The freight out of the USA to New Zealand is the stopper for me when purchasing items at 10kg+ its seriously expensive. My machine is manufactured out of all Chinese manufactured parts all except for my probe. So the accuracy is the same throughout - good enough for me. When I purchase out of China, the minimum consignment for LCL is 1m3 so what I do is run around 2-3, sometimes 4 suppliers. Get the supplier I am spending the most money with, to receive and consolidate everything into one freight consignment. Has worked a treat for a while now. Last time I bought a bunch of PLC tapping arms and sold them to pay for mine. Is a good system.
Think Big Tool Company. (I absolutely love the name) They are the suppliers I am talking too. The unit has a 1/60 gear ratio, with (quote) "the core transmission mechanism adopts a cam transmission mechanism with high precision, zero backlashes, and wear resistance" - looking at the drawing its a flash type of worm drive with bearings on all the drive surfaces?
When you guys are talking about nm (I am a foot lbs guy) are you discussing the chuck rotating during machining and how much torque it needs to withstand the machining forces? To be honest with such a geared down motor I did not even consider I would need to worry about torque with such a large mechanical advantage. Avoid the backlash further by running one direction only?
My other question was for you Craig, 150rpm is quite quick I would have thought, did you find you needed that for rapid positioning? So this unit I like is like I say 1/60 ratio. Anyone tell me I am wrong here thats why I am here. 1/60 ratio @ 1000rpm top speed for my Nema 34, is 16rpm. 16rpm on a 100mm part, with a circumference of 340mm would give a surface speed of 544mm/min - which is yes, quite a slow machining speed compared to 2400mm/min which is what I dial into a lot of programs.
But, if I was to bin the Nema 34 one day and put a 8000rpm servo on the unit I am looking at something considerably quicker - but that would be upgrade time.
Oh - another question for you guys, do you have a little hydraulic pump setup for your brake or is pneumatic the norm? Considerably different, I am thinking I might go for the oil I have a couple of little pumps in my shed off operating tables. Or am I better to stay with the air. When my machine is running my little 2200kw compressor is also running a lot. Perhaps the brake not needing air is a good thing too.
My plan has stuck. I am going to purchase one of the 170mm units for approx US$1350. Inside that purchase will be a couple of large HGR rails that will go on the machine to raise my gantry by 40mm to clear the unit. This will be a quick upgrade from the last SBR rails I have. You know what started this? I was looking for one of those cheap 4 post turrets to put on my little cnc lathe.... then started thinking what else would be nice. It never ends......