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simonr

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Posts posted by simonr

  1. I started with a cheapo plasma - and gave it to BusShed as I could never get it to work well (*see later!)

    Then I bought a cheap, used Hypertherm and it was amazing.

    Mark (BusShed) said it worked perfectly!  However, his compressor had a huge reservoir.  I later discovered that the evenness of the air supply is critical.  If you have a piston compressor with a small reservoir, the air pressure pulses with the mains frequency.  Since the torch voltage also pulses at 50Hz, you can see problems if the phase of the pulses in the air pressure are in or out of phase with the torch voltage.  The phase is affected by things like the length of hose.

    When I bought the Hypertherm, I also bought a cheap used Hydrovane compressor - and I think that's why it worked so well by comparison.

    Sometimes people complain about the cost of Hypertherm consumables (roughly £10 per Nozzle or Electrode) where you can buy 100 Chinese ones for the same.  However, there is a big difference!  The airflow through the Hypertherm is much tighter & more cylindrical which concentrates the arc more and gives you a cleaner cut.  The arc being more concentrated also increases the cutting depth for a given power.  They also last a lot longer.

    RTech are not bad for the price but their HF Start is too (electrically) noisy for CNC.  I used to have one of theirs too but it was only useful for hand cutting.  The HF Start on the Hypertherm however doesn't cause any upset to the electronics.

    In your place, I'd buy a used Hypertherm Powermax 30 or 45 (the main difference is the duty cycle).  I have a 30 now and it's fantastic for both hand and CNC.  It's only 30A, but out performs the 50A RTech and the 60A Chinese one in terms of tidy cut depth.
    image.png.725209f1abdbd8e3f9af186624ecec71.png

    This is my current (3rd) itteration of my DIY CNC Plasma - you can just see the Hypertherm on the floor underneath.  I get nice cut quality up to 10mm & OK up to 15mm.

    P.S. Don't believe the "50mm cut depth" type adverts - they are mostly very optimistic.  For a clean cut, I would bet on about 3A per mm for Hypertherm, 6A for Chinese.

    • Like 2
    • Thanks 1
  2. Something worth mentioning here is your Volt Meter (Multimeter).

    The accuracy of a mid-range meter can easily be +/-1.5%.  Cheap ones, even worse. 
    Even a high-end meter will only be +/-0.3V DC Volts just after it's been calibrated.  I would never rely on it to be better than +/-1%.

    A mid-range meter showing 14.5V could actually be anything from 14.3V to 14.7V.   (On a high end meter, 14.35V to 14.65V)

    Thus I shouldn't worry too much about such small apparent voltage differences.   

  3. The distance is important - but most scanners will tell you when the distance is correct.

    A turntable with a fixed, adjustable scanner is useful for some scanners.  Mine needs you to kind of 'paint' the surface - so having it fixed isn't helpful.

    I do have one of these: https://www.amazon.co.uk/gp/product/B07BJ3FQ9Z/ref=ppx_yo_dt_b_search_asin_title

    A super-cheap turntable which has been useful for things that are just a bit too heavy to move around - things like a hub assembly.  As Fridge suggested, I've used a wheely trolley for bigger things like a 60kW electric motor for a wind machine.

  4. 33 minutes ago, elbekko said:

    But what this thing really needs is a start/stop button on the handle, instead of having to reach over to the phone/computer.

    I've also noticed the phone app has an undo button while scanning, but the computer one doesn't for some reason. That's too bad.

    It wouldn't be hard to design a handle + phone holder with a couple of buttons linked to levers which press on the appropriate bit of the phone screen.  You can get pen type stiluses which will trigger a touch on a phone screen - so if the lever had the rubber tip from one of these, they could simulate the touch.

    I downloaded this handle for the Einstar - which makes the thing much more comfortable & stable to use:

    image.png.bb1c85fca2694c31fbaf1dd651f7bcf0.png

    I re-mixed it a bit, adding the boss on the right which takes a 1/4 Thread insert.  I have one of these screws which pokes through te other hole to secure it to the scanner, which, when not in use screws into the thread for storage.

