I recently had a discussion with a fellow model club member about fitting a Rosebud grate to a Polly V locomotive. There is quite a lot of discussion on various forums of this style of grate so I won’t repeat what has already appeared in the likes of Model Engineer. The gist of the design is to replace conventional live steam bar type grates with a plate having a matrix of holes with back countersinks such as to occupy around 15% of the grate area. The effect of this change is to get better combustion of the fuel and better efficiency. Most users report only a fine powder residue after steaming and have observed that the fire appears to ‘float’ on the plate surface. The back side countersinks appear to create a sort of Venturi effect to boost the draught to the fire.
How to Calculate the 15% matrix
So all this got me thinking. This would be an easy job to run on the Tormach and all I needed was the design entering on Fusion 360. Which brought me round to the calculation of the 15% surface area for the holes on the new rosebud plate. Those who know me will bear witness to my weakness for doing spreadsheets and this little problem suggested a spreadsheet was needed.
Below is a simple sketch of a rosebud fire grate with dimensional attributes. In the calculation I have allowed for a border around the holes in case there are any no-go areas for the hole matrix. I have now updated the spreadsheet to allow holes to be ignored such as where used for mounting pillars. I also give the XY coordinate of the corner holes relative to material centre to help the machining layout.
Below is a screen shot of the resulting rosebud grate spreadsheet and you can download it as a ZIP file via the following link – rosebud_grate_calculator 2
Here is the finished Fusion 360 drawing ready to run on the Tormach. This shows the bottom surface with the 4mm through holes having been half depth countersunk. Clearly four of these holes will need to be sacrificed for mounting legs onto the locomotive ash pan and these are removed from the above calculation.
So all is in place ready to cut metal and I will keep you posted on the progress and steaming results in due course. (There is a slight problem at the moment in that we have a steaming ban in place because of all the dry vegetation at the club track).
This may not be what it seems but …. for over two years I have had two shelf supports fastened to the workshop wall with screws and plastic wall plugs. The load on the shelf has barely changed over this period.
The other night while relaxing on the terrace we heard a very loud crash and on investigation found the shelf, contents and both brackets in a heap on the workshop floor. Fortunately no major damage ensued to anything.
On investigating further I noticed that the blocks used for the wall material was warm to the touch. This is a consequence of the extraordinary long period of very hot weather we have experience in the UK. The plugs had come out of the holes intact with the screws still in place.
So my thought is that the warmth in the wall has somehow changed the characteristics of the grip in the wall. This could be the plug plastic degrading in some way i.e. going soft and having less grip, or maybe the hole in the block work has expanded in diameter enough to lose the grip on the plugs. Either way it suggests my civil engineering was marginal in the first place !
The shelf is now back up with an extra set of fixing holes and some seriously larger screws.
It has been a bit quiet due to a visit to France. As ever France continues to be a contradiction to me.
We are having some work done on the house – a terrace and balcony on the rear of the property and a new wall bordering the driveway to define the terrain. This has been ongoing for nearly a year since first discussed and agreed with the builder. There is always a reason why the project is delayed be it weather, subcontractors etc. Like many other similar encounters there is no communication either positive or negative to let you know what is going on. You arrive expecting to see something as promised and it is not done. It results in a confrontation, a shrug of shoulders and ‘tomorrow’ (Demain). I used to think Peter Mayle was joking in his book ‘A Year in Provence’ but now I am not so sure.
I can’t help but contrast this with when I was in business when I always stressed to my team that they must manage the client expectations. If the job was going to be late tell the client early on so there are no surprises. If you are going to delivery before expected then also tell them so they think you are wonderful. This clearly does not fit with the French psych. That having been said they are nice people and we have some great times out there.
Anyway the light is at the end of the tunnel and the work they have done looks excellent and very well engineered. It has just taken a very very long time …..
Martel Steam Railway
Speaking of tunnels we had a friend staying and we visited the Martel Steam Railway for a steam train ride. The Martel line is a few miles long and has a very steep gradient from the village of Martel down to the valley side overlooking the Dordogne. The society runs both steam and diesel engines and the carriages are really just open trucks with a roof over them. It was busy and it was hot (mid 30s). We had the added pleasure of a brass band on the journey playing ‘umpahpah’ music.
There is a lot of history regarding the line. For a steam engine the gradient is very steep and the engineering of the line involved a number of tunnels of varying length. During WW2 the line had to be pressed into service for all mainline traffic following resistance action on other routes. If you are in the area it is worth a visit.
As you might have guessed from the above we are in France and the weather is somewhat hot being in the late 30s centigrade. It is too hot to sit outside so I am inside playing IT.
For the past three visits I have seen an issue with my desktop having long and erratic ping times and download speeds as tested with Okla speedtest. I have had support visits from the service providers and still no joy.
I brought out my new XPS13 and discovered that if the resident desktop machine is not online everything is normal for all connected devices (25ms ping and 8Mbps download) (That is fast for rural France …). If I boot the desktop everything goes very pear shaped.
Huge frustration to say the least with all sorts of things on the desktop being checked and services stopped etc to no avail.
I noticed last night that when ever I turned the desktop off, the shut down process was held pending Backup and Sync closing down. A search today revealed that Google Backup and Sync is a connection killer. While I wasn’t really aware I had every loaded it in the first place, I certainly know now that I have unloaded it. Normal service resumed. Magic.
The other issue that has arisen which I had forgotten about is that in France the use of Port 25 on POP connections is regarded as spam by France Telecom. The XPS was not sending messages due to being set to 25 and it now is set to 587 outgoing (110 incoming).
So a useful hour (or two) spent inside from the heat has got me two ticks on the problems to be solved list.
Not getting a lot done in the workshop at the moment. Major distraction with the soccer World Cup (we dare to dream …) plus some garden engineering projects have kept me away from things.
It’s great how workshop resources have a significant use and payback when doing other activity. We had to stake some sleepers (not sure if this is a universal name – the wooden beams used to lay railway steels on) in a new feature in the garden and these needed staking together with through rods.
The Kennedy hacksaw came into play to cut the rods to length and the bench grinder to sharpen the ends to penetrate the soil. The SDS drill was indispensable to cut the holes in the sleepers etc etc. All of which justifies the acquired assets to the lady of the house so some points scored.
I also want to install a new desk in the office in our house in France. The current one is running out of space for the IT router, switch, CCTV DVR, ham radio transceiver, computer etc etc. I debated buying the materials to make a desk but then looked on EBay and found a complete desk for GBP10 in easy pick up distance. While picking it up the seller had a drawer unit in poor condition that she threw in for free. After a day’s remedial work I have a good looking desk with some new chrome handles that were on offer at the local DIY store. Total material cost under GBP15 which can’t be bad. I just have to transport it to France on the next run along with all the other items currently stacked up ready to go. The car could be low on the suspension.