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My own cnc is walking!

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Finally, after months of slow building, and careful inserition of costly components (L297s and L298s go for as high as 14

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Very intresting project!but I'm wondering: what are you going to use that 4th axis for? Tilting :(

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>Very intresting project!>but I'm wondering: what are you going to use that 4th axis>for? Tilting :(Can be useful for example to turn pieces you're working.Numerically controlled lathes are also called indexed lathes.In a normal lathe the piece is always rotating, thus makeing standard linear operation impossible.Indexed lathes are able to keep the piece fixed and/or rotate it of a precise number of degrees.It is this way that romboidal forms on wood/glass columns are made.

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Hi ClaudioI'm also working on a small CNC, mostly for NC-drilling of PCBs.Mine will be smaller and simpler, built from MDF, not metal.I get my L297/L298's from reichelt.de where they are under 4EUR per piece. (No, I don't work there, but they just got great prices).Today I got my two first linear slides I bought on ebay. They are also from IGUS.What is the size of the PCB in your first picture ?It looks awfully big. Is that just an illusion or is it actually larger than a euro size board (100x160mm) ?Manuel

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I tried ebay too, but when i looked there were only THK/STK recirculating balls bearings.Admittedly not that costly (especially compared to the price of new), they where always cheap, but they where always in USA and trans-oceanic shipping for something 1m long and weighing 5kg or more... well space travel is cheaper!>What is the size of the PCB in your first picture ?>It looks awfully big. Is that just an illusion or is it>actually larger than a euro size board (100x160mm) ?About 280x180mm...It actually IS awfully big :DAnd since it is industrial made (meaning the person who developed it had it printed from an industrial manufacturer), it would have been very costly if made in double layer.So it has something like 100 bridges! :-eekYeah, i really hand-made 100 bridges!If i think of that, my wrists still ache :)

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>About 280x180mm...>It actually IS awfully big :D>And since it is industrial made (meaning the person who>developed it had it printed from an industrial manufacturer),>it would have been very costly if made in double layer.At some places, double sided boards don't cost much more than single sided ones. (Sometimes its even the same price)>So it has something like 100 bridges! :-eek>Yeah, i really hand-made 100 bridges!>If i think of that, my wrists still ache :)Wow. 100 bridges ... Reminds me of my dual keymatrix boards, 2x 64 diodes. And my hands were aching after those as well :)Manuel

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>Check out www.korry.com: http://www.korry.com/products/knobs/>for example - they have measurements and 3-way drawings..Gaaaahahhahhahah (Homer style)I don't even want to know how much is one of those...I bet more then i can afford for a single knob...But the time will come i will have something like that!

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Hi Claudio,Couple of questions.Are you using unipolar or bipolar stepper motors.Where did you get the plans diagrams pcb drawings for the controller?I want to use bipolar as I have read that they are a little higher in holding torque.Do you know of any DIY 3 axis bipolar controllers which have Pause and home inputs that I can make myself?David

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>Are you using unipolar or bipolar stepper motors.Hybrid, they are 6 poles motors, can be used both unipolar and bipolar.The controller uses them in bipolar mode.>Where did you get the plans diagrams pcb drawings for the>controller?On an italian forum, there you could get a complete 3ax controller fully tested for 190

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Is your controller double sided or single sided?Yes, I would appreciate you asking about the plans.I have one good plan but it's for 3 axis controller for unipolar steppers, which if I understand correctly, are not as good as bipolar.Where can I get more information on hybrid steppers?

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>Is your controller double sided or single sided?Single, that's why there are 100 bridges.>Yes, I would appreciate you asking about the plans.He usually connects in the evening, so i will let you know.>I have one good plan but it's for 3 axis controller for>unipolar steppers, which if I understand correctly, are not as>good as bipolar.Yes, bipolar do have more torque but not that much more.>Where can I get more information on hybrid steppers?Sincerely i don't know.But i think i have understood this:pure unipolar have 8 contacts, 4 single coils 2 poles eachbipolar have 4 contacts, 2 coils 2 poles eachhybrid have 6 contacts, 2 coils 2 poles each with center tap for each coilUsually unipolar are also convertible in bipolar by connecting together two leads from two coils, thus makeing something like an hybrid, with a center tap made of the union of the two leads.But then there is also something regarding how the motor is really constructed, which affects working in this or that mode.Some may work, some may not.I am unable to provide details on this i am afraid :(

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>Is your controller double sided or single sided?>>Yes, I would appreciate you asking about the plans.>>I have one good plan but it's for 3 axis controller for>unipolar steppers, which if I understand correctly, are not as>good as bipolar.>>Where can I get more information on hybrid steppers?All(?) unipolar motors can be run as bipolar. They have a bit more torque in bipolar drive.The only difference between bipolar-only motors and unipolar ones are the center taps on one or both of the motor coils.A good resource on stepper motors is "Jones on Stepping Motors" http://www.cs.uiowa.edu/~jones/step/A unipolar driver is easier to design and build. you just need 4 transistors per motor, while the bipolar one requires 8 of them arranged as H-bridges. In an H-bridge you need to make sure that you don't turn on the wrong transistor pair as it would short the supply voltage to ground. Such problems don't exist in a unipolar driver.Manuel

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