    EINSTAR HANDLE 2.STL

    • Like 2
  5. 7 hours ago, De Ranged said:

    Simonr what is Xtract3D like for surface profile work

    I don't know!  I tend to use it for planar surface & feature extraction - for reverse engineering.  For that, it's very useful.

    Speaking to one of my friends, he says he uses Blender when he's trying to work with 'sucked sweet' (as he put it) type shapes to extract surfaces & bring them in to SW.  However, I've never used Blender so have no idea about the workflow

  6. On 3/9/2024 at 1:16 AM, De Ranged said:

    solidworks has only really sorted mesh tools in the latest version

    That's true - but it's still pretty clunky to use!  I use an add-in called Xtract3D which is better, but still not perfect.

    Fusion has a much better toolset for dealing with meshes.

     

    I've been using Chalk Spray: https://www.amazon.co.uk/Montana-Chalk-Temporary-Marking-Eco-Friendly/dp/B00JEECAEW/ref=sr_1_5

    It has the advantage of being available in multiple colours.  The scan specific spray always seems to be white, which is great until you want to scan a shiny white thing!

  7. The results look good.  I would also be interested to see what kind of measurement accuracy it delivers.

    It's worth trying with an object you can scan all the way around to see if the scan at the end lines up with that at the start.  That's a good test of the cumulative accuracy.

    Hairspray works quite well for matting down surfaces.  You can get chalk spray which is better, but more expensive.

    Your scanner appears to cope with shiny surfaces a lot better than the einscan - but the more help you can give it, the better the results.

    I do use retroflective location markers too - but they are surprisingly expensive & you can eat a whole lot of them! 

    I drew & printed a load of these https://www.thingiverse.com/thing:5787919/files

    If you insert a magnet and cover the sides with marker dots, you can scatter them over something you're scanning - but re-use them again & again.

    • Like 1
  8. 12 hours ago, elbekko said:

    Yeah, I think I'll order a Ferret Pro, unless someone chimes in with a "OH HELL NO!" soon :P

    I'll be very interested to know how you get on.  I almost ordered one last night - but realised I'd need to upgrade my phone to work with it.  Apparently, mine (S10) is too slow / old!  If I factor in the cost of the phone, it becomes less attractive.

  9. 31 minutes ago, miketomcat said:

    We had a boat 3D scanned

    I used it to scan a replica Roman boat (which was used in Indiana Jones) in order to make a cradle to support it on a motion platform.  It's owners were a bit precious about it and we only had to boat for a couple of days filming.  I went to their yard to scan it - then we had accurate measurements to build the rig & internal structure for lights, camera etc, knowing it would all fit when it arrived at the Studio.  The compound curves of the hull - and that none of the internal beams were particularly straight would have made it near impossible to measure with a tape with the required accuracy!

    I do often have to survey structures (quite often boats) and for me, this has been a game changer!

     

    • Like 2
  10. The Creality CR Scan Ferret looks surprisingly good - and half the price of mine.

    Being able to use a phone as the capture device would be very useful for getting in & around vehicle bits.  Mine has a long umbilical to my laptop but it needs mains to power the scanner with a chunky power brick at the laptop end.

    I'm quite tempted to buy one - my only hesitation is the lack of storage in a typical phone.  One of my raw scans was over 600GB.  Maybe it does something clever to compress the data?

    A while later... Having watched a few videos about it, the CR-Scan is limited ot 2000 frames per scan, or about 60 seconds of scanning.  While this doesn't give enough time to walk around a whole vehicle, you could split it up into multiple scans & stitch them together.  The Einstar is only limited by how much storage space you have.  My 600GB scan took several hours.
    image.png.cb714c2f92456d60f76ed80d4272cb35.png

    This is one component from that scan - an engine from a Willy's Jeep. 

    • Like 4
  11. 11 minutes ago, elbekko said:

    That's definitely good feedback! Probably would help to do it in multiple scans and not one big scan?

