[Thad E Ginathom]

Good luck with the mill! Hope all gets fixed easily.

[Jeroen]

Last Saturday I dropped the mini mill off at the shop in Rotterdam where I bought it about 18 months ago. I checked I have had it for 18 months, but it comes with a 24 months warranty. I should have it back next week.

Last Monday I also dropped off the lump of metal and the fly wheel drawing at my local machine shop. No problem they said, it will be ready next week.

So today I had a go at the Pulley. In essence a pretty straight forward turning job, with one exception. It needs a 8mm groove. I had not idea on how to go about it. But my Dutch model engine forum came to the rescue. There are some very knowledgeable folks out there. They told me I need a �profile bit�. Not sure if that is the correct name. In essence a special bit that will cut the 8mm diameter into the pulley. Impossible to find, appears all machinist tend to make their own. I was very lucky that one of they guys, Willum, offered to make me one. It arrived today and he also included a whole bunch of other goodies:



The plastic bag of wires came from China today as well. All needed for the ignition. Well, I need one of these wires, but the Chinese never sell anything separately. You need to order at least 25 units. I think I paid a couple of euro�s including freight and handling. I don�t know how they do it. Still waiting for my magnet. Minimum order amount was 100, but the unit price is one Euro cent!!!

Cutting such an 8mm groove was likely to put a lot of stress on my little lathe and the material. So I cut off a piece of brass and fitted it into my lathe precisely with as little overhang as possible. Pretty straightforward turning initially:





Now for the tricky part, the groove and its special cutting bit. I had to switch back to my old tool post to hold it. Difficult to get it aligned properly.





In the end I found this set up works pretty well:





Turning at a couple hundreds of RPM only, slowly feeding in the carriage and using plenty of cutting fluid!

I had marked the outer edges of the 8mm groove and the centre line carefully. Helped a lot getting the tool bit positioned correctly.

These days, I consider myself an old hand at parting! No drama, no noise, no vibration, just a smooth cut!



Very, very pleased with my own very first pulley!!!









Perfect fit on the crank shaft too:



I still need to drill and tap the holes for the locking bolt. I will have to wait until i get my mini mill back. All in all, a very good day�s work I thought!

Learned some new skills! End results looks and fits well!

Jeroen

[Thad E Ginathom]

How beautiful your pulley looks! You and the lathe did a good job there.

I think... you can reduce the cutting force for a task like that by cutting out a step shape within the curve, and then cutting the whole profile. Of course, as you know: unlike you, I have never operated a lathe (well, ok, when I was 15 at school). Might have been Joe Pi I saw doing something like that.

[Jeroen]

Originally Posted by Thad E Ginathom

you can reduce the cutting force for a task like that by cutting out a step shape within the curve, and then cutting the whole profile. .

Correct. However, this was just brass and it went fine. My mate also gave me two different cutting bits, half / 1/4 circle that can be used for this purpose, or alternatively you can use a parting blade to make several rough cuts within the curve.

I was very pleased to see my little lathe having no problem with this cut in one go though!

Jeroen

[Jeroen]

Some more parts have arrived for the electronic ignition of Debbie. So I thought I better make a sort of a test set up, see if I can a spark going! My friend Ruud from my Dutch model forum had done this before, and wrote about it on the forum. I printed the image from his set up and just copied it. My spark plug came from him too!



I have bought two different kind of Hal sensors. Primarily because I don’t know yet how I will mount these. I don’t want it to look to new age. So maybe the simple PCB version I can mount into something.



The set up is really simple. There is a battery pack (4xAA batteries), a box with all electronics and the Hal sensor. That is all!!. Soldered the wires from the battery pack onto the electronic box.

Make shift hook up of the spark plug to the electronic box



The one part that has not arrived yet, are the magnets. You buy them in bulk, 100 pieces at a cost of next to nothing. Luckily I still had some magnets left from my modeltrain days. I used these magnets to operate reed relais. Reed Relais under the track, magnet under the carriage. Worked very well. Long before digitisation made it into model railway control.

Anyway, with the magnet near the Hal sensor, I could see a very nice spark. Test successful!!



I had also ordered some brass tubing. The carburator as well as the expansion vessel require a piece of tubing. In theory I could have milled it from solid brass, but that is a waste of time and materials. So I managed to find a place that sold the correct size tubing, by the cm!





Jeroen

[Jeroen]

I have been in touch with the service department of the Proxxon dealer. They have repaired my mini mill! They had to replace the chuck, the bearing and some other parts. This morning the whatsup-ed me a couple of videos showing the mill in running with measuring gauge set up, similar to what I had shown them.

Less than a few thousands of millimeter play, so that is well within tolerances.

I should have it back early next week.

Made the two ends of the expansion valve. Pretty straight forward turning job. Also, cleaned up the little tube I got earlier. As soon as I have my mill, I can drill the final hole and start soldering!



