Member postings for Colin LLoyd

Ian, I just went and bought one of the Chinese CNC Engravers on Ebay - generically known as 3-axis 3020 or 3040 machines (the numbers refer to the engraving area (30 x20 cm, 30 x40 cm)). I run this exclusively on a dedicated Linux PC using LinuxCNC as the machine operator software and Inkscape with its Gcode extension to create patterns for export to LinuxCNC. The machine has worked effectively, with most failures being down to me using wrong speeds or wrong routing bits for the base material. I've never had a failure with the overall CNC aspects of the machine. I'm now converting mine to use a Pulse Width Modulated 2W Blue Laser to surface burn photo-realistic images onto wood.

Colin

My advice to anyone starting out with 3D printing is to keep things small and quick to start with. Not too many layers, not too long to complete build - this way you will quickly come to appreciate the foibles of your particular machine and where you need to investigate failures and consequent adjustments. As a complete beginner (graduated to novice now) at all aspects of machine engineering (lathe, milling, scrollsaw, CNC engraving, and 3D printing) - I never started by trying to produce a "wanted" object - just turned, milled, cut lines, engraved circles, printed a small round pill box - on scrap metal, plywood, PLA, etc). This way, I was never disappointed with the machines, only with my own failure to see the obvious, and not so obvious, when things went wrong.

With my 3D printer, the major problem was with the long 45mm linear bearings on the z-axis. These require either near perfect rods to slide on - or in my case, putting the rods into the lathe and emery papering down the rods from an interference fit on parts of the rod to slick movement with minimal loss of X-Y position. You could feel the resistance of the bearings on the rod and when this had been removed.

Colin

Hi Ian - glad I could help. If you want to start thinking about the assembly - there is a whole series of videos (27 to be precise) showing the assembly procedure in detail. Here's the link for the whole series

**LINK**

Colin

I'm no automotive engineer, but I know that items on my car fail quicker from percussive potholes than from prolonged steady oscillation on motorways. But the point about the moving quill is well taken - just that, in my case, it looks more trouble than it is worth to create such a solution.

To all the forum members who imply that you shouldn't over-tighten the drawbar - I agree (and I don't over-tighten) - but that was not my point. I just don't like giving anything a mild tap with a (in my case copper) hammer when a less neanderthal method can be applied. I am dealing with small lightweight lathe and milling machines with appropriate small and lightweight bearings but with the same frictional forces applying to the tapers as for hulking great brute machines. It seems to make sense, if it can be achieved, to apply some model engineering finesse to the procedure.

Colin

Hi Ian, I'm no expert and have only experience with one 3D printer but I bought the Geeetech i3 Prusa Pro B printer off ebay (currently selling for around £159) and have had no cause to complain - except for things that were my fault. It depends on whether you want to buy one fully assembled or in kit form that you have to assemble yourself. With the Geeetech you have access to about 8 videos showing you in minute detail how to assemble. Despite never having built a 3D printer before, I found the whole process quite easy if you took your time and applied Model Engineering practice to the assembly. if you do get a Geeetech, then feel free to contact me if you get stuck. Just make certain that the model you choose can print many different filaments but generally ABS and PLA and that the model comes with a heated bed - these can be added as an upgrade - but best to get one from the word go. There are many suppliers of this printer on ebay - go with the seller with the best rating. I got mine from "Geeetech-official" ebay seller but the kit had to come from China - so might not suit you if you wanted it before the middle of January. Hope this helps.

Colin

Hi Jason, my drawbar top has a square section for spanner (10mm each side) and 12mm deep.

Thanks Jason for the explanation - it helped. But I don't think this will work on my particular Amadeal XJ16-300 mill which doesn't have the necessary spindle protuberance above the spindle locking nut to allow mike's cap to work. As you can see from the diagram below - the spindle locking nut is virtually a flush fit on the spindlewith no opportunity to drill the cross spindle holes. So I think my only choice is to go with some form of over-the-top bridge setup.

Colin

Thanks John - and yes it seems to be a neat solution - if I could only work out how it actually works. Despite the text explanation, I can't understand what the drawbar is pushing against - and without knowing this I cannot make a bespoke version to fit my particular milling machine drawbar - whereas I unsderstand fully my swing bridge design. Perhaps a cross section of mikesworkshop version would help to explain the principle. In the meantime, I will try and draw a cross-section of mike's and see if that helps me.

Colinj

Having looked at the various suggestions for releasing the taper/drawbar without resorting to use of a soft hammer - and failing to work out how some of them work - my fault with my limited appreciation of terms used in metalworking - I wondered whether a simple swing bridge above the drawbar that is bolted to the spindle housing would suffice. The diagram illustrates, in principle if not in practice, what I mean. I haven't made it yet - as forum members may have suggestions for either saying it won't work or improving it. The gap between the drawbar (in red) and the bridge is sufficiently small so that unscrewing the drawbar forces it against the bridge and, by reaction, releases the taper spindle. The slotted bridge allows the bridge to be swung completely out of the way for either withdrawing the drawbar or maintenance/changing of the belt drive.

Message to Iain - I note that you are using bulldog clips to hold the glass plate to the table. Might I recommend you use Rapesco SupaClip 60 spring clips instead. Bulldog clips can get in the way of the extruder nozzle as it travels across the table. Supaclips are much flatter. The Supaclip 60 is the largest I think Rapesco do - but these will hold the glass plate very nicely - and the Supaclips have many other uses around the workshop or office. You can get them from any number of suppliers including Amazon.

Colin

Hi Neil, - Slic3r and Cura are both mapping options within Repetier-Host and both have a "brim" function - something that I never knew until now - so rather than make a surrounding support in OpenSCAD I will try this function first to see if it cures my problem.

I've had no problems at all with running Repetier-Host/Slic3r under Windows 7 from a Sony Viao laptop via USB to my Geetech Prusa i3 Pro B Printer. I know the latency problem is there with CNC machines - as I have to run my CNC engraver/router from a desktop PC using LinuxCNC software via its parallel port. USB - being a serial communication - cannot deal with the often parallel operations that CNC machines operating at speed need to deal with. 3D printers don't run at the speeds that CNC machines do - so I just wonder whether this is why USB communication seems to work (at least for me) with 3D Printers. The problem with USB may also be a legacy from USB 1.0 - something that may not be there with USB 3.0 or 3.1. Of course - if the software on board the 3D printer cannot accept USB 3.0 then that may be the problem. There are CNC USB controller boards that evidently take the place of the parallel port communication - although I suspect that these boards just buffer the serial data into a parallel port configuration before sending the data to the various stepper motors etc -see, for example

https://planet-cnc.com/hardware/

Colin

Thanks John - the only bit of your advice that I haven't done until now is "maintenance while hot". I even make the teflon sleeves a bit longer so that it forms a pressure seal against the nozzle. The only times I've had to do maintenance on the hotend is with PLA - which if you leave it in place after a "build" tends to break off leaving a short length in the hot end - I've learnt not to do this now and reverse the filament out of the hotend - while hot. This breakage doesn't happen with ABS - and its quite OK to leave the filament in the hotend - ready for the next print

On another matter - has anybody had the following problem with Mk8 hotends: while I have no difficulty in removing the extruder nozzle from a heater unit - the hollow screwed tube that contains the teflon tube and connects the aluminium heater block to the stepper motor/filament supply unit often becomes welded somehow to the aluminium block (whether leaked liquid filament glueing it or actual metal welding I don't know) to the extent that trying to unscrew the tube (using twin locking nuts) causes the tube to shear off. The only solution then is to drill and ream out the screwed (in both senses of the word) tube or just get (or make) a new aluminium block.

Perhaps there is a high temperature grease that I can apply to the thread before inserting into the aluminium block. Any comments/suggestions would be welcomed.

Hi Jeff - thanks for the advice - because I haven't had problems before I never thought about using sacrificial parts - but I will from now on - and your suggestions make perfect sense.

Neil - Cura is an option in Repetier-Host that I might try. Again, Like Jeff - your suggestions make perfect sense and I will keep these in the back of my mind in future.

The apparent "brim" around the outside of the wall is actually part of the pickup cover allowing the two items (pickup and pickup cover) to be joined to the pickguard. On the question of PVA - do you just use any DIY PVA from the likes of B&Q or some specialist "fine" PVA as sold as paper and cardboard glue by Smiths? Also what dilution do you use?

I'd just like to echo Jeff's wish for a "Merry Christmas" to all forum members.

Just an update on recent 3D printing experience. I thought I was doing very well with my ABS printing until I tried to make an open guitar Pickup Cover for a Uketele project (It's a Ukelele with a solid Telecaster body for a friend's young son). All seemed to go well with my normal hairspray adhesive coating to the heated bed at 100 deg C and extruder at 230 deg C. First few layers all OK - but as the sides built up, the ends were beginning to curl away from the heated bed - eventually the whole build detached from the bed and followed the nozzle around the table in a sort of Viennese Waltz. My conclusion is that the bottom layer was lacking in material to adhere to the bed. My solution (although I haven't yet tried it) is to infill the bottom layer with a thin but extensive rgion to provide the adhesion - this infill will then be cut out afterwards. The photo shows my OpenSCAD drawing of the pickup cover with the infill region (the light green region at the bottom of the "walled" area). I'm also waiting for some Kapton tape to arrive - will give that a try as also the diluted PVA glue approach. I'm told that "Purple" glue Sticks also work as a bed adhesive - anyone know what these are?

In tropical rain-forests it's the only way - you can't meander cables through the canopy. Quite often the crossbow bolt would strike a branch and fly off at a tangent. The guys on the ground generally hid behind wide tree trunks when I was cross-bowing.

Neil - One of the reasons I liked working abroad is the lack of health and safety silliness. Of course I took safety seriously, both for myself and for my colleagues. As an example of the silliness - in the UK I would be required to wear a hard hat and have a safety harness around my waist attached to the tower. With tower sections only 1.96 m high, you are constantly banging your head on the section above - so distracting you. When you are building these towers - you stand on the top and open out the section and then attach "clawed" poles to create a stable cage. You don't need a hard-hat - there is nothing above you. And the harness is connected to the section below you - so you constantly fall over it. Fear is a great safety function. To get the cables attached to the tower, I used to fire crossbow bolts with fishing line attached at 45 degrees declination to targets on the ground beneath the trees. Colleagues on the ground would then attach nylon cord to the bolt and I would reel in the fishing line. Then the ground crew would attach the 10mm diameter woven steel cable to the nylon cord and I would then pull the cord and steel cable up to the tower. With cables at the top being nearly 80m long and having a set of 4 cables every 4 sections, this process was rather tiring. Crossbows are probably banned in the UK now.

I have no idea why they are called thimbles - but they were an essential part of the long steel cables I used to support tall aluminium scaffold towers that I built over both UK forests and tropical rain forests in Brazil and Cameroon - the tallest being 52m high, 27 sections each 2m x 1.5m x 1.96m tall. Photo shows one of the towers in J--Parana, Rondonia, Brazil.