I understand by your thinking that your method would be to envelope the whole machine. Unfortunately doing it this way would mean that all the robot arms and centre platform could not be reprapped as they would become unstable at 100 Deg C along with the part as they are made from the same material. The reason I suggested a liquid is that the top of the machine could remain relatively cool compby martinprice2004 - Delta Machines
Its the difference in temperature between certain areas of the part that cause the cracking. Industrial machines use heated chambers, so the part cools uniformly at the end of the print. For very large thick parts, you coudl still get cracking as the core would cool less quickly than the outer, but this is a known problem in metal casting and plastic moulding. You just design your parts with unifby martinprice2004 - Delta Machines
I have just been doing some trials for a printed core for a carbon fibre bike frame. I printed in ABS which is less dense than PLA. My idea was to try to get a core that was as light as PU foam over which I could skin carbon fibre for strength. I failed miserably even though I went to very thin walls with 5% fill. I wasn't going to use the ABS for strength, just for shape, the carbon skin would pby martinprice2004 - Let's design something! (I've got an idea ...)
I was just looking over the Rostock Delta and is struck me that because the part is now stationary, there is a method that could be used to give a "heated chamber" effect, this could mean that we could finally print large parts in ABS. The part could be printed in a walled bath and as the part is printed, hot fluid could be introduced around the part just below the print height. It has been sugby martinprice2004 - Delta Machines
Tracked down this video also. It shows the Z axis in action. I would love to do this sort of Z axis on a Prusa or ultimaker, a hollow tube, bowden extruder and a rack and pinion raising and lowering the z axis tube. Perhaps a nema 14 or smaller stepper for power. Plungerby martinprice2004 - Polar Machines, SCARA, Robot Arms
Just found this video on youtube. Parallel SCARA It has a nice over and under arm configuration and looks like it would make a nice reprapped design. I assume the Z axis is a vertical plunger type in the tool head. Has anyone done any work on this type of Z axis?by martinprice2004 - Polar Machines, SCARA, Robot Arms
I think step format would be nice as it preserves the assembly structure better and seems to be the new standard for higher end CAD systems. An upload in .step format to grabcad would certainly raise the profile of this printer. edit. I downloaded and installed 123D and now have a copy in .step format. It doesn't convert exactly, but there is sufficient to get me going. Thanksby martinprice2004 - General Mendel Topics
Has anyone got an assembly of this machine in something like step or iges format as I would love to modify my machine to an extruded frame?by martinprice2004 - General Mendel Topics
I am of the opposite view than has been expressed. 280 x 280 isn't that much larger than a standard prusa. If you are only modifying it in one direction the changes wouldn't be that significant. You could get the printer up and running and then have a look at the stiffness if thats an issue. There are some very simple mods you can do easily to bring the stiffness back to what it was. 1) Put M10by martinprice2004 - Reprappers
It seems like there are a few people here thinking along the same lines. My SCARA robot Z axis could easily be adapted to take your harmonic drives on the front, so I suggest you concentrate on getting the XY axes sorted and make sure it has a large working envelope. I have also considered modifying my design to a parallel arm, but using two geared motors rather than the harmonic drives you have.by martinprice2004 - Polar Machines, SCARA, Robot Arms
models / firmware uploaded. see link below HF08 robotby martinprice2004 - Robots!
I have just uploaded a video of the robot in action. Models, firmware etc. will be uploaded shortly. Helium Frog HF08 Hexapod Videoby martinprice2004 - Robots!
The robot is now complete. It took its first brief walk this weekend. Video to be uploaded this week.by martinprice2004 - Robots!
