Thanks Viktor this is just what I need. I did look through the forums, but its becoming so large that I missed this! Perhaps I should have take the hint from "Laser" in the title! I'll do a bit of reading up on the subject. Martinby martinprice2004 - Powder Printing and Selective Laser Sintering
I am looking to do some work on developing a laser sintering machine. I'm Ok on the mechanical side of things, but know very little about lasers. Can anyone help? I need know the following:- I want to use a laser diode (I want to buy one, not salvage one from a DVD) what specifications do I need to melt ABS powder. I would prefer a visible beam as I feel this is a safer option. I live in the UKby martinprice2004 - Powder Printing and Selective Laser Sintering
You can check if its a thermoplastic, just warm it through a candle and pull it whilst its warm. Dont burn it just soften it. Its a thermoplastic if it stretches nicely and when cool has the same properties as before, ie its flexible and looks the same. This can be used for rapid prototyping. Its a thermosetting if when you heat it it either doesn't stretch, just burns, or after cooling it lookby martinprice2004 - Polymer Working Group
My two pennyworth. The reason the industrial revolution happened in the first place was to improve efficiency. There are many arguments that the reprap will reduce energy requirements, but this is just plain wrong. Large manufacturing plants are extremely energy efficient compared to distributed manufacturing which is the main reason they exist. Imagine the energy requirements to make all the pby martinprice2004 - General
There are many videos on youtube for selective laser sintering, but I found this one particularly interesting for a few reasons. 1) The use of nylon powder is suggested. This is commercially available for powder coating. Some powder coatings use a nylon/epoxy mix which probably would be of little use, but others use "pure" nylon powder. 2) A heated chamber is used to hold the nylon just below tby martinprice2004 - Powder Printing and Selective Laser Sintering
Just a couple of comments and a few questions. Bulking out the resin sounds like a good idea, something like a powder filler mixed in with the resin might work. The resin would tend to be more self supporting whilst curing (a phenomenon discovered by the Romans in concrete!), so you may be able to produce usable parts even with the longer curing times you are experiencing. The only downside I caby martinprice2004 - Polymer Working Group
Spraying across a rotating drum is used in the ceramics industry. Fluid slurry is spray dried . It is basically spun across a disk shaped like a "china mans hat" and then falls in a drying atmosphere. The particles are perfectly round and of uniform size. Unfortunately the machine is usually housed in a six storey building! I think to get ABS to a low viscosity fluid may not be possible as it deby martinprice2004 - Powder Printing and Selective Laser Sintering
I have been looking into the problem of producing ABS powder a little further. It appears that industrial plastic powders are produced in a pulverizer. The most common form of this type of machine for plastic seems to use two rotating surfaces such as grinding wheels positioned a set distance apart. The grain size of the powder is set by the distance between the wheels. Rod or plastic shards areby martinprice2004 - Powder Printing and Selective Laser Sintering
Just tried to extrude some ABS wire at 220 degrees C onto playdough and although it didn't stick, it also didn't melt or soften any more like plasticine (English Clay). Playdough is wheat based, I wonder how it extrudes and sticks to itself.by martinprice2004 - General
I agree a support medium where plastic can adhere to would be an advantage, but is not always needed in many situations. For example in horizontal holes it would remove the need for pointed 60 degree tops by only providing support as there is already deposited plastic very close. It would also be useful for long horizontal bridges. With careful support design you could probably overcome even thoby martinprice2004 - General
I have had a look throught he forums and I cannot see anyone who has suggested using grease as a support material. Has this been tried? I can see that there are several reasons why this could be useful. Advantages:- 1) There are hundreds of types of varying viscosity and greases that can stand very high temperatures and have stable viscosity. 2) Grease is easily applied through a syringe extrudby martinprice2004 - General
I know a little C code. I hate coding an arduino as you have to do it in a text editor so there is no trace / debugging facilities. These problems are usually caused by incorrect variables settings either in a loop or other structure. Try explicitly declaring variables to zero or actual values before using them (including any boolean variables) if you haven't already done so. It may be that theby martinprice2004 - Controllers
I have just bought an arduino mega and am looking to use it to control a reprap. I'm looking for details on modified firmware and setups for controlling 3 steppers and a DC motor extruder and temperature control. Are there any blogs out there with further details of someone that has done this? I would also really like to eliminate the extruder driver board and run this directly from the mega. Aby martinprice2004 - Controllers
Is it just me or are these suggestions becoming progressively more dangerous! I was hoping to make my fortune by coming up with a new rapid prototype method to replace conventional manufacturing, but I have now abandoned that idea. I'm going to put all my money in hostpitals specialising in eye surgery, cancer or the treatment of burns. (I'm only joking....these ideas are really great....)by martinprice2004 - Powder Printing and Selective Laser Sintering
Viktor Yes I see your point, plastic is not a hard material and responds differently to ball milling. The water slurry should stop it melting however. I do know if you examine sand on many beaches in the world a portion of it is plastic dust mixed with sand, so this gives me the thought that it might work. Heres an article about the environmental problem of plastic in sand. Nat Geographicby martinprice2004 - Powder Printing and Selective Laser Sintering
There seems to be some discussion as to the best method of making plastic powder, ie by using a sander etc. I used to work in an industry and they used to make ceramic powder by using grinding balls in a rotating drum. The raw material would be mixed in a slurry and put in what was effectively a big washing machine with large marbles in it. After a few hours rotating the slurry would be air driby martinprice2004 - Powder Printing and Selective Laser Sintering