Hi, > Nice picture, ouch it's 1.4Mb though... > You seem to be getting some sag in the > middle of the gantry, you could add a cross > brace or box section to the gantry and > one supported rail would be a big improvement > compared to the 2 unsupported rails. :o) I do not thing it makes a difference for the kind of weight it is carrying. The rails are oversized and remember that you do not have drag as in a mill. > it has good power, high speed and 1/28th mm > resolution is fine for 0805 SMD stuff. How about the repeatability and backslash ? Those are the problems I have seem on the printer mechanisms I used. The printing head support was too loose without the belts being too tight. I had to put another support on the mechanism to tighten the belt well enough. On the printers I used you had a preset compensation for the backslash. If you go the printer way try to modify it as little as possible. I used just the parts and made all the mechanics again. Do you need just one machine ? I plan to have a solution that can scale up with my production. That is another reason to go for comercial new parts. > Yep, oven was my first idea. I'm currently doing > solder paste by hand, and toaster oven. But, after > some tests it is a LOT slower than glue and dip > technique. Modern VCRs are made this way, they use > a heatproof red glue spot, pick and place SMD, then > wave or dip solder the board. Soldering takes about > 4 seconds, even with my crude test attempts. That's > much faster and easier than in a toaster oven. > You don't need paste, which is expensive and goes > off, and it's easier to build a glue applicator > than a paste one as glue flows better. Loctite has some nice solutions in that area and you can even use 454 gel cyanoacrilate !! It works great !! The only problem is that you need a good dispenser for it. Dispensing paste is not that critical, specially if you use water at the end of the system. Water does not compress so it is easier to control the time and pressure as the syringe goes down. You just have to control the time and pressure and it is quite repeatable. Wave solder is ok if you glue and have a very controlled fluxing and cleaning of the board but I would never trust dipping a critical board ! You will stress every component over their specs ! It is ok for toys and low cost consumer products that do not have to work for too long or for the twainese manufacturers that never see the end customer. Keeping the solder clean is also a big problem and you will probably get a big number of bad joints whenever the operator changes mood ! There are inexpensive wave soldering machines around, there are small ones for short run productions. There are also fast ovens but they are surely not inexpensive. > I'm really interested in what your doing, but if > i'm going to build from scratch I still think glue > and dip is going to be better. If the production is too big I would go for the comercial machinery or let a factory do it for you. It may not be worth the risc. My production levels do not allow sending them out and I cannot handle it without some automation, that is the reason I went to the house made solution. It is dependable and repeatable but not too fast or energy efficient. You could try making a 3 or 5 zone oven. All you would need are some pizza oven conveyors, some infrared heaters and temperature controllers. The problems is that a 3 zone oven gives much worse results the a well controlled toaster oven !!! I tried that and the oven manufacturer got really dissapointed. If you really decide to go to the dip solution make sure you can get a hold of some xray inspection equipament to really see how the solder joints are. It can be very dangerous to put some thousands of boards out and find out that 10% of the joints fail in 2 years !! It may happen and actually has happened many times with trough hole components. I am sure you have already got some of your TV's with boards full of cold solder joints. Solder paste and oven is the most reliable way to do it, not the fastest or the cheapest. > I have a suggestion here. Get the parts loose, > not on rolls. Sprinkle them on a white tray, > then use a cheap video camera into the PC and > just get the picker to identify the part > orientation and pick it up. You only need a video > still capture board, a cheap mono one, some > VERY easy image reconition stuff which you can > get off the net from the robot soccer guys. Hey, that is a really cool idea ! The main problem would be to correlate the real position of the components to the distorted camera view and to solve the problem of refilling the trays and making sure that you do not have one component over the other or on the back side when using SOT23 transistors ! It is pretty hard to get the components out of the rolls and not flip half of them on their back side. I am really not sure what would be easier, a roll feeding system or the camera. > I think you could use a mechanical tweezer and > rotary head, just sprinkle the parts and let it > do the rest. Believe me on this one :-) It is easier with the vaccum tweezer. You just turn the vaccum on and them rotate the component to whatever position you need. With the mechanical tweezer you have to get the right force and will have to rotate the head 2 times to get the job done. The first time to grab the component and the second to put it at the right orientation at the board. > Gluing parts holds then very secure > if the board goes through other processes before > soldering, like having some larger parts added > to the board by hand. Gluing is ok but if you go for the oven it is another step. By my experience it is completely unecessary for small parts or parts that go on the top side of the board. > Gluing is also safer for > double sided boards?? I also thought that way and got glue from loctite for the components on the bottom of the board. I still have the glue on the fridge and never used it after the first day ! The only components that insist on falling once in a while are the AVX surge supressors. They are pretty dense and fall once in a while. If you get the right solder paste the surface tension is more than enough to hold the components on the bottom side. > So do you have any pictures of the "old ugly" > unit you are actually using now? I would love to > see it. :o) Unfortunately I have not taken any pictures and I got a small pneumonia ( is that the right spelling ) and the doctor made me promise I would stay put at home :-( It is not being used at all ! It did not get to be good enough and I decided to make another one before using it with components. It can draw nice rectangles and squares but I have not finished the pick and place part of the software. Is is an very ugly plotter with very bad resolution :-) I will take some pictures as soon as the doctor let's me get out of home... I will send them to you privately.. best regards, Alexandre Guimaraes -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.