    That would help - and the software generally has tools to automatically splice scans together.  While this is normally used so you can scan both sides of an object, it equally works for side by side, so long as both scans contain a couple of reference points for alignment.

    One of the mistakes I made at first was confusing resolution for accuracy.

    If you set very high resolution, say 0.1mm - it just records lots of points, filling up memory very quick.  If you set a lower resolution, say 2mm, the precision of the location of the points is just as good, just fewer of them.

    Now I tend to do a low res scan of the whole of the object and multiple high-res ones for things like mounting centres - then stitch them together at the end.

    • Like 2
  12. I have an Einstar Scanner - and it's pretty good for the money.

    If anything, the software for the scanner is more important than the scanner itself.  The Einstar uses the same software as their more expensive Einscan scanners - and as such is also prety good.

    Bear in mind (also) that you need a PC with a decent amount of memory for it to be useful.  I use my laptop with 64GB and it has coped with everything so far.

    It takes a bit of figuring out - but you can get good results.

    One of the issues that most of the cheap scanners have is the inaccuracy is cumulative.  I tried scanning a Chassis about 10 years ago - and although the scan looked OK, when I tried to turn it into a CAD model, it was obvious that it was twisted & deformed by about 15mm at the opposite corner to where I'd started.

    The Einstar seems to manage about +/-0.5mm on any two points per metre apart.  It's still not perfect but +/-3mm on a chassis is a lot better than +/-15mm.

    • Like 2
  13. I thought it was OK to read - and I agree with his style changes!

    I've test driven one - and thought it was wonderful to drive.  I was very tempted to buy one but just couldn't persuade myself I liked the styling of the exterior.  Interior is pretty good though.

    I keep hoping it will grow on me.

    I'm not seeking for a retro looking Defender, just something that embodies the feeling you get from original Defenders, G Wagons and a few others.  They look a lot better covered it accessories to break up the solid colour, but I'm not a fan of covering vehicles in boxes, ladders & stuff.  The guy might be on to something, that all it needs is a different paint style, just to break it up rather than to look retro.

  14. 21 minutes ago, elbekko said:

    Reverse engineering ECM to gearbox communication will most likely be a lot more involved, although hopefully in '99 it wasn't so bad yet.

    If anything, it's become easier!  More modern vehicles have more individual networks as well as bridges between them - which limit the amount of data traffic on any one network.

    My general approach has been to build / write a 2 port bridge and insert it between the ECM and the thing you want to control.  All traffic has to flow through the bridge.

    Initially, you just block individual packets from reaching the device, and look for when it starts to malfuction.  This will tellyou the address of the device from the ECM's point of view.  The packets sent by the device will give you the addresses of everything it wants to talk to.  You then just filter out everything outside that address range.  If it continues to work, you know you've got everything.

    Then it's relatively easy to see which packets change with things like RPM or Temperature.  Try waiting for a packet addressed to the device to come from the ECM, change the data and send it on to the device.  Some devices require the timing of packets to be accurate - so letting the ECM initiate the transfer, avoids that mostly.

    By breaking down the problem, it becomes much easier & quicker to solve.

    This was the last one I made: https://github.com/SimonRafferty/Polaris-GENERAL---CANBUS-Bridge
    But I've used the same hardware & software configuration several times.

    • Like 2
  15. 14 hours ago, FridgeFreezer said:

    Being programming sort of person I use OpenSCAD

    You might imagine me being similar.  I have used it, but compared to the modern CAD packages, it felt like a rediculous way to model something!

    For something free, I would either go for OnShape or Fusion.  Onshape is fantastic - and I'd use it professionally, except we're not allowed to use Cloud based software.  Fusion is very capable, but lacks a few of the features I use a lot in Solidworks.

  16. 22 minutes ago, elbekko said:

    But even for the P38, there's barely any information available on the CAN messages

    The reason is JLR (and other manufacturers) guard this info very closely!  I worked for a company who had bought (and it was a LOT of money) the list of CAN PID's for Range Rover.  They wouldn't even let me look at it!  The NDA appeared to list the specific people permitted to view the data.  They were developing the surround-view camara system for JLR & even though they were working on a project for JLR, they still had to buy the info.  Even their list was redacted to the extent that some of it had to be reverse-engineered.

