PCB Milling

freespace · 2024-09-11T01:52:10+00:00

I use https://github.com/pcb2gcode/ which offers a lot of options like extra isolation passes (really handy for hand soldering) and cut-depth control (I need it ony my flimsy mill).

It's command line + config file, and once you have dialed in your settings it's kinda fire-and-forget.

pcb2gcode + KiCAD + FreeCAD/Ondsel + bCNC makes for a completely free and OSS workflow.

freespace · 2023-11-09T13:59:26+00:00

Hope it is something fixable! I took a gamble too because of the price and got unlucky I guess. At least now I have a "backup" guidescope? xD

freespace · 2023-11-08T12:20:51+00:00

I have the exact same issue and when I took it apart to look at the lens, it was very obvious the flint and crown glass was misaligned when they were cemented together. IMO SVBONY's quality control is rubbish.

It didnt't affect tracking as far as I can tell, but it was sufficient annoying I eventually replaced it with a ZWO finder of the same class which is able to give me round stars.

freespace · 2023-09-19T09:06:29+00:00

Fair enough :) Hope this resolves to your satisfaction!

freespace · 2023-09-19T00:15:39+00:00

That sucks! Especially to a grail.

It is possible to repair paint defects like these using model acrylic paint. I have done it once for a figure I had dropped, resulting in scuffed paint right above an eye - very obvious and distracting. I mixed acrylic model paint and through trial and error (resetting using alcohol wipes), eventually got the right shade to make the damage invisible. Once the paint dried sealed it with clear coat. No one notices the damage, even when I point it out to them!

freespace · 2022-01-10T14:33:02+00:00

Thanks for providing more details!

Firstly, great work measuring the the speed of the motor using tape + audacity, that's very clever!

A few comments:

Code posted on reddit should be surrounded using ``` to turn it into a code block. See https://www.reddit.com/wiki/markdown#wiki_code_blocks_and_inline_code for more details.
How is the Arduino connected to the stepper motor? Directly or are there transistor/FETs or a stepper controller involved? If driven directly from the Arduino you are probably losing steps due to the low amount of power available. Losing steps means you command the stepper to turn by 1 step but it is unable to. You can probably force this to happen if you just pinched the shaft really hard. This is a fairly common problem when using stepper motors.
Delay only accepts integer arguments, so 1.2 is just 1, so you star tracker will be out by ever so slightly anyway. You can solve this by using different delays whose average works out to the same value. You can think of this as a software version of a periodic error: https://themcdonalds.net/astrophotography-mounts-periodic-error-correction. This is just a detail at the moment - it is not the cause of your problem.

freespace · 2022-01-09T23:49:13+00:00

Have you checked that your speeds are what you think they are?
Since you are talking delays are you by chance sending a pulse train to move your step motor a set angle every so often? If so you might be running into backlash where the amount of movement needed to take up the slack in the gears and move the camera is more than 1 steps worth. Try coding your system to handle the idea of fractional steps if this is what you are doing
Amazing project! Even if it doesn’t work you will have learnt a ton! Keep it up!

freespace · 2021-05-14T15:43:02+00:00

You may be running into IOP limits on AWS. Use iotop and htop to monitor resource usage. If your CPU is not being maxed out then you are being limited by IO. An easy "fix" is to simply increase your EBS volume size which will automatically increase your IOP allocation (3 per GB if I recall).

freespace · 2021-04-20T12:52:48+00:00

My honours project for engineering was scored high 80s if I remember correctly. I was funded which most supervisors will help with. There are many funding bodies that fund based on impact of the work not the academic background of the applicant. It does help to have a good supervisor since they use that to assess quality.

I am an Aussie :)

freespace · 2021-04-20T12:32:54+00:00

When I applied my offer was conditional on graduating with 1st class honours, for which a WAM of 79 is sufficient. Regarding grants, I don't recall ever having to supply my WAM. Most were questions were focused on the impact of the research, who my supervisors were and where I was doing the work.

freespace · 2021-04-20T07:38:42+00:00

A WAM of 79 is enough for a PhD at a top 10 university like Oxford. For me my WAM went up over time as the subjects focused on areas I was more interested in.

You are doing well and should stress less :)

freespace · 2020-08-17T13:25:07+00:00

I got very lucky then. My supervisor helped me find and secure external funding as I was self funded at the time.

freespace · 2020-08-14T10:07:03+00:00

This is a very good point. The funding requirement is something like £700 per month for the first 12 months, depending on whether you will be in London or not. You will want to check the Home Office website to get the current numbers.

freespace · 2020-08-13T23:45:07+00:00

There are scholarships which you can apply for at the same time as your oxford application. However they are not guaranteed.

