Thursday, 8 October 2020

3D Printing in Winter

I had previously suffered some disillusion over a very low success rate with the 3D printer but I've had quite a run of success over the summer. Oddly, I had my first unsuccessful print the other day, completely out of the blue. The next print was fine but it got me wondering as to why.

Generally the 3D printer is fairly tolerant but I noted that the failed print happened right when the temperature dropped outside. The printer is upstairs in my den but it is next to the most northerly corner of the house and there is this point in the year when the temperature drops but it isn't cold enough to put the heating on.

Reading the label on the next bottle of resin I noted that it said that it works best between 25 and 30 degrees centigrade and we were definitely no longer that warm so what to be done? Reviewing the Facebook support group for my printer I noted that someone had used reptile heaters to heat the printer. You can get ones with thermostats built in but they appeared to have limited control.

In the end I elected to purchase a device that is basically a control box that has a thermometer on a cable and two mains sockets to turn the heaters on and off. I also purchased two small reptile heaters. I then had to drill some holes and into the printer to feed the cables without fouling the lid or any internal mechanisms. The reptile heaters were glued to the inside sides of the printer and the thermometer is glued to the back. All this is carried out with the Bosch cordless glue gun which is in itself a fantastic piece of kit.

Now I can set the temperature to be maintained between 26 and 28 degrees centigrade and if I put it on far enough in advance the resin will be at a suitable temperature for printing. It would benefit from more heat, these reptile pads are only 5W each but the next size up would not fit. It took a few hours the first day but the second day it hadn't cooled off that much and was up to temperature within 90 minutes. At 10W total it could be left on all day. That's less power than this computer uses and 0.3% of our kettle. 

Saturday, 3 October 2020

Welshpool No 85

The other project on the go is the Dundas Models Sierra Leone No 85 which runs on the Welshpool & Llanfair. Again, it's a quick build to provide extra locomotive power for the layout as and when exhibitions are back on.

Since being on the WLLR it has had some interesting liveries but after the lining of Triumph I have opted for the full black that was used on the WLLR just prior to it being withdrawn for overhaul. 

The model has gone together well. I would have to say it has been one of the crispest and simplest to put together. The only place that has needed filler is round the smokebox door, the side tank pieces being of slightly different length. Unfortunately you can't just trim a piece off the other end as that end fits tightly into the rear of the cab but really it is a minor inconvenience.

One aspect of modelling it in the year before overhaul is that it had the extra coal bunkers on the front of the water tanks. The bunkers supplied in whitemetal are, of necessity, quite thick. In real life the metal of the bunker would have been half an inch maximum but the thickness of the whitemetal was such that it translates to 3 inches in real life.

I found some brass offcut and bent it to shape but I made the mistake of not filing the groove at the bends with the result that the corners were curved rather than rectangular. Once I had corrected my error it still looked rather rounded. 

I knew I had to redo them but then I realised I could probably just print them. It was the work of a couple of minutes followed by a couple of hours of printing time but it gave me the opportunity to experiment with printing direct on the print bed which worked unexpectedly well, despite the fact that I made the wall thicknesses to be 0.4mm which comes out to just over 1 inch in real life.

The picture shows the three different forms, left to right. I am sure others can fabricate these parts quicker than I can print them but as it was literally 5 commands to design them and 1 extra command to produce the mirrored part, I am happy with what I can achieve.

3D Printing in Winter

I had previously suffered some disillusion over a very low success rate with the 3D printer but I've had quite a run of success over the...