More tiny work

[fumopuc]

Hi George, thanks for showing your fixture and the making of your tiny wheel.

[gbritnell]

I have all four wheels finished. On my larger baler the rear axle is held in place by two trunnion blocks. Due to the small size of this model I made the trunnions as part of the axle. I turned, drilled and tapped just far enough to allow some strength for milling the trunnions then put the part back in the lathe to turn the remainder. I also did this with the front axle to machine the brackets for the tongue assembly.
The axle screws are 0-80 thread and I slotted the hub caps so that they could be tightened with a small screwdriver. The front axle is mounted to the yoke with a .7mm screw which I made from 303 stainless steel. The yoke is brass with the same thread on the post. I made the nut for the yoke from brass.
gbritnell

[Tennessee Whiskey]

Positively amazing George; just nothing else you can say.

Cletus

[crueby]

I can carve you a little horse to pull it if you want! Well, just stand there anyway.

[Dave Otto]

Another amazing little masterpiece George.
The wheels are work of art! Did you screw the spokes into the hub? I would be interested to know some details on their construction.

Dave

[gbritnell]

 First I'll answer Dave's question. The wheel rims were turned and parted off. The hubs were turned and left on the stock for something to hold onto. An aluminum fixture was made to hold the rims and was mounted in the dividing head at the proper angle. All the spoke holes were drilled .020. The hubs were set up at the same angle and drilled the same. The fixture was then modified for spoke clearance and the hubs and rims were mounted on the fixture. The spokes were all cut a little long and inserted through the  rims and into the hubs. My original plan was to solder both the rims and hubs but after soldering the spokes to the rims the whole thing was so solid that I skipped soldering the spokes to the hubs. I would have been a job to clean all the solder from around the hubs/spokes. The excess spoke material was then nipped off and filed smooth to the rim.

 Now onto the progress report. The next order of business was to start making the A-frame bracket for the tamping arm assembly. The original plan was to make up the brass angle then make a jig out of wood to assemble it but after fooling around for hours trying to get bends and corners made I decided to machine the part from solid brass. By using ever smaller end mills (down to 1/32) I got the bracket machined. It sure was a lot easier than trying to assemble it from bits and pieces.

 The next piece is the ladder-like arm that connects the main ram shaft to the rocker arm. I put a piece of .125 x .75 brass stock into the mill vise and took a cleanup cut. I then cut it to the proper width and deep enough to get 2 pieces. I then drilled the pivot and connection holes. The pivot holes are .030 to use M.075 bolts and nuts. The ladder holes were drilled .024. I then used a .016 jewelers slitting saw to cut the two strips from the stock. The cross pins were turned in my ER-11 collets from .125 stock. The tips that go through the rails were turned .024 and the main shaft was turned .031. The pins were cut off and mounted in my .032 collet to turn down the pin on the other end. At this point I made up all the M.07 screws, first because I would need them and secondly to use them as assembly screws to hold the arm together for soldering.

 The next piece is the main rocker arm. On the full sized baler and my 1 inch model this arm is made from two pieces. The two pieces are held together by angle brackets and one fits inside the other at the hinge point. Holding them together is a long bolt with a heavy spring. The purpose of this joint is to allow the tamping end to pivot away from the connecting link when too much hay/straw is fed into the packing chamber. For this tiny assembly I opted to assembly the arm as one piece. All the side plates were cut and drilled like the ladder arm. The brackets were machined from solid brass so that the corners would be nice and sharp. Spacer bushings were made and the screws were used to hold the whole thing together for soldering. For the spring I used a piece of .020 copper wire. I wound it onto a .036 so that the M.09 bolt would pass through.
 

[gbritnell]

 This is a new experience working with such small screws and nuts. As I mentioned I have been using M.075 for all the pivot joints. The diameter is .0295. The nuts I made are .05 across the flats.
It's really hard to tell the size by looking at a picture but here they are next to a dime.

[gbritnell]

 The tamper on the full sized machine is made from wood with iron trunnions, brackets and plating. Having virtually no way of making the trunnion blocks and mounting them to a wood tamper I made the part from brass, this way all the shapes could be machined as one. I used my drawing dimensions and offset them by .047 for using a .094 end mill. The part is 1.06 long so I worked my way back toward the chuck in the dividing head to keep as much chatter out of the part. The full sized tamper has a main board with two side boards riveted to it. To replicate this I used a .040 slitting saw to cut the gash in the tamper. As I worked my way back I turned the part 90 degrees and drilled the pivot holes. The final machining was to form the bearing blocks. The part was cut from the turning stock and the tool marks were filed out. The last two shots show the parts kind of assembled onto the main frame. I haven't decided how the A-arm is going to be mounted to the frame yet, solder or M.05 screws.
gbritnell

[steam guy willy]

lovely work there, Who is the chap on the coin and do modern coins have Obama embossed on them like our queen over the pond !! ??

[crueby]

Stunning work!

It reminds me of the Crabtree collection of miniature ship models at the Newport News museum in Virginia.

[Flyboy Jim]

lovely work there, Who is the chap on the coin and do modern coins have Obama embossed on them like our queen over the pond !! ??

That's President Franklin D. Roosevelt (President from 1933 - 1945) on the dime in the picture.

Jim

[kvom]

lovely work there, Who is the chap on the coin and do modern coins have Obama embossed on them like our queen over the pond !! ??

Here you have to be dead to be on coins or bills.

[fumopuc]

Hi George, impressive. I have tried to find the thread chart for M 0,75 but also in Germany not so easy. It is the DIN 14 1-1 but I could not find a free chart in the net.

[Zephyrin]

You may may have a copy of the ISO 1501 norm for metric threads under M1.0 for more than 100€ or 88 CHF, man, not cheap !

I got this in catalog (Bergeon maybe )
all figures in mm
Dia   Thread   Taping dia
0.3   0.075   0.24
0.35   0.075   0.28
0.4   0.1           0.32
0.45   0.1           0.43
0.5   0.125   0.48
0.55   0.125   0.53
0.6   0.15           0.58
0.65   0.15           0.63
0.7   0.175   0.68
0.75   0.175   0.73
0.8   0.2           0.78
0.85   0.2           0.83
0.9   0.225   0.88
0.95   0.225   0.93
1   0.25           0.97

very impressive work !

[gbritnell]

 Thanks gentlemen for the comments.

 When I started this project I started a separate thread asking where I could find M.08 screws. The supplier that I had used in the past had gone out of business. I got a lot of helpful information, especially from the fellows in Europe. During my search a gentleman contacted me about a set of watchmakers taps and dies and said he would like to donate them for the project. I asked to pay for them and the postage but was told it wasn't necessary.
 As a model builder I can't begin to say how grateful I am for this addition to my tool collection especially since I have a watch repair friend who told me the cost of such taps and dies.
gbritnell
 As a side note I am using my 6 inch Atlas/Craftsman lathe running at high speed to cut these small screws and am using a magnifier to see what I'm doing. Well to the naked eye the screw shafts look nice and smooth but when viewed close up they're not so smooth. I can't say in terms of surface finish what not smooth is but having never worked this small before it's surprising to see the surface imperfections.
 The lathe has tapered roller bearings and they are well adjusted. Just not the best quality I'm assuming.