would make it relatively easy to fix the problem. I was aware of that. However, until now I always thought I could manage without them.
So I clamp a 1.1 mm pin in the spindle and try to position it as carefully and accurately as possible over one of the holes. With the coordinates of the hole from the programme, I can then move both axes back to the original zero point and reset them. Fortunately, this succeeds with acceptable accuracy.
Then I can finally start the machine again for the final operation.

[Barney]

Fantastic - But I surrender now going to flower arranging classes !!!
Barney