Jeroen

[Thad E Ginathom]

Good news about the mill. Sounds like a good company

[Jeroen]

Work on Debbie continues at a steady pace:

I produced all the various piece of piping, between de cilinder, carburator and expansion vessel. Two with M6 thread. Still need to produce the soldering blocks too, but I need my mini mill for that!



My recently acquired jeweller pliers came in handy. Great to hold these tiny, polished parts for some last filing/sand papering.



Next I decided to commence work on the One Way ball valve, or check valve. This is a critical component of Debbie. Without it Debbie will fail to operate. If the check valve doesn’t operate properly she won’t work either. So really important to stick to all the dimensions



I am hoping to produce all three parts from this one piece of brass



This is as far as I got:



The problem is the specified thread: M8 x 0,75mm. I have two sets of M8, but not the fine 0,75mm. As all of this appears to pretty critical I decided to stick to the exact specifications and quickly ordered a tap and a die M8 x 0,75mm.

The designer, Jan Ridders, has written extensively on the design of this valve. So, I will try and produce it as accurately as I can.

One final job; I replaced the honing stones on my honing tool



I am not happy with it. The replacement set came with very different way of attaching the honing stone. It is one of these cases, where I could shoot myself. The complete set cost Euro 7,50. The set of honing stones cost Euro 5. But I like fixing things and I don’t like throwing stuff out. But this is a case of where it is much better to get a complete original as a replacement. Oh well, another order to HBM I guess.


I need to follow up on my fly wheel and pick up my mill next week. I am also looking into finding a good way of holding the various parts that needs soldering. During our soldering course, we had the use of some very simple but very effective clamps. Cant find them anywhere. But one of my mates from my Dutch model forum might come to the rescue, again!



Jeroen

[Jeroen]

Managed to get quite a few parts made and buggered a few more along the way!

I also have my mini mill, back and so far it appears to working well again!



My new tap arrived, got some more good use out of my special tap follower. Very handy!



Next, started work on the little the bottom end of the check valve:



I am quite pleased how it turned out:



Perfect fit!



With the little ball in place I tried blowing and sucking and this little valve seems to working quite well! No leaks!



Drilled into the tubular section of the check valve. I will need to solder a small tube here.



With all of these little succeses I moved on to yet another new part, the top half of the check valve. There is was not so lucky! One more for the scrap bin.



Second try, so far so good



The little end protruding is 6mm and it needs a 5,5m straight bottom hole. I did not have a correct cutter for that, so I modified an ordinary drill



And failed miserably!! So I ordered the correct size cutter. The designer Jan Ridders talks extensively about this check valve and how vital it is to get all dimensions correct. So no improvisations allowed.





Whilst waiting for the correct cutters to arrive I started on the back plate of the carburator. The carburator body is just a piece of tubing.

First attempt and I got it wrong again. i somehow muddled up the interpretation of the drawing completely!



Luckily I could still modify this: Now with the correct sizing and shape



The tubular body fits nice and tight onto this back plate. So that will make soldering easy I hope!



Today or tomorrow the cutters and some more taps/dies I have ordered should arrive.

Also, my friend Willum from the Dutch Model engine forum has made me a special stand for the soldering yet to be done. Very similar to the stand we used during our soldering workshop. Incredible generous of him. He has helped me out with so much and send me all kinds of stuff already.

Jeroen

[Thad E Ginathom]

Nice to see more action from the bench, and to welcome back your mini-mill

Originally Posted by Jeroen

The tubular body fits nice and tight onto this back plate. So that will make soldering easy I hope!

It might not. Lesson learnt at the jeweller's bench: surfaces to be soldered must be a good fit, but not a tight fit: the solder needs to be able to flow in there. On one occasion, I could not solder two push-fit components, and this was my problem.

[Jeroen]

Originally Posted by Thad E Ginathom

N
It might not. Lesson learnt at the jeweller's bench: surfaces to be soldered must be a good fit, but not a tight fit: the solder needs to be able to flow in there. .

True, but this kind of soldering relies on capillary working for the solder to flow. So I reckon it will be fine. But I have been wrong many times before, especially when it comes to metal working. So we will see!

On the matter of soldering, look what arrived yesterday.

The perfect soldering aid! This clamp is about identical to the one Ruud and I were using during our soldering workshop about half a year ago. They are ideal as it will allow you to move the flame all around the workpiece and it has the little lever you can use to keep bits in position. Willum, our friend from the Dutch model engine forum made us one each. Very kind and very useful.

Willum also send me this drill bit tool for sharpening.



The back plate of the carburator is a very nice fit. Still needs to drill two holes for the various connections though



The front plate is somewhat different as it has a sight glass. The rear of it is identical to the back plate. Fairly easy and straight forward job.



Parted it off and clamped it back into the four jaw chuck. I am getting very good at putting stuff into the four jaw chuck and having it run true, within 0,02mm in less than a few minutes. As the saying goes: practices makes perfect.



Pleased with the end result:





The little eye sight makes for a snug fit, completely flush with the front. It looks a bit odd, the protective cover sheet is still on. Once I have glued it in place it will look completely transparant so you can see the level of the fuel.





