Sunday, 8 September 2019

New bikes

All the cycling, Shelley has been doing, has inspired me to go out riding myself. That has led to me getting a new bike.

It's the first full suspension bike I have had. So much nicer to ride on the terrain round us, than the hard tail, front suspension only, bike that I have had for the last 14 years.

Shelley has a Merida One-Twenty 7.800, 2015 model year.

I now have a Giant Stance 29er 2, 2020 model year.

I am very pleased with it. We did over 18 miles on Saturday, nearly all off-road. I kept up most of the way but I was struggling with the pace towards the end. A nice ride.

I made a couple of adjustments on Sunday. Most important was a new, more comfortable, saddle. That means more padding.

I shortened the handlebars, from the massive 780mm width down to 720mm.

I fitted a dropper post that my brother, Roy, and I serviced to get it working.
It's all setup ready to go.


Saturday, 7 September 2019

Rockshox Reverb service

My brother, Roy, offered to lend me a dropper post to try out. There was a condition. It needed to be serviced because, at the time, it was not working.

There are plenty of existing online tutorials, including the manufacturers videos, to show you how to carry out the service. Roy had already bought the kit of spare parts. Mainly rubber rings and other seals.

The following are bits of information that would have helped us to know, in advance. We might have known this, if we had read other articles!

Read the list of tools. Do not rely solely on the video.

You will need some specialist tools or some way to do the same thing.

None of them are expensive. The bleed tool is the most difficult to find an alternative to. You need something to block the hole but you also need to be able to release it to make sure nothing leaks out.

The 'oil height' tool is only used to suck out any remaining oil up to a level. A carefully held tube in a syringe would be able to do the job adequately. Just don't suck out too much fluid.

The 'IFP height' tool is also not essential but some correctly fitting metal or hard plastic pipe would be necessary. For the price of the tool, I would recommended to use it.

We did not have the appropriate offset spanners to use with a torque wrench. We used care and a guess, based on experience, of how much to tighten. Erring on the side of not breaking anything.

One tricky job is clamping the inner tube without damaging or marking it. We took it apart, very nervously, with it clamped between two flat blocks of wood.
Before we started the re-assembly, I made my own specialist clamp.

For the inner tube of the piston, it needs a 10mm hole, which I drilled in to some hard wood. I cut through the middle of the hole, along the grain, to form the two halves of the clamp. It works well.

 While I was at it, I added different size holes.

It took a few hours but we got everything done and back together and working, first time.

Having seen it apart, we know that the cause of the post getting stuck, was only the outer tube. In future we would probably carry out a service just to clean up the outer slide. That can be done without any specialist tools and may not need any replacement parts. Only if that does not work, would we buy the kit and service the hydraulics.

Once serviced it is necessary to bleed the shocks. Rockshox have another video to explain that.

I have since, fitted it to the bike.


Tubeless bicycle puncture repairs

If there is any advert for using tubeless tyres, it is how easy they are to repair a puncture.

Firstly, I would thoroughly recommend using the goop they put in them to seal small punctures automatically.

Shelley has Stan's Tire Sealant in hers. On our ride today we heard a loud hissing and could see the white sealant spraying out. All it took was to rotate the tyre so that gravity brought the sealant down to the hole and the hissing stopped.

We didn't even have to add any more air. Shelley rode the, nearly, 10 miles home without any ill effects of the puncture.

Since then, I've tried to add some more air and the extra pressure has burst the seal where the puncture is.

That was easily fixed with some tyre repair strips.

It was very easy to use the tool to insert the tiny 'anchovy' style strip in to the hole. About two thirds in and one third out. That can then be cut down, leaving about 3mm protruding.

The puncture was sealed immediately and I was able to pump it up to a much higher pressure than needed.

I thoroughly recommend carrying this type of repair kit.


Thursday, 15 August 2019

Inkscape fix for tiny icons on 4K screens

When opening Inkscape (v0.92.4) in Windows on a high resolution (4K) monitor it does not adjust the interface scale. All the icons are tiny.