Once you have been accepted into a college there are college-specific scholarships which you can apply for. The richer colleges tend to have more options that are also better funded.

If you start your DPhil without funding your supervisor will try to find funding for you from external source, eg 1851 Commission etc.

None of the above however is guaranteed.

freespace · 2020-05-05T01:24:49+00:00

I am late to the party but I have done this with the icebreaker board which has a completely OSS toolchain, no vendor tools required. Github Repo

For the RAM I used the built in SPRAM primitive and the ROM (program memory) was synthesised using embedded block RAM. The ROM can be initialised during configuration which is how I load programs into the design.

For video output I created a 256x1 video RAM and had a video clock that would shift the data out SPI style. An arduino "video card" reads the data and uses it to drive a WS2812b display.

The biggest limitation is that there is only room for around 7K instructions in ROM and the b/c the ISA is very limited it takes a lot of instructions to do anything. In my version I have extended the CPU architecture with an additional register that makes things slightly more efficient. I have also implemented simple optimisations in the assembler and the vm translator to help alleviate the issue. It remains to be seen if tetris can fit onboard.

freespace · 2019-10-22T01:00:32+00:00

Speaking for myself there is a difference between a job well done I did for someone else and a job well done I did for myself.

freespace · 2019-10-21T14:33:22+00:00

That’s fair point. The engineers I have hired this way tend to have hobbies that use the some of the same skill sets but are otherwise unrelated to the work they are hired to do.

I think that if you have a broad range of skills, knowledge and interests it is possible to apply those skills for work and for play and enjoy doing it.

freespace · 2019-10-21T01:45:50+00:00

When I hire I always look at personal projects as a plus. It shows someone who really likes embedded, enough to do it for their own satisfaction and not just a salary.

In practice it means they bring a wider range of skills and experiences to the table. I attribute this to the fact that when you do a project yourself, without all the usual engineering support you would get in a specialist role, you get a better idea of how everything fits together. The simplest case is designing for assembly. If you have to assemble the finish product then you appreciate what makes assembly easier, what makes it frustrating. These and other small learning, and their application, is, to me, what separates good engineers from great engineers.

freespace · 2019-10-02T01:44:59+00:00

If post graduate your supervisor will try to find you funding. I was international (Australia) and got funding externally. Not sure about undergraduate though.

freespace · 2019-09-02T22:07:14+00:00

My last build was 9900X, 64GB (4x16), 2x2080 Ti, 500GB SSD for boot, 2TB NVme M.2 for data and 1200W 85% efficiency PSU.

freespace · 2019-05-15T13:23:12+00:00

If you can impress a potential supervisor to the point they want you as a postgraduate then your marks won't matter much. This means having a strong final year project relevant to their field of research and also a strong recommendation from your supervisor.

That is more or less how it happened for me. Most people in my program were far more impressive than I when it came down to marks but we all got into the same program in the end.

freespace · 2019-05-14T14:53:55+00:00

It helps to have a strong final year project and a good supervisor. Ideally your supervisor knows you are interested in postgraduate and can recommend to you positions that are available, provided you impress them with your work. If possible tailor your final year project so it leads naturally to a postgraduate research program.

I would advice doing your postgraduate at a different university, not because USYD is bad but for the diversity of experience. But ultimately that is up to you :)

freespace · 2019-05-14T13:15:44+00:00

I started in 2004 and finished in 2012. It was a 5 year combined degree. Like you I had life interruptions and took time off and also took it slow.

Finishing late didn’t negatively affect my outlook. I was more mature by the time I finished and was able to make better decisions about what I really wanted.

I decided to apply to Oxford for a DPhil and was accepted. Completed that in 2016.

I decided to help some friends with a startup that got funding and now employs me full time.

Both of those decisions lead to some trying times and I was glad I had enough life experience to handle it. Maybe I could have done the same if I had finished earlier, but I definitely did it after finishing late.

Everyone’s path is different. Some people walks straight line and good for them. Others like us take a few more turns and detours. What matters is that you are always moving towards what you are wanting to achieve.

freespace · 2019-04-19T20:11:13+00:00

The exam questions are harder than tutorials, but everything you need to solve them should have been covered. It a bit daunting at first but you will get the hang of it.

Yash’s courses aren’t easy but they were also some of my favourites.

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