I spent a little time fucking around (pun intended) with the new machine. I got a 5/16″ ID 32 tooth timing pulley with the minimal number of teeth. It is the perfect match to the rest of the machine. Speed, power, acceleration are more than i could hope for in a small machine. This machine will satisfy all but those who need a telephone pole rammed up their holes at 60 MPH. There is no slipping because of the timing belt and the torque is amazing with the little (physically, not power) motor. I am also amazed at how well the little switching power supply works with the rest of the components. This greatly simplifies the design and reduces the cost.
I don’t know why it works so well with these minimal components, just some sort of lucky match, maybe.
I still need to do some real testing to make sure it performs as well in the real world as it seems to in the virtual. Once i do some hole fucking testing i will give it the good fucking seal of approval. Once this is granted, there is no reason to not build one of these machines. Low cost, low weight, high power, speed and acceleration. No slipping. No dithering.
As soon as i give it the real test, i will start working on a parts list and some construction details. I will probably just take some pictures and write a brief guide to construction. Most of the parts are stock so there is a lot less cutting etc to do.
My only concern, at this point is how durable the light weight components might be. They are so inexpensive that if parts do need to be replaced occasionally it should not be a big deal especially considering that they all screw together easily.
There is one other minor concern. The NEMA 24 motor has an 8 mm shaft and the perfect pulley has a 5/16″ bore. That means that you have to increase the pulley bore by about .0024″ or reduce the shaft diameter by the same amount. An 8mm drill bit adds a little to the cost and ideally the hole would be drilled in a lathe. The other option is to use a NEMA 23 motor with a .25″ shaft but i really like the bigger shaft of the NEMA 24. Not a size queen, just an engineer who likes to over-design a little.
It depends on which side of the Atlantic you are, in Europe the 8mm bore pulleys are common !
I would not have thought that 24v was be enough, it is cheaper but also better looking than a transformer or dc/dc converter in a metallic enclosure.
I am thinking of an even simpler version with the aluminium profile moving, like this:
http://www.openbuilds.com/builds/v-slot%E2%84%A2-belt-pinion-example-build.97/
A 3mm pitch 6mm wide belt should be strong enough for the needed torque with a 44 or 50 teeth pulley if I believe this document
http://www.sdp-si.com/D265/PDF/D265T146.pdf page 10
i am not sure i can see all the details of the rail belt system but it looks like the motor is on the carriage which would add a lot o f mass that needs to be accelerated.
No the motor is fix, it is like the version with the urethane roller.
The aluminium profile can be a 20x20mm and one end threaded to screw attachments.
i forgot to answer about the power supply. 24 volts is quite low but works well with the gecko and this particular NEMA 24 motor. i was surprised at how well it works. since i am using a cheap DD/DC converter from the main ps to power the shagmatic and other 5 volt stuff i can not go over 40 volts. i can not find a 36 volt inline supply, 48 volts yes, but that would require a more expensive DC/DC converter. would be good to find a source for 5 amp 36 volt supplies.
36V 9.7A Power Supply
http://tinyurl.com/hss22us
LOTS of 36V supplies in many Amp ratings…
http://tinyurl.com/h9fzw66
looking for an inline type. nt a problem finding closed switchers but like the idea of a notebook computer type. notebooks use 19 to 21 volts and these work really badly. 24 volts seems to be the minimum. probably makes sense to just use a 48 volt and find a reasonably priced DC/DC converter. there is a high voltage three terminal regulator that i have used but i did not like the way they worked. they got hot and were not terribly reliable. using a high voltage one followed by a 5 volt reg might work better.
just looked on digikey and there are a number of not very expensive DC/DC regulators in the $14 to $35 range. i will add one to my cart and eventually get and test it.