Demented My (very jealous) compliments on your progress, most excellent. Re control PC's Intel are turning out a board at (D201GLY2, sort of EPIA competitor) circaby aka47 - Mechanics
I think nophead has it pretty much summed up. A consequence of this to be considered is loading, particularly in stepper based systems which use optimistic positioning. Your design ideally needs to take into account the pull-in of your steppers (the ability of the stepper motor to move from standstill the number of steps you have instructed it to move without losing one or two along the way) anby aka47 - Mechanics
Having looked at the designs using the ball bearings I think any spherical or even hemispherical bits would do particularly the hemispherical type of bolt heads. Folk not wanting to go the PC board route could then wire the bolt's together using wire or crimp up ring terminals. A quick rummage around on t'internet threw up these folk:- They even seem to do a battery powered felt tip pen forby aka47 - General
That sounds cool. What is the curing time, is it long enough to ensure that the next layer to be printed would bond to the first ?? aka47by aka47 - Polymer Working Group
OK Dumb Ass question time. 3mm has been selected for the feed filament diameter. I have no real opinion either way on this but am quite curious as to how the choice of 3mm instead of something else say 5mm was arrived at??? Is there something artful and clever about 3mm or was it just a convenient figure ?? I's just gots ta know. aka47by aka47 - Plastic Extruder Working Group
Just had a look at your touch down tool length measuring thingy. I think that is pretty cool. I certainly like the idea of breaking the contact rather than waiting for a contact to make. A simple but very effective way to achieve the desired results and resolution. The links you provided and their onward links re probe heads were rather interesting too. I can see some mileage in a touch probeby aka47 - General
Hurro guys sorry to interrupt but you had such a great discussion going I couldn't resist X & Y isn't a problem as I read, most of you have hinted at. End stops can be used to resync whenever. Or as per an earlier discussion a center opto interrupter plate could be used to scale/sync and continually check for error. The Z axis is the problematic one. Particularly as Victor points out, at oby aka47 - General
Russian.. Wow thats revolutionary... Nearly as good as the Chinese space program.. aka47by aka47 - General
Jared I had a look at the link and think the technique has the potential for a lot of mileage. If I wanted to add carriage based feedback to a smaller carriage for an existing piece of kit I think I would be looking seriously at buying of the shelf calipers and adding in serial ports to my axis controller. (Bearing in mind the one that is on chip is already earmarked for interfacing to a motionby aka47 - Mechanics
Bob, good news excellent. I hadn't got any to test so am relieved. I will still need to use a bearing though because I intend to build up something for a test bed for the Servo Controller I am working on and this does use cheep DC Brushed motors. which have more end float than we want. nophead sir, a plumbing block incorrectly named because of too much rum is actually a plumber block aka pillowby aka47 - Mechanics
BTW I think Radial is at 90 degree to the shaft so is not what you need to be looking at for end float. Many manufacturers don't quote end float as the motor isn't intended to be used in this way particularly not budget models with plain bearings. aka47by aka47 - Mechanics
yes you can take the drive out of line. At the cost of increasing frictional losses and increasing the amount of backlash by adding in two more gears and the backlash between their mating teeth, you still need a bearing to support the lead screw because the motor isn't doing it anymore. Overall no gain and a more losses including precision. In drive trains the simple rule applies, the more iteby aka47 - Mechanics
Wow That is about the coolest thing I have seen this year. Obvious once you have seen it but taking a great deal of latteral thinking to get there. Hmmmmmm I like that. Perhaps a Dremmel Milling machine will do after all..... How many tools do you think would be the minimum to be able to make most things without changing tools mid run. So lets see may be :- 1 endmill/drill (to open up a hby aka47 - Let's design something! (I've got an idea ...)
As bob suggests backlash is common and a sprung nut on the lead screw is a common solution. However the issue I am describing would still be present if the nut on the lead screw were preloaded (like the z axis assembly on the Darwin this is spring preloaded, although arguably it doesn't need to be because gravity is a pre-load in itself). All motors are deigned to take a load that is perpendicuby aka47 - Mechanics
Endfloat I was messing about with a motor that was kicking about here and toying with the McWire repstrap lead screw idea but using M6 stud instead of M8 (M6= 1 turn per mm, M8 = 1.2mm per turn) Also because the motor end shaft was 6mm. Something I did notice is that the motor had a degree of endfloat that was greater then the required 0.1mm of precision I wanted from the mechanism. endfloat iby aka47 - Mechanics
Things that use solar insolation to combine CO2 and H20 exhausting Oxygen and making things from the carbon and hydrogen are extremely common they are called.......... plants >< We need though to be able to take plant matter and convert it into exhausts, bucky balls and carbon fiber That would be clever I wonder if the strength to weight ration of carbon fiber composites is such that wby aka47 - Let's design something! (I've got an idea ...)