This can be corrected by using one of the compatibility mode options in Windows.

Navigate to the Inkscape executable.
Right click and open the properties. Select the Compatibility tab and press the button to 'Change high DPI settings'.

Enable both tick boxes and select the settings from the drop boxes for, when: 'I open this program' and 'System (Enhanced)'.

OK out of that and next time you run Inkscape the interface should be a more usable size.


Wednesday, 14 August 2019

AI to SVG online conversion reviews

I needed to convert a single Adobe Illustrator (AI) file to a Scaleable Vector Graphics (SVG) file. Primarily I want to be able to reproduce it at any size with the minimum loss of quality.

AI and SVG are both vector graphics formats. AI is proprietary and SVG is open.

Good quality - finished result

I was surprised when I did the first conversion online that the result was a poor quality, apparently raster image, not a vector. I tried another site and got a much better result. That's when I decided I should write a quick review to remind me of which sites to use in the future.


The process was very simple. I uploaded the same file to each site, as instructed by that site. I asked for it to be converted and then I downloaded the file when it was ready. I compared the results in Inkscape.

It was a friend's file, so there was no value for me to pay for the conversion. It was at no cost or not at all.

I did not do any thinking, I expected the online site to select the best output for me. That may not have been appropriate if I was testing raster graphics but for vector graphics, I would expect a perfect reproduction without any need for input from me.

Speed: Quick. The 2 meg file took only a few seconds.


Output: Top quality vector graphic. Perfect. The black was blacker than the others and closer to my expectations.
I was able to ungroup components and re-position them.

Speed: Quick. The 2 meg file took only a few seconds.


Output: Top quality vector graphic. Perfect. The black was a bit greyer than I expected.
I was able to ungroup components and re-position them.

Speed: OK. Took less than a minute to convert.


Zamzar - close up of the tip of a petal - shows flaw

Output: Acceptable but slight flaws in the vector positions. The black was a bit greyer than I expected.
I was able to ungroup components and re-position them.
Speed: Quick. The 2 meg file took only a few seconds.


Output: Raster graphic encapsulated in a vector file. That is not what I expected nor what I wanted. Poor result. No groups.


I used a scan of some finished artwork to confirm which of the vector conversions was closest to how the original designer intended.


CloudConvert and Convertio produced almost identical results except for a slight variation in colour. Both will be perfect for my needs.


A bit about Vector Graphics

There are only a few applications whose main purpose it to create vector graphics. Adobe Illustrator is probably the most widely used professional application. It is very well known and liked. For those of us that are reluctant to invest that cost for the odd bit of casual drawing, it is more common to use the free Inkscape application.


Tuesday, 13 August 2019

CNC plotter pen holder

To help test my CNC proof of concept I have designed a couple of pen holders which I have 3D printed.

One utilises a modified ballpoint pen and the other fits a fine point marker pen.
At the moment I have only tested the one for the ballpoint.

Ballpoint Pen
I have cannibalised a couple of ballpoint pens to make one that has a spring tip. I took the inch long spring from a cheap retractable pen along with part of the ratchet mechanism.

The spring fits at the opposite end of the pen, pushing down towards the tip. I cut down the ink tube, a little at a time, until the spring, sitting on the ratchet, sitting on the tube, would fit in the pen and have about the same amount of give as I would put on the pen when writing.

The pressure was trial and error but as it worked first time, I guess it was not too difficult to judge.

The result of modifying the pen, is that all I need for the tool holder is a clamp. I just made it fit the same holes as the spindle would use on my budget Chinese CNC machine.

1x M4 wingnuts
1x M4 A type (standard) washer
1x M4x40mm bolt

Marker Pen
The design for the marker pen is a bit more complex. I could not modify the pen, so the holder had to be spring loaded to get the right pressure.

Again, I used the roughly 1 inch long spring from a give away retractable ballpoint pen.

In this version the pen sits at an angle and pivots. It's only a little bit of movement but enough to keep the pressure on the pen tip.

Unlike the pen holder, the motion of this version means that the marker is not perfectly aligned, at all times, so this is OK for testing in place of a spindle but it is not ideal for detailed plotting.

