Sunday, 22 May 2022

Antique style signs

Every time we open our garden for charity, I notice something else that could look nicer. Several of the signs we have about the place were faded and tatty. I could buy better looking replacements for some of them, but there are a couple I could not buy anything that I liked the look of.


As usual, I made my own.




Designed and 3D printed in ColorFab nGen filament, which should withstand the weather. I used a paint pen to colour the text and gave them a coat of clear lacquer to better resist scratching. 


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Thursday, 19 May 2022

Adding 3D text in FreeCAD

 Adding 3D text to a model in FreeCAD version 0.19 is fairly easy but it has a few steps.


Start in the Draft workbench.


Create a ShapeString. 




I always position them at Zero, Zero, Zero, and move them afterwards. The cursor automatically repositions the text and is a nuisance, making that bit of the user interface unusable, in my opinion.


Type the text to display in the String field and choose a font file. In windows, this can be selected from the "C:\Windows\Fonts" folder. Alternatively, the font files can be copied and saved elsewhere for more convenient use.

All text is initially drawn facing the top.

To align it to a model, go to the properties of the ShapeString.


Select Map Mode and then the face on the existing model to align the text to.


To change the position, select Attachment from the properties and change the Position x, y and z values. These are relative to the original position, so it is a bit of trial and error to work out which moves in what direction.


To attach or remove the text from the model, go to the Part Design or Part, workbench, depending on your preference, select the ShapeString and use the usual extrude or pocket options. 

In Part Design, the ShapeString object will need to be dragged in to the body, in the tree, before using the tools.

In the Part workbench you will additionally have to use a binary join, after creating the lettering.


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Sunday, 17 April 2022

Another bike build finished

I enjoyed building the last mountain bike, so at the slightest excuse, I've built another one.


The process was the same as before, with some minor additions, such as foam tube to quieten the hoses inside the frame and some strengthening heat shrink on the shift cable.

Before

I bought a neglected 2017 Giant Trance off of eBay. It was so poorly maintained, the only bits I've re-used is the frame and the two bolts that hold the rear brake calliper on! I only wanted the frame and price reflected its state.














Stripped off all the parts, sanded, masked up, painted and put back together with new bearings.




Reassembled with a new SRAM crankset and cassette, new Shimano XT derailleur, new Shimano brakes, and a used, but good condition, Rockshox Pike fork. Raceface Turbine 35mm rise bars and some very nice Corki grips from Amazon.


New Hope Fortus 26 wheels and I added some new decals to the forks.

I chose to use the same colour paint as on Shelley's Land Rover. Atlantic Green, as used on the Heritage Land Rover Defenders that came out in about 1999.





It's a very nice colour for a Land Rover and a bike.




Shelley is very pleased with how the bike rides. The older models are good but somehow these newer Giant Trance's inspire confidence.


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Tuesday, 29 March 2022

1x vs 2x drivetrain

I am a fan of 1x, single, chainring drivetrains. However, my interest is in the reduced complexity and the ease of use. I also ride a mountain bike off-road, most of the time. Many road bike users, still prefer double (2x) or even triple (3x) chainrings. I asked myself, am I missing out on something?

Ease of Use

Most, if not all, new users of 2x gearing get confused about when to change between chainrings. There is invariably an overlap between the ratios, so when you drop to a smaller sprocket on the front derailleur, to make going up hills easier, it is often necessary to change up to a smaller sprocket on the rear, to have a gradual change of ratios, rather than a big jump. There is an optimum point to change, but that takes experience to become natural. Obviously, this is even worse with a triple. 

Many novice riders, don't change the chainring they are riding on, until they find they can't pedal any more.

With a 1x system, that confusion is eliminated. To go faster, move up the gears, to go up steeper hills, move down the gears. One lever, easy.

Complexity

If you don't maintain your own bike, this is probably not of interest. I personally find that adjusting, especially worn, front derailleurs, can be trouble. At the very least, it's two things to adjust, instead of one.

There's one less lever on the handlebar and one less cable to route.

Weight and Efficiency

I don't race, so I'm not particularly worried about weight but 1x systems are lighter. However, I have read that they are less energy efficient because of more friction, caused by the chain being at a greater angle to some of the sprockets.