The postman also brought my new 5,5mm cutter, so I returned to the check valve to finish the last part. It took several attempts to dril the perfect 5,5mm diameter hole, 2,5mm deep into the 6mm shaft of this part!.





But as usual, third try was the lucky one!





The complete assembly, still need to solder on the connecting pipe later



All in all, pretty productive two sessions. The biggest challenge is the cold. I have my hot air blower going full blast. But after a few hours standing in front of my lathe and workbench I am absolutely frozen, my fingers don�t work anymore, so I just have to stop.

Also received the M5 tap and die I need for the extra air inlet tube. Jan Ridders specifies all these appendices with very fine thread. I have a full set of metric taps and dies, both regular and fine, but these call for extra fine.

More to come soon

Jeroen

[Jeroen]

On and on we go. Work on Debbie keeps progressing!

The guys from my little machineshop called earlier this week. They apologised as they had not gotten around to making my fly wheel. Not to worry I told them. They had another good look at the drawings and told me they would be producing the fly wheel from stainless steel! Not the lump of regular steel I bought off them earlier. No extra charge.

I picked it up yesterday and it looks marvellous! They did a fantastic job!



Put together some parts loosely, just to get a feel on how it all looks together.





There is no way I can compete with a professional machinist. Still, I think my pulley holds its own, next to the professionally made flywheel!



Some more details



It is really cold in my garage, so my wife keeps bringing me cups of hot chocolate milk to keep me going.



Next parts I produced are the boss for the air intake to be soldered onto the carburator and the air intake screw that fits into it





Decided my lathe needed a thorough cleaning and some oiling. These brass chips are very fine and they get in everywhere. So cleaning and some maintenance is pretty essential to keep it in good running order.

In order to lubricate the lead screw bearing, the gear cover has to come off.





Next part the extra air inlet tube and the respective adjustment nut.

I had ordered specially a 5mm x 0,5 tap and die. What I had not noticed is that this die is smaller in diameter than all my other dies! So it would not fit in my special tool I made, or in any of my die holders. As we are in the middle of a lock down and I just cant pop out and get something I decided to improvise.

Put the die into a M20 socket, big nut underneath and added copious amount of (red) lock tire. I did have to bring it inside the kitchen to properly set and cure. But it did the trick!



First time I used my mini mill in earnest since I got it back after its major overhaul. Worked really well. The guy was texting me yesterday. He is also sending me two new belts by mail. The belts are still ok, but I want to have them in stock. These things tend to snap at an inconvenient time always.



So another very nicely looking part done





I got to use my fancy soldering stand as well. In order to loosen up the die from the socket, all you need to do is apply some heat, in my case a torch.

Jeroen

[Thad E Ginathom]

Great progress, Jeroen.

I'm sure you could have produced the flywheel, if you had a bigger lathe. The pro advantage though is always that they get right on with the job with no doubts and few problems. Experience, and being in practice. I bet you could have made that when you were at sea?

Anyway, it looks lovely. And stainless is a nice touch.

[Jeroen]

Originally Posted by Thad E Ginathom

I'm sure you could have produced the flywheel, if you had a bigger lathe. The pro advantage though is always that they get right on with the job with no doubts and few problems. Experience, and being in practice. I bet you could have made that when you were at sea?

Thanks, yes, actually the flywheel is not that difficult at all. It is just the size of the thing in relation to my lathe. And my mini mill too. Those holes are 16mm and I cant drill anything like that in my mini mill.


Despite the cold and the snow I spend a few hours in my garage today. It’s about 6oC, well insulated. It is probably going to take a day or two before it gets really cold inside.

Had a good look at the flywheel. There are three M3 threaded holes. The guy told me he hates threading M3 in big pieces of stainless steel. If you break the tap, you’re done. You will never get it out, and will have to start from scratch.

I was checking the holes and the depth of the thread. Not entirely according to specification. So I was very brave, or very stupid, and took my M3 taps to them!



The bolt will go in about 6-7mm, which is fine. These bolts will hold the cam in place, but that also has a boss which fits on the hub. So I don’t think it is going to be a problem. Went through all the drawing and the various bits I still have to do and made a list of some small things I still need to get.



Decided to produce one part only, the muffler! Decided to make it our of regular steel. Because I had a piece or round bar the correct size.



Now, as many of you will be aware I work on cars a lot. So I can claim quite a bit of experience working on and fitting mufflers.

I can unequivocally state this is the most gorgeous muffler I have ever seen. It is also the smallest, and to date, the only muffler I have ever produced!





Jeroen

[Jeroen]

Not much progress on Debbie. I did try last Saturday, but it was very cold in my garage. Even with the air heater on.



First job was with the hack saw, cutting off a chunk of brass to produce the mounting block for the muffler. If anything that is good exercise and kept me warm.





But behind my mini mill, just standing still, turning those little control wheels it became to cold very soon. This is how far I got.



It has started to thaw, raining as we speak. So the snow and ice will be gone in the next day or so. Hopefully some warmer weather to look forward to.

Jeroen