This is a very interesting development. I have been considering developing an extruder which adds filler to ABS filament in the extruder head. Ready made plastic filament just takes this one stage further, but does fix the plasic / filler ratio which means you won't be able to print parts with varying properties very easily. I think adding a non melting filler to ABS would potentially eliminateby martinprice2004 - General
Just to confirm You are not expecting my code to completely control a reprap machine. The code is to give you examples so you can write your own. It is just so you can see how the com ports are programmed in a C# program. If you just wan t plug and play solution, use pronterface. Its very good and works well. You need to have the same baud rate set on your host software as in the firmware otheby martinprice2004 - Developers
@arthurmani The program doesn't do any fancy error checking, so it won't check if the port is valid etc. It will say the port does not exist, or is denied. This could be because the port is bieng used by another program, you aren't running as administrator and dont have permission. You can double check the com ports by using the hyperterminal program. Usually found in the start button / progrby martinprice2004 - Developers
I am just writing a simple Visual C# 2010 program to send my own g codes to my hexapod robot. You should be able to crib all you need on how to send codes from it, including setting up the com port etc. There are a few pitfalls such as the firmware not recognising end of lines etc. My hexapod code is based on reprap firmware, so the program should be compatable. Just modify the buttons on the foby martinprice2004 - Developers
As suggested water may not be an option, but oil such as cooking oil etc might be worth a try. Cooking oil has a flash point of around 300 degrees c if I remember rightly, so having a hot bath at around 140 degrees you might be able to deposit PLA at 160 + without too much loss of heat or boiling of the liquid. It would also be good to stop warping if printing with ABS using a hotter bath, but yoby martinprice2004 - General
Excellent design. It looks like you may benefit from having the motors / harmonic drives spaced slightly further apart as this would improve stability a little and avoid the arm elbows inverting. How are the harmonic drives working out?by martinprice2004 - Polar Machines, SCARA, Robot Arms
I am always interested to hear Dr Bowyers' views on the whole open source debate as he is clearly a thoughtful man and has been at the whole Reprap thing longer than anyone! I read his reprap policy with interest as below. . I can understand that he doesn't want to persue licence infringements as lets face facts it would take up most of his valuable time, but I was curious to his main reasoninby martinprice2004 - General
I have always suspected Bre was a self centred megalomaniac. This just proves it. I have removed all my objects from thingiverse this evening and replaced them with a rather nice test cube.....power to the people!!! The next question is. where is the best place to host them. I read about something on Gary Hodgsons website?by martinprice2004 - General
Could be your stepper motor settings in firmware. Check the steps per revolution and also whether you stepper drivers support 8x microstepping or 16x. This is the most common reason why you get scaling problems.by martinprice2004 - Reprappers
I have been thinking of an extruder which prints ABS filament, but also drags in a surrounding powder into the mix. Plastics are often incorporated with a filler, such as glass powder, or graphite etc. either for strength,cheapness or colour. The reason I mention this here is that you could print the main part with a say 20% mix of the additive for a strong part, but print the support material wby martinprice2004 - Plastic Extruder Working Group
How about a crawling robot! Another one which is open source is the iCub. Its a little too sophisticated for reprap fabrication, but the designs might be worth having a look at. iCubby martinprice2004 - Robots!
Work continues on the Hexapod robot design. Two legs are assembled and have the firmware to a stage where the legs move on command for a linear gait. I want to check the firmware with two legs first. The Hexatronic HX5010 servos seem to be up to the job, the inner (Coxa) servos hunted a little, but this was solved by incorporating a friction joint which I can adjust using a nyloc nut from belowby martinprice2004 - Robots!
This is a good idea to have the home position off the bed. It enables you to purge the extruder if you want without it falling on the heated bed and it gives you the option of warming up the extruder off the heated bed surface at 0,0,0 There is an additonal benefit in that you can have a negative Z axis end stop below the Z height of the bed. You home slightly below the bed height to set the datby martinprice2004 - Huxley
You have a distinct advantage using rack and pinions in a delta robot. One of the problems with R & P is backlash, but in a delta this is helped by gravity assisting you because the racks are near vertical. I think that a delta with telescopic arms is a good idea. Perhaps you could use a pantograph setup or a sarrus linkage to avoid using linear rails.by martinprice2004 - Delta Machines
A rapid prototype machine which you have sitting on your desk is designed to enable you to try out off the wall designs that may or may not work. I suggest you try to build this device or at least one axis and do some trials. Even if it moves poorly but can be seen to work, this may inspire others to chip in more constructively with ways to improve what you have. Post the designs so others canby martinprice2004 - Developers
There are alternative ways to move the motor off the print head. Gary Hodgson was working on one here. It may overcome the hysteresis problems you could get. Off carriage extruderby martinprice2004 - Mechanics
I can see the averaging using several legs improves things. I wonder whether there is a plane horizontal configuration of say 4 servos in a line with multi links that would do a similar thing.by martinprice2004 - Robots!