I'm not going to go into detail, but here's a link to an article that does some testing:

https://www.cyclingabout.com/drivetrain-efficiency-difference-speed-between-1x-2x/

In short, they conclude that on average a 2x system is 96.2% efficient and that a 1x system is 95.1% efficient. Alternatively, and taking the worst case rather than the average, a cyclist that expends 250W of energy on a 2x system would need to generate 256W using a 1x system, to achieve the same performance.

In that testing, they do not take into account the extra power required to move the additional weight of the 2x system. However, using an online cycling power calculator, I've concluded that the small weight saving, of about 250g, has a negligible effect on the power required. Only about 0.1W.

Gear Ratios

This is the bit I am most interested in comparing. Most articles, that I can find, look at the total quantities of gears and not the individual usable ratios available. The following is an article that I thought covered the basics well: https://www.yellowjersey.co.uk/the-draft/bike-gears-explained/

From time to time I've read comments saying that you can go faster with a 2x system or that you end up just spinning when you get too fast. I was pretty sure that was unlikely because both systems are still limited to either an 11 or 10 tooth highest gear so it is the number of teeth on the chainring that determine the maximum speed regardless of it being a 1x or 2x system.

For my own interest, I wanted to remove the overlapping ratios of a 2x system to better compare to a 1x system. When I was young, people would say a 10 speed bike and the equivalent now, might be a 30 speed bike but you don't actually get that many usable ratios because of the overlap. Modern terminology has changed and it is more often referred to, using the same examples, as 2x5 or 3x10, meaning 2 or three chainrings and 5 or 10 sprockets on the rear cassette. That is a better way of saying it.

For my examples, I've compared two common setups. A 2x10 and a 1x12. It's not easy to compare because, at the moment, it's typically 2x for road bike and 1x for mountain bikes. These two having a different target terrain and therefore different chainrings.

1x mountain bikes, typically have 30 or 32 tooth front chainrings and 11 to 50 tooth (T) cassettes. Having a slower top speed but easier for climbs, compared to a road bike.

2x chainrings usually have no more than a 16 tooth difference between the cog sizes. Say 52T and 36T or 50T and 34T The cassettes for road bikes tend to be a maximum of 11T up to 36T. For mountain bikes, that can be 11T to 42T.

Shimano MicroSpline and SRAM XD hubs can both go as small as 10T sprockets on the cassette.

To compare like for like ratios, I've had to show some less common combinations of chainrings and cassette sizes.


My conclusion is that for my riding, I am not at any disadvantage with a 1x groupset. A 2x10 with a cassette of 11x42, gives the widest range of ratios. However, the more common 2x10 with 11x36 cassette is almost identical to the ratio range of a 1x12 with an 11x50 cassette.

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Download the spreadsheet:

GearRatios1x2x.xlsx


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Thursday, 3 March 2022

Defender 300TDi heated seats

This is the second time I've added heated seats to Fender. This time I've done what I think is a tidier job.

Fender is a 1998, 300TDi, so there was no factory fit heated seats option. As usual, I've had to work out my own wiring. There is a convenient feed for air conditioning, which I've used for the heated seats.


It's not very many week ago that I fitted the heated seat wiring to our TDCi Defender, Thunder Truck


As then, I've fitted relays. Land Rover wire their heated seats directly via the switches. I am unsure of the rating of the switches and the after-market heated seat pads do not state what current each circuit requires. All I know for sure is that they are fitted with a 20A fuse, so it is safe to assume each seat uses no more than 10A. I've used that to size all the wire gauges.



I'm using an extended fuse box cover. I bought it so I had enough space for the extra relays without struggling but it was also the ideal place to mount the heated seat switches.


I made a bracket to mount the relays under the existing fuses.




Measuring where to cut the rubber mat

Before fitting the new Exmoor Trim seats I fitted the under seat rubber mat. Another Exmoor Trim product.


I've used some 1/2" (12.7mm) spacers to stop the seat rails catching on the thick rubber mats. The mats are so thick, I've found, that it needs at least 12mm spacers for the seat to move freely.




I needed longer seat bolts, so I bought some stainless steel M8x40mm torx pan head bolts which do the job nicely. I've done the same in both Defenders.






With the mats and the seats in, I threaded the cables before fitting the carpet and cubby box.



I've used Discovery 2 (D2) heated seat switches because, at the time I was looking, I could not get Defender TD5 or TDCi switches. The D2 switches are the same as the Defender switches, they just have different style caps. I've wired them so that the tell-tale lamps and the backlights work.





Tested and working well. Nice and warm.

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