    I was surprised by the level of secrecy!

    13 hours ago, FridgeFreezer said:

    I disagree - in many ways it's never been easier or more accessible.

    Some & some.  Accessing some of the functionality is fairly easy & cheap.  Some of it, not so much.  At least with something mechanical, you can figure out most of it by looking & measuring.

    Most of the problems in vehicles are still mechanical or (basic) electrical.  It's rare for problems to be with the firmware and often the same firmware can assist in diagnosing the problem.  So, for most of problems, the computers just give you another tool to help figure it out.

    That said, I do like vehicles having CAN networks - just because it gives even more options to hack / improve / repurpose things.

    • Like 1
  17. 1 hour ago, FridgeFreezer said:

    Did you print the labels in yellow 1st, and what was the process for that?

    I have a Bambu Labs printer, which will print in 4 colours / materials.  There have only been a few occasions where printing in 2 materials has been useful - such as felxible button caps in a hard plastic shell, kind of like a keyfob.  However, printing decals has been very useful!
    image.thumb.jpeg.937515c7698d2ee652330033889c2eac.jpeg

    • Like 2
  18. A few more things of limited interest!

    Bike computer in a waterproof box.

    image.png.0ae774fd2f0bb605c69a253cc6c2539c.png

    A panel for a battery box.  I love the ease with which I can make tidy panels!

    image.png.c64741fd82cd1c0c2aca0d286f00dd37.png

    Variable power supply, powered by a DeWalt Battery.

    image.png.476b6c02d4c7a8e836775b1fc6abf72d.png

    This is a bi-stable clamp with printed springs.  It's actually to hold the cable-lock on my bike.  Push the cable in-between the jaws & it snaps shut.  It works well & has a very satisfying action!  I printed this in PETG as PLA is too brittle for the springs.

    image.png.9426ac6ca1c73849482a09ae98b02ebc.png

     

     

    • Like 3
  19. PETG is good - I always had problems with it - however, as you say, maybe the problems have been solved!

    Generally, PLA will give better appearance prints.  It's stiffer than PETG, but more brittle.

    PolyMax is stronger than regular PLA giving the stiffness of PLA with most of the strength of PETG, but on the whole beter print quality.

    I use PETG, PAHT or HIPS if I need higher temperature resistance.  Current favourite is PAHT which gives the best compromise all round.

  20. On the filament front, particularly if you're wanting to print something tough, PolyMax PLA is about as good as it gets.  It's not cheap - but it's better value than cheap filament for consistancy and number of successful prints.

    In terms of useful tools, where it really wins is printing fixtures for specific jobs.  One such was wanting to drill a hole between two diagonal corners of a cube.  At first glance, it appears simple - then you realise that you have to deal with compound angles, none of which are whole numbers.
    image.png.bd270b541b1e681f09f7cb7ae9fd77e5.png

    After our machinest spent a couple of days trying to figure out a way (only manual, basic machines) I printed a socket in 2 halves which went in a Lathe - made the job very easy.

    I recently needed to drill a series of 12 holes in a heatsink, 15.85mm apart.  It was much quicker to draw & print a drill (centre punch) guide than to mark them all out manually (I needed to make 12 of them).  End result was spot on.

    image.png.b604ffae8e4c04c1011257abab7f6f73.png

    Also good for making panels & enclosures.

    • Like 1
  21. 10 minutes ago, Sigi_H said:

    In my experience not. Inside the circuit almost no transients are created

    Perhaps, I should have phrased it 'noise' as people often interpret 'transient' as high voltage spikes - where it just means brief.

    Stick a scope on pretty much any pin on a typical microcontroller & you'll see plenty, particularly if WiFi or BT are active.

    All of these things are layers - add as many as you think you need for the level of reliability you want.  If you're just switching the interior light on & off, you can get away with none.  If you're controlling more critical systems, more.

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