Demented sir Those links are pretty cool. I am currently working (besides on the universal servo controller) on a Dremmel based manual milling machine that can be later pressed into service as a rep strap (when motorized up etc), using standard aluminum extrusion the 30 x 30 mm type with slots and accessories etc. I had a brain wave the other day as to how to cut any hole size you fancy usingby aka47 - Let's design something! (I've got an idea ...)
Triffid Thans for that I have added the link you provided into the bibliography section of the servo doc. cheers aka47by aka47 - Mechanics
I have been looking into using Chain as a backlash free Precision Rack and Pinion replacement. The most practical size appears to be 6mm pitch drive chain. The spec is well in excess of what we need. I think that it can be used thus:- Take a single length of chain for the Rack (Not a loop) secure at either end of the axis using a tensioner at one end. On the carriage plate use 3 Sprockets (Nby aka47 - Let's design something! (I've got an idea ...)
Things to print...... Given that we are looking at using Skate Bearings (608 Deep Groove Bearings, 22x7x8mm) I think there is possibly the demand for a range of printable accessories that can be used with these bearings ie :- An 8mm wide clip on tyre than would allow the bearings to be used as rollers in the 8mm slots of standard Aluminum Extrusions (Bosch Rexroth, Kanya, & DIY Store Channby aka47 - Let's design something! (I've got an idea ...)
I do try to be M$ free where ever possible, Some vendors tool sets though mandate a windows environment. Arrrgh MPLAB and Altera's IDE's being cases in point. Whilst their tool sets aren't great there ahead of the open source state of the art and relatively inexpensive/free. I am drawing near to the end of the Design Considerations Section of the Wiki docs. Any chance folk could have a rumby aka47 - Mechanics
Ian The compiler is the C18 from microchip (using their IDE) and the ICD (In circuit programmer/debuger) is also theirs too. I run this under a VMware XP machine on my Linux Workstation. Everything else here is almost exclusively Open Source. As I prefer to use the Flash programmable micros these days (saves the time waiting for Eprom program and UV erase when tweaking code, plus the multiple iby aka47 - Mechanics
Something I missed picking up on. Sorry Zach's question re running a 24v motor at 12v, there is no earthly reason why not if you are prepared to put up with half the power and how this translates into torque/speed. Given that the spec'd motors from MFA are roughly the same torque/speed for 12v and 24v models. Running the 24v at 12v would give you somewhat less torque/speed. If the Laser navigaby aka47 - Mechanics
I guess if it comes to a discussion of any Micro. What about dong away with a separate micro altogether and using a soft core in a PLD like the Xilinx IP Free offerings. Rather than implementing a lot of the control loop in software hard code it in Programmable logic. I guess if after all someone wants to take the design work etc and port it to another micro, fine. Incidentaly depending on whby aka47 - Mechanics
Zach The problem I have at the moment with using processors other than the PIC 18F's is that I have already invested in and am setup with the Programmer, ICD, Compiler etc that make development somewhat more straightforward. Don't worry though you will be able to run the controller as if it were a stepper motor driver IC but it will be driving a servo motor arrangement instead. This will ensureby aka47 - Mechanics
Hurro Zach The design that is currently floating about mostly in my head has the ability to accept inputs from two types of encoder. 1. An SPI interface that can talk to the Laser Navigation (mouse type) optical sensor. See the Wiki page bibliography for the Cypress Data Sheet. 2. A Logic Level Quadrature Interface. What you choose to make the quadrature stream is up to you. Magnetic (Maybe thby aka47 - Mechanics
OK First and most important, Happy new year etc guys. Second I have started work on the Universal Servo Controller as promised and will use this thread in the new Motors section :- To discuss the design etc as it unfolds. The doc which is the "where we keep where we have got to" can be found in the wiki at Third, many thanks to Zach for sorting out permissions etc so I could do this.by aka47 - Mechanics
OK First and most important, Happy new year etc guys. Second I have started work on the Universal Servo Controller as promised and will use this thread to discuss the design etc as it unfolds the doc can be found in the wiki at Third, many thanks to Zach for sorting out permissions etc so I could do this. We are currently working through the design and specification stages and will be progby aka47 - Mechanics
Looks like someone beat us to it in some ways and they are suggesting using pepakura too. They look to be folding up a chassis/case using ABS and home made ABS/Acetone Weld/Glue. Clever....by aka47 - Mechanics
A quick update (Just back from London visiting rellies) I picked up one of the MFA/COMO 12v motors without the extended shaft. Maplin stock them as well as most model shops. (940D with 100:1 planetary gear head) the motor itself has a sticker on it saying it is wound for 4.5 to 15 v dc so I wouldn't advise running it at 24v for long if at all........ Having clamped the output shaft into a viceby aka47 - Mechanics