This design took a few attempts to get the mechanism right. It's a bit larger than I would have liked but it had to be to accommodate the 13mm diameter of the marker pens that I had to hand. I will, most likely, use this on a larger machine.

2x M4 wingnuts
2x M4 A type (standard) washers (optional)
2x M4x40mm bolts


Pen holder STEP, Fusion 360 and STL files (Zip)
Marker holder STEP, Fusion 360 and STL files (Zip)
Licence attribution - small business exception

My designs in the Fusion 360 Gallery.
My models in the GrabCAD library.
My designs on


Shapecut Series:
Part 1 - Magic Eye to CNC
Part 2 - CNC proof of concept design
Part 3 - CNC controller enclosure


Monday, 12 August 2019

Using DXF2Gcode with UCCNC

I have now output a drawing from my proof of concept CNC machine.

Created in Inkscape, saved as a DXF file, processed in DXF2Gcode, loaded in to UCCNC and plotted using a pen as the tool in my CNC machine.

I needed to configure DXF2Gcode to stop the pen crashing in to the page as it tried to act like a cutter. In the process I have learnt some of the configuration for the post processor but apart from a minor compatibility change for UCCNC, the post processor can remain almost as default.

I found some of the choices in DXF2Gcode disappointing. There is a save function for the post processors but not for the Machine settings. That seems to be the reverse of what would normally be needed but perhaps that's just because I am new to CNC control. I'll investigate this further.

Workflow for a plotter
  • Load the DXF file. This takes a few moment. It's not very quick.
  • Turn off layers that are not required. Just untick. The display usually changes to reflect this. (View-Show Disabled Paths)
  • Worth saving the project at this stage.
  • Change settings (Options-Configuration...)
    • Machine config (to generate a single pass and avoid crashing in to the paper)
      • Slice depth = -0.01mm
      • Final mill depth: -0.01mm
  • Apply those changes
  • Options-Postprocessor configuration... (now I have created a suitable config.)
    • Choose configuration file: Plotter_WIP_v7b.cfg (or whichever file is appropriate)
    • Apply that
  • Move the starting point somewhere appropriate (Options-Move Workpiece Zero)
  • Export-Optimize and Export shapes

That works with UCCNC. I have to press the Cycle Start button twice, so I think I still need to sort out the correct G code startup sequence.


On Windows 10
Config file location: C:\Users\%USERNAME%\.config\dxf2gcode\config
Post processor file location: C:\Users\%USERNAME%\.config\dxf2gcode\postpro_config

Each G code needs to be on a separate line. The default startup sequence puts them all on one line. This is easily changed by inserting the returns in to the Startup field on the post processor config page.


Shapecut Series:
Part 1 - Magic Eye to CNC
Part 2 - CNC proof of concept design
Part 3 - CNC controller enclosure


These are some notes that I didn't know where else to put.


DXF2Gcode source:

Alternatives to DXF2Gcode
I've struggled to find a comparable alternative. Most are now inactive projects that have no working links or are far behind what DXF2Gcode can do.
Most of the time I will use Fusion 360. That is more than capable of carrying out this task but it needs a lot more setup than I think should be necessary for most simple profile and 2D cutting jobs.
Here is a list prepared by others:
The Path Workbench on FreeCAD looked interesting but as it stands at the moment, the DXF file importer, built in to FreeCAD v0.18, failed to import any of my test DXF files correctly. I was therefore unable to test it for what I wanted.
Another one to try is FreeMill.

Paid for products
I have not tried them but the following have been recommended on forums:


The Travelling Salesman Problem (TSP)
In reading about CNC G-code generation I kept coming across references to TSP and the Travelling Salesman Problem.
Most articles did not explain what this was but that it was to do with optimising the g-code.

I eventually managed to find an article that explained it. In short:
What is the shortest travel time for the sales person to reach all the destinations on his agenda.

In the context of CNC this relates to the long travel between cuts. What is the optimum number and lengths of travel to accomplish the task in the shortest time.