Most G code generation software allows you to add start code to your G code file. A good method is to set the end stop somewhere near, then modify the zero position in software (you do a slight move in Z and reset the datum). It saves constantly having to move the mechanical end stop.by martinprice2004 - General Mendel Topics
It sounds to me like You haven't got the Z datum dialed in correctly. The first layer should squeeze a little on the bed, so either lower it in Z or increase the extrusion rate on the skirt and first layer.by martinprice2004 - Printing
Metal Injection Moulding may also be of interest to this discussion. A binder and metal mix is injected into a mould then fired. 3D printing such a mixture shouldn't be too much of a leap from this process. The Wiki page is here Wiki Page Here is an example of a company that does it and some of the parts that are possible. UK Companyby martinprice2004 - Reprappers
Pronterface is only reflecting what your G code is generating. The fault is with your G code. What ever you use to generate your G code, such as SFACT etc. Should have a setting in it to offset the part in the build area. Adjust this to half the build area dimensions and you should be somewhere close.by martinprice2004 - General
As usual when you ask a question like this you inevitably receive a few "It won't work", "its been tried before" comments, so I will counteract these with a positive one. Mixing a hard powder / fibre with a soft plastic does work. Its actually quite common in industry using glass filled plastic, titanium dioxide, chalk, carbon black and many other materials. There's a quick guide here. Plastiby martinprice2004 - Reprappers
Having a resin dispenser at the rear of the machine would need to have a motor to pull it in and out depending on the size of the tube and also how many layers you had laid down. I wouldn't be too hard to pull this back and forth in sync with the rotation to produce square or hexagonal tube. Alternatively the part could be tilted back and forth. After all this is how camshafts on automotive engiby martinprice2004 - CNC Routers, Mills, and Hybrid RepRapping
Excellent design. You need to ensure you have good tension on the filament though to produce a strong tube. This gives the fibres pre tension, but also avoids any voids or resin rich areas in the tube. You can do this by taping over the tube after lay up to squeeze out the excess resin, but this is messy. A better method may be to apply the resin separately at the back of the machine onto theby martinprice2004 - CNC Routers, Mills, and Hybrid RepRapping
I also understand that hanging shoes over power lines is used by gangs / drugs gangs to mark territory. Perhaps home defence may also come in useful when you start taking down their markers.by martinprice2004 - Laser Cutter Working Group
I am sure the local constabulary will be interested in your plans to use a cutting laser in the street. I am liking the quadcopter idea though! Here's a YouTube video to inspire you. Don't worry about the cost as it doubles up as a home defence unit. Inspirational Videoby martinprice2004 - Laser Cutter Working Group
Yes the circuit is a closed loop. To get it working you can connect them together and the robot should then function. When you wire the machine up with full safety guards, all the guard switches can be wired in series, so if one breaks the robot halts. As Viktor said, this is an interim solution and a full guard system should be added as soon as possible. Asimov's Laws have not yet been appliby martinprice2004 - Polar Machines, SCARA, Robot Arms
Thanks you for organising the meeting. I was really interested to hear your development stories and as mentioned above was surprised at the different uses you are using your repraps for. I am looking forward to the next meeting.by martinprice2004 - Beds/Herts/Cambs RepRap Usergroup
I have not had a look at the other 123 packages, only the design one (123d). There are other programs for sculpting and scanning which are also free which might accept other formats. .stl direct import is on the cards for a future release of 123d, but I believe it does accept .obj files. You might be able to go through Blender3d to get to .obj and then into 123d. Also have a look at some frby martinprice2004 - General
You can release your work under a creative commons licence. There are several to choose from including one which allows modification and private use, but prevents commercial exploitation. Creative commons You should consider why you are asking yourself this question. If you want recognition for your designs (i.e. Fame), not releasing it for commercial exploitation is probably a bad idea as youby martinprice2004 - General
Try the Autodesk packages. They are free. Download and use the "123 Design" for what you want. It is a full featured CAD package. Acad 123by martinprice2004 - General
External emergency signal is often some extra inputs on the panel connectors which are connected to other parts of the machine cell such as door guards or external E-stops. The robot when it sees this circuit broken applies all its brake circuits and pops up an error like the one you are seeing. The circuit is almost certainly a closed loop, so it is operated when the circuit breaks (For safetyby martinprice2004 - Polar Machines, SCARA, Robot Arms
There seems to be a few ways its done. One method It took me a while to figure this particular one out, it looks like the Z axis is a large pitch lead screw, the slow motion part of the video shows it. I think you may drive the lead screw directly with one motor and the lead screw nut with another. 1) Both motors turning the same direction. The shaft just spins with no rise or fall. 2) Turniby martinprice2004 - Polar Machines, SCARA, Robot Arms
@ttsalo Yes, similar thoughts struck me. The shafts from the pulleys are long and will twist a little even though the torque is low. The error is exaggerated by the long moving arms. The drive gears would be better placed at the top. I'm also not too keen on a rising table. There are a few benefits of a fixed bed which I would want to keep on my design. It was probably built this way to keep theby martinprice2004 - Polar Machines, SCARA, Robot Arms
Whilst working on my single arm SCARA robot I came across this video which I though I would post to show the potential speed and accuracy of these robots. If anyone has and details or images of how the end Z axis is implemented (it can plunge in Z and can rotate) please post any links. SCARA Robotby martinprice2004 - Polar Machines, SCARA, Robot Arms
@woo Linear rails are very difficult to print and no one has yet achieved it. Removing them and using an alternative method would enable more of the machine to be printed.by martinprice2004 - Polar Machines, SCARA, Robot Arms
Sounds to me like the easiest way would be with a single nozzle fed by several coloured filaments. this would save the complexity of head changing, If you used a square or hexagon nozzle block and fed the filament from the side you could tap the 4 or 6 sides and feed in. The heater element placed on the top to directly heat the area just above the nozzle. You could vary the extrusion speed of eby martinprice2004 - Developers
I thought I would post a link here to Quentin Harleys' "Morgan SCARA" robot. A really nice build and it prints very well. Morgan SCARA Now if we can just get rid of the linear rails for the Z axis we would be really on our way to a fully printable robot. I hope he posts the models soon as I am sure this will be a popular build.by martinprice2004 - Polar Machines, SCARA, Robot Arms
I haven't done any FDM printing off my various delta and scara robots, but I cannot imagine there will be a problem if the nozzle rotates slightly when moving across the part. There might even be some benefit. There is a potential problem if you use a bowden extruder (which would be best for this robot) as there will be twist in the outer bowden cable. This is bad, so you would have to float eitby martinprice2004 - Polar Machines, SCARA, Robot Arms
Inverse Kinematics are fairly simple for a delta and even easier for this configuration as Z is removed from the calculation. You probably only need pythagoras rule in this instance as arm lengths (hypotenuse) and distances in X are known. By the way you have no control of the head rotation of this robot. The extruder rotates around Z as you move in X. I would add an extra arm in a parallelogby martinprice2004 - Polar Machines, SCARA, Robot Arms
As Dale said this is really an enormous topic with no real straight answers. I am a CAD designer and there are a few rules as to how you would model a part. 1) Method 1 is imagine you are making the part on a milling machine. First block it out, then add the details. So for a holed block you would shape the block, then machine the holes. Its a simplistic approach, but works well for basic partsby martinprice2004 - 3D Design tools
Welcome to the ACL (Anti Cartesian League!) Its one type of "parallel robot". I think it would make a great robot design. Here's my variation on a similar theme. Your concept would be a little more compact though. HF04 How would you implement the Z axis? Rising table, moving the linear rails in Z or a Z axis on the end effector? Do a Google image search for "parallel robot" or "parallel lineby martinprice2004 - Polar Machines, SCARA, Robot Arms
I did suggest this configuration in another post, but on reflection, a H-Bot might be better for XY axes rather than XZ. Mechanically a H-Bot is probably less accurate than one with separate belts for each axes as the belt is effectively twice as long (or at least twice as long). The belt stretch and slack will make the positioning less accurate. OK you gain a bit by the doubling of the belt runby martinprice2004 - Developers
By the way is it possible to do a 3 axis H-Bot design with one belt and 3 motors? My brain isn't big enough to work out the cable configuration if it is even possible.by martinprice2004 - General
They do pop up now and again. I always find that an image search on google such as "H-Bot robot" is sometimes better than a webpage search. These two videos also popped out on youtube. Macron Dynamics Another one here H-bot 2 There's also a few images of a T-Bot configuration on the google search which works on a similar principle. Would make a nice X Z axis on a prusa.by martinprice2004 - General
Great to see this creating a stir. I wish them well with this. I was wondering if a design with a bowden extruder base station would be feasible. This way the pen would only need the heater. The pen diameter could then be much smaller. Maybe an airbrush type design with the filament coming in sideways through the palm of your hand may also be quite good for balance and ease of use.by martinprice2004 - General
Congratulations on issue 1. Very professional and lots of content and images. My highlights were the interview with Adrian Bowyer and information about new developments such as resin printers. I hope this will encourage others to submit articles for publication. I was a little disappointed when I opened my copy that you had failed to include a free toy.....not to be put off though I printed mby martinprice2004 